Studies in the Application of Extraction Methods to Analytical Chemistry. Jack Kenneth Carlton Louisiana State University and Agricultural & Mechanical College

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1950 Studies in the Application of Extraction Methods to Analytical Chemistry. Jack Kenneth Carlton Louisiana State University and Agricultural & Mechanical College

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«m O A I- 0imi.3TRY

A Dissertation

Submitted to the Grad.us.te Faculty o f the Louisiana State University and Agricultural and I'eohanieal College in partial fulfillment of the requirements for the degree of Doctor of Philosophy

The Department of Chemistry

by Jack Kenneth Carlton B.3,# Centenary College, I9^2 !i*%, Louisiana State University, 1949 June, 1951 UMI Number: DP69352

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Unpublished theses submitted for the master^ and doctor*s degrees and deposited in the Louisiana State University Library are available for inspection* Use of any thesis is limited by the rights of the author* Bibliographical references may be noted, but passages may not be copied unless the author has given permission.

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LOUISIAMl STATE UNIVERSITY LIBRARY AOimowL^Dam’W

13*o author wishes to express his sincere appreciation to Hr*

Philip W. West for his advice and assistance as director of this research*

Ho is very grateful to Or. J* L* !£., Erickson, Dr* Max Goodrich and Dr-. Gunther Siohorn for th eir helpful suggestions in the prepar ation of this manuscript*

So wishes to acknowledge the financial Sid provided by the

Office of Naval Research.

Ho also wishes to acknowledge the encouragement of his w ife,

Mary 3&len9 to whom he la especially grateful for typing the dissertation*

He would Ilk© to take this opportunity to express his deepest appreciation to hia mother, Mrs* J* K. Oarlton, for her help and inspiration. table of ©ohtmps

CHAPTER PAOS

X * Introduction X

II* An Experimental Survey of the Extractiono f

Metallic Complexes with Organic Solvents 7

Experimental 8

Discussion of Results and Conclusions 12

Bibliography 26

XIX, The Extraction of head Iodide with Methyl

Isopropyl Ketone ^2

IV, Specific Spot Test for Gold IMploying

Par&roa&ni lino Hydrochloride y*>

V, Extraction Pi pot for Spot Teat Analysis *>4

VI, Summary ?5

V II, V ita ?6

i l l U3T OF TABLES

$A8&E PACE

X. Solvents Uaed in the Extraction itudy 15 IX* Conditioning Agents Used in the Extraction Study 16

XXX. Metal Ions Included in the Extraction Study 11

IV. Extractions Bnploying Potassium Iodide as

Conditioning Agent

V. Extractions Sftploying Assnonium Thlooyanate

ae Conditioning Agent m vx. Extractions HJaploying Hydrochloric Acid as

Conditioning Agent 23

VII. Extractions Employing pyridine as Condition

in g Agent 25

iv ABSTRACT?

A Bystem&tio investigation has boon mads of the extraction, of metal l i c s a lts and complex®© by organic solvents* The conditioning agents employed in this survey included athylonedi a nine, ©thylcnodiaminet©tra&c©tia s o ld , rcanr&tol, hydrochloric acid, potassium iodid©, ammonium thiecyamt®, p y rid in s, perchloric acid, a c etic acid and malonio acid* Th© solvents used were n-butyl chloride, petroleum ether, benaene, n~arnyl alcohol, chloro form, methyl isopropylkotano, isopropyl ether, butyraldehyd©, carbon tetra c h lo rid e and e th y l ao etate* .Methyl iso p ro p y l koton© and butyr&ldehyd© were found to be vory good solvents for the extraction of metallic complexes.

Only those solvents used which contained oxygen were found to extract the complexes included in this study* Several extract!one war© discovered which hold promise for application in qualitative and quantitative analysis*

The extraction of load iodide with methyl isopropyl fcoton© has boon thoroughly investigated as a part of those studio©* It has boon found that when lead solutions are treated with a large excess of potassium iodide and adjusted to the proper acidity, lead iodide can bo extracted with methyl isopropyl ketone * The extraction performed in this manner was 91% complete in a single pace* Interferences wore kept at a minimum through the use of a preliminary extraction which was applied after treat ing the aqueous solution with ammonium tin.ocyanato and hydrochloric acid.

Hie perarosanilino hydrochloride teat for gold was rendered specific for that metal by extracting an acidic aqueous solution of auric chloride with ethyl acetate* In this manner, gold was separated from the platinum metals, a group which constituted tho principal intorfaranc© in the

v detection of gold* After the separation of phases the organ!o layer was evaporated* taken up with a few drops of water and applied to the reagent on Spot test paper* The teat was found to be sensitive to [3 ge^maa of gold*

A device was needed for the rapid extr&otlon of small volumes of aqueous solutions with only a few drops of organic solvent. An extraction pi pet was designed and prepared and hao carved quit© well in this capacity. nrrRODUOTXon

The use o f e x tra c t!o n techniques as a moans of e ffe c tin g a n a ly tic a l separations has for many years provided the chemist with a very useful tool, and especially in recent years have these techniques become general ly popular* The increased interest in this field can be attributed in part to the appearance of a considerable number of extraction devices, suchm the countercurrent extractors discussed annually In the review articles o f O rsig (6 , 7 , 8 ) f and the development of numerous colorimetric proced ures based on the extraction of organic-metallic complexes15 (, 35# 24,

27, 52)* The extraction of inorganic complexes also holds many interest ing possibilities, and the applications of those extractions to analytical separations, as well as to colorimetric procedures, are to be found throughout the literature. It is with the extraction of inorganic complexes that this investigation is primarily concerned.

Before embarking upon a discussion of the experimental work and the results of this investigation It night be well to discuss the various classes of extractions and tho uses to which they have been put*

Generally, extractions can be classified according to the follow ing categories* liquid-liquid, liquid-solid, 11quid -gas and s o lid -gas* Be cause this study was Gonflnod to liq u id -11quid systems only brief mention w ill be mado of tho other claosiflcntions.

Probably the most familiar type of liquid-liquid extraction being employed In analytical chemistry is tin t in whioh a particular component of an aqueous mixture is extracted into an organic solvent with tho form ation of a highly colored organic phase which la then readily adapted to

(« (2)

ft photometric analysis. In auoh ft iaann®r cobalt can bo rioter mined, after treating I t with a.mmonium thiooyanata and extracting it with arsyl alcohol

(18, 19, 38)* the blu© color of the thlooyanatc complex is sufficiently intense to provide an excellent means of do to raining cobalt colorimetric** ally. Similarly, iron can be extracted as the thiooyanato complex by a

mixture of amyl alcohol and ethyl ether55 (> 55) I th e blood red co lo r of the organic phase ie then measured photometrically after the separation o f phases, The tMooy&nate o f molybdenum can be e x tra c te d by normal butyl acetate with the formation of& redd!sh-brovm color* A colorimetric do* torrid.nation of molybdenum based on this extraction has boon reported by

James (15)* Oolorimotrio procedures have been developed for the dotorn&n- ation of bismuth, both as the thioeyanato complex5 ^) ( and as the iodide complex (12), In the former procedure amyl alcohol was employed as solvent, and in the latter a 5*1 mixture of amyl alcohol and ethyl acetatew m used.

One of the more outstanding examples of the use of extraction techniques in colorimetric procedures is the determination of chromium by extract* ing the blue per chromic acid and Treasuring the intensity of the blue extract.

Amyl acetate has been used in a procedure reported by Bishop and Dwyer (1)•

There are two principal advantages of employing an extraction procedure in colorimetric analyses. First, in many oases tho desired component la separated from 'color masking or reaction maoking interferences5 and second, small amounts of material can bo easily concentrated from relatively dilute solutions, dxcept for the oilmlnation of color masking interferences, the advantages listed above are manifest in all procedures employing extraction techniques, The second group is comprised of extractions whloh can bo utilised also to isolate a desired component without depending upon tho develop** mont of a color* tho importance of suoh a general separation technique

Is becoming increasingly apparent, and by employing ©xtr&otlon in con** junction with complex! ng agents many of the qualitative and quantitative analysas ©f metallic* ions could bo greatly improved with regard to sen sitivity* ^any of the metal chlorides are extraetable from hydrochloric

©old solution using diethyl ether (25)* It has been reported that ferric chloride is extract&d better and over wider ranges of concentration when isopropyl ether is used as solvent(9) * Uranium and thorium nitrates have been extracted by ethyl ether (22)* Sine is extracted by ethyl other as the thioc yam te in the dithisone detection of aims reported by Vanes si

( 56) * Mercury can bo determined gravimotrioally after extraction of the iodide by ethyl ether (1?) * The extract is evaporated and the mercury weighed as mercuric iodide* Thallium la separated from lead, silver and bismuth by extracting the bromide with butyl acetate (20) * Sold can be separated from the platinum mo tain-hy extracting the chloride into ethyl acetate (16). Peatcvalent antimony may b® separated from trival out anti mony by extracting a hydrochloric acid solution of thon© ions with isopropyl ether (10). "antavalent antimony is extracted almost 100$ while trivalent antimony is less than 2% extracted.

A third group which involves two i real sol bl© 11 quids, but whloh dooe not represent true extraction, lo one in which a precipitate is formed and is gathered at the interface when an organic solvent la shaken with the aqueous solution, Examples of tho use of ouoh methods are found both w

i a q u a lita tiv e and q u a n tita tiv e a n a ly s is . Ammoniaoal so lu tio n s o f z in c » when

treated with reaoroinal, produce a blue precipitate. Th© detection of aino

in low ©oneentrationo is facilitated by shaking the aqueous solution with

ether, which causes the precipitnt© to ©ottl® at the interface (2fj), Mercury

is detected by the violet precipitate produced on the addition of cryogenius

s e n s itiv ity I s in creased when benaen© ia added and the p r e c ip ita te i s c o lle c t

ed at the interface (2), Nickel ia detected as the dimethylglyoxim© complex

with oaxisHim sensitivity whan the aqueous solution of the precipitate is

shaken with carbon tetrachloride, thus collecting the precipitate at the Inter

face (14). Silver and chloride determinations by the Volhard. method may employ

benzene as a collecting agent to prevent the Interference of th© silver chloride

precipitate in detecting the end point of the titration (5 ) . In tho iodometric

determ!nation of selenium, benssono is added to gather the reduced selenium at

the interface to prevent its interference in the perception of the end point

of the titration (^1) •

The extraction of a particular component from a colid mixture by an or

ganic solvent provides a method of separation which in many cases is quite

selective. Generally, the techniques involved are time consuming, requiring

the conversion, of the desired constituent into the salt fora in which it is

extracted. In apit© of this limitation, solid-liquid extractions offer a

means of separating some ions whloh aro difficult to separate by othor means*

Lithium can be aeparetcd from sodium and potassium by extraction of tho anhy

drous chlorides with arayl alcohol (21). The alkali and alkaline earth bromides

can be separated into two groups by extracting tho dry residue of thect© salts with amyl alcohol (4). Lithium, calcium, strontium and magnesium comprise

one group while the other members constitute the other group. Lithium stearate 0) o*n be determined tur bidimetrioa 11 y due to its Insolubility in amyl alcohol, in which the other alkali metals are soluble (^6)# Miller and Tr&ves (21)

report the separation o f calcium and sodium from potassium by the extraction

o f th e ir perchlorates by amyl a lcoh ol, potassium perchlorate being insoluble

in the a lco h o l. Aluminum nitrate con be separated from beryllium nitrate

by extracting the solid mixture of these salts with amyl alco h o l. Beryllium

nitrate is soluble in th is solvent, whereas aluminum nitrate is not (5) •

The extraction of a particular component of a gaseous mixture by passing

the mixture over a solid adsorbent i s a familiar laboratory practice which

exemplifies the solid-gas type of extraction# The uses of calcium chloride

and as sari ts in adsorption trains to remove water vapor and carbon dioxide,

respectively, are good exasaplaa of the eolld-*gas extraction system 29 ( ).

The analysis of gaseous mixtures by means o f the Great apparatus (*P) provides the best example of the liquid-gas extraction system. An alkaline

pyrogalloi solutioni s used to extract the oxygen from a gaseous mixture of known volume, and potassium hydroxide solution is employed to extract carbon dioxide from tho m ixture. Oar bon monoxide is extracted by moans of a solu tion of cuprous chloride#

From tho preceding paragraphs tho importance and usefulness of extraction techniques in analytical separations con roadily bo seen. Th® study reported in the following pages is the result of a systematic investigation which was mad© in an effort to obtain information regarding tho efficiency of com® of the solvents which have not boon extensively employed In extraction procedures, and to discover, if possible, some extractablo inorganic and organic salts of complexes which mlght find use In analytical determination©* The solvents (

included in the systematic study were chosen to represent as many classes of organic oompeunds as possible and also to include at least one member of four classes ©f solvents proposed by T3well, Harrison and Berg (11). Thee© four classifications &r© based on th© tendency of the solvent to form hydrogen bonds with the material extracted and consist of the hydrogen donor type solvent, th© hydrogen acceptor type solvent, th© hydrogen accaptor-donor type solvent and th© solvents which do not enter into hydrogen bond formation.

Th© conditioning agents were selected to include a large group of the ions ©osssonly employed as complex formers* Obviously, some lim it had to be imposed on th© number of both conditioning agent® and solvents used in tho study* Originally, ten solvents and nine conditioning agents wer© decided upon but as th© study progressed it developed that th© extraction of some othor complexes might prove interesting. 3o i t was th a t upon th© com pletiono f th© original survey pyridine was added to the list of conditioning agents*

Immediately following th© report of the extraction study appears a de s c rip tio n o f th© experim ents performed in th© in v e stig a tio n o f one o f th® system© resulting from th© original study, th© extraction of load iodide by methyl isopropyl ketone. This investigation I© presented in the form in which it was submitted for publication*

Reprints of two published works appear as the final portion of this dissertation* Both paper a ar© concerned with th® application of extraction methods to analytical chemistry * It was th© neatness and rapidity of th© ex traction procedure used in th© isolation of gold which prompted tho systematic investigation of the extraction of metallic complexes by organic sol von to. An Sxpfwriaamtia Survey « f til# Hlstr&ction

«£ M etallic Ocsaplexe# with Organic Solvents

(7) SXF*mHmTTAL

Tli® organic solvents employed in th© extraction study are listed ia fable I# Th® solvents were limited to those which did not tend to form emulsions and which wore at most only partially miacibl© with water* In addition, the lowest boiling Immiscible, oar partially sNfcu*

Bible, member o f a ©lass was selected in order to facilitate evaporation when th is technique was req u ired before te s tin g fo r th© presence o f th© extracted complex.

Ohloroferm represents the hydrogen doner type solvent mentioned earlier, methyl isopropyl ketone th® hydrogen acceptor typ®, buiyralde- hyd© th e aaeeptor-donor type and bona ana the typ® of solvent which does not eater in to hydrogen bond form ation. Benson®, chloroform , carbon tetrachloride and ethyl acetate were available as reagent grade chemicals.

Methyl isopropyl ketone, isopropyl ether, n-arayl alcohol, n<-bwiyl chloride and butyrallehyde were redistilled.

As stated previously, th® conditioning agents wore chosen on the b a s is o f their ability to form complex lone and molecule®, A H at of these complex fo rm ® ra is found in Table I I , Tthylcm®'Ii a ,vdno, ®thy1 onediamin ® - tetraacetio acid, perohloric add, hydrochloric acid, pyridine and acetic a c id wore wed without dilution while rmrmitol, malonio acid, potassium io d id e and avnonium hhiooyonat© wore uaod a® saturated solutions, Th© orl giual intent of the investigation was to us® each conditioning agent and each solvent with all of tho common metal ions available in tho labora tory. This would amount to on® hundred extractions with each >netai ion, and since thirty-on© m e ta l Ions wore included in the survey, the total

(8) (9)

msaber of extractions attempted ran to thirty-on© hundred* To have per

formed the©© extractions on a macro scale employing conventional equipment

and technique a would have meant th© use of quite largo volumes of solvent

as w ell as considerable loss o f time in making separations and evapor

ation s when these were required. In order to avoid this loss of time ond

so lv en t an extraction pi pet was used which hod previously boon designed

for the separation of minute amounts of gold from th© platinum metals in

a spot test for gold reported by West and Carlton (57)* Using this pipat

only 10-15 drops o f solvent war© required in oaoh extraction, separations

were effected rapidly, and when evaporations wore necessary, a gentle

blowing upon tho surface of tho solvent quickly accomplished this in moat

eaco s.

Because only a single ion was extracted in each o&s©, v©ry simple

tests could be used in detecting the presence of the motel ion after

extraction and separation o f phases. If tho organic phase was colored,

two blanks were e tractod for comparison! one contained only tho metal

ion and the other only tho conditioning agent. In this way it vma pos

sible to determine whether tho solvent reacted with tho conditioning

agent to produce a colored organic layer, or the metal ion was extract-

able directly, without conditioning. This latter possibility became

m anifest in some oaaos in which it was nooeo?.a:"/ to prepare tho motal loti in acidic solution. Ordinarily, the aqueous phase was tea tod with tho

reagent and compared with a control containing the sans amount of metal

ion which was present in the aqueous phase before extraction. In tho (10)

eases in whloh extra©ti on was suspaoted, but tho organic layer was un** aolored, the organic phase was evaporated and bested* or extracted with on aqueous solution of the reagent* In this manner a double chock was obtained on the extraction and an eotimata was then rando on the degree to which the matal salt or complex was extracted, Thee© extractions were classified as partial extraction (lees than *50/5) * good extraction 50 ( $ -

90^) and excellent extract!on (greater than90 %)*

The metal lone which wore included in the extraction survey are listed in fable III* along with the test or teats used in thoir detection after extraction and separation of phases. The metal ions wore prepared as 15> solutions. Tho procedure employed in the extraction survey was as foil owe; in a clean 5 ndllilitor booker 2 drops of the conditioning agent and 2 drops of th© tost solution were mixed* To this was added

10-15 drops of solvent and the two layers wore 'mixed thoroughly in an ex tract! on pipot. In th© event any color developed in the organic lavor, a blank containing 2 drops of th© metal ion and another blank containing

2 drops of th© conditioning agent were extracted. Tho colors resulting from the last two extractions were compared with that of the flrat* If no color developed on the extraction of tho conditioned metal ion oaoh p h a .e e was passed into a as par a. to 5 ml. H i lite r beaker and tho reagent was added to the booker containing the aqueous phaao, Tho resulting color, or precipitate, was compared with that obtained by adding tho reagent to a solution containing th© amount of itseial Ion known to l?p pres ©nil in tho aqueous pha.ee before extraction. If extraction was suopootod, the organic phase was extracted with an aqueous solution of a owitabl© reagent* In (11)

seas® Instances thor© was reason to believe that a complex was extracted

fey tho organic solvent which was more stable than tho compound possible

between th© reagent and the metal ion. In those oasas th© organic phase was evaporated, taken up with 2 drops of concentrated nitric acid and

evaporated again. After diluting with a few drops of water tho reagent was added and th® reaction observed. An estimation of the degree of ex*

traction was made as proposed in an earlier paragraph.

the suooess^il results of th© extractions attompiod by the procedure

outlined above ar© found in Table I? through Table; VH. dxsoussiono t mid oqhcjlusxohs

ftifi study of tho extraction of metal oomplejcos revealed several vary in te r e stin g phenomena. Some o f th© complexes developed colors in the organic phase which were much more intense than that present in aqueous solution* For example, bismuth iodide in methyl isopropyl ketone is a very dark rcddiCh*ierang© w hile in the aqueous phase it has a yellow color*

Copper thiooyan&ts in methyl isopropyl ketone is a very internee reddish- brown as compared to a imioh lifte r color o f th© same hue in aqueous solution. Cobalt thiocyanat© in aqueous media i s a violet-pink, while in many organic so lv en ts the color of th© complex is a brilliant blue*

Also Interesting is the way in which several precipitates in aqueous solution are readily dissolved in some organic solvents. Mercuric iodide provides an excellent example} the bright orange precipitate of merOurio iodide is quickly d isso lv ed when shaken with methyl isopropyl ketone, the other oxygen containing solvents, with the exception of isopropyl ether, exhibit a similar solvent action toward this prcotpitate. Load iodide, a yellow precipitate in aqueous solution, is soluble In methyl

Isopropylketone. When solutions of gold are treated with ammonium thlooyanate an orange precipitate i s formed which is soluble in methyl iso propyl ketone, feutyraldebyde, amyl alcohol and ethyl acetate.

the efficiency of the oxygen containing oolvonta in th© extraction o f metal comploxes was a till another very interesting phenomenon observed during the extraction study. Butyral&ehyd© , ethyl acetate, methyl iso propyl ketone and amyl alcohol were very good aolvents while isopropyl

(12) (I?)

eth er was only fa&r. Benzene, carbon tetrachloride, chloroform, n-butyl

©hloride and petroleum ether were observed to extract none of tho com plexes . Methyl isopropyl ketone appaa.ro d to be tho boat solvent employed in the study, although no quantitative experiments were performed to de term ine whioh solvent was actually the boat extractant. It would bo interesting to conduct experiments to show how th© efficiency of extract ants varies with chain length in a homologous series such as th© methyl ketones* Similar experiments might b© carried out with th© aldahydea, the esters, th© alcohols and the ethers.

Probably the moat significant result of the extraction study was toe realization that extract!on, as a means of separation, offers so many and so varied possibilities for increased specificity in both qualitative and quantitative analysis. In the second portion of this report is pre sented a discussion of th© extraction of lead iodide by methyl isopropyl ketone which serve© as a good example of th© us© of extraction techniques as a means of isolating a particular ion. On a micro or acsidiaioro aoale, using toe extraction pi pet, too or three preliminary extractions may b© performed in much less tima than is required to execute a precipitation, filtration and washing. ?%ny very sensitive tocits reported in the litera tu re m ight bo made more s e le c tiv e through th© use of a prelim inary extraction designed to Isolate too doairod ion in aithor tho organic or the aqueous phase.

At present, throe systems aro being investigated as o. direct result of the extraction survey. Thoa© aro th© extraction of bismuth iodide (X4)

by methyl Isopropyl ketone* th e e x tra c tio n of mangsneo® w ith b u ty ra ld e - hyde after treatment with sodium tetraborate, and the extraction of parchromio acid with ethyl acetate. TAB&S X

S olvents Uaed In th© Sxtraetion Study n-Butyl chlorido Methyl iaopropyl kotono

Petroleum ether Isopropyl ethor

Benzene Butyral&ehyd© n-Amyl alcohol Oarbon tetrachloride

Ohioreform Sthyl acetate

(15) TABLHJ I I

Oondttioning Agents Used in th© Bxtraction Study

Sthylenadiaminotstraaoetio acid Perchloric aoid

Potaccium iodide

Mannitol Hydrochloric aold.

Halonio aold Aramoniurn thiocyanat©

Acetic aold Pyridine

(16) tabls III

Metal Iona Included in the Sxtraotion Survey

M etal Ion Means o f D etection

h i4* Flame Teat

Na4 2in© Uranyl Aootate

K4 Flam® T est

Oe4 Flame Test

Ag4 C hloride

S u lfid e

Au444 Visual

S u lfid e

Ou44 Visual

Ammonium Hydroxide

F*444 Visual

Ammonium Thioeyanate

Go44, V isual

Ammonium Thioeyanate

Ui44 Visual

S u lfid e

Ba44 Sulfate

On4*4* Oxalate

sr44 Oxalate

Al444 Amanium Hydroxide

Pb44 S u lfate

Sulfid©

(17) TABL2 XII (Qontlnuod)

Hota.1 Ions Inoluded In tho Sxtraotian study

Matal Ion Moans of Doioction

pt++*+ V isual

P i* * Visual

nh*1 V isual

Hu1 V isual

IrT W t V isual

Or V isual

Parchromic Aoid

m V isual

Bi Thiourea

GA** Oulfido

Hg*+ Oulfid©

’M * * lu lfid o

3n’ . O ulfido Poroxid©

Sb*** Hhodamlna D

AaH lulfld©

(18) fABIS IV*

Extractions Employing Potasolim Iodide a© Conditioning Agent

Metal Ion Solvent Extent of Extraction

Methyl iaopropyl ketone E x cellen t

»**A®yl alcohol E xcellent

Butyraldehyde E xcellent

Ethyl Acetate E xcellent

?b*+ Methyl isopropyl ketone P a r tia l

Methyl iaopropyl ketone E x cellen t

n-Aayl alcohol Good

Butyraldehyde Good

Ethyl acetate Good

Iaopropyl ether P a r tia l

Hg*+ Methyl isopropyl ketone ExoQllent

n-Aayl aleohol Good

Butyraldehyde Good

Ethyl acetate Good

HU*** Methyl iaopropyl keton© P a r tia l

n-Aayl alcohol P a r tia l

Butyraldehyde P a r tia l

Ethyl a c e ta te P a r tia l

(19) *ABLE I? (continued)

Extractions Employing Pot&aeiura Iodide as Conditioning Agent

M e ta iro n S olvent Extent of .Extraction

Methyl isopropyl kotone E x cellen t

n-Atnyl alcohol Good

Butyraldehyde Good

Sthyl acetate Good

X g**** Methyl isopropyl ketone E x cellen t

n-Arayl alcohol E x cellen t

Butyraldehyde E xcellent

Ethyl acetate E xcellent

Methyl isopropyl ketone E xcellent

Butyraldehyde E x cellen t

n-Asjyl alcohol Good

3thyl acetate Good

O u ^ Methyl iaopropyl ketone P a r tia l

Butyraldehyde P a r tia l

n-A*ayl aloohol P a r tia l

Ethyl acetate P a r tia l

(20) T W V

Extraction* Saploying Ammonium Thiooy&natom Conditioning Agent

Metal Ion Solvent Extent of Extraction

?**+* Methyl iaopropyl katone 3xoellent

n«*Amyl alco h o l Good

Butyraldehyde E x cellent

Sthyl aoetate Good

Iaopropyl other P a rtia l

In4** Methyl iaopropyl kotono Good

n-Anyl alcohol Good

Butyraldehyde Good

Sthyl aootato P a r tia l

Iaopropyl othor P a r tia l

Hg^ Methyl iaopropyl ketone Good

n-Amyl alcohol CyOOd

Butyraldehyde Good

Sthyl acetate P a r tia l

Iaopropyl other P a r tia l

?'ethyl iaopropyl ketone E xcellent

n—Amyl aloohol Good

Butyraldehyde Good

Sthyl aoetate P a rtia l

Isopropyl other P a rtia l TABLE V (oonti mod)

Extractions Employing Ammonium TMoeyamt©as Conditioning Agent

Metal Ion Solvent Extent of Extraction

UOg*"*' Methyl isopropyl fcotono E x cellen t

Butyraldehyde E x cellent

n-Ajayl alcohol Good

Ethyl acetate P a r tia l

Ru4** Methyl Isopropyl lteton© Good

Butyraldehyde Good

n-Amyl alcohol P a r tia l

Ethyl acetate P a r tia l

Fd4* Methyl isopropyl kotons Good

Butyraldehyde Good

n-Ainyl alcohol Good

Ethyl acetate P a r tia l

Pt**’*4, Methyl isopropyl ketone P a r tia l

Butyraldehyde P a rtia l

n-Amyl alco h o l P a rtia l

Ethyl acetate P a r tia l

0o++ Methyl isopropyl ketone E xcellent

Butyraldehyde Excellent

n—Voyl aloohol Excel lent

Ethyl acetate P a rtia l

OyW Methyl isopropyl koton® Good

Butyraldehyde Good

n —Amyl alco h o l P a r tia l

Ethyl acetate P a r tia l

(22) TABLE VI

Extractions Employing Hydrochloric Acid as Conditioning Agent

M etal Ion Solvent Extent of Extraction

Methyl Iaopropyl kotone E x cellen t

Butyraldehyde E xcellent

n-Amyl alcohol Good

Ethyl acetate P a r tia l

Isopropyl ether P a r tia l

Au4"*'*’ Methyl isopropyl ketone E xcellent

Butyraldehyde E xcellent

n—Amyl aloohol E xcellent

Ethyl aoetate E xcellent

Isopropyl ether E xcellent

Methyl isopropyl kotono Good

Butyraldehyde Good

n-Amyl aloohol Good

Ethyl acetate P a r tia l

Iaopropyl other P a rtia l

nu Methyl Isopropyl ketone P a r tia l Butyraldehyde P a rtia l

n —Amyl aloohol P a rtia l

Ethyl acetat® P a rtia l

0 5 ) TABIPC VI (continued)

’Extractions Smploying Hydrochloric* Aoid ao Conditioning Agent

M etal Io n Solvent Extent of extraction 3n+* ^ Methyl iaopropyl ketone deed

Butyraldehyde Good

n-Aiayl aloohol Good

3thyl aoetate Partial

Iaopropyl ether P a r tia l

3V*“M* Methyl iaopropyl ketone iSxoellent

Butyraldehyde E xcellent

n~Amyl alcohol Good

3thyl aoetate Good

Iaopropyl ether P a r tia l

Ab~ + Mothyl iaopropyl keton® P a r tia l

Butyraldehyde P a r tia l

n*-Amyl aloohol P a r tia l

Ethyl acetate P a r tia l

(2b) TABliS VI X

Sxtr&Gtiona 'Employing Pyridine as Conditioning Agent

K atal Ion S olvent Sxtent of ^xtr&etion

Fa*** Butyraldehyde Good

Ou** Butyraldehyde ^xo el le n t

Oo** Butyraldehyde Good

Mft** Butyraldehyde Good

( 2 5 ) BIBLIOGRAPHY

1* Bishop, W* B, B* and Wyer, P, P*

Us® o f Hydrogen Peroxide and Amyl Aoetate for the Miorodot©rmin~

ation o f Chromium

Auatralian Chem* Inst* J* and Proo* 2S 27© (1955)

Ohem. Abe* JQ, 4781 (1956)

2* Bomet, L,

Color Reactions of Oryogoninwith the Heavy Metals

J. phans* ohlm* 50* 556 (1924) Ohea. Abe, 1S>, I 588 (1925)

5* Browning* P , 2* and Kusirian, R * B*

Detection and Reparation o f Aluminum and Beryllium by th e

Action o f Amyl Aloohol on the Nitrates

OriE* Com* 8th Intorn* Conry . Appl. Ohem* 87

Ohem. Aba, 6, 5246 (1912)

4. Galey, ’* R,

The Detection and Dstimation of R'nall Amounts of Lithium

J . Am. Ohem* Doc. £ 2, 2754 (1950)

5* Caldwell, J. R. and Mayor* H* V,

Deter d.nation of Chloride, a Variation of the Volhard Method

Ind, Png* Ohem., Anal, .>1* 2, 5® (1955) 6 m Craig, L. 0.

ix tra c tio n

Anal* 2 2 2 a* 2 1 , 8 5 ( 19219 )

(25) (27)

7« Cfralg, t , 0*

Extraction

isal* 5te* i$U ^ (1950 S* Oraig, L* 0*

Extraction

AQale Oha^. 2J, 41 (1951)

9 . Dodson, R, W,, Forney, G, J , and Bw ift, E. H,

the Extraction of Ferric Dhlorido from Hydrochloric Acid Solutions

J* Aft. 3he%, 3oo, 55* 2575 (1956)

10, Edwards, ?, 0, and Voigt, A, F,

The Beparation of Antimonic Ohlorido from Antimonous Oh 1 or!do

by Extraction with Isopropyl Other

Anal, Ohem. 21, 1204 (19^9)

11* Swell, R, II,, Harrison, 0. M, and Berg, h.

Aaeotropio D istillation

Ind. 2nr. Oham. j d , 871 ( 19-W+)

12, Haddock, L, A,

The Determination of Traces of Bismuth Inthe Pro canoe of

Other Metals

Analyot 39, 1 65 (193*0

13, James, L, H,

O olorim etrio D eterm ination of Molybdenum

2LIHL# Aiml, Jit 89 (193^0 (as)

14* Koronraan, I, H* and Dudnik, V* V.

Fractional Flotation Teat with Nickel

i* isslijt& £&&" (£• 2 * 2 « 2 *) M* W a ( 1 9 5 9 )

g&sau Aha* 7 3 0 8 ( 1 9 4 0 )

15, Laugt S, P.

Oater^Lnaticm of Bismth in Biological Material

Qhsm# 31* 169 (1949) 16* to n h e r, y, and Kao, <5. R.

Studios on the Ohondstry of Gold

1 * f t o * OHoffi* 30 , 126 (1926 ) 17# lAvaroedgo, 3. (J*

A Rapid Method for tho Estimation of Mercuric C<a in

Aqueous Solutions

Analyst 5 5, 21? (1906)

1 8 * Nadar, B*

Colorim etric Determination of Cobalt aa tho Cobalt Thloeyan&te

Complex

ate Qhmsie 55. 206 (194a)

Ohara. Aba. 2 1 , 4984 (1943)

1 9 # Kellor, J. W*

Colorimetric Dotorminationof Cobalt in tho Proaonoo of Nickel

Trana* 7ng » Os ram. Soo* 3 , 1^2

Jhem* Aba, 4, 1440 (1910) a©* M ille r, g* g .

Qualitative 3*ndraioro Analysis with Referene© to Noyes and

Bray1 a System i The Thallium group

J* O hm . 3oo. 144, 72 (1941)

21. Miller, 0* Q. and Travee,

Determination of 3 odium and Potassium in Insoluble-) 3111oates

£ . i2£* 122* 1590 (193$) 22. Mioeiftttelli, P*

Separation ©f Thorium and Uranium by Means of Sther

AtU aeoad. Uneel & 1019 (1928)

Ohm* ££0 . 23, 1554 (1929 )

25* Moeller, T« and Oohen, A* J«

Analytical Applications of 8-11ydroxyquinolino Derivatives of

gallium and Thallium

Anal. Qhern. 22, 686 (1950)

24. Moeller, T. and 2ogg, X. 3.

Chloroform Solutions of Iftthiocyamtodipyrldin©Qoppor (XI)

Anal. O hm . £2, 612 (1950)

25. Mohler, II* and Mldraar, R,

M itt. Lebengau Kv^. 22, 1%) (19% )

3®- 22» ^15 (1931) j£$# uyiius, 7. and tluttner, 0.

The Use of iTther in the Analysis of Metals

Bar. 44, 315

qhom. Aba. 2# 2475 (1911) (JO)

!?• Parry* M* H, and Sorfass, 1, J*

O olorim etric Godetorirination of Cobalt and Nickel

iEtik* S te e H* 5*5 (1950) 26. Pow#U* A. 0*

ThaJsiimation of Small 'Quantities of Oobalt

i * 3oc. Q hm . Ind. Jg, 275 (1917)

29. Sootti W. W*.

Standard Slotfeodg » f ahesadoal A nalysis. Volumes I and J J

0* Van Nostr&nd Company, I no., Hew York, 5th Sd, (1959)

So# P, 1559 and P. 255

50. Scott* *. W*

Standard Methods of OhOndQal Analysis. Volume II

0. Van No stran d Company, In o ., Now Y ork,'5th Id, (1959)

3#e P . 2 ^ 9

5 1 . Ihlbata, 3.

Detenai nation of 3®Ionium

ioienee llepts. Tohoku Img, Univ.. First lor, jgjS* 2/39 (1957)

H bl* JS* ( 1935a) 52. Shirlay, a. L,, Bonner, S, J, and Millar* 1. J.

Anal. Ih&m. 21, 500 (191®)

55, Indth, H# 1, and Oook®, J. H.

The Determination of Very Imall luantltioe of Iron

A nalyst 21, 90? (1926) (51)

J4* Tomraila,

The Determination of Bia?auth with Alkali Thiooyanaies

J&aLs* I!# 79 (i954)

SSE» 1&* £ f 5554 (1954) $$4 Vanossi, H«

Anayas s e e , qutm. Argentina J g , 48 (lp 4 l)

O hm , Aba* ^ ^ 5 (1941)

55, Vanosai, H*

Identification of-.Sine Ion with Dithisjon®

Annies sec, elent, argentlna 154, 75 (1942) ernes. Aba, 3 1, 579 (1945) 57. West, P. W, and Garlton, J* K,

Specific Spot feat for Gold employing Pararosaniline Hydrochloride

Anal, Ohem, 22, 1055 ( 1950 )

53, Yagoda, H*

An Extension of the Iaoamyl Aloohol Separation of the Alkali and

A lkaline Sarth M etals to tho Less Ooramon A lk alies, Lithium , Geeium

and Rubidium

I* id* Ohem, 3oo. ^4, 934 ( 1952 ) The Satraotion ofLead Iodide by Methyl Isopropyl Ketone

Subm itted to AHAJ.YTIQAL cmEMXRTRY fo r p u b licatio n

( 53) MS 'iXTBAOTION OF USAD IOBID13 BY M3THYL IWROPYL K:STOM3

PM lip W. l/ost end Jock K* O&rlton Ooatea Oheraioal Lab oratorio a Louisiana State University Baton Rouge, Louisiana

It la tha purpose of this papor to inaugurate a series of studies dealing with th e extraction of inorganic and organic complexes* In those oases in which ooloriraetria procedures are practical the procedures will be incorporated as a part of the paper or will b® forthcoming, the use of extraction teohniques in a n a ly tic a l separation© has become In creasin g - ly popular in th e la s t few years, particularly in those cases in which it is possible to selectively extract a desired component into an organic solven t and at the same time develop a highly colored organic phase which is readily adaptable to colorimetric procedures* Ordinarily, selectivity is accomplished through the use o f oomplexing agents, careful control of the pH, or a combination of these conditions.

Organic reagents have been found to lend themselves readily to ex traction procedures through the formation of oho la to compounds which are soluble in organic solvents. The uo© of dlthiatone in the determination of load offers one o f the best and most familiar examples of organic re agents employed in th is manner. Other organic reagents which have boon utilised similarly for various metal extractions are 8-quinolinol, oup- fe rro n , o-uitroa©phenol, sodium dl ethyldi thl oo&rbo/oats and dimethyl- glyos&mo, toname a few.

(1) m

larly sueoeptible to solution in organic solvents, Several of those

produced colored organ!o phases of ouffioisnt intensity to merit further

investigation of the possibility o f employing them in colorimetric

procedure o. The extraction o f in o rg an ic complexes as a rap id moans of is o la tin g a p a r ti oular icm has a number of interesting applications both

in eliminating interferences and in isolating desired constituents for

subsequent color development and photometric measurement.

The extraction of lead iodide from acidic aqueous solutions has been

found to be possible when the proper organic solvent was employed* the moat efficient solvents being the ketones* and in particular* methyl iso propyl ketone. The removal o f p r a c tic a lly a l l in te rfe re n c e s was accomplished by a preliminary extraction in whichmmmivm thlooyanate and hydrochloric acid were used to condition the aqueous solution and methyl isopropyl ketone was used as th® solvent, Aftor separation of the phases* th® aqueous phase was treated with potassium iodide and again extracted with methyl isopropyl koton®. Lead iodide* under these conditions* was practically completely extracted with cadmium and ruthenium constitut in g the only interforencos * By employing ouch a procedure* load can be is o la te d from aqueous solutions of all the iona except aadrdum and ruthen ium and can be subsequently analysed either qualitatively or quantitatively by any ono of a number of accepted procedure®. (3)

s& A m m

AnBsonlum thlocyanate, 0* P,, a saturated solution.

Hydrochloric acid, 0 . P#f co n cen trated .

Lead nitrate, 0, P., a solution containing 11*9 milligram of

lead per li t e r #

K ethyl iso p ro p y l k eto n e, :2a«traan Kodak, r e d is tille d *

PotaesiuBB iodide, 0* P., a saturated solution. A study of th® extraction of the metal iodides revealed that a number of the® were ©xtraotabl© Into organic solvents, fhoae metals having iodides which were at least partially extracted into on© or more of the organic solvents employed were bismuth, mercury, iron, lead, copper, palladium, cadmium, rhodium, gold and ruthenium. Among the organic solvents found to be useful in this extraction were butyraldehyde, n-amyl alcohol, methyl n-amyl ketone, methyl isobutyl ketone, methyl n~ propyl kotone, methyl iaopropyl ketone and otftyl aoetate* After observing the solvent properties of these organic liquids, methyl iaopropyl keton© was found to be the most desirable solvent because it wao relatively in expensive, highly effective In dissolving the metal iodides, did not tend to form erulsions, and was a t most only partially n&aoibl© with water, th is r d s o i b i l i t y was reduoed considerably in the presence of strong electro ly te s such as potassium iodide, ammonium thlocy&nate and hydrochloric acid, which wars eventually used in the extraction.

The extraction of lead iodide from neutral solutions into methyl isopropyl ketone was Incomplete as evidenced by flotation of the lead iodide precipitate in the organic phB.eo, On the addition of hydrochloric acid, the precipitate was dissolved completely In the organic phase* It was found that load iodide vms moot completely extracted from aqueous solutions containingyf* by volume of concentrated hydrochloric acid, Th© m ethod employed in analysing fo r load was th© m odification of th©

(4) f t schar-Laopoldl method suggested by U intor and co-workero (X), in this

««*» ae well as in the determination of the distribution ratio and the effect of iodide concentration upon th® extraction, the aqueous phase was analyzed for lea d . The Klott-dummerejon Photoelectric Colorimeter was used in measuring th© o p tic a l don a i t y o f1 ead-di thi zone solutions prepared in the analysis of lend throughout these experiments* A green f i l t e r was used to allow maximum transmission in th© region of 5^3 m illi microns.

Th© distribution of lead between the organic and aqueous phases was determined after extraction and separation of th© phases by analyzing the aqueous layer for lead c o n ten t. The lead solution which was extracted contained 11# tnicrogroma o f load, 5*75 m illiliters of a saturated solution o f potassium iod id e and 1.2*5 m illiliters of concentrated hydrochloric acid, diluted to 25 mi H i liters. This solution was shaken in a 60 m illi liter separatory funnel w ith 25 m illiliters of methyl isopropyl ketone which had been previously saturated with 5^ hydrochloric acid, and one hour was allowed for equilibrium to be reached between the phases. Th© aqueous phase was then passed into a 60 vd.Illliter pyrex separatory funnel and its load content determined by the dithi son© method previously men tion ed , I t was found tliat 4 micrograms of load remained In th© aqueous phase a f te r extraction, thus providing a distribution ratio of 28*8/1, or an extraction which is 97% complete in on© pass.

In attempting to determine the effect of iodide lone upon the distribution ratio a very interesting phenomenon wna obnorved. A series (6)

of aqueous solutions was prepared containing ^ by volume of concentrated

hy&roehloriQ aold and 119 mlorograras of load* Thooe wars treated with

potassium iodide sufficient to provide ratios of load ions to iodide; ions

o f 1*10* 1 *100, 1 11000 and 1*10000* In Table X* is found a tabulation

of the reaulta of extracting those solutions with methyl isopropyl ketone

previously saturated with hydroohlorio acid*

Since a considerable quantity of iodine was liberated from the more

concentrated iodide solutions and extracted into the organic layer, it was thought that this free iodine may p ossibly have been responsible for

the more complete extraction o f lead. However, by adding Iodine to the

weaker iodide so lu tio n s and extracting, no change was brought about in

th© d istrib u tio n r a tio . I t was thought possible that th© presence of on excess of strong electrolyte in the more concentrated Iodide solutions sight have an enhancing effect upon the degree to which load iodide was extracted. This was tested by adding potaosixsa nitrate, a non-interfering

electrolyte, to the weaker iodide solutions to be extracted* d© suite indicate some effect but th e re was insufficient evidence to establish that excess electrolyte was responsible for the more favorable distribution

r a tio .

X ppell mi nary interference study was next conducted to determine which lone were extracted as thoir iodides from a c id ic aqueous solution©« For this study the ions w«r® grouped m indicated in Table II* The lone arc

p r e s e n t e d in th eir more common forma although it is realised that in many

cases they ®3$st as complexes. One m illiliter of a 1^ solution of each (T) io n wao u sed . To *aeh group war* added 1 M illiliter of a saturated solution of potassium iodide and sufficient concentrated hydrochloric acid to m*k* th® solution w ith re sp e c t to acid* Each so lu tio n was thsa shaken thoroughly in a separatory funnel with 5 ml Hi liters of methyl Iaopropyl keton© * and after allowing time for phase separation the aqueous phase was discarded. The organic layer was concentrated to approximately 1 m illiliter by evaporation and a speatrograpMoally pure oar bon eleotrode (National Oar bon Company) was soaked in th© solu tio n for two h o u rs. The electrodes prepared in this manner were dried in an oven for JO rainutee at 1X0°0. and then analysed by means of a

Ba.uaoh and Lomb Large Littrov/ spectrograph. Examination of the plate re su ltin g from this analysis revealed partial extractions of the ions as shown in Table XI.

A second series of solutions waa prepared consisting of the above groups o f ions and each containing 1 m illiliter of %% lead solution.

These solutions were treated and analysed as before* from a study of the re milting spectrogram it waa found that In the proeence of lead* rhodium and ruthenium wore extracted quite well* though otherwise their extraction was sli^ t. A s im ila r but lea a significant influence was exerted by land upon the extraction o f platinum .

A previous observation of th© extraction of th© iodide© o f iron* b iorr&ith* mercury* palladium and gold had definitely ©established those ions as interferences in th® extraction o f load iodido by methyl iso propyl koton©. 'therefore* to avoid the complexity which th© opootral w

lin e s of those elements, particularly iron* would have introduced, they

dure* Iron, ooppor, si no, mercury, gold and palladium can be completely

iodide were removed, After this preliminary extraction had been performed,

potassium iod id e was added and the solution was shaken with an additional

portion of solvent.

lating lead, a apoctrographio study waa made similar to th© one described in a previous paragraph.* The ions to be studied wer© grouped according to Table III* To aaoh group was added 1 m illiliter of a saturated solu

tion 5v£ in hydrochloric acid* After a©paration of phases, 1 m illiliter o f a sa tu ra te d so lu tio n o f potassium iodld© was added to th© aqueous phase, and this solution was then thoroughly shaken with 5 m illiliters of methyl isopropyl ketone. After separation of th© phases, the organic phase was evaporated to a volum© of about 1 m illiliter.. The electrodes (9)

ware soaked in the solution thus obtained for 2 hour a, dried for m hour a t 110*0* and finally analyzed by means of the Largo Li throw Spectrograph*

0I30U33IQH him OCHClLiniOSIS

The extraction of lead into mo thy 1 iaopropyl ketone w&© found to have a very favorable distribution, ratio when, the proper acidity waa main ta in e d and a co n sid erab le excess o f Iodide io n s was p resen t in th© system.*

The effect of iodide ion concentration upon the distribution ratio waa significant in that a ratio of iodide ions to load ions much greater than the stoichiometric ratio of these iono in known lead compound© was re quired for optimum extraction*

The use of a preliminary extraction to remove the interferences ao- oompli3heo the purpose neatly and efficiently without adding materially to the time required to complete th© isolation of load* The time con suming* relatively cumbersome techniques of precipitation wore thus avoided*

Since the extraction of lead iodld© did not produce a highly colored organic phase, th© method did not lond itself to use in a direct color!- m etric procedure. However* by v irtu e o t i t s favorable d is trib u tio n r a tio and high selectivity, tbs extraction should find application as a moans of isolating load for analysis by standard procedures. (10)

A0KK0V/Lm«3'!*

the authors wish to oxpreos thsir appreciation for finm aial

«**i8tsno« provided ths» under a contract with the Offlos of Hav&l

Ro search , TAB1»3 I .

Tho S ffe o t o f Iodide Ion doncontrail on cm the Distribution Ratio

Ratio of Fb++ to I- lUCtrlbut!on Ratio

x a o 0 /1 IslOO o#aiA x a o o o l M / l

1 s10000 8.95/1

(U) TABL2 I I .

Iona Included In the Preliminary Interference Study

Group 1 Group 2 Group 5 Qroup 4 + + + 0 a ++ *2n+* •A s" * *Rh

Ba++ *0d++ *3-bt++ *Ru+++

3 T Oo44" •3n*'M'+ a p t ++++ +-+ % N i4' + A l* ~ Os *++ +

_ *■ ■*- + + *0u++ 0 r ^ + Ir

* Partially extracted

(12) TAB 1*3 I I I .

Group 1 Group 2 Group 5 ■Jroup 4 Group ^ Group 6 Group T +4 + + +4 +1 Ou Gn++ 3b *** Bit+ + Pt Pd Ru „ +4+* 4 4 0 d +" 3 n +t+'t‘ Hg+4_ Au +4‘h Rh Pb

P b ^ Pb+ + Pb + + Pb'h+ Pb++ Pb+"i'

(i? ) BIBLIOGRAPHY

(X) ■‘in t e r , 0 , B*, Robinson, H. , Lamb, F. Vi. and *!illart 3* J*»

Ind. and ^ig* Ohara., A nal, -d., 2* ^6^ (1955)

(I*) Spool flG Spot Test for Ck>Xd I&nploying Pararooaniline Hydrochloride

Reprinted from AMLYTIC!AL OHSM VTHY

Volume 22, page 1Oy?, August* 19^0

(55) Reprinted from ANALYTICAL CHEMISTRY, Volume 22, Page 1055, August 1950 Copyright 1950 by the American Chemical Society and reprinted by permission of the copyright owner Specific Spot Test for Gold Employing Pararosaniline ^84510

PHILIP W. WEST AND JACK K. CARLTON Louisiana State University, Baton Rouget La.

AS A RESULT of the studies of West and Amis (11) oi the reaction thiocyanate, ethylenediaminetetraacetic acid, pyridine, aniline, l i . of pararosaniline hydrochloride with palladous ion, it was malonate, tartrate, and citrate. In those cases where complexa- found that gold reacted with the reagent in such a manner as to tion of interferences was successful, gold was also masked so suggest definite possibilities for use as a spot test for gold. Fur strongly as to prevent its reaction with pararosaniline, except ther investigation revealed that the reaction, the nature of which that pyrophosphate was effective in sequestering palladium with has been established by West (9), had a sensitivity comparable out adversely affecting the reactions of gold. Inasmuch as the with other tests for gold described in the literature (2-4, 7, 8). complexation of the other interfering ions could not be effected In addition, the selectivity of the reaction was found to be far through the use of pyrophosphate, other means were sought by superior to most reactions involving gold, and on this basis which these interferences could be eliminated and specificity showed special promise for spot test work. attained. Lenher (6) reported that gold can be extracted from aqueous REAGENTS solutions by many organic compounds, the esters and particularly Pararosaniline hydrochloride, 0.05% aqueous solution. Ethyl ethyl acetate being most efficient for this separation. Later acetate, c .p . Lenher and Kao (6) showed that maximum separation was ob Tetrasodium pyrophosphate. Saturated solution adjusted to tained when the aqueous solutions contained hydrochloric acid in pH 7.0 with hydrochloric acid (prepared fresh each day). concentrations of 10% by volume. Because these extraction Hydrochloric acid, c . p . (concentrated). techniques seemed promising, an investigation was undertaken to EXPERIMENTAL determine the feasibility of adapting them to spot test proce dures. By using a dropper pipet for extraction and phase separa Of the media commonly employed in spot test analysis, filter tion, an elegant method was developed which serves to isolate paper holds an advantage over the spot plate for use in this test gold from all potential interfering ions. [Although a medicine because the reaction sensitivity was found to be greater using cer dropper can be used, a modified pipet (1) provides more thorough tain papers than when test tubes or spot plates were employed. mixing and sharper separation of phases.] Such a procedure not The effect of using different grades of filter paper on sensitivity only serves to prevent interferences but affords a simple, rapid was found to vary to a remarkable degree, the greatest sensitivity method of concentrating gold from relatively dilute test solutions. being afforded by Schleieher and Schtill No. 595 filter paper. D if In practice, the extraction involves the addition of a few drops of fusion of 0.05% pararosaniline hydrochloride (Schultz No. 511 extractant to one or more drops of the test solution. Thorough from the National Aniline and Chemical Company) through this mixing of the aqueous layer and ethyl acetate is then accomplished paper leaves a concentration of the reagent in the form of a ring by drawing them into and expelling them from the dropper pipet about 7 mm. in diameter with only slight diffusion of the reagent several times, finally drawing both layers into the dropper and beyond this point. Diffusion of the reagent in other papers was allowing a short time for phase separation. After the aqueous sometimes faster, but distribution of the reagent in those cases did layer is disposed of, the ethyl acetate layer is added to a spot plate not leave the ring of concentrated reagent in which the violet- depression or a microbeaker where the solvent is evaporated. black precipitate of gold fuchsia is most easily discernible when The auric chloride is then put into solution by means of a drop of gold is to be detected in small amounts. saturated sodium pyrophosphate which serves to complex any The order of spotting of reagent and test solution was found to be important, be cause gold, when spotted on Table I. Scope of Interference Studies paper, was apparently ad Na + Be + + BO*- CO3-- NH* + s — F~ Fe + + CN- sorbed so strongly that it L i+ Mg + + B4O7 Si0 3- - n o 2- S2O3 c i - F e + + + Fe(C N )------reacted only slowly with re K + Ca+ + Al + + + Ti++++ NO3- SO 3-- C103- Co + + F e(C N ) ----- agent which was subsequently Cu + + Zn + + Se + + + GeOa H2PO2- SO 4-- C104- Co + + + CNS- Rb + Sr+ + Ga + + + Sn+ + HPO3-- Cr + + + Mn + + Ni + + Acetate added to the spot. When Ag + Cd + + Y + + + Sn ++++ P4O13 CraCb MnC>4~ Ru + + + Oxalate the order of spotting was re Cs + Ba + + In + + + Pb + + PeO.s ~ C rO i" B r- Rh + + + Malonate versed, the reaction took place Hg + La + + + Zr++++ p o 3- SeOs"- Br0 3 - Pd + + Adipate I- quickly with maximum sensi Hg + + Ce + + + Th++++ H PO4-- Se04- - Os +++ Succinate Tl + P2O7------MoCh- - IO3- Jj* + + + + Phthalate tivity. y + + + T eO j-- ReCh- Pt++++ Tartrate Interference studies were vo3- TeCfi-- Citrate made according to the general II AsOj W O4-- Lactate procedure described by West HA8O4-- U0 2 + + Gluconate Sb++ + UO 4-- Glycol (10), and palladium, rhodium, Sb+++++ Diethylene glycol platinum, and mercurous mer Bi + + + Inositol cury were found to react with Sorbitol the fuchsin in a manner Mannitol Sucrose analogous to gold. Attempts Dextrose to eliminate these interferences Aniline were made using such com- Pyridine plexers as ammonia, cyanide, 1056 ANALYTICAL CHEMISTRY

traces of palladium that might have been carried over because of iodide only slowly to give the characteristic brown complex. incomplete separation. Failure to eliminate the interferences of rhodium, platinum, and mercurous mercury made the use of pyrophosphate impractical RECOMMENDED TEST PROCEDURE for general work. In those cases in which palladium constitutes Place 1 drop to 1 ml. of test solution in a spot plate depression the only serious interference, pyrophosphate is an invaluable or microbeaker and add one tenth as much concentrated hydro sequestrant and permits the simplification of the test by eliminat chloric acid. Then add 10 to 15 drops of c .p . ethyl acetate and ing the necessity of using the extraction procedure. with a dropper pipet draw and expel the mixture six to eight times, Solutions of pararosaniline hydrochloride should be prepared finally drawing the contents into the pipet. Allow a few seconds for separation of the two layers and discard the aqueous layer. fresh about once a month, for if allowed to stand for longer periods Wipe the tip of the pipet with filter paper and expel a small drop of time they may prove ineffective in detecting amounts of gold of the ethyl acetate solution while the tip is pressed against the near the limit of identification. Freshly prepared solutions of paper, then transfer the remaining contents of the pipet to a chloroauric acid gave a much better response to the reagent than second depression or microbeaker. Invariably a small drop of the aqueous layer adheres to the tip of the pipet and is released with those which had been standing in the laboratory for some time. the last drop of the ethyl acetate in the pipet. For this reason it To increase the sensitivity of the test numerous filter papers is recommended that the final drop of ethyl acetate be retained in were tried, including Schleicher and Schiill Nos. 497, 589, 590, the pipet. By means of a piece of glass drawn into a fine tip, 595, 597-Y, and 604; Whatman Nos. 1, 2, 4, 5, 30, 40, 41, 42, 44, blow into the ethyl acetate until it has evaporated and add one drop of saturated tetrasodium pyrophosphate. Put one drop of 50, and 120; Reeve-Angel Nos. 201 and 202; E&D (Chicago 0.05% pararosaniline hydrochloride solution on Schleicher and Apparatus Co.) Nos. 615 and 618. The paper found to be most Schiill No. 595 filter paper and as soon as the reagent is absorbed satisfactory for this test was S. & S. No. 595, for it not only place the test drop in its center. possessed excellent absorption characteristics but also was found If the test drop is spotted into the reagent drop carefully it will form a convex surface with the ring of concentrated reagent as its to be of very uniform quality. boundary and diffusion of the test drop takes place through this ring. When gold is present in small amounts it is precipitated in the ring as a violet-black precipitate, and when present in large ACKNOWLEDGMENT amounts the test color is a deep brown. The limit of identifica The authors wish to express their appreciation for financial tion employing this procedure is 5 micrograms of gold at a limit ing concentration of 1 part in 100,000 (based on 0.5-ml. volume of assistance given them under the contract with the Office of Naval test solution). Research.

REMARKS LITERATURE CITED Interference studies were made using 1 % solutions of the ions (1) Carlton, J. K., A n a l . C h e m ., 22, 1072 (1950). to be tested, in the presence of 0.01% gold, thus providing a ratio (2) Feigl, F., and Rajmann, E., Mikrochemie, 9 , 165 (1931). of interfering ion to gold of 100 to 1. The ions investigated in the (3) Frierson, W. J., Virginia J. Sd., 3, 279 (1943). interference studies are listed in Table I in their more common (4) Holzer, H., Mikrochemie, 8, 275 (1930). (5) Lenher, V., J. Am. Chem. Soc., 35, 546 (1913). forms. In many instances the ions concerned are present as (6) Lenher, V., and Kao, C. H., J. Phys. Chem., 30, 126 (1926). complexes, but where structures of such complexes may be in (7) Malatesta, G., and diNola, E., Boll. chim. farm., 52, 461 (1913). doubt, only the valence of the central atom is indicated. (8) Rossi, L., Quimca e industria, 12, 277 (1935). The conditioned reaction showed no positive interferences and (9) West, P. W., Anal. Chim. Acta, 2, 133-9 (1948). (10) West, P. W., J. Chem. Education, 18 , 528 (1941). the only negative (masking) interferences were those given by (11) West, P. W., and Amis, E. S., I n d . E n g . C h e m ., A n a l . E d ., 18 , cyanides and sulfides. The use of pyrophosphate ion to complex 400 (1946). palladium provides a method of sequestering that ion so effectively that it is not precipitated by dimethylglyoxime and reacts with R e c e i v e d October 27, 1949.

P r i n t e d i n U. S. A. Extraction Pi pot for Spot toat Analysis

Reprinted from ANALYTIC* AL 0HE!I3TRY

m Reprinted from ANALYTICAL CHEMISTRY, Volume 22, Rage 1072, August 1050 Copyright 1050 by the American Chemical Society ami reprinted by permission of the copyright owner

Extraction Pipet for Spot Test Analysis. Jack K. Carlton, Louisiana State Cniversity, Baton Rouge, La. n order to apply extraction techniques to spot test analysis I and preserve the essence of the spot test method, a small and simple device was needed, in which the component liquids could be thoroughly mixed and allowed to sepa rate as rapidly as possible. A dropper pipet, with a few modifications, satisfied these requirements.

The pij>et consists of a capillary tip 6 cm. long, 7 mm. in outside diameter, and 1.8 mm. in inside diameter; a bulb blown just above the capillary tip, 4 cm. long, 1.15 cm. in outside diameter, and about 2- to 3-ml. capacity; an upper stem 5 cm. long, 7 mm. in outside diameter, and 5 mm. in inside diameter; and a rubber bulb of 10-ml. capacity. The over-all length of the pipet is approximately 15 cm. None of these dimensions is critical. When low boiling liquids such as ether, chloroform, carbon tetrachloride, and carbon di sulfide are used as extractants, a capillary of about 0.7- or 0.8-mm. bore is recommended. Mixing is accomplished by drawing the liquids into tiie pipet and then expelling them, repeat ing the procedure several times, quickly. By us ing a rubber bulb of considerably greater capac ity than that of the pipet, a large quantity of air is drawn into the pipet after the liquids have been drawn up, and the bubbling of this air through the two liquid layers provides a very efficient, mixing of the two layers.

Care should be exercised in using the pipet to avoid the loss of the liquids being mixed. When the liquids are drawn into the pipet the pressure of the fingers on the rubber bulb should be released slowly, so that when the air begins to bubble through, the liquids will not spatter into the rubber bull) or on the sides of the upper stem, to which droplets might adhere and consequently be lost. On expulsion, pressure should be applied to the rubber bulb slowly to avoid spattering when the air begins to bubble through f he liquids which have been passed into a small beaker. The use of extraction techniques in spot test analysis offers a means of separating an ion from its interferences which might prove valuable in a manner similar to the use of masking agents. West and Carlton |(A nal . C hem ., 22, 1055 (1950)] use such an extraction in separating gold from the platinum metals. For

J'jtlNTKl) IN r. s. \ SUMMARY

1* A systematic study ha® bean mad® of the extraction of metal complexes

cluded in the survey in order to determine their value as solvents

in the extraction of metallic complexes, Isopropyl ketone and

butyraldehyde proved to be very good solvents.

2* The iodide# chloride and thioey&nato complexes of several of the metal

ployed In the study.

5* A d e ta ile d in v e stig a tio n was made o f one o f th e systems in th e ex

traction study# the extraction of lead iodide by methyl iaopropyl

kdtone*

4* It was found that lead ions# when treated with a large excess of iodide

ions and adjusted to the proper acidity# were extracted quantitatively

into methyl isopropyl ketone. Interferences were minimixed by perform

ing a preliminary extraction with methyl isopropyl ketone after

conditioning with ammonium thiooyanatci and hydrochloric acid.

5. A spot tost for gold was developed employing peraroBan! lino hydrochlor

ide as reagent. ^poclfiGity was attained through the use of an ex

tr a c tio n procedure by means of which gold was is o la te d from i t s

interferences, The test was sensitive to y gar-wm o f gold*

6. An extraction pipet was designed to facilitate extraction and separation

of small quantities of materials.

(33) VITA

Jack Kenneth Carlton was born Octobor 6f ip21 in Bedleyvillo,

Texas. He received hie elomemtary and high school education in tho publlct school system of Dhreveport, Louisiana* Ho was graduated from

Centenary College of Shreveport in Juno of 1943 with a B* C. in Chemis try* After graduation ho was employed by tho Chemical carfare Condo© as P-l and P-2 ohoiaiat for fifteen months before volunteering for servioo in the Navy. Ho received an honorable dischargein June o f

1946 and entered the graduate school of Louisiana State University the following September* He was awarded the degree of Master of

Ceienoe in Chemistry On June 4, 1949* He has held teaching as si a tan t- sMps for two years and for the past two years has held a research fellowship sponsored by the Office of Naval 'Research*

He was married to Mary iSllen Potree on June 1,1948 and now has two daughters.

He is at present a Candidato for tho degree of Doctor of Philo sophy.

(3*) EXAMINATION AND THESIS REPORT

Candidate: Jack Kenneth Carlton

Major Field: Chemistry

Title of Thesis: Studies on the Application of Extraction Methods to Analytical Chemistry

Approved:

P 4 J L j « 1a). L Q j u j f Major professor and Chairman

^D^anToJtheI 1 —- _ - ^ J < - | 5 ’ ra'duate School O n a!

EXAMINING COMMITTEE:

• L . S . i & * o m —

— ^ 2

J i - 1 3 . U s

Date of Examination:

May 8, 19^1