Determination of Suiphite, Sulphur Dioxide, Thiosulphate and Thiocyanate, with Notes on the Determination of Total Sulphur and Other Sulphur Compounds 1985 Methods for the Examination of Waters and Associated Materials HMSO This document contains L 6 ci pages Determination of Suiphite, Sulphur Dioxide, Thiosulphate and Thiocyanate, with Notes on the Determination of Total Sulphur and Other Sulphur Compounds 1985 Methods for the Examination of Waters and Associated Materials London Her Majesty's Stationery Office This booklet supplements the booklets in this series on the determination of sulphates and sulphides. It contains much general information of use in the analysis of samples containing other forms of sulphur. Five specificmethods for Sulphite and Sulphur Dioxide, Thiosulphate and Thiocyanate are given. This is followed by a section on ways of determining the total sulphur content of a variety of samples followed by a review type discussion of ways of proceeding should a significantamount of the sulphur presentbe in other forms than those mentioned and there be a need to know either what forms are present,or whether the sample contains certain specific sulphur compounds. The layout is as follows: Introduction, including (i) suitability of the methods given, (ii) a list of forms in which sulphur has been foundto occur in water, sludge and sediment samples, and (iii) a note on ultra-precise titration. A. A spectrophotometric method for Suiphite and Sulphur Dioxide using pararosaniline B. A titrimetric method for Sulphite and Sulphur Dioxide by iodometry C. A titrimetric method for Thiosulphate in simple solutions by iodometry D. Manual colorimetric and volumetric methods for thiocyanate using ferric ions E. An automatedcolorimetric method for Thiocyanate using ferric ions F. Methodsfor the determination of Total Sulphur G. Notes on other methods for analysing complex mixtures of sulphur compounds H. Notes on Analytical Quality Control References Although many of the methods in this booklet are well known and widely used, due to a scarcity of test data all must be regardedas tentative. I,' Contents About this series i Warning to users 2 Introduction 3 Suitability of methods given in this booklet 3 Sulphur compounds which may be present in samples 6 Note on accurate measurement using burettes and pipettes 9 Figuresl&2 11 A Determination of Suiphite and Sulphur Dioxide by Pararosaniline Spectrophotometricmethod 12 Al Performance characteristics 12 A2 Principle 12 A3 Interference 13 A4 Hazards 13 AS Reagents 13 A6 Apparatus 15 A7 Sampling and sample preservation 15 A8 Analytical procedure 16 A9 Sources of error 17 AlO Checking the accuracy of analytical results 18 B Determination of Suiphite and Sulphur Dioxide by lodometry 19 Bi Performance characteristics 19 B2 Principle 19 B3 Interferences 20 B4 Reagents 21 B5 Apparatus 21 B6 Sampling and sample preparation 22 B7 Analytical procedure 22 B8 Calculation 22 B9 Sources of error 23 BlO Checking the accuracy of analytical results 23 Bil Preparation of Oxygen Free Nitrogen 23 C Determination of Thiosuiphate by lodometry 25 Cl Performance characteristics 25 C2 Principle 26 C3 Interferences 26 C4 Reagents 26 CS Apparatus 27 C6 Sampling and sample preparation 28 C7 Analytical procedure 28 C8 Calculation 29 C9 Changes of range 30 ClO Sources of error 30 Cli Checking the accuracy of analytical results 31 D Determination of Thiocyanate, Manual Colorimetric and Volumetric Methods 32 Dl Performance characteristics 32 D2 Principle 33 D3 Interferences 34 D4 Hazards 35 D5 Reagents 35 D6 Apparatus 36 D7 Sample storage and preservation 36 D8 Volumetric analytical procedure 36 D9 Manual colorimetric analytical procedure 37 DiO Sulphide removal procedure 38 Dli Analytical quality control 38 D12 Silver, Mercury and Cadmium recovery 38 E Determination of Thiocyanate. Automated Colorimetric Method 39 El Performance characteristics 39 E2 Principle 40 E3 Interferences 40 E4 Hazards 42 E5 Reagents 42 E6 Apparatus 43 E7 Analytical procedure 43 E8 Extending the range of the method upwards 45 E9 Removal of interferences 45 ElO A dialysis procedure for Coke Oven Effluents high in Thiocyanate 46 Ell Checking the accuracy of analytical results 47 F Determination of the Total Sulphur Content 49 Sulphur recoveries for these methods 49 Fl Objective 50 F2 Principle 50 F3 Preliminary discussion 50 F4 Aqueous Alkaline Bromine Oxidation 51 F41 Hazards F4.2 Reagents F4.3 Apparatus F4.4 Procedure F5 Hydrogen Peroxide Oxidation 52 F5.1 Hazard F5.2 Reagent F5.3 Apparatus F5.4 Procedure F6 Peroxide Fusion method 53 F6.1 Reagent F6.2 Apparatus F6.3 Procedure F7 Oxygen Flask method 54 F8 Other combustion methods 55 F9 Spectrophotometric direct methods 55 F9.1 X-ray fluorescence F9.2 Ultra-violet emission spectrophotometry F9.3 Inductively Coupled Plasma Emission Spectrophotometry F9.4 Flame Photometry FlO Sources of error 56 G Other Techniques which have been used for analysingcomplex mixtures of Sulphur Compounds 57 Gi Methylene Blue Colorimetric 57 G2 Reaction with Cyanide 57 03 Ion Chromatography and HPLC 57 G4 Potentiometry 57 05 Polarography 58 06 Electrophoresis 58 G7 Packed column and thin layer chromotography. and gas chromotography 58 G8 Direct Spectrophotometry 58 G9 Determination of Dithiocarbamates 58 H Analytical Quality Control 59 References 60 Address for Correspondence 61 Membership responsible for this method 62 London 11cr Majesty's Stationery Office About this series This booklet is part of a series intended to provide both of Analysts (to review Standard Methods for Quality recommended methods for the determination of water Control of the Water Cycle). The Standing Committee quality, and in addition, short reviews of the more of Analysts is a committee of the Department of the important analytical techniques of interest to the water Environment set up in 1972. Currently it has 7 Working and sewage industries. Groups, each responsible for one section or aspect of water cycle quality analysis. They are as follows: In the past, the Departmentof the Environment and its predecessors, in collaboration with various learned 1.0 General principles of sampling and accuracy of societies, have issued volumes of methods for the results analysis of water and sewage culminating in Analysis 3.0 Empirical and physical methods of Raw, Potable and Waste Waters'. These volumes 4.0 Metals and metalloids inevitably took some years to prepare, so that they 5.0 General nonmetallic substances were often partially out of date before they appeared in 6.0 Organic impurities print. The present series will be published as a series of 7.0 Biological methods booklets on single or related topics; thus allowing for 9.0 Radiochemical methods the replacement or addition of methods as quickly as possible without need of waiting for the next edition. The actual methods and reviews are produced by The rate of publication will also be related to the smaller panels of expertsin the appropriate field, under urgency of requirement for that particular method, the overall supervision of the appropriate working tentative methods and notes being issued when group and the main committee. necessary. The names of those associated with this method are The aim is to provide as complete and up to date a listed inside the back cover. Publication of new or collection of methods and reviews as is practicable, revised methods will be notified to the technical press, which will, as far as possible, take into account the whilst a list of Methods in Print is given in the current analytical facilities available in different parts of the HMSO Sectional Publication List No 5. Kingdom, and the quality criteria of interest to those responsible for the various aspects of the water cycle. Whilst an effort is made to prevent errors from occur- Because both needs and equipment vary widely, where ring in the published text, a few errors have been found necessary, a selection of methods may be recom- in booklets in this series. Correction notes and minor mended for a single determinand. It will be the additions to published booklets not warranting a new responsibility of the users — the senior technical staff to booklet in this series will be issued periodically as the decide which of these methods to use for the deter- need arises. Should an error be found affecting the mination in hand. Whilst the attention of the user is operation of a method, the true sense not being drawn to any special known hazards which may occur obvious, or an error in the printed text be discovered with the use of any particular method, responsibilityfor prior to sale, a separate correction note will he issued proper supervision and the provision of safe working for inclusion in that booklet. conditions must remain with the user. L R Pittwell The preparation of this series and its continuous Secretary revision is the responsibility of the Standing Committee 1 July 1986 1 Warning to users The analytical procedures given in this booklet should and wastes, containment in the event of breakage, only be carriedout by competent trainedpersons. with access to taps, escape routes, and the accessibility of adequate supervision when necessary. the correct and properlymaintained first-aid, fire-fight- ing, and rescue equipment. Hazardous reagents and Local Safety Regulations must be observed. solutions should always be stored in plain sight and below face level. Attention should also be given to Laboratory procedures should be carried out only in potential vapour and fire risks. If in doubt, it is