United States Patent (15) 3,695,813 Griffith et al. (45) Oct. 3, 1972

54 BURNER AND METHOD FOR trophotometric Detection Limits; Analyst Nov. 1969 DETECTION OF Vol. 94 pp. 1,033- 1,035 72 Inventors: Paul A. Griffith, La Habra, David A. Rohrer, Whittier, both of Calif. Primary Examiner-Edward G. Favors 73) Assignee: Beckman Instruments, Inc. Attorney-Paul R. Harder and Robert J. Steinmeyer (22) Filed: Nov. 27, 1970 57) ABSTRACT 21 Appl. No.: 93,337 An improved burner and method of construction is disclosed for use in detecting and halogen containing compounds. A ring of is coated on (52) U.S. Cl...... 431/126, 356/87 the inner surface of a secondary flame supporting (51) int. Cl...... F237/00 structure. A primary flame supporting structure is 58) Field of Search...... 431/4, 79, 126; 356/87 located within the secondary flame supporting struc ture. The indium ring is coated over a palladium, gold 56) References Cited or rhodium base coating deposited on the secondary flame supporting structure. The method of coating the OTHER PUBLICATIONS indium ring is also disclosed. Herrmann & Gutsche: Improvement of Flame-Spec 4 Claims, 1 Drawing Figure

PATENTEDOCT3 1972 3,695,83

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INVENTORS PAUL. A. GRIFFITH DAVID A. ROHRER

BY 2.TTORNEY 3,695,813 1. 2 BURNER AND METHOD FOR DETECTION OF HALOGENS - nected to a source of flame supporting gas such as air. This invention relates generally to the detection of Located on the inner surface of tube 14 just below tip halogen and halogen containing compounds and more 22 is an indium coating 23 in the form of a thin ring and particularly to a new and improved burner and process is deposited over a thin metallic substrate of palladium, of making the burner for use in the detection of such gold or rhodium. The sample to be tested for the compounds. presence of halogen or a halogen containing compound In U.S. Pat. No. 3,504,976 there is disclosed new and may be entrained into the primary flame 17 by any novel process and apparatus for the detection of suitable means such as by adding the sample to either halogens and halogen containing compounds. More 10 the fuel gas or the support gas. Other methods of en specifically, there is disclosed a process and apparatus training the sample, either liquid, gas or solid, into the whereby the halogen containing sample, in vapor orgas flame, are disclosed in the aforementioned patent and form, is passed over a heated indium surface where the the reference cited therein. If desired, the second flame sample reacts with the indium to form a volatile indium supporting structure 14 and the secondary flame 18 . These are burned in a flame which im 15 may be surrounded by a chimney 20 having an inlet 21 parts such energy to the indium halide as to cause them for receiving a suitable combustion support gas such as to photometrically radiate. Such radiation is spectrally air. The chimney 20 is preferably of Vycor or Pyrex to unique to offering a distinctive means of allow the radiant energy to pass therethrough. It is ob detection both quantitatively and qualitatively with the vious, however, that if desired, the chimney 20 may be ability to discriminate between interfering compounds. 20 omitted. One of the advantages of the process and apparatus dis The quantity of combustion supporting gas admitted closed in the aforementioned U.S. Patent over the prior to tube 14 is insufficient to allow complete combustion art Beilstein test is that the indium halides radiate at of the fuel gases in primary flame 17. The remaining unique wavelengths making it possible to determine hot fuel gases and the hot sample are passed over the specifically which halide is present. The original Beil 25 indium and burned in the secondary flame as they stein test although affording a degree of sensitivity to escape from tube 14. the halides did not provide detectable radiation specific Turning now to the method of forming the indium thereto making it impossible to distinguish which halide ring 23 the tube 14, supporting the secondary flame, is was present. preferably of a non-metallic construction such as In the aforementioned U.S. Patent the indium was 30 Vycor, quartz or alumina oxide. It has been found deposited on a suitable substrate such as beryllium highly advantageous to coat the indium over a thin film copper in the form of a loosely coiled spiral, a screen or of palladium coated onto the inner surface of tube 14 a tube. The spiral, screen or tube was then supported although gold or rhodium may also be used, the process on indentations within the second flame supporting remaining the same. structure above the primary flame or was suspended 35 The following process has been found to produce within the structure by a palladium wire. good results in coating the indium over a palladium While these structures have adequately served their film. A Vycor tube is dried in a light flame and the tip purpose, it has been found that the indium metal tends 22 dabbed into a drop of liquid bright palladium which to ball with prolonged usage of the burner thereby af. 40 was allowed to coat the area on the inner wall of the fecting the sensitivity of the detector. Further, certain Wycor tube to form a ring of one-quarter to one-half of these structures impede the flow of gas through the inch depth. Any liquid palladium adhering to the outer second flame supporting structure. surface of the tube may be wiped therefrom. The liquid It is the primary object of this invention to provide a palladium is then allowed to air dry overnight to new and improved burner of the type disclosed in the 45 remove the volatiles and the tube placed in a cold oven aforementioned U.S. Patent and a method of deposit and heated in air to 500°C for about 20 minutes. A ing the indium onto the inner wall of the second flame good, heavy uniform coating of palladium has resulted supporting structure. from this process. Indium metal is heated in an at It is a further object of this invention to provide a mosphere free of oxidants until it just melts, i.e. at ap burner for use in the determination of halogen com 50 proximately 160C. The palladiurn coated tip of the pounds which offers improved structural stability, less Vycor tube is lightly heated and dipped into the molten resistance to gas flow, more uniform temperature and indium and withdrawn. A smooth coating of indium temperature gradient control of the indium and secon will adhere to the palladium coating. Any indium ad dary flame and which provides greater freedom from hering to the outer surface of the tube may be wiped interference from fewer emissions and more uniform 55 therefrom. This coating is allowed to cool and, if distribution of the indium on a substrate. desired, may be again lightly heated and shook to The single FIGURE of the drawing illustrates a new remove any unevenness which may occur in the indium and improved burner for use in the determination of coating. After cooling, the indium coated tube is util halogen compounds. ized in the construction of the burner hereinbefore Referring now to the drawing, there is illustrated a 60 described. first flame supporting structure comprising a tube 11 It has been found that by coating the indium over a having a tip 12 for supporting a primary flame 17. The thin film of palladium at the end of the secondary flame tube 11 is adapted to be connected to a source of fuel supporting structure adjacent the tip thereof a uniform, gas such, for example, as hydrogen. A second flame 65 even distribution of indium on the substrate is possible supporting structure comprises a tube 14 which sur and there is no or little tendency of the indium to ball rounds and encloses the tip 12 of tube 11 and is con after prolonged usage of the burner. Gold and rhodium nected at its lower end to an inlet 15 adapted to be con have also been used with similar results. The improved 3,695,813 3 4 burner offers less resistance to the flow of gas through tending beyond the tip thereof; and the secondary flame supporting structure, provides means for supplying a combustion support gas to said more uniform temperature and temperature gradient chimney. - over the indium coating and greater control of the 3. A burner for use in the determination of halogen secondary flame. 5 compounds comprising: What is claimed is: a first flame supporting structure having a tip for sup 1. A burner for use in the determination of halogen porting a flame; compounds comprising: a second flame supporting structure having a tip for a first flame supporting structure having a tip for sup supporting a flame, said second flame supporting porting a primary flame; 10 structure formed of glass and extending beyond a second flame supporting structure having a tip for and surrounding said first flame supporting struc supporting a secondary flame, said second flame ture; supporting structure extending beyond and sur a thin coating of palladium deposited on the inner rounding the tip of said first flame supporting wall of said second flame supporting structure ad structure; 15 jacent the tip thereof; a thin coating of metal, taken from the group consist a thin coating of indium deposited over said palladi ing of palladium, gold or rhodium, deposited upon un; the inner wall of said second flame supporting means for supplying a fuel gas to said first flame sup structure adjacent the tip thereof; porting structure; and a thin coating of indium deposited over said thin 20 means for supplying a support gas to said second coating of metal; flame supporting structure. means for supplying a fuel gas to said first flame sup 4. A burner according to claim 3 further comprising: porting structure; and a radiant energy transparent chimney surrounding means for supplying a combustion support gas to said and extending beyond the tip of said second flame second flame supporting structure. 25 supporting structure; and 2. A burner according to claim 1 further comprising: means for supplying a combustion support gas to said a radiant energy transparent chimney surrounding chimney. said second flame supporting structure and ex xir k ck k sk 30

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