Inter-element interferences in the determination of arsenic and antimony by hydride generation atomic absorption spectrometry with a quartz tube atomizer

The interferences between arsenic and antimony on each other during the hydride generation atomic absorption spectrometry (HGAAS) determination of arsenic and antimony using a quartz tube atomizer (QTA) were examined. In order to eliminate or reduce such interferences by selective heat decomposition of arsine and stibine, a Pyrex adsorption U-tube trap containing glass wool was placed between the drying tube and the quartz tube atomizer. Although at 250 °C stibine decomposes and is held almost completely by the trap, arsine is also decomposed to an extent of 24% and, therefore, thermal decomposition is not useful to eliminate antimony interference on arsenic determination. The effect of coating the glass wool in the U-tube with antimony on the arsenic suppression of the antimony signal was studied. The results showed that the antimony coating in the U-tube could not hold arsenic effectively and its interference on the antimony signal could not be eliminated by this means. In the second part of the study, oxygen was supplied to the quartz tube atomizer during atomization in order to study the effect of supplying oxygen on the antimony signal and on the interference of arsenic in the antimony determination. Sensitivity was increased in the presence of oxygen and interferences of arsenic on antimony determination was decreased by about 10% when oxygen was supplied. It was also observed that the extent of interferences depended mainly on the interferent concentration rather than the analyte concentration.     

A metallic furnace atomizer in hydride generation atomic absorption spectrometry: Determination of bismuth and selenium

A flow injection hydride generation system with a metal furnace atomizer (Inconel 600® alloy) was employed for Bi and Se determination. The presented methods have linear ranges up to 200 and 500 μg L^− 1 for Bi and Se, respectively, with good linearities (r² = 0.9997 and 0.9974, respectively). The limits of quantification obtained according to IUPAC recommendations were 2.3 μg L^− 1 for Bi and 6 μg L^− 1 for Se, and the relative standard deviations (N = 6) based on Bi and Se analytical responses from real samples were 2.7% and 10%, respectively. Accuracy evaluations were based on certified materials such as SRM 361, SRM 363, and SRM 364 (steel alloys) for Bi, Mess-3 (marine sediment), SRM 397 (human hair), and Bio-Rad2 — 69042 (urine) for Se. Good agreements between the results were obtained at the 95% confidence level, according to the t-test.     

Determination of selenium by hydride generation with reducing tube followed by graphite furnace atomic absorption spectrometry

Summary Selenium was determined in biological samples (tea and bovine liver, NBS, SRM 1577) by a combination of hydride generation with reducing tube, graphite furnace atomization and atomic absorption detection. The selenium was reduced by a pellet of sodium borohydride which was placed in a horizontal glass tube. 1.6–2.0 l/min of argon flow rate and 2400° C of atomization temperature were the best experimental conditions. Copper produces a severe effect on absorbance, even if present in only 2 times the amounts of selenium. Ion-exchange resin (Dowex 50 W-X8) was used for the separation of Cu, Ni and Co. A detection limit of 1 ng was obtained with a precision of 5–6%.

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Selenbestimmung durch Hydriderzeugung im Reduktionsrohr mit nachfolgender Graphitofen-AAS

Zusammenfassung Durch Kombination von Hydriderzeugung und Graphitofen-AAS wurde Selen in biologischen Proben (Tee, Rinderleber, NBS, SRM 1577) bestimmt. Die Reduktion erfolgte durch Natriumborhydrid in einem horizontalen Glasrohr. 1,6–2,0 l/min Argon und 2400° C Atomisierungstemperatur erwiesen sich als optimal. Kupfer übt selbst bei nur doppelter Menge einen störenden Einfluß aus. Zur Abtrennung von Cu, Ni und Co wurde ein Ionenaustauscher (Dowex 50W-X8) verwendet. Die Nachweisgrenze beträgt 1 ng bei einer Reproduzierbarkeit von 5–6%.

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Paper read at the meeting of 9th ICAS/XXII CSI, Tokyo, September 1981     

Determination of antimony in wine by hydride generation graphite furnace atomic absorption spectrometry

 A method was developed for the determination of Sb in wine by electrothermal atomic absorption spectrometry, based on preconcentration by hydride generation with collection directly in the graphite furnace. Thiourea was added for prereduction of Sb(V) to Sb(III). The hydride was directly generated from diluted wine. Palladium was used as modifier in the collection step; the overall efficiency of the hydride/trapping system was found to be 67%. Sb was determined in several samples of red wine; the concentrations found were in the range 0.6 to 5.7 μg/L Sb. The detection limit of the method was 39 pg Sb, corresponding to 0.13 μg/L Sb in wine when 0.3 mL wine was analyzed. Received: 3 November 1995/Revised: 22 February 1996/Accepted: 24 February 1996     

Determination of antimony in wine by hydride generation graphite furnace atomic absorption spectrometry

 A method was developed for the determination of Sb in wine by electrothermal atomic absorption spectrometry, based on preconcentration by hydride generation with collection directly in the graphite furnace. Thiourea was added for prereduction of Sb(V) to Sb(III). The hydride was directly generated from diluted wine. Palladium was used as modifier in the collection step; the overall efficiency of the hydride/trapping system was found to be 67%. Sb was determined in several samples of red wine; the concentrations found were in the range 0.6 to 5.7 μg/L Sb. The detection limit of the method was 39 pg Sb, corresponding to 0.13 μg/L Sb in wine when 0.3 mL wine was analyzed. Received: 3 November 1995/Revised: 22 February 1996/Accepted: 24 February 1996     

The atomic absorption spectrometric determination of arsenic,bismuth, lead,antimony, selenium and tin with a flame-heated silica t-tube after hydride generation

A modified technique with a simple T-tube for atomisation held above conventional atomic absorption burners is described. The absolute sensitivities are in the range 0.3–11 ng and the r.s.d. is usually below 5%. It is confirmed that prior oxidation of lead markedly increases the sensitivity.     

Determination of antimony by using a quartz atom trap and electrochemical hydride generation atomic absorption spectrometry

The analytical performance of a miniature quartz trap coupled with electrochemical hydride generator for antimony determination is described. A portion of the inlet arm of the conventional quartz tube atomizer was used as an integrated trap medium for on-line preconcentration of electrochemically generated hydrides. This configuration minimizes transfer lines and connections. A thin-layer of electrochemical flow through cell was constructed. Lead and platinum foils were employed as cathode and anode materials, respectively. Experimental operation conditions for hydride generation as well as the collection and revolatilization conditions for the generated hydrides in the inlet arm of the quartz tube atomizer were optimized. Interferences of copper, nickel, iron, cobalt, arsenic, selenium, lead and tin were examined both with and without the trap. 3σ limit of detection was estimated as 0.053 μg l^− 1 for a sample size of 6.0 ml collected in 120 s. The trap has provided 18 fold sensitivity improvement as compared to electrochemical hydride generation alone. The accuracy of the proposed technique was evaluated with two standard reference materials; Trace Metals in Drinking Water, Cat # CRM-TMDW and Metals on Soil/Sediment #4, IRM-008.     

Study of processes in the hydride generation atomic absorption spectrometry of antimony,arsenic and selenium

Studies of the decomposition rate of the reducing agent sodium tetrahydroborate in alkaline and acidic media and of the reaction rate of the formation of the hydrides under the usual analytical conditions are described. The stripping of the hydrides with different lengths of the stripping coil, with different amounts of hydrogen in the carrier gas and with sodium hydroxide added during and after the stripping process are discussed. Some evidence for the existence of an intermediate during the decomposition reaction of the sodium tetrahydroborate is given. The role of temperature, hydrogen and oxygen during the atomization of the hydrides in an electrically heated quartz cuvette is discussed. Under certain conditions, antimony atoms form dimers or elemental antimony precipitates in the heated cuvette.     

微型氢化物发生-原子吸收光谱法测定纺织品中的痕量砷和锑

采用三毛细管微型在线氢化发生技术和装置, 建立了氢化物发生-电热石英管原子吸收法测定纺织品中痕量As、 Sb的分析方法. 研究了共存离子对As、 Sb检测的干扰及消除方法. 结果表明: 该方法除Co、 Sn对As和Ni对Sb有干扰外, 其它干扰元素允许量都较大. 采用酒石酸和KI混合掩蔽剂可抑制Co、 Sn对As和Ni对 Sb的干扰. As和Sb的检出限分别为0.7和0.4 ng/L, 已用于测定纺织品中痕量As和Sb的分析.     

Determination of antimony in solder alloy by hydride generation followed by graphite furnace atomic absorption spectrometry

Summary Antimony was determined in solder alloy (NBS; SRM 1276) by a combination of hydride generation with reducing tube, graphite furnace atomization and atomic absorption detection. Stibines were generated in a horizontal glass tube, in which a pellet of sodium borohydride was placed. 1.2–1.3 1/min of argon flow rate, 2,300° C of atomization temperature and 1.2–2.5 M of acids concentration were the best experimental conditions. The strong supression of the antimony signal by nickel, cobalt and copper was effectively eliminated with 1,10-phenanthroline. A detection limit of 1.2 ng was obtained with a precision of 4–5%. The reducing tube used in this technique is extremely simple and can be connected to all the types of graphite furnaces. Furthermore, this technique can be used for the determination of mercury [1].

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Bestimmung von Antimon in Lotlegierung durch Hydriderzeugung mit nachfolgender Atomisierung im Graphitrohr und AAS-Detektion

Zusammenfassung Antimon wurde nach diesem Verfahren in Lotlegierung NBS (SRM 1276) bestimmt. Die Stibine wurden in einer horizontalen Glasröhre erzeugt, die gekörntes Natriumborhydrid enthielt. Der Argonfluß betrug 1, 2–1,3 l/min, die Atomisierungstemperatur 2300° C und die Konzentration an Säure 1,2–1,5 M. Die starke Unterdrückung des Sb-Signals durch Ni, Co und Cu konnte erfolgreich mit Hilfe von 1,10-Phenanthrolin verhindert werden. Die Nachweisgrenze lag bei 1,2 ng, die Präzision betrug 4–5%. Die benutzte Reduktionsröhre ist sehr einfach und kann an alle Typen von Graphitöfen angeschlossen werden. Das Verfahren läßt sich auch zur Quecksilberbestimmung [1] einsetzen.

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Paper read at the meeting of the Japan Society for Analytical Chemistry, October 1983     

Simultaneous determination of arsenic and antimony by hydride generation atomic fluorescence spectrometry with dielectric barrier discharge atomizer

Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 μg L⁻¹, respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.     

Multiple microflame quartz tube atomizer: Study and minimization of interferences in quartz tube atomizers in hydride generation atomic absorption spectrometry

A systematic study was performed to evaluate the performance of a multiple microflame (MM) quartz tube atomizer (QTA) for minimizing interferences and to improve the extent of the calibration range using a batch system for hydride generation atomic absorption spectrometry (HG AAS). A comparison of the results with conventional QTA on the determination of antimony, arsenic, bismuth and selenium was performed. The interference of As, Bi, Se, Pb, Sn and Sb was investigated using QTA and MMQTA atomizers. Better performance was found for MMQTA, and no loss of linearity was observed up to 160 ng for Se and Sb and 80 ng for As, corresponding to an enhancement of two times for both analytes when compared to QTA (analyte mass refers to a volume of 200 μl). For Bi, the linear range was the same for QTA and MMQTA (140 ng). With the exception of Bi, the tolerance limits for hydride-forming elements were improved more than 50% in comparison to the conventional QTA system, especially for the interferences of As, Sb and Se. However, for Sn as an interferent, no difference was observed in the determination of Se and Sb using the MMQTA system. The use of MMQTA-HG AAS complied with the relatively high sensitivity of conventional QTA and also provided better performance for interferences and the linear range of calibration.     

Study of some interfering processes in the arsenic, antimony and selenium determination by hydride generation atomic absorption spectrometry

Summary A detailed study of interfering processes in the determination of As, Sb and Se using a twin-channel hydride generation flow-system is presented. The influence of As, Sb, Se and Sn on all three studied elements has a similar character and occurs in the gas phase only. In the presence of bismuth and tellurium interferences occur also in the liquid phase. It was found that arsenic and antimony may influence the analytical signals of elements with analytical lines in the range from 190 to 235 nm by non-specific absorption due to molecular band spectra.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Determination of arsenic by hydride generation with a long absorption cell for atomic absorption spectrometry

A method is described for the determination of arsenic involving hydride generation and atomic absorption spectrometry with an improved long graphite-tube furnace capable of considerably higher temperatures than the conventional quartz-tube heaters. Arsine is generated with sodium tetrahydroborate, held in a nitrogen-cooled trap and then swept with helium into an alumina tube (19 cm long) placed within the graphite furnace. The optimum conditions for determination of arsenic are given. The detection limit is 0.2 ng ml^?1 with RSD of 2–3%. Results for various NBS Standard Reference Materials agreed well with expected values and were as follows: orchard leaves, 10 ± 1 μg g^?1; tomato leaves, 0.28 ± 0.03 μg g^?1; bovine liver, 0.046 ± 0.005 μg g^?1.     

Determination of serum selenium by hydride generation flame atomic absorption spectrometry

Serum is rapidly digested with a mixture of nitric and perchloric acids at a temperature of 180 +/- 10 degrees C, and hydrochloric acid is used to reduce selenium(VI) to selenium(IV). Selenium is determined by hydride generation flame atomic absorption spectrometry. The results show that this method has the advantages of being sensitive, accurate, rapid and simple. After the serum is digested and diluted, 4.0 ml is taken for the determination. The characteristic concentration, detection limit, variation coefficient, recovery rate and linear range are 2.93 mug 1(-1), 1.55 mug l(-1), 1.6-5.0%, 97.3-99.2% and 0.0-320.0 mug l(-1) respectively. Serum at 4 degrees C and in frozen state can be preserved for at least 7 and 14 days, respectively.     

Determination of arsenic by arsine generation with reducing tube followed by graphite furnace atomic absorption spectrometry

Summary A sensitive method for hydride generation and graphite tube furnace atomic absorption spectrometric measurements with a reducing tube has been developed for the determination of arsenic in tea and orchard leaves. Arsines were generated in a horizontal glass tube, in which a pellet of NaBH₄ was placed. 1.5–2.0 l/min of argon flow rate and 2,400° C of atomization temperature were the best experimental conditions. The strong supression of the arsenic signal by Ni and Co was effectively eliminated with 1,10-phenanthroline. A detection limit of 0.3 ng was obtained with a precision of 3–4%.Paper read at the Meeting of the Japan Society for Analytical Chemistry, June 1980     

Determination of arsenic and antimony in milk by hydride generation atomic fluorescence spectrometry

A highly sensitive procedure has been developed for total arsenic and antimony determination in milk samples by hydride generation atomic fluorescence spectrometry after microwave-assisted sample digestion. The discrete introduction of 2 ml of digested sample in the automated continuous flow hydride generation system allows us to reduce drastically the sample and HCl consume and to determine several elements from a same sample digestion. The method provides detection limits of 0.006 and 0.003 ng ml⁻¹, a sensitivity of 2390 and 2840 fluorescence units per ng ml⁻¹ for As and Sb respectively, and average relative standard deviation of 2.3% for As and 4.8% for Sb. The analysis of cow milk samples, obtained from the Spanish market evidenced the presence of As at concentration levels from 3.4 to 11.6 ng g⁻¹ and Sb levels from 3.5 to 11.9 ng g⁻¹, thus in a proportion near to 1:1, which is in contrast with the 10:1 natural ratio between As and Sb and could evidence the effect of the introduction of new alloys and polymer materials in the industrial process of milk. The method was validated by the comparison of data found for commercial samples by using the proposed procedure and reference methods based on dry-ashing and AFS, and microwave-assisted digestion and inductively coupled plasma mass spectrometry determination.     

Determination of bismuth in metallurgical materials using a quartz tube atomizer with tungsten coil and flow injection-hydride-generation atomic absorption spectrometry

A method for the determination of bismuth in metallurgical materials using hydride generation coupled with a merging zones flow system and atomic absorption spectrometry using a quartz tube atomizer with tungsten coil is proposed. The parameters related to the bismuthine generation, the flow injection system and the use of a tungsten coil were studied and the optimized system shows a wide calibration range and good stability over time, without losses in sensitivity. The analytical curve is linear from 10 to 750 μg l⁻¹ of Bi with R0.999. A detection limit of 1.9 ng Bi and an analytical frequency of 60 determinations per hour were obtained. Five metallurgical reference materials were analyzed with the proposed method after their acid dissolution. The results obtained were in good agreement with certified or recommended values, and the relative standard deviations were lower than 5%.     

Determination of selenium in fish flesh by hydride generation atomic absorption spectrometry

Selenium was determined in freeze-dried fish flesh from perch, pike-perch and the fish flesh reference materials MA-A-2 No. 1174 and MA-B-3 No. 151 (both from the International Atomic Energy Agency) by hydride generation atomic absorption spectrometry. Four different decomposition procedures were tested. They yielded consistent results for the four specimens, but the certified concentration level of selenium in the reference material MA-A-2 was not reached. This indicated losses or the presence of very stable selenium-containing compounds in this fish flesh. Neutron activation analysis of the reference material, however, was in agreement with those results obtained.