Investigations of a reduced palladium chemical modifier for graphite furnace atomic absorption spectrometry

Voth-Beach, Lucinda M.; Shrader, Douglas

doi:10.1039/ja9870200045

Cited by 115 publications

(49 citation statements)

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“…The addition of hydrogen has been proposed for pre-reduction of Pd modifier on the surface of graphite tube yielding metallic Pd in order to increase its efficiency. 34 Contrarily to Cr determination, in this matrix 30 the use of chemical modifier and hydrogen addition were necessary due to the high matrix interference observed in the selected wavelength for As. Analytical signals for As in BaSO 4 with palladium and also hydrogen addition during pyrolysis step showed better profile and lower BG signals using both correction systems, specially for Z-SoS-ET AAS ( Figures 1C and 1D).…”

Section: Pyrolysis and Atomization Profiles For Arsenic In Barium Sulmentioning

confidence: 99%

Arsenic determination in pharmaceutical grade barium sulfate using direct solid sampling electrothermal atomic absorption spectrometry

Bolzan¹,

Moraes²,

Mattos³

et al. 2010

J. Braz. Chem. Soc.

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Um método para determinação de arsênio em BaSO 4 por espectrometria de absorção atômica com aquecimento eletrotérmico e introdução de amostras sólidas (SoS-ET AAS) é descrito. Foram avaliados dois sistemas de correção de fundo (BG), deutério e efeito Zeeman (Z). Com o uso combinado de hidrogênio e Pd o BG foi diminuído. Resultados exatos e precisos foram obtidos usando Z-SoS-ET AAS. O desvio padrão relativo usando Z-SoS-ET AAS foi menor que 9,5%. O limite de detecção foi 0,005 mg g -1 e a massa característica foi 25,4 pg. Os resultados foram comparados com os obtidos usando o método de preparo de amostras sugerido pela Farmacopeia Europeia, com determinação usando espectrometria de emissão ótica e espectrometria de massas, ambos com plasma indutivamente acoplado, porém os resultados foram cerca de 20% menores. Vantagens como simplicidade, elevada frequência de determinações e boa exatidão foram obtidos em comparação com o método descrito na farmacopeia.A method for arsenic determination in pharmaceutical grade BaSO 4 by solid sampling electrothermal atomic absorption spectrometry (SoS-ET AAS) is described. Two background (BG) correction systems, deuterium and Zeeman-effect (Z), were evaluated. Background was decreased by using hydrogen combined with Pd. Accurate and precise results were obtained using Z-SoS-ET AAS. Relative standard deviation using Z-SoS-ET AAS was lower than 9.5%. Limit of detection was 0.005 mg g -1 and characteristic mass was 25.4 pg. Results were also compared with those obtained using the preparation method suggested by European Pharmacopoeia for BaSO 4 followed by determination using inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry. Results were around 20% lower than results obtained using the proposed method. Some advantages as simplicity, higher sample throughput were found when compared with the official method currently described in pharmacopoeia.

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Section: Pyrolysis and Atomization Profiles For Arsenic In Barium Sulmentioning

confidence: 99%

Arsenic determination in pharmaceutical grade barium sulfate using direct solid sampling electrothermal atomic absorption spectrometry

Bolzan¹,

Moraes²,

Mattos³

et al. 2010

J. Braz. Chem. Soc.

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“…[13][14][15][16] This probability was also investigated using sodium azide, NaN 3 as a reducing reagent. Under conditions optimized in the presence of 10 µg Pd (ashing, 500˚C; atomization, 1500˚C), the effect of different amounts of sodium azide on the absorbance of cadmium was investigated.…”

Section: Amount Of Matrix Modifier Componentsmentioning

confidence: 99%

“…[7][8][9][10][11][12][13] Recent studies have indicated that the stability effect of palladium for volatile elements is concerned with its metallic form. 9,[13][14][15][16] Therefore, palladium as a modifier is commonly used under reducing conditions. Palladium has been used with several reducing agents together, such as hydrazine, hydroxyl ammin hydrochloride and ascorbic acid.…”

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confidence: 99%

Effectiveness of Palladium–Sodium Azide Modifier for the Direct Determination of Urinary Cadmium by Graphite-Furnace Atomic Absorption Spectrometry

Saraçoğlu

Elçi

1999

ANAL. SCI.

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Since the toxic effects of cadmium and its compounds are well known, the monitoring of this metal in body fluids is of substantial importance. The level of cadmium in urine is an important indicator of human exposure to this metal.Graphite-furnace atomic absorption spectrometry (GFAAS) has been widely used for the direct determination of Cd in urine, owing to its high sensitivity, speed and minimal contamination risks. However, the direct determination of Cd by GFAAS is not easy. Most of the difficulties can be explained by the combination of the matrix urine with a relatively high inorganic salt concentration and analyte, cadmium, that has a relatively high volatility. It can be concluded from recent studies that the most promising technique is to use matrix modifiers for volatilizing Cd at a temperature that leave inorganic salts in the graphite tube. Until now, several matrix modifiers, such as ammonium phosphates, ammonium nitrate and sulfate, magnesium nitrate, nitric acid, sodium hydroxide and palladium salts, have been used in the determination of Cd in various matrices by GFAAS.1-10 Among these modifiers, palladium, which was first reported by Shan and Ni 11 , has experienced increasing interest for the determination of volatile elements by GFAAS. 7-13 Recent studies have indicated that the stability effect of palladium for volatile elements is concerned with its metallic form.9,13-16 Therefore, palladium as a modifier is commonly used under reducing conditions. Palladium has been used with several reducing agents together, such as hydrazine, hydroxyl ammin hydrochloride and ascorbic acid. To the best of our knowledge, hitherto, palladium has not been combined with sodium azide as a reducing agent.The aim of present work was to experimentally evaluate the applicability of palladium combined with sodium azide for the determination of cadmium in urine. Experimental ApparatusA Hitachi (Model Z-8000) atomic absorption spectrometer with a Zeeman-effect background corrector equipped with a Hitachi Model graphite furnace atomizer (part No. 180-7400, uncoated tubes) was used through this work. The peak area (integrated absorbance) and peak height were automatically printed out and displayed using a Hitachi data processor. However, the peak-area absorbances were used to evaluate cadmium and the background absorbances. For cadmium, a hollow cathode lamp wavelength was set up 228.8 nm and a slit width to 0.7 nm. Argon served as a sheath gas at a flow rate of 200 ml min -1 . The absorbance of the atomization was measured without argon gas flow.Samples of 10 µl during the study were injected into the furnace using Eppendorf microliter pipettes with disposable polypropylene tips. The mass of the injected cadmium in the linear range of the calibration curve was 40 pg for optimization and comparison studies. Reagents and solutionAll reagents were from E. Merck and of pro analysis grade. A stock solution of cadmium (200 mg A combination of palladium and sodium azide is proposed as a mixed modifier for cadmium determinat...

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“…Palladium is a very effective chemical modifier and can be used to stabilize many elements to several hundred degrees higher than the temperatures possible with current methods [1][2][3][4][5][6][7][8][9]. Of the elements tested, the greatest temperature shifts are achieved for the semi-metallic elements such as As, Se, Te, Bi, Sb, Pb, TI, Ga, Ge and P. Ash temperatures can be raised 400-800 'C higher than current methods allow.…”

Section: Park Ridge Il 60068mentioning

confidence: 99%

Graphite-furnace AAS - Application of reduced palladium as a chemical modifier

Shrader¹,

Beach²,

Rettberg³

1988

J. RES. NATL. BUR. STAN.

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Chemical modification techniques are widely used in graphite furnace atomic absorption spectrometry (GFAAS). Palladium is a very effective chemical modifier and can be used to stabilize many elements to several hundred degrees higher than the temperatures possible with current methods [1][2][3][4][5][6][7][8][9]. Of the elements tested, the greatest temperature shifts are achieved for the semi-metallic elements such as As, Se, Te, Bi, Sb, Pb, TI, Ga, Ge and P. Ash temperatures can be raised 400-800 'C higher than current methods allow. Temperature shifts are somewhat less for the transition elements and ash temperatures can be raised 200-500'C. Palladium has no similar effect on elements in Groups I and 11 of the Periodic Table. The change in stability is believed to be due to the formation of an intermetallic species. This improvement in stability permits more efficient removal of matrix constituents during the ash step and vaporization into a hotter environment during the atomize step. Background and interference problems are thus reduced or eliminated.Steps taken to guarantee that palladium is present as the reduced metal as early as possible greatly improve performance of the modifier. The palladium modifier solution can be pre-injected and the graphite tube heated to 1000 'C. Such a method has been used to stabilize mercury [10]. It is assumed that at this temperature palladium metal is present on the graphite surface. The sample can then be introduced. The addition of a reducing agent such as 5% hydrogen in 95% argon, ascorbic acid, or hydroxylamine hydrochloride also appears to guarantee that the palladium is present as the metal early in the temperature program. The use of hydrogen as a reducing agent appears to be the method of choice for a number of reasons. It is cleaner, leaves no residue, and is less subject to contamination. It is also easy to use. A pre-mixed gas of 5% hydrogen in 95% argon can simply be introduced into the furnace. More importantly, the problem encountered with high concentrations of nitric acid is eliminated with the use of hydrogen.Reduced palladium metal allows the retention of the analyte element on the graphite surface until a higher gas phase temperature is achieved. This appears to give many of the analytical advantages normally associated with platform atomization while using the simpler wall atomization technique.Investigations to elucidate the mechanism of palladium chemical modification have been conducted. Also, comparison of palladium modifier methods with current modifier methods in spike recovery studies from difficult matrices was accomplished.Scanning electron micrographs of graphite surfaces with palladium deposits obtained by different reduction methods were obtained to investigate whether the physical form of palladium influenced the modifier behavior. It was found that reduced palladium metal was indeed present on the graphite surface after reduction and that the most effective reduction method was the use of 5% hydrogen in 95% argon with a palladium solution...

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Investigations of a reduced palladium chemical modifier for graphite furnace atomic absorption spectrometry

Cited by 115 publications

References 0 publications

Arsenic determination in pharmaceutical grade barium sulfate using direct solid sampling electrothermal atomic absorption spectrometry

Arsenic determination in pharmaceutical grade barium sulfate using direct solid sampling electrothermal atomic absorption spectrometry

Effectiveness of Palladium–Sodium Azide Modifier for the Direct Determination of Urinary Cadmium by Graphite-Furnace Atomic Absorption Spectrometry

Graphite-furnace AAS - Application of reduced palladium as a chemical modifier

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