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|Title: ||Comparison of direct solid sampling and slurry sampling for the determination of cadmium in wheat flour by electrothermal atomic absorption spectrometry|
|Other Titles: ||Talanta|
|Authors: ||Araujo, Rennan Geovanny Oliveira|
Rampazzo, Roger T.
Costa, Pedro A.
Silva, Márcia M.
Vale, Maria Goreti R.
Ferreira, Sergio Luis Costa
|Keywords: ||Cadmium;Wheat flour;Slurry sampling;Solid sampling;ET AAS|
|Issue Date: ||2008|
|Abstract: ||Two analytical methods for the determination of cadmium in wheat flour by electrothermal atomic absorption spectrometry without prior sample digestion have been compared: direct solid sampling analysis (SS) and slurry sampling (SlS). Besides the conventional modifier mixture of palladium and magnesium
nitrates (10 g Pd+3 g Mg), 0.05% (v/v) Triton X-100 has been added to improve the penetration of the modifier solution into the solid sample, and 0.1% H2O2 in order to promote an in situ digestion for
SS. For SlS, 30 g Pd, 12 gMg and 0.05% (v/v) Triton X-100 have been used as the modifier mixture. Under these conditions, and using a pyrolysis temperature of 800 ◦C, essentially no background absorption was observed with an atomization temperature of 1600 ◦C. About 2mg of sample have been typically used for
SS, although as much as 3–5mg could have been introduced. In the case of SlS multiple injections had to be used to achieve the sensitivity required for this determination. Calibration against aqueous standards
was feasible for bothmethods. The characteristic mass obtained with SSwas 0.6 pg, and that with SlSwas 1.0 pg. The limits of detection were 0.4 and 0.7 ng g−1, the limits of quantification were 1.3 and 2.3 ng g−1 and the relative standard deviation (n = 5) was 6–16% and 9–23% for SS and SlS, respectively. The accuracy
was confirmed by the analysis of certified reference materials. The two methods were applied for the determination of cadmium in six wheat flour samples acquired in supermarkets of different Brazilian
cities. The cadmium content varied between 8.9±0.5 and 13±2ngg−1 (n = 5). Direct SS gave results similar to those obtained with SlS using multi-injections; the values of both techniques showed no statistically
significant difference at the 95% confidence level. Direct SS was finally adopted as the method of choice, due to its greater simplicity, the faster speed of analysis and the better figures of merit.|
|Description: ||Acesso restrito: Texto completo. p. 400-406|
|Appears in Collections:||Artigos Publicados em Periódicos (Quimica)|
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