Determination of ultratrace cadmium in food and environmental samples by ETAAS after vapor generation and in situ preconcentration

Abstract

A method is described for the determination of ultratrace cadmium by coupling a continuous flow vapor generation system with in situ preconcentration technique and electrothermal atomic absorption spectrometry (ETAAS). A graphite tube coated with Ir as permanent chemical modifier was used for trapping cadmium vapor species. The effects of the flow rates of carrier gas and sample injection in vapor generation systems on the trapping measurement for cadmium were respectively investigated. Graphite tubes with different characteristic surfaces were comparatively studied for trapping cadmium vapor. The experimental results showed that the permanent chemical modifier of Ir is an alternative to the thermolabile modifier of Pd for simplifying the trapping measurement. The trapping efficiency of cadmium on the graphite tube coated with Ir was estimated. The trapping temperature and time were also investigated. A detection limit (3σ) of 0.005 μg·L^-1 was obtained for this proposed method. The relative standard deviation (RSD) was 1.4% for 0.5 μg·L^-1 of Cd (n=11). This method can be applied to the determination of ultratrace cadmium in food and environmental samples with good agreement between the certified and found values.

Key words： vapor generation; ETAAS; permanent chemical modifier; in situ preconcentration; cadmium

References

1 Andrew T, Simon B, David J H, Linda M W O, Mark W (2000). Atomic spectrometry update. Clinical and biological materials, foods and beverages. J Anal At Spectrom, 15(4): 451-487

2 Dimiter L T (1999). Hyphenated vapor generation atomic absorption spectrometric techniques. J Anal At Spectrom, 14: 147-162

3 Dimiter L T (2000). Vapor generation or electrothermal atomic absorption spectrometry? - Both. Spectrochimica Acta, Part B, 55: 917-933

4 Dimiter L T, Vera I S, Leonardo L, Alessandro D, Rositsa G (2000). Permanent modification in electrothermal atomic absorption spectrometry-advances, anticipations and reality. Spectrochimica Acta, Part B, 55: 473-490

5 Drasch G, Meyer L V, Kauert G (1980). Auwendung der gtaphitrohrkuvette zur arsenbestimmung in biologischen prober mit der hydride-AAS-technik. Fresenius’ Z Anal Chem, 304(2-3): 141-145

6 Guo X M, Guo X Wei, Huang B L (2000), The gaseous phase enrichment techniques in hydride generation. Spectroscopy and Spectral Analysis, 20(4): 533-536

7 Heidi G I, María L F S, Alfredo S (1997). Vesicular Hydride generation-in situ Preconcentration-electrothermal atomic absorption spectrometry determination of sub-parts-per-billion levels of cadmium. J Anal At Spectrom, 12(11): 1333-1336

8 Heidi G I, Maria L F, Alfredo S (1998). Vesicle-assisted determination of ultratrace amounts of cadmium in urine by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry. J Anal At Spectrom, 13(9): 899-903

9 Henryk M, Mariusz K, Ralph E S (1997). Determination of cadmium in environmental samples by hydride generation with in situ concentration and atomic absorption detection. Analyst, 122(4): 331-336

10 James M, Gerhard S, Ian L S, Phil J, Steve J H (1999). Simultaneous multi-element determination of hydride-forming elements by “in-atomiser trapping” electrothermal atomic absorption spectrometry on an iridium-coated graphite tube. J Anal At Spectrom, 14(10): 1593-1600

11 Lee D S (1982). Determination of bismuth in environmental samples by flameless atomic absorption spectrometry with hydride generation. Anal Chem, 54: 1682-1686

12 Leonardo L, Claudia S, Dimiter L T (2003). Hydride generation atomic absorption spectrometry with different flow systems and in-atomizer trapping for determination of cadmium in water and urine-overview of existing data on cadmium vapour generation and evaluation of critical parameters. Talanta, 61: 683-698

13 Lian L, Steven, Cornelius C, Molena H, James S W (1998). Determination of arsenic in water at sub-part-trillion levels by hydride generation Pd coated platform collection and GFAAS detection. Talanta, 47: 569-583

14 Mark R C, Owen B, Simon R N C, Jennifer M C, Malcolm S C, Douglas L M (2001). Atomic spectrometry update. Environmental analysis. J Anal At Spectrom, 16(2): 194-235

15 Matusiewicz H, Sturgeon R E (1996). Atomic spectrometric detection of hydride forming elements following in situ trapping within a graphite furnace. Spectrochimica Acta, Part B, 51: 377-397

16 Sturgeon R E, Willie S N, Sproule G I, Robinson P T, Berman S S (1989). Sequestration of volatile element hydrides by platinum group elements for graphite furnace atomic absorption. Spectrochimica Acta, Part B, 44(7): 667-682

17 Sun H W, Suo R (2004). Enhancement reagents for simultaneous vapor generation of zinc and cadmium with intermittent flow system coupled to atomic fluorescence spectrometry, Anal Chim Acta. 509: 71-76