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Frontiers of Agriculture in China

ISSN 1673-7334

ISSN 1673-744X(Online)

CN 11-5729/S

Front Agric Chin    2009, Vol. 3 Issue (3) : 294-299     DOI: 10.1007/s11703-009-0051-9
RESEARCH ARTICLE |
Determination of ultratrace cadmium in food and environmental samples by ETAAS after vapor generation and in situ preconcentration
Ran SUO1,2,3(), Weijuan AN1, Na LI1
1. College of Food Science, Agricultural University of Hebei, Baoding 071001, China; 2. School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; 3. Tianjin Rice Technical Engineering Center, Tianjin 300457, China
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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.

Keywords vapor generation      ETAAS      permanent chemical modifier      in situ preconcentration      cadmium     
Corresponding Authors: SUO Ran,Email:ransuo@yahoo.com.cn   
Issue Date: 05 September 2009
URL:  
http://academic.hep.com.cn/fag/EN/10.1007/s11703-009-0051-9     OR     http://academic.hep.com.cn/fag/EN/Y2009/V3/I3/294
Fig.1  Schematic diagram of the vapor generation and trapping system
Note: Numbers of (1)-(9) represent peristaltic pump, KBH, sample, waste, carrier gas, mixing tube, gas/liquid separator (GLS), transfer line and graphite tube, respectively.
steptemperature/°Cramp time/shold time/sinternal gas flow/(mL?min-1)
11101050300
21303050300
312003020300
42000 (for Ir)2600 (for Zr)13300
Tab.1  Temperature program for graphite tube coating
steptemperature/°Cramp time/shold time/sinternal gas flow/(mL?min-1)read
1120110300
230010400
3300110300
41600040yes
52300410300
Tab.2  Temperature program for trapping and measurement
Fig.2  Effects of trapping temperature on the signal
Note: (a) Zr-coated, (b) Ir-coated, (c) Pd-coated and (d) uncoated.
Fig.3  Effects of atomization temperature on the signal
Note: (a) Ir-coated; (b) uncoated.
CRMscertified value/(μg?g-1)found value/(μg?g-1)
wheat flour (GBW 08503)0.031±0.0020.028±0.007
rice flour (GBW 08502)0.020±0.0020.024±0.009
peach leaf (GBW 08501)0.018±0.0040.016±0.004
tea (GBW 08505)0.023±0.0040.019±0.006
Tab.3  Analytical results (average ±, =7)
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