Determination of Lead, Cadmium, Chromium, and Arsenic in 13 Herbs of Tocolysis Formulation Using Atomic Absorption Spectrometry
CHWAN-BOR FUH 1*, HUEI-IA LIN 2 AND HWEIYAN TSAI 3
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Department of Applied Chemistry, National Chi Nan University 1, University Road, Puli, Nantou 545, Taiwan
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Department of Applied Chemistry, Chaoyang University of Technology 168 Gifeng East Road, Wufeng, Taichung County 413, Taiwan
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School of Applied Chemistry, Chung Shan Medical University 110, Sec 1, Chien-kuo N. Road, Taichung 402, Taiwan
(Received: July 12, 2002; Accepted: September 10, 2002)
ABSTRACT
The contents of Pb, Cd, Cr, and As in 13 herbs of tocolysis formulations were studied using three kinds of sample pretreatment and atomic absorption spectrometry. Thirteen herbs were pretreated with either incineration, wet digestion, or microwave digestion, and the results of recoveries and precision about these elements were compared. The average recoveries of 13 herbs via incineration, wet digestion, and microwave digestion pretreatments were 80±12%, 85.7±3.3%, and 94.5±2.1%, respectively. Among them, microwave digestion pretreatment had the highest recovery and precision. The average relative standard deviations for the four measured elements (Pb, Cd, Cr, and As) from incineration, wet digestion, and microwave digestion pretreatments were 8.8±1.7%, 7.1±3.3%, and 3.4±0.8%, respectively. The detection limits for Pb, Cd, Cr, and As using microwave digestion pretreatment were 0.45 ppb, 0.03 ppb, 0.20 ppb, and 0.64 ppb, respectively. Concentrations of Pb, Cd, Cr, and As measured from the tocolysis formulation using microwave digestion pretreatment were 28.0±0.7 ppb, 1.11±0.03 ppb, 8.5±0.3 ppb, and 1.52±0.04 ppb, respectively. Lead was found to have the highest concentration among the four determined elements in 13 herbs. Schizonepetae Herba contained the highest Pb (60.5±2.1 ppb), Cr (23.3±0.5 ppb), and As (8.8±0.1 ppb) among the 13 herbs. Ligustici Rhizoma contained the highest Cd (3.76±0.04 ppb) among the 13 herbs.
Keywords: tocolysis formulation, sample pretreatments, atomic absorption spectrometry