An improved HPLC-ICPMS method for determining inorganic arsenic in food: Application to rice, wheat and tuna fish

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• 作者：Georg Raber^a ; ^{georg.raber@uni-graz.at} ; Natascha Stock^a ; Pia Hanel^a ; Manuela Murko^a ; Jana Navratilova^b ; Kevin A. Francesconi^a
• 关键词：Inorganic arsenic in food ; HPLC&ndash ; ICPMS
• 刊名：Food Chemistry
• 出版年：2012
• 期刊代码：48_03088146
• 类别：abs
• 出版时间：1 September, 2012
• 卷：134
• 期：1
• 页码：524-532
• 文件大小：560 K

摘要

Because arsenic occurs in food both as toxic inorganic forms and as (presumed) non-toxic organic forms, there is a pressing need for robust analytical methods to selectively and quantitatively determine inorganic arsenic in food products. We report an HPLC-ICPMS method based on sample extraction with trifluoroacetic acid/H₂O₂, and measurement of arsenate by anion-exchange HPLC-ICPMS using aqueous malonic acid as mobile phase. The method showed good extraction efficiencies (generally >90%) and column recoveries (>95%) for samples of rice, tuna fish and wheat. Moreover, the use of 5 or 10 mM malonic acid at pH 5.6 gave sharp well-resolved HPLC peaks and a conveniently short retention time of 5 min for arsenate, which together contributed to a low limit of detection based on signal to noise ratio of three of 0.05 渭g As L^鈭? (for 20 渭L injection) corresponding to an LOD of 1 渭g As路kg^鈭? dry mass in the samples. The inorganic arsenic and total arsenic content (dry mass basis) of 10 rice samples was 25-171 渭g As路kg^鈭? and 36-218 渭g As路kg^鈭?, respectively, whereas the 24 tuna fish samples contained much lower levels of inorganic arsenic (<2-18 渭g As路kg^鈭?), although the total arsenic content was much higher (730-5030 渭g As路kg^鈭?). The single wheat sample contained 166 渭g As路kg^鈭?, which was present mainly as inorganic arsenic (152 渭g As路kg^鈭?). The combination of low acid concentration for extraction, high buffering capacity of malonic acid at pH 5.6, and good peak shape results in a highly reproducible and sensitive method for the determination of inorganic arsenic in food.