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

• Published in: Food chemistry Vol. 134; no. 1; pp. 524 - 532
• Main Authors: Raber, Georg, Stock, Natascha, Hanel, Pia, Murko, Manuela, Navratilova, Jana, Francesconi, Kevin A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2012; Elsevier
• Subjects: arsenates; arsenic; Biological and medical sciences; Cereal and baking product industries; detection limit; Fish and seafood industries; food analysis; food contamination; Food industries; foods; Fundamental and applied biological sciences. Psychology; high performance liquid chromatography; HPLC–ICPMS; Inorganic arsenic in food; malonic acid; Marine; Oryza sativa; quantitative analysis; rice; sampling; Thunnus; Triticum aestivum; tuna; wheat; Inorganic arsenic in food; HPLC–ICPMS; Edible fish; Arsenic; HPLC―ICPMS; Tuna (Tunny fish); HPLC chromatography; Cereal; Method; Application; Wheat; Food; Rice
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2012.02.113

► Inorganic arsenic is efficiently extracted from food under mild conditions. ► A new HPLC mobile phase provides excellent resolution of arsenic species. ► Method can quantify inorganic arsenic in food at the 1μgkg−1 level. 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 10mM malonic acid at pH 5.6 gave sharp well-resolved HPLC peaks and a conveniently short retention time of 5min for arsenate, which together contributed to a low limit of detection based on signal to noise ratio of three of 0.05μg As L−1 (for 20μL injection) corresponding to an LOD of 1μg As·kg−1 dry mass in the samples. The inorganic arsenic and total arsenic content (dry mass basis) of 10 rice samples was 25–171μg As·kg−1 and 36–218μg As·kg−1, respectively, whereas the 24 tuna fish samples contained much lower levels of inorganic arsenic (<2–18μg As·kg−1), although the total arsenic content was much higher (730–5030μg As·kg−1). The single wheat sample contained 166μg As·kg−1, which was present mainly as inorganic arsenic (152μg As·kg−1). 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.