Simultaneous Extraction of Arsenic and Selenium Species From Rice Products by Microwave-Assisted Enzymatic Extraction and Analysis by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry

• Published in: Journal of agricultural and food chemistry Vol. 57; no. 8; pp. 3005 - 3013
• Main Authors: Guzmán Mar, Jorge L, Hinojosa Reyes, Laura, Mizanur Rahman, G. M, Kingston, H. M. Skip
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-04-2009
• Subjects: alpha-amylase; alpha-Amylases - metabolism; Analytical Methods; arsenic; arsenicals; Arsenicals - analysis; Arsenicals - isolation & purification; chemical speciation; Chromatography, Ion Exchange - methods; enzymatic treatment; extraction; inductively coupled plasma mass spectrometry; ion exchange chromatography; mass spectrometry; Mass Spectrometry - methods; microwave treatment; microwave-assisted enzymatic extraction; Microwaves; Oryza - chemistry; Pronase - metabolism; proteinases; rice; rice flour; rice products; Seeds - chemistry; selenium; Selenium Compounds - analysis; Selenium Compounds - isolation & purification; seleno amino acids; Sensitivity and Specificity; rice-based cereal; ion chromatography (IC); inductively coupled plasma-mass spectrometry (ICP-MS); microwave-assisted enzymatic extraction (MAEE); selenium (Se); rice; Arsenic (As); speciation
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf803598k

A microwave-assisted enzymatic extraction (MAEE) method was developed for the simultaneous extraction of arsenic (As) and selenium (Se) species in rice products. The total arsenic and selenium content in the enzymatic extracts were determined by inductively coupled plasma mass spectrometry (ICP-MS), while the speciation analysis was performed by ion chromatography coupled to inductively coupled plasma-mass spectrometry (IC-ICP-MS). The main factors affecting the enzymatic extraction process were evaluated in NIST SRM-1568a rice flour. The optimum extraction conditions were 500 mg of sample, 50 mg of protease XIV, and 25 mg of α-amylase in aqueous medium during 40 min at 37 °C. The extraction recoveries of total As and Se reached 100 ± 3 and 80 ± 4%, respectively. The species stability study during the MAEE process did not show transformation of the target species in rice products. The results of As speciation obtained for SRM-1568a were in agreement with previous studies of As speciation performed on the same reference material. The proposed method was applied to the determination of As and Se species in rice and rice-based cereals. Arsenite [As(III)], arsenate [As(V)], dimethylarsinic acid (DMA), and selenomethionine (SeMet) were the predominant species identified in rice products.