Speciation Analysis of Arsenic Compounds by High-Performance Liquid Chromatography in Combination with Inductively Coupled Plasma Dynamic Reaction Cell Quadrupole Mass Spectrometry: Application for Vietnamese Rice Samples

• Published in: Journal of analytical methods in chemistry Vol. 2019; no. 2019; pp. 1 - 10
• Main Authors: Le-Van, Dung, Tu, Minh Binh, Chu, Dinh Binh, Ly Bich, Thuy, Trinh, Hong Quan, Nguyen, Thi Ngoc Bich, Dang, Xuan Hoang, Do-Hong, Quan, Vu-Thi, Hong-An, Nguyen, Manh Ha, Vu, Hai Anh, Nguyen, Tien-Thanh
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Publishing Corporation 01-01-2019; Hindawi; John Wiley & Sons, Inc; Hindawi Limited
• Subjects: Acids; Ammonium compounds; Ammonium paratungstate; Anion exchanging; Arsenates; Arsenic; Arsenic compounds; Carbon; Carbonates; Chromatography; Contamination; Elution; Ethylenediaminetetraacetic acid; FDA approval; Federal regulation; Flow velocity; Food; High performance liquid chromatography; High temperature; Inductively coupled plasma; Ionization; Ions; Mass spectrometry; Methods; Nitric acid; Plasma; Polymethyl methacrylate; Quadrupoles; Reference materials; Rice; Scientific imaging; Speciation; Spectroscopy; Vietnam; Red River Delta; Singapore; United States > US
• ISSN: 2090-8865; 2090-8873
• DOI: 10.1155/2019/5924942

In this work, high-performance liquid chromatography in combination with inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry was introduced and optimized for speciation analysis of five major arsenic species including arsenobetain (AsB), arsenite (As(III)), monomethylarsonic (MMA), dimethylarsenonic acid (DMA), and arsenate (As(V)) in rice samples. Five arsenic compounds were separated on a Hamilton PRP X100 strong anion-exchange column employed with the mobile phase that is compatible with mass spectrometry, containing ammonium carbonate, methanol, and disodium ethylenediaminetetraacetic acid. Arsenic compounds were detected online by inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry utilizing oxygen as the reaction gas at a flow rate of 0.7 mL·min−1. Five selected arsenic species were baseline separated at the optimum experimental conditions. The excellent LOD and LOQ values of the developed method were achieved in the range of 0.5 to 2.9 μg·kg−1 and 1.7 to 9.6 μg·kg−1 for all species of arsenic, respectively. The ionization effect in plasma during chromatographic gradient elution was systematically investigated by using postcolumn injector. Arsenic compounds in rice samples were extracted by diluted nitric acid at elevated temperature. The extraction efficiency and the interconversion of target compounds during sample preparation were also assessed. The full validation of the developed method was performed by using certified reference material, BRC 211, from European Institute of Reference and Standard for speciation analysis. The recovery of all selected arsenic species was in the range of 70 to 135.5%. The validated method was also applied to analyze rice samples collected from some contaminated rice fields. The results showed that As(III), DMA, and As(V) were found in all rice samples. Average concentration (range) of inorganic arsenic and DMA in all rice samples were 130.3 (65.5–228.1) and 32 (8.2–133.01) μg·kg−1, respectively. However, total concentration of inorganic arsenic in most of investigated rice samples was below the maximum residual level according to US-FDA and European Union standards.