Simultaneous separation and determination of six arsenic species in rice by anion‐exchange chromatography with inductively coupled plasma mass spectrometry

Abstract

The simultaneous separation and determination of arsenite As(III), arsenate As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) in rice samples have been carried out in one single anion-exchange column run by high-performance liquid chromatography with inductively coupled plasma mass spectrometry. To estimate the effect of variables on arsenic (As) speciation, the chromatographic conditions including type of competing anion, ionic strength, pH of elution buffer, and flow rate of mobile phase have been investigated by a univariate approach. Under the optimum chromatographic conditions, baseline separation of six As species has been achieved within 10 min by gradient elution program using 4 mM NH4 HCO3 at pH 8.6 as mobile phase A and 4 mM NH4 HCO3 , 40 mM NH4 NO3 at pH 8.6 as mobile phase B. The method detection limits for As(III), As(V), MMA, DMA, AsB, and AsC were 0.4, 0.9, 0.2, 0.4, 0.5, and 0.3 μg/kg, respectively. The proposed method has been applied to separation and quantification of As species in real rice samples collected from Hunan Province, China. The main As species detected in all samples were As(III), As(V) and DMA, with inorganic As accounting for over 80% of total As in these samples.

Arsenic Species Analysis at Trace Level by High Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry

“…AsC, a cation irrespective of the pH, implied that the elution was almost unaffected; hence, it was the first form to be separated. Since AsB existed as the zwitterionic form while As III existed as a weakly ionized compound [21], the interaction with stationary phase was weak, so AsB and As III cannot be completely separated through high concentration in the mobile phase. Owing to the fact that other three arsenic species have low p Ka values in descending order of DMA, MMA, and As V , they sequentially appeared at the end in the separation process.…”

Coupling nanoliter high‐performance liquid chromatography to inductively coupled plasma mass spectrometry for arsenic speciation

“…Considering arsenic species mostly in the form of anions, anion exchange chromatography is also most commonly utilized for arsenic speciation . We also studied the feasibility of SAX‐based nanoHPLC in arsenic speciation using similar instrumentation to RP nanoHPLC.…”

Simultaneous separation and determination of thallium in water samples by high‐performance liquid chromatography with inductively coupled plasma mass spectrometry

“…HPLC with inductively coupled plasma (ICP) MS is one of the most effective methods for speciation analysis, which has high element selectivity, high sensitivity, broad linear range, and relatively low LOD . In fact, this method has been widely used in the determination of metal species such as arsenic and chromium . According to the behavior of Tl, this method is very promising.…”