Arsenic speciation in water by high-performance liquid chromatography/inductively coupled plasma mass spectrometry-method validation and uncertainty estimation.

RATIONALE

In order to obtain reliable analytical results for the separation and determination of arsenic species by high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS), the analytical procedure must be fully validated and the measurement uncertainty of the analytical result should be estimated.

METHODS

The total arsenic concentration of the samples was determined by ICP-MS. Separation of the arsenic species, AsB, As(III), DMA, MMA and As(V), was accomplished by liquid chromatography, which was hyphenated to inductively coupled plasma mass spectrometry, used for detection purposes. Automated handling of these systems was achieved with Chromera software.

RESULTS

The separation capability between the analytical signals of arsenic species, AsB-As(III), As(III)-DMA, DMA-MMA and MMA-As(V), was 1.3, 1.1, 5.1 and 4.6, respectively. The limit of detection (LOD) values ranged from 0.070 µg L(-1) for DMA to 0.13 µg L(-1) for MMA. The expanded uncertainty U [%] values for coverage factor k = 2 estimated for AsB, As(III), DMA, MMA and As(V) were 12 %, 13 %, 5.6 %, 9.6 % and 8.6 %, respectively.

CONCLUSIONS

This study reports, for the first time, building the uncertainty budgets for five arsenic species and estimation of the expanded uncertainty (for k = 2). The qualitative and quantitative parameters determined in the validation process indicate that the presented analytical procedure can be applied for the determination of AsB, As(III), DMA, MMA and As(V) in water.