Estimation of Measurement Uncertainty for the Analysis of Arsenic in Water by Hydride Vapor Generation–Atomic Absorption Spectrometry

Abstract

Every person should have the right to have access to an adequate supply of safe drinking water. However, the presence of different chemical contaminants compromises its quality. Among these chemical contaminants is arsenic, particularly its inorganic species, which when consumed at certain levels in drinking water can cause cancer and heart, respiratory, and neurological problems. For this reason, the determination of arsenic in water requires the use of a validated test method. In this context, the estimation of measurement uncertainty (MU) is an important tool that identifies the impact of each step of the measurement protocol on the overall accuracy and reliability of measurement results. This study is important for drinking water consumers to have accurate test results and can be used by testing laboratories as a guide in their MU calculations for arsenic analysis. In this paper, MU estimation was presented as a validated test method for the analysis of arsenic in a water sample by hydride vapor generation–flame atomic absorption spectrophotometry (HVG-FAAS) using the bottom-up approach. The concentration of arsenic found in the water sample was 0.530 ± 0.07 μg L–1 (k = 2, norm.), which complies with the maximum allowable level (MAL) of arsenic at 10 μg L–1 set in Philippine National Standards for Drinking Water (PNSDW) of 2017. The concentration of arsenic in the sample solution is the major contributory component to the estimated uncertainty with 90.60%; 7.07% is due to overall bias and 1.87% to method precision. Based on this outcome, this study can provide a suitable procedure for estimating MU in HVG-FAAS analysis of arsenic in clean water. Further studies can be done for dialysis water, wastewater, and environmental water.