In vitro bioaccessibility round robin testing for arsenic and lead in standard reference materials and soil samples
Authors: Dodd Matt , Lee Deanna , Nelson Jasen , Verenitch Sergei , Wilson Ross 
Published: February 2024

Abstract
In this study, we assessed the suitability of using a standard reference material (SRM) other than National Institute of Standards and Technology (NIST) 2710a or NIST 2711a in USEPA Method 1340 to determine arsenic (As) and lead (Pb) in vitro bioaccessibility (IVBA) and the capabilities of Canadian-based laboratories to perform the method. Five laboratories participated in an initial round robin study and analyzed NIST 2710a, NIST 2711a, BGS119, and Enviromat SS-2. Intra- and inter-laboratory variability were generally acceptable with percentage relative standard deviations (RSD) of less than 20%. The mean total As and Pb concentrations obtained for BGS119 (332 and 936 mg/kg, respectively) and the mean IVBA values (As = 14.3% and Pb = 78.1%) suggested it may be a suitable and acceptable SRM, whereas the concentration of As in Enviromat SS-2 as received (3.2 mg/kg) was deemed too low. Ten soil samples from sites with varying land use were analyzed in a follow-up round robin study using the modified IVBA method that included BGS119 as SRM. The concentrations of As and Pb in the IVBA extracts reported by the participating laboratories were comparable. The mean As IVBA values for the field-collected samples ranged from 0.1% to 56.4%; for Pb, they ranged from 7.0% to 121%. The lowest IVBA values were measured in mine site samples; the highest values were associated with smelter-affected soils. The low IVBA values correlated with high iron content. Intra- and interlaboratory reproducibility were acceptable (RSD &lt; 30%). Based on the findings of the study, laboratories can use the modified method to provide reproducible and comparable As and Pb IVBA data. The use of BGS119 as an alternative SRM to assess contaminated sites in the province of British Columbia for regulatory purposes is recommended, as it is representative of As and Pb concentrations in contaminated soils in British Columbia. Integr Environ Assess Manag 2024;20:1486–1495. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Key Points
Reproducible and comparable arsenic (As) and lead (Pb) in vitro bioaccessibility (IVBA) data were obtained by participating laboratories using the British Columbia Laboratory Manual method, which is based on USEPA Method 1340. In vitro bioaccessibility analyses, intralaboratory reproducibility for each participating laboratory based on the relative standard deviation was less than 30%, whereas the interlaboratory reproducibility for the pooled data was also equal to 30%, indicating good and acceptable precision. NIST 2711a can be used as an alternative standard reference material (SRM) for As IVBA assay in the province of British Columbia for regulatory purposes because it is representative of As concentrations in contaminated soils in the province. BGS119 can be used as an alternative SRM for As and Pb IVBA assay in the province of British Columbia for regulatory purposes because it is more representative of As and Pb concentrations in contaminated soils in the province.