Determination of the method detection limits for acid extractable metals in environmental solids: a comparative approach

摘要

The accurate determination of method detection limits (MDLs) for acid extractable metals in environmental solid samples (soils, sediments and solid wastes) has been shown to be difficult because not only is it difficult to obtain a representative reference soil sample but also sample spiking is difficult. The use of reagent water as the reference matrix for the determination of MDL in soils does not reflect the matrix effect of real world samples. This paper proposes a comparative approach for determining MDLs for acid extractable metals in soils by first comparing the MDL derived from environmental surface waters with the MDL estimated from the replicate analyses of real soil samples, before assigning a rational MDL values for use in soils. This comparative approach does not require spiking soil and provides more realistic MDL values than the reagent water-based MDLs because they reflect the matrix effect of soils. This paper also provides a method for quantitative description of the matrix effect, which has been a qualitative description in the literature to date. The assigned MDL is verified using the relative standard deviation (RSD) obtained from the analysis of soils of different textures.