Determination of Trace Perchlorate in Soil using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Abstract

The international standard (IS) currently used for determining perchlorate in soil is not applicable to trace perchlorate. We developed a quantitative analysis method using liquid chromatography–tandem mass spectrometry (LC-MS/MS) for the trace perchlorate in soil. The perchlorate was extracted from air-dried soil (<150 μm) with distilled water. We proposed the optimum extraction method that included mechanical shaking followed by centrifugation. An internal standard material (Cl18O4-) was added to the extracts and standard solutions at concentration of 5 μg L-1. The samples were analyzed by LC-MS/MS equipped with a reversed phase C18 column packed with core-shell particles containing trimethylsilane functional groups. Samples that may be interfered with organic matter present in the soil should be purified with a C18 cartridge. The method detection limit and limit of quantitation for our method was 1.31 and 4.36 μg/kg, respectively. We verified the proposed method through interlaboratory comparison test; both coefficients of variation for repeatability (CVr) and reproducibility (CVR) were less than 5%. Therefore, we concluded that the proposed method may be used for precise quantitative analysis of trace amounts of perchlorate in soil.