Determination of N,N-dimethyldithiocarbamate in wastewater using pre-column derivatization and high-performance liquid chromatography

Abstract

A simple and sensitive method using pre-column derivatization followed by high-performance liquid chromatography (HPLC) was developed for the determination of N,N-dimethyldithiocarbamate (DMDC) in wastewater samples. I₂/KI solution was used as the pre-column derivatization reagent, and the optimum derivatization conditions were as follows: pH = 9.0, derivatization time = 15 min, I₂/DMDC = 4 : 1 (molar ratio). After derivatization, DMDC was determined by HPLC–variable wavelength ultraviolet detector system at λ = 254 nm. Methanol–water (40/60, v/v) was chosen as the mobile phase. Under the above optimum conditions, good linear regression between DMDC concentration and chromatogram peak area was achieved when the DMDC concentration was in the range of 50–10 000 μg L⁻¹. The limits of detection (LOD) and limits of quantitation (LOQ) were 12.8 μg L⁻¹ and 42.6 μg L⁻¹, respectively; the recovery percentages ranged from 99% to 101% for the synthetic water samples. The method was used to analyze real wastewater samples. Liquid–liquid extraction was adopted to enrich DMDC in wastewater samples, and n-hexane was used as the extraction solvent. The relative recovery for the spiked real samples ranged from 84.7% to 96.5%. This method provided high accuracy, good repeatability, simple operation and high recovery, and thus could be applied for routine analysis of DMDC in water and wastewater samples.