LC/MS studies on characterization and determination of N,N′-ethylenebisdithiocarbamate fungicides in environmental water samples

Liquid chromatography/mass spectrometry (LC/MS) has been applied to analyze N,N'-ethylenebisdithiocarbamate fungicides (EBDCs: manzeb, maneb and zineb) in environmental water Samples. The EBDCs that are zinc and/or manganese salts are transformed into readily water-soluble sodium salts by adding an alkaline EDTA solution. The N,N'-ethylenebisdithiocarbamate anion is extracted into chloroform-hexane (3: 1) as an ion pair with tetrabutylammonium, and then S-alkylated with methyl iodide. The extraction and derivatization are carried out at room temperature. The derivatized ethylenebisdithiocarbamic acid dimethyl ester is introduced into an LC/MS equipped with a negative ion electrospray ionization interface. Identification of the compound is performed with the specific quasi-molecular ion, and the quantitative analyses are carried out using the peak areas. The average recoveries and coefficients of variation of EBDCs at sub-ppb level are 79.1% and 29.3% (n = 6), respectively. The limit of detection based on standard deviation of 0.043 mug/L for manzeb is achieved.