Direct analysis of zinc pyrithione using LC-MS

Zinc pyrithione has been widely used as one of the booster biocides in antifouling paints on the bottom of vessels. A direct analysis method for zinc pyrithione has been developed using LC-MS without trans-chelation and degradation. The addition of ammonium acetate in mobile water phase was effective in stabilizing zinc pyrithione in HPLC, and the optimal concentration was 20 mM. The lower temperature was favourable in preventing decomposition and transformation. The column temperature was set at 298 K. The temperatures of the drying gas and the vaporizer in the mass-selective detector were found to be 523 K. Under these conditions, a mass spectrum and chromatogram of zinc pyrithione in methanol were successfully obtained by LC-MS for concentrations between 3.5 and 10 mg L−1.