Determination of 7 nipagin ester preservatives in leather by ultra performance liquid chromatography-tandem mass spectrometry coupled with gel permeation chromatographic clean-up

A novel method has been developed for the rapid separation and determination of 7 nipagin ester preservatives in leather by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with gel permeation chromatographic (GPC) clean-up. Nipagin ester preservatives in leather were extracted by ultrasonic extraction with methanol. The extract was dried by a rotavapor and purified by GPC, then redissolved in the solvent of methanol-water (1 : 1, v/v). The chromatographic analysis was performed on an Acquity UPLC (R) BEH C-18 column (50 mm x 2.1 mm, 1.7 mu m) with a gradient elution of methanol and water as the mobile phases. The analytes were detected by electrospray ionization (ESI) tandem mass spectrometry with multiple reaction monitoring (MRM) in negative ion mode. Good linearity (r > 0.99) was observed between 0.1 and 1.0 mg/L for all the analytes. The recoveries and relative standard deviations (RSDs) were checked by spiking samples with the 7 nipagin ester preservatives at the three levels of 0.5, 1.0 and 3.0 mg/kg. The average recoveries of the 7 nipagin ester preservatives were from (79.44 +/- 5.67)% to (98.07 +/- 9.50)%. The precision values expressed as RSD ranged from 4.24% to 14.00% (n = 6). The limits of detection were 4 -12 mu g/kg and the limits of quantification were 13.2 - 39.6 mu g/kg for the analytes. The method is simple, rapid, sensitive and accurate, and suitable for the quantitative determination and confirmation of 7 nipagin ester preservatives in leather.