Modified gas chromatographic/mass spectrometric method for determination of daminozide in high protein food products.

Abstract

A modified version of the Conditt and Baumgardner gas chromatographic/mass spectroscopic (GC/MS) method for determination of daminozide in peanut butter and raw peanuts is described. Daminozide in the food product is hydrolyzed to unsymmetrical dimethylhydrazine (UDMH) by sodium hydroxide digestion. The generated UDMH is distilled from the food matrix and captured by reaction with salicylaldehyde in a condensation trap. Resulting high pH distillates generated by peanuts and peanut products are adjusted back to a pH of 5-6 through addition of glacial acetic acid. After thermal incubation and extraction into methylene chloride, salicylaldehyde dimethylhydrazone is separated from interferences by capillary GC and quantitated by MS using the selective ion monitoring (SIM) mode. Quantitation of daminozide is based on the ratio of the salicylaldehyde dimethylhydrazone molecular ion (m/z 164) to the molecular ion (m/z 153) of the internal standard, 4-nitroanisole. Confirmation of daminozide identity is determined by relative intensity of the m/z 164 ion to the m/z 120 (C7H4ON) ion. Improved m/z 164 ion intensity and reduction of neighboring interferences due to acetic acid treatment permitted a daminozide detection limit of 0.005 ppm in a 50 g sample and an associated 0.02 ppm limit of quantitation. This modification is specific for high protein samples that generate high pH distillates such as peanuts and peanut products and is not specifically intended for analysis of low protein samples.