Gas chromatographic determination of diphenylamine in apples and pears: method validation and results of Spanish Official Residue Monitoring Program 1995

A simple, fast, and inexpensive method is described for the determination of diphenylamine residues in apples and pears. The diphenylamine is extracted with acetone, and the extraction is followed by liquid-liquid partitioning and further analysis by gas chromatography with nitrogen-phosphorous detection. The method was validated with fortified samples at 4 concentration levels. A gas chromatographic/mass spectrometric confirmatory procedure was developed and applied in routine analysis. The detection level of the proposed method is 0.005 mg/kg, and recoveries ranged from 80 to 100%. The method was used to analyze 100 apple and pear samples from the Residue Monitoring of Hygiene Food Program 1995 of the Spanish Ministry of Health, which is conducted by our laboratory. The results obtained confirmed the viability of the method for routine analysis for this compound. A first evaluation was completed for the presence of diphenylamine residues in apples and pears produced in Spain.