Determination of daminozide residues in apple pulp using HPLC-DAD-UV

This paper reports an HPLC-UV method to determine daminozide residues in ap ple pulps adopting the recently introduced EU limit of 0.01 mg/kg for baby food preparation (Commission Directive 1999/39/CE). The method is based on alkaline hydrolysis of daminozide to N)T-dimethylhydrazine (UDMH), which is recovered by distillation and subsequently derivatizated with salicyl alde hyde to salicyl aldehyde-N,N-dimethylhydrazone under strongly basic conditi ons. The resulting solution was cleaned up with Extrelut 20 NT and dichloro methane as eluent, then analyzed by HPLC with a C18 column and a mobile pha se programmed from 50:50 AcCN/H2O to 100% AcCN. The salicyl aldehyde-N,N-di methylhydrazone was selectively detected through two diagnostic UV absorpti on maxima at 295 and 325 nm, which have strong molar absorbivities. Recover ies of daminozide at 0.01 mg/kg were above 80%. The limits of detection (LO Ds) of salicyl aldehyde-N,N-dimethylhydrazone expressed as daminozide conce ntration were 100 pg/muL at 295 nm and 150 pg/muL at 325 nm, and the limits of quantitation (LOQs) of daminozide were 0.0013 mg/kg at 295 nm and 0.002 2 mg/kg at 325 nm.