Analysis of metalaxyl residues in wines by SPE in combination with HRCGC and GC/MS.

Solid phase extraction (SPE) with the porous carbon sorbent CARB GR was used for the preconcentration of metalaxyl residues from a variety of Slovak grape wines with subsequent capillary GC and GC/MS analysis. Recovery was tested at various concentrations of metalaxyl in standard solutions (recovery, R > or = 92%, relative standard deviation RSD < or = 4.3%) and in wines. The value of recovery in spiked wines was dependent on the concentration (studied in the range 0.02-1.96 mg/l) and on the variety of wine (R = 80-99%; RSD = 2-7%). Limits of quantitation (for a sample volume of 50 ml) were determined to be 0.75 microgram/l with GC-FID and 0.50 microgram/l with GC/MSITD. Concentration levels of metalaxyl residues were determined in treated wines (with 0.25% Ridomil plus 48 WP) and a strong dependence on the protective term before the harvest was shown.