CONTINUOUS-FLOW AND LIQUID-CHROMATOGRAPHIC DETERMINATION OF P-TOLUENESULFONAMIDE IN ICE-CREAM - INTERLABORATORY STUDY

A collaborative study of the continuous flow (CF) and liquid chromatog raphic determination of p-toluene-sulfonamide (p-TSA) in ice cream was conducted by the Project Group on Collaborative Studies (PCS) of the Inspectorate for Health Protection, Food Inspection Service, The Nethe rlands. The procedure involves extraction of samples with water follow ed by cleanup of the extracts by dialysis in the CF system. Dialysates are injected by using a loop injector (500 muL) on a reversed-phase o ctadecylsilane bonded-phase (C,8) column, chromatographed with methano l-water (25 + 75, v/v) as mobile phase, and quantitated by fluorescenc e detection at 230 nm (excitation) and 295 nm (emission). Seven ice-cr eam samples containing 0-6.35 mg/kg p-TSA at 4 different levels (1 bla nk and 3 pairs of split-level samples) were singularly analyzed accord ing to the proposed procedure by 11 laboratories. The data were analyz ed by the International Union of Pure and Applied Chemistry/Internatio nal Organization for Standardization/AOAC protocol for statistics. No Cochran and Grubbs outliers were found among the participants. For all samples analyzed, repeatability relative standard deviations (RSD(r)) varied from 2.08 to 3.67%, whereas the reproducibility relative stand ard deviations (RSD(R)) ranged from 7.79 to 11.68%. The average p-TSA values for the split levels 1, 2, and 3 were 0.55, 1.02, and 4.44 mg p -TSA/kg, respectively, with mean recoveries ranging from 76 to 79% (ov erall recovery range for all levels, 63-101%). No false-positive resul ts were reported for the blank sample, and no interference was encount ered by the presence of vanilla in samples.