Liquid chromatographic method for determination of patulin in clear and cloudy apple juices and apple puree: Collaborative study

A collaborative trial was conducted to validate the effectiveness of a liqu id chromatographic (LC) procedure for determination of patulin in both clea r and cloudy apple juices and apple puree. The test portion of clear apple juice was directly extracted with ethyl acetate; cloudy apple juice and app le puree we re treated with pectinase enzyme before extraction. After back- extraction into sodium carbonate to remove interfering acidic compounds, th e extract was dried and concentrated, and patulin was determined by LC with UV detection. Clear and cloudy apple juices, apple puree test samples natu rally contaminated with patulin, and blank test samples for spiking with pa tulin were sent to 14 collaborators in 12 different European countries. Tes t portions of each of the 3 test sample types were spiked with patulin at 7 5 ng/g. Recoveries of patulin ranged from 80 to 92%. Based on the results f or spiked test samples (blind pairs) and naturally contaminated test sample s (blind pairs at 3 levels), the relative standard deviations for repeatabi lity (RSDr) and reproducibility (RSDR) ranged from 8 to 35% and 11 to 36%, respectively. Although HORRAT values of <1.4 were obtained for all 3 matrix es at patulin levels ranging from 26 to 121 ng/g, better performance values (RSDr values 6-10% and RSDR values 11-25%) were obtained for clear and clo udy apple juice spiked above 50 ng/g, which is either the statutory limit o r the advisory level for patulin contamination in apple juices in many coun tries.