Evaluation of radioimmunoassay performance for staphylococcal enterotoxin in foods: application of external quality assessment survey.

An external quality assessment survey for staphylococcal enterotoxin A, B, and C2 determinations was performed in the collaborative study. Three analysts in two laboratories took part. Three types of food, cheese, salami, and pasta, were artificially contaminated with either one toxin only or all three toxins. A total of 378 analyses were performed. The group mean of the analytical values corresponded fairly well to the given enterotoxin concentrations. However, a considerable interlaboratory imprecision was found despite analyses being performed with the same reagents and methodology.