Dp. Schwartz et Ar. Lightfield, PRACTICAL SCREENING PROCEDURES FOR SULFAMETHAZINE AND N-4-ACETYLSULFAMETHAZINE IN MILK AT LOW PARTS-PER-BILLION LEVELS, Journal of AOAC International, 78(4), 1995, pp. 967-970
Relatively simple and inexpensive procedures for screening milk for su
lfamethazine (SMZ) and one of its metabolites, N-4-acetylsulfamethazin
e (ASMZ), are detailed. Both methods detect at the low parts-per-billi
on level and are suitable for both field and laboratory use. Milk is p
assed over Chromosorb 102, which adsorbs SMZ. The drug is eluted and p
urified by direct passage of the effluent over small beds of buffered
anion-exchange resins and alumina and is finally isolated and detected
colorimetrically. For ASMZ, the procedure is modified so that SMZ is
removed in the purification steps. The isolated ASMZ is then hydrolyze
d to SMZ for detection. Application of the methods 5 years apart (1988
and 1993) shows that SMZ is still being used but to a lesser extent i
n 1993. Of over 250 samples screened in the 2 studies, only 2 were est
imated to contain SMZ at 10 ppb, and the majority contained SMZ at 1 p
pb. ASMZ was detected in a number of samples that were negative for SM
Z.