A rapid, simple acetaminophen determination is available.

contribution in the measurement. Concentration of active chemical ingredients , additives, timing parameters, and electronic time constants are variables that help to establish the positive characteristics and define the limitations of each method. To the Editor: We read with interest the recent Letter of Rosenbaum et al. (1) expressing their concerns about possible interference by salicylates with quanti-tation of acetaminophen by use of the colorimetric assay for acetaminophen recently recommended by the American Academy of Pediatrics' Committee on Drugs (2). We also expressed our opinion (3) that the methodology recommended by the Academy of Pediatrics was " neither simple nor reliable. " Furthermore , we are of the opinion that this method cannot be recommended for hospital clinical laboratories, owing to its lack of sensitivity and specificity. The spectrophotometric analysis for acetaminophen that we previously described (3) can be summarized as follows. Serum proteins are precipitated with trichloroacetic acid (50 g/L solution). The supernate is removed and heated in a boiling water bath for 20 mm. Any acetaminophen present is then coupled with o-cresol in basic solution and the absorbance is measured at 615 nm ins suitable spectrophotometer. Our assay requires only 0.2 mL of serum, is linear to at least 1000 mg/L, and there is no interference from salicylates. Subsequently we described the use of liquid chromatography to quantitate acet.aminophen and salicylate simultaneously (4). We would like to present here additional documentation indicating no interference from salicylate in our acet-aminophen colorimetric assay. Serum standards containing known concentrations of added acetaminophen and salicylate were analyzed in quintu-plicate for acetaminophen (Ac) by our procedure (3) and for salicylate (SA) by the Trinder method (5). The results are summarized in the following tabulation: Dnig found, mg/k (SD) The results indicate no interference by salicylate in the analysis for acet-aminophen by our method (3). This method has been in routine use at this institution for the last year and is currently used by numerous other hospitals around the country. We believe that it is easy to perform, reliable, rapid, and ideally suited for determining acetami-nophen concentration in cases of suspected poisonings. For laboratories equipped for it we would recommend our liquid-chromatographic procedure (4) for the simultaneous analysis of both compounds because of its greater speed, reliability, and precision. in cases of coexisting acetaminophen and salicylate overdose.ments of acetaminophen and salicylate in plasma by liquid chromatography. To the Editor: The comments of Miceli and …