We have adapted the commercially available EMIT kit [Clin. Chem. 23, 1161 (1977)] to the Gilford System 3500 Analyzer. Sample volume is 10 microliter. We compare reagent blank-corrected absorbance changes at 340 nm between 15 and 55 s for samples and a series of calibrators, and calculate results with use of a logarithmic transformation. Within-run precision (CV) for a serum pool with 4.0 mg of added lidocaine per liter was 2.7% (n = 45); day-to-day precision was 3.3% (n = 15). Analytical recoveries of 2 to 6 mg of lidocaine per liter were 90-102% (average, 97.3%). Results correlated significantly with those by a gas-chromatographic technique. No clinically significant interferences by concomitantly administered medications were observed. The procedure is rapid (42 samples per hour) and is well suited to the fast response required in monitoring lidocaine therapy. Usefulness of the assay data in the management of arrhythmias in the coronary care unit is discussed.
We assayed serum and urine specimens for amylase activity by the nephelometric (I),dyed-starch (Amylochrome) (II), and mayloclastic (III) techniques. For serum, the correlation coefficients of the regression lines were: I vs. II, 0.978 (n = 106); I vs. III, 0.736 (n = 110); and II vs. III, 0.739 (n = 108). For urine, they were I vs. II, 0.938 (n = 49); and I vs. III, 0.752 (n = 46). Because calculation of the Kolmogorov-Smirnov statistic showed the distributions to be nongaussian, Spearman rank correlation coefficients were determined and showed that I and II correlated well but neither method correlated with III. The clinical data show that I and II gave above-normal activities in every case of pancreatitis, but III gave normal values in two of eight cases. In all cases, I and II were more sensitive, giving higher amylase activities (as compared with the upper limit of normal) than did III. The nephelometric procedure is most suitable for routine and emergency testing; the dyed-starch assay is equally sensitive and reliable, but less convenient. The amyloclastic procedure appears to be less reliable.
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