ABSTRACT
We report a liquid-chromatographic method for assay of total and free propranolol and its metabolite, propranolol glycol, in plasma. An ultrafiltration device is used to separate the free drugs from the protein-bound drugs. The total and free drugs are isolated from plasma or ultrafiltrate by liquid-solid extraction on a Waters C18 SEP-PAK and the drugs are quantified on a C18 mu-Bondpak radial-compression column. The mobile phase consists of equal parts of methanol and a solution of potassium 50 mmol/L phosphate and 2.5 mmol/L 1-pentane-sulfonic acid, pH 5.0. Detection was by fluorescence, with excitation at 296 nm and emission at 338 nm. Time required for sample preparation for total-propranolol assay is 40 min per eight samples. Sample preparation for free-propranolol assay requires an additional 1 h per eight samples. Chromatography requires 15 min per sample. The extraction recovery is approximately 75% and the assay curve is linear from 5 to 400 micrograms/L. The run-to-run CV is 4% for total propranolol, 15% for free propranolol.
Subject(s)
Propranolol/blood , Binding, Competitive , Blood Proteins/analysis , Chromatography, High Pressure Liquid/methods , Humans , Pharmaceutical Preparations/blood , Propranolol/analogs & derivatives , Protein Binding , Spectrometry, Fluorescence , UltrafiltrationABSTRACT
In this method, we use the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane in measuring free testosterone in serum. Two independent assays are combined: total testosterone and the ultrafiltrable fraction of added [3H]testosterone. The unbound fraction is determined in 0.15-0.5 mL ultrafiltrates of 0.6 to 1 mL of variably diluted serum that has been equilibrated with [3H]testosterone at 37 degrees C. The assay is rapid (less than 1 h), practicable (requires 0.6 mL of serum), and reproducible (CV 3.2% within assay, 3.9% between assays). Accuracy was evaluated as the fraction of free testosterone in the ultrafiltrate of dialyzed serum vs that in a prior dialysate; they were the same confirming the validity of the free testosterone measurement. Samples from ostensibly healthy men and women and from hirsute and pregnant women gave results that agreed with those obtained by equilibrium dialysis. Total testosterone concentrations for normal and hirsute women showed considerable overlap, but data on free testosterone concentrations in these populations were better resolved.
Subject(s)
Testosterone/blood , Ultrafiltration/methods , Adult , Female , Hirsutism/blood , Humans , Indicators and Reagents , Male , Pregnancy , Time Factors , TritiumABSTRACT
A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.
Subject(s)
Hydroxyindoleacetic Acid/urine , Chromatography, High Pressure Liquid/methods , Colorimetry/methods , Humans , Indicators and Reagents , Naphthols , Nitroso Compounds , Spectrophotometry, Ultraviolet/methodsABSTRACT
Some general guidelines can help in the assessment of clinical chemistry training and training programs. A clinical chemist must be, first of all, a good chemist, but to this must be added other knowledge and skills. A program that begins with a bachelor's degree in chemistry equivalent to the American Chemical Society's standards is proposed for the clinical chemistry technologist. The model provides more flexibility as the education proceeds toward the doctoral and postdoctoral levels and as the opportunities and responsibilities become increasingly more diverse. An essential portion of the training at all levels is experience in a clinical laboratory. It is strongly recommended that this be started early and be continued throughout the program. Certification by an independent agency (National Registry in Clinical Chemistry or American Board of Clinical Chemistry) is strongly recommended as a final step in all plans.
