Evaluation Of Measurement Methods Research Articles

Direct measurement of individual human exposures and body burden: Research needs

Abstract Recent technological advances have made it possible for the first time to measure hundreds of toxic compounds in air, water, food, breath, blood, and urine at the concentrations encountered during normal daily activities. Monitoring studies need to be performed to capitalize on the opportunity to determine human exposure to these compounds, many of which are carcinogenic. Some additional development or evaluation of measurement methods is also required.

Evaluation of kit methods for measurement of total plasma cholesterol

The performance of 6 commercial kits for the measurement of total plasma cholesterol concentration, using enzymatic and chemical methods, was compared to the Lipid Research Clinics (LRC) method. Primary cholesterol standards, the purity of which was verified by spectrophotometry, thin-layer and gas chromatography by the Lipid Standardization Laboratory. Center for Disease Control, were used with the LRC method. All kits were used according to the manufacturers’ instructions and the standards recommended by each manufacturer were employed. Four frozen plasma pools (cholesterol range 1.8-9.0 mmol 1) were analysed in quadruplicate on 5 separate occasions. Accuracy and precision varied greatly amongst the kits. One enzymatic kit was consistently more accurate over the concentration range tested (reference value ± 3%). Overall, the enzymatic kits were more precise than the chemical kits (coefficient of variation 0.7-4.4%, vs 2.6-51%). Fresh plasma samples (n = 143-191; cholesterol range 4.9-12.5 mmol 1) obtained by venepuncture were analysed by each kit method and the LRC method. The mean difference in cholesterol concentration between each kit and the LRC method was within ± 0.5 mmol 1. Two enzymatic kits produced mean differences within ± 0.1 mmol 1 of LRC value. In 4 kits the difference varied with the cholesterol concentration (P Forty plasma pairs, obtained by venepuncture and fingerstick. were analysed by each kit method. Each enzymatic kit gave higher results for cholesterol in samples obtained by fingerstick as compared to those obtained by venepuncture (mean difference = 1.8%); the chemical kits gave no significant difference between plasma pairs.