Control Coefficient Of Variation Research Articles

A User-Friendly Sample Preparation Alternative for Manual and Automated LC-MS/MS Quantification of Testosterone.

We describe an LC-MS/MS method for serum testosterone using a novel extraction media, AC Extraction Plate™ (AC Plate,Tecan Schweiz). The AC Plate principle is essentially that of a liquid-liquid extraction (LLE) but employs a stationary nonpolar phase coated on the wells of 96-well plates instead of a nonmiscible organic solvent for partitioning testosterone out of serum, leaving interfering substances behind. This low complexity sample preparation protocol has been validated for and used in production in our laboratory with both manual and automated liquid handling. The primary advantage of this method is the highly reproducible nature of an extraction method that does not require LC-MS/MS expertise or specialized extraction equipment. We modified the existing vendor application and validated the method for matrix effect, recovery, precision, trueness [accuracy relative to certified reference material (CRM)], specificity, reportable range, sample stability, various sample containers, and correlation with other methods.Method performance is excellent, with a reportable range of 4-750ng/dL, between-day quality control coefficient of variation (CV) over 12months of <8%, mean accuracy of <4.0% bias against CRM, no interference from hemolysis, icterus, lipemia, serum separator tube gel, or common steroids/metabolites, and mean bias of 1.3% versus 4 other LC-MS/MS testosterone methods. An investigation of calibration stability and robustness supports sparse (3 versus 6 calibrators) and/or historical calibration for routine use.

生物応答を用いた排水試験法案の検証と事業場排水の実態調査

In view of developing a bioassay for use into effluent management system in Japan, short-term toxicity tests using fish, daphnids, and algae were selected as a battery of bioassays, which evaluate the integrated effect of effluent, and "a draft protocol of bioassays for effluent testing" has been prepared. To examine the robustness, sensitivity and reproducibility of the draft protocol, we conducted an inter-laboratory trial where the same effluent was tested by 9 laboratories in Japan. No observed effect concentrations (NOEC) of the test effluent in all the laboratories were within the median +/-1 dilutions, suggesting that the variability between laboratories was at acceptable level. Furthermore, testing of reference chemicals by 10 testing laboratories showed that the reproducibility of the bioassays was relatively higher than that exhibited in the inter-laboratory validation of similar bioassays conducted by US EPA. However, the percentage of minimum significant difference (PMSD) and control coefficient of variation (CV) in the almost all the Japanese laboratories were at acceptable levels (as appears in the US EPA report), indicating that the intra-laboratory precision and the sensitivity of each test was sufficient. We investigated the value of using IC20 for fish, IC25 for daphnids, and IC5 for algae as an alternative to NOEC. With this approach, toxicity survey of 91 effluent samples conducted from 2008 to 2013 found that 36% of effluents were toxic to at least one of the three test species even after 10-fold dilution. The test species that demonstrated toxic effects were different in each sample; thus, we suggest that effluent toxicity evaluation should be based on more than one species due to different sensitivities.

Test-strip method for measuring lactate in whole blood.

We have developed a dry reagent strip system for measuring lactate in whole blood. The test strip contains lactate oxidase (no EC number assigned), horseradish peroxidase (EC 1.11.1.7), and N-ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine. The system is designed to measure with a reflectometer the color that developed in the test strip, although the lactate concentration can be estimated without the reflectometer. The between-run coefficients of variation for controls at three concentrations were 2.9-5.3%. The lactate concentrations in blood samples from healthy subjects before and after exercise correlated well (r = 0.97) with the results measured by the comparison method with the use of lactate oxidase. This dry reagent strip system provides a convenient and rapid test for measuring blood lactate in clinical and sports medicine.