Comparison of Performance between the Elecsys 4th and 5th Generation STAT Cardiac Troponin T Immunoassays.

OBJECTIVE: To evaluate the analytical and clinical performance of the 5th GEN cTnT assay by comparing it with the 4th GEN assay. METHODS: Imprecision, analytical measurement range (AMR), reference interval, and quantitative comparison were studied. Qualitative comparisons of the two assays for randomly selected patients with the cTnT test orders and patients with elevated N-terminal proB-type natriuretic peptide (NT-proBNP), decreased estimated glomerular filtration rate (eGFR), and increased procalcitonin were performed. RESULTS: Within-run and between-run CVs of the 5th GEN assay were 0.6-2.3% and 3.1-5.0% with AMR of 8-10,000 ng/L and reference interval of <19 ng/L. Regression analysis of the two assays showed linear relationship: y (5th GEN)=0.899x (4th GEN)+26, r=0.9993 with a positive bias of the 5th GEN assay in samples with cTnT <150 ng/L and a negative bias in samples with cTnT >500 ng/L compare to the 4th GEN assay. Agreement was 88.1% (95% CI: 80.4 to 93.1%) between the two methods according to the 99th percentile threshold. In patients with elevated NT-proBNP, decreased eGFR, and increased procalcitonin, agreements were 79.4%, 92.7%, and 100%. CONCLUSION: The 5th GEN cTnT assay demonstrates excellent precision and acceptable AMR. Compared to the 4th GEN assay, the 5th GEN assay shows a negative bias for samples with cTnT >500 ng/L but a positive bias for samples with cTnT <150 ng/L and identifies more patients with elevated cTnT.

Automated Measurement of Plasma Cell-Free Hemoglobin Using the Hemolysis Index Check Function.

BACKGROUND: The Roche Cobas chemistry analyzer's hemolysis index (HI) check function can directly report hemoglobin (Hb) concentrations. We aimed to validate the HI check function for the measurement of plasma cell-free Hb. METHODS: Plasma samples (6 µl) were taken by the analyzer and diluted in normal saline to measure the absorbance for Hb at 570 and 600 nm. Hb concentrations were calculated based on the molar extinction coefficient. Imprecision, lower limit of quantification (LLOQ), and analytical measurement range (AMR) of the assay were evaluated. The accuracy was determined by comparing the results between the new method and an existing spectrophotometric method. We further studied interference of icterus and lipemia and carryover. The performance of the assay in proficiency testing was also evaluated. The reference range was transferred from the existing method. RESULTS: Within-run and total CVs were 1.7%-4.2% and 2.1%-7.0%, respectively (n = 20). The LLOQ was 11 mg/dL (CV = 8.1%) with the upper limit of AMR of 506 mg/dL. The results of the new method correlated well with the existing reference assay: Y (new method) = 0.974 x (reference method) + 4.9, r = 0.9990, n = 52. Bilirubin with a concentration up to 60 mg/dL and lipemic index up to 389 did not show significant interference. No significant carryover was detected. The average standard deviation index in proficiency testing was 0.03 ± 0.29. The reference range was <22 mg/dL. CONCLUSIONS: Plasma cell-free Hb measurement using the HI check function meets the analytical requirements of the plasma cell-free Hb assays. It is simple and cost-effective.

Removal of PCBs from a Contaminated Soil Using CF-Systems® Solvent Extraction Process.

The U.S. Environmental Protection Agency's (EPA) Superfund Technical Assistance Response Team (START) in cooperation with EPA's Superfund Innovative Technology Evaluation (SITE) program evaluated a pilot scale solvent extraction process developed by CF-Systems. This process uses liquefied propane to extract organic contaminants from soils, sludges, and sediments. A pilot-scale evaluation was conducted in Golden, CO at Hazen Research, Inc., using CF-Systems' trailer-mounted organics extraction unit. Approximately 1,000 pounds of soil, with an average poly-chlorinated biphenyl (PCB) concentration of 260 mg/kg, was obtained from a remote Superfund site. Six 100-pound batches of the contaminated soil were extracted using multiple extraction sequences. Three of the six batch runs were subjected to three extraction sequences each, so that process variability could be evaluated. Results showed that PCB removal efficiencies varied between 91.4 and 99.4%, with the propane-extracted soils retaining low concentrations of PCBs (19.0-1.8 mg/kg). Removal efficiencies of oil and grease (O&G) were found to be 96.0 to 99.6% with propane-extracted soils retaining O&G concentrations from 279 to <20 mg/kg. Overall extraction efficiency was found to be dependant upon the numberof extraction cycles used.