Free cortisol method comparison: Ultrafiltation, equilibrium dialysis, tracer dilution, tandem mass spectrometry and calculated free cortisol

2011 ◽  
Vol 412 (11-12) ◽  
pp. 1043-1047 ◽  
Author(s):  
Carel J. Pretorius ◽  
John P. Galligan ◽  
Brett C. McWhinney ◽  
Scott E. Briscoe ◽  
Jacobus P.J. Ungerer
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Equilibrium Dialysis ◽  
Method Comparison ◽  
Tandem Mass ◽  
Free Cortisol ◽  
Calculated Free Cortisol ◽  
Tracer Dilution

Clinical utility of an ultrasensitive urinary free cortisol assay by tandem mass spectrometry

Steroids ◽  
2019 ◽  
Vol 146 ◽  
pp. 65-69 ◽  
Author(s):  
Amy Luo ◽  
El Taher M. El Gierari ◽  
Laura M. Nally ◽  
Lillian R. Sturmer ◽  
Dylan Dodd ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Clinical Utility ◽  
Urinary Free Cortisol ◽  
Tandem Mass ◽  
Free Cortisol

scholarly journals Iothalamate Quantification by Tandem Mass Spectrometry to Measure Glomerular Filtration Rate

2010 ◽  
Vol 56 (4) ◽  
pp. 568-574 ◽  
Author(s):  
Jesse C Seegmiller ◽  
Bradley E Burns ◽  
Abdul H Fauq ◽  
Naveen Mukhtar ◽  
John C Lieske ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Glomerular Filtration Rate ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Multiple Reaction Monitoring ◽  
Method Comparison ◽  
Tandem Mass

Abstract Background: Glomerular filtration rate (GFR) can be determined by measuring renal clearance of the radiocontrast agent iothalamate. Current analytic methods for quantifying iothalamate concentrations in plasma and urine using liquid chromatography or capillary electrophoresis have limitations such as long analysis times and susceptibility to interferences. We developed a liquid chromatography–tandem mass spectrometry (LC-MS/MS) method to overcome these limitations. Methods: Urine and plasma samples were deproteinized using acetonitrile and centrifugation. The supernatant was diluted in water and analyzed by LC-MS/MS using a water:methanol gradient. We monitored 4 multiple reaction monitoring transitions: m/z 614.8–487.0, 614.8–456.0, 614.8–361.1, and 614.8–177.1. We compared the results to those obtained via our standard capillary electrophoresis (CE-UV) on samples from 53 patients undergoing clinical GFR testing. Results: Mean recovery was 90%–110% in both urine and plasma matrices. Imprecision was ≤15% for the m/z 614.8–487.0 and 614.8–456.0 transitions over a 10-day period at 1 mg/L. Method comparison for 159 patient samples (53 clearances) provided the following Passing–Bablok regressions: plasma iothalamate LC-MS/MS (y) vs CE-UV (x), y = 0.99x + 0.36; urine iothalamate LC-MS/MS vs CE-UV, y = 1.01x + 0.31; corrected GFR LC-MS/MS vs CE-UV, y = 1.00x + 0.00. Interfering substances prevented accurate iothalamate quantification by CE-UV in 2 patients, whereas these samples could be analyzed by LC-MS/MS. Conclusions: Iothalamate can be quantified by LC-MS/MS for GFR measurement. This method circumvents potential problems with interfering substances that occasionally confound accurate GFR determinations.

scholarly journals Sample Multiplexing: Increased Throughput for Quantification of Total Testosterone in Serum by Liquid Chromatography-Tandem Mass Spectrometry

2020 ◽  
Vol 66 (9) ◽  
pp. 1181-1189 ◽  
Author(s):  
Julia D Colletti ◽  
Mildred M Redor-Goldman ◽  
Agustin E Pomperada ◽  
Amit K Ghoshal ◽  
William W Wu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Method Comparison ◽  
Total Testosterone ◽  
Tandem Mass ◽  
Limit Of Quantification ◽  
Chromatography Tandem Mass Spectrometry ◽  
Deming Regression ◽  
Liquid Chromatography Tandem Mass

Abstract BACKGROUND For high-volume assays, optimizing throughput reduces test cost and turn-around time. One approach for liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays is sample multiplexing, wherein the analyte of interest is derivatized in different specimens with reagents of different molecular weight (differential mass tagging). Specimens can then be combined and simultaneously analyzed within a single injection to improve throughput. Here we developed and validated a quantitative, sample-multiplexed LC-MS/MS assay for serum total testosterone (TT) based on this approach. METHODS For the sample-multiplexed assay, calibrators, controls, and patient specimens were first extracted separately. After mass tagging with either methoxyamine or hydroxylamine, they were combined and injected into the LC-MS/MS system. To evaluate assay performance, we determined limit of quantification (LOQ), linearity, recovery, and imprecision. A method-comparison study was also performed, comparing the new assay with the standard LC-MS/MS assay in 1574 patient specimens. RESULTS The method was linear from 2.5 to 2000 ng/dL, with accuracies from 93% to 104% for both derivatives. An LOQ of 1.0 ng/dL was achieved. Intra-assay and total CVs across 4 quality control concentrations were less than 10%. The assay demonstrated good agreement (Deming regression, 1.03x + 6.07) with the standard LC-MS/MS assay for the patient specimens tested (TT, 3 to 4862 ng/dL). CONCLUSION Sample multiplexing by differential mass tagging of TT increases LC-MS/MS throughput 2-fold without compromising analytical accuracy and sensitivity.

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