Evaluation of a bracketing calibration-based isotope dilution liquid chromatography–tandem mass spectrometry candidate reference measurement procedure for 17α-hydroxyprogesterone in human plasma

Development of a designed comparison method based on isotope dilution liquid chromatography–tandem mass spectrometry for determining plasma renin activity and its clinical assessment of renin activity stability in plasma

“…A bracketing calibration was used to quantify Ang1. 16 Appropriate amounts of Ang1 standard and IS working solutions were exactly weighed using an electronic balance and fully mixed to produce the six-point bracketing calibrators with analyte-to-IS ratios ranging from 0.25 to 6. 60 mL of generation buffer was added to 200 mL of plasma, and the mixture was fully agitated and then incubated at 37 °C for 3 h. 5 mL of formic acid and 50 mL of IS solution were added to stop the incubation reaction.…”