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A simple and rapid liquid chromatography-tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the quantitation of indirubin-5-nitro-3′-monoxime (5-NIO) in rat plasma using 5-chloro-5′-chloro-indirubinoxime as the internal standard. The sample preparation involved protein precipitation using acetonitrile. Separation was achieved on an Xterra column C18 (2.1 mm × 50 mm, i.d. 5 µm) using a mixture of 0.1% formic acid-water/acetonitrile (18:82, v/v) as the mobile phase at a flow rate of 300 µL/min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization and multiple reaction monitoring (MRM) in negative ion mode. The total chromatographic run time was 2.5 min, and the calibration curves of 5-NIO were linear (correlation coefficient range: 0.9989–0.9999) over the concentration range of 0.2–2000 ng/mL in rat plasma. Also, the detection limit of the method was 0.05 ng/mL and it showed good accuracy and precision within the concentration range of 0.45–376 ng/mL. This validated method was successfully applied to estimating the pharmacokinetic parameters of 5-NIO following intravenous administration of 5-NIO to rats. [ABSTRACT FROM AUTHOR]

Abstract: A highly selective, sensitive, and robust liquid chromatography–tandem mass spectrometric method for the determination of 5-thio-d-glucose concentrations in rat and human plasma was developed and validated. The sample preparation procedure involved protein precipitation and solid phase extraction, which efficiently removed sources of interference present in the plasma. Chromatographic separation was obtained using an NH2-column with distilled water and acetonitrile as the mobile phase under gradient conditions. Detection was performed using tandem mass spectrometry equipped with an electrospray ionization interface in negative ion mode. The selected reaction monitoring (SRM) transitions for 5-thio-d-glucose and an internal standard (5-thio-d-glucose-13C6) were m/z 195→ m/z 105 and m/z 201→ m/z 108, respectively. The correlation coefficients of the calibration curves ranged from 0.9997 to 0.9999 over a concentration range from 10 to 3000ng/mL plasma. The validated method was successfully applied to a pharmacokinetic study in rats. [Copyright &y& Elsevier]