Quantitative analysis of naltrexone and 6beta-naltrexol in human, rat, and rabbit plasma by liquid chromatography-electrospray ionization tandem mass spectrometry with application to the pharmacokinetics of Depotrex in rabbits.

To improve the analysis of naltrexone and its primary metabolite 6beta-naltrexol, a sensitive and specific method for the analysis of subnanogram-per-milliliter concentrations of these analytes in human, rat, and rabbit plasma was developed utilizing liquid chromatography (LC) coupled to electrospray ionization (ESI) tandem mass spectrometry (MS-MS). Plasma samples were extracted utilizing a liquid-liquid extraction technique. Chromatographic separation was achieved using an isocratic solvent system consisting of dilute formic acid and methanol pumped through an ODS-AQ HPLC column.

Determination of riboflavin by high-performance liquid chromatography with riboflavin-depleted urine as calibration and control matrix.

A simple method, exposure to natural-light, was developed to remove riboflavin from urine to enhance its use as the biological matrix for the preparation of calibration and control samples. Riboflavin-depleted urine containing less than 1 ng/ml of riboflavin was used to validate a high-performance liquid chromatography with fluorescence detection method for the determination of urinary riboflavin. The linearity of the assay (r2=0.

A high-performance liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric method for determination of risperidone and 9-hydroxyrisperidone in human plasma.

Risperidone, a benzisoxazole derivative, is an antipsychotic agent used for the treatment of schizophrenia. We developed a liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS-MS) method with improved sensitivity, selectivity, and dynamic range for determination of risperidone and 9-hydroxyrisperidone in human plasma. A structural analogue of risperidone, RO68808 (5 ng/mL), is added as the internal standard to 1 mL of human plasma.

A liquid chromatographic-electrospray-tandem mass spectrometric method for quantitation of quetiapine in human plasma and liver microsomes: application to study in vitro metabolism.

Quetiapine is an atypical antipsychotic agent for the treatment of schizophrenia. After an oral dose it is absorbed rapidly and extensively metabolized in the liver, resulting in low plasma concentrations of the parent drug. A sensitive analytical method is needed.

Detection and time course of cocaine N-oxide and other cocaine metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Gas chromatography/mass spectrometry (GC/MS) is often used for detection and measurement of cocaine metabolites in biological specimens. However, cocaine N-oxide, a recently identified metabolite of cocaine, is thermally degraded when introduced into a GC/MS. The major degradation products are cocaine and norcocaine.

Stability of plasma gamma-hydroxybutyrate determined by gas chromatography-positive ion chemical ionization-mass spectrometry.

An effective method for the determination of gamma-hydroxybutyric acid (GHB) in human plasma is described that utilizes a simple liquid-liquid extraction procedure and gas chromatography-positive ion chemical ionization-mass spectrometry (GC-PCI-MS). The method has been used to study the stability of plasma GHB under several storage conditions. Following the extraction with acetonitrile, GHB and deuterated GHB (GHB-d(6)) were derivatized with N,O-bis[trimethylsilyl] trifluoroacetamide (BSFTA).

Quantitative analysis of selegiline and three metabolites (N-desmethylselegiline, methamphetamine, and amphetamine) in human plasma by high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

This report describes a sensitive and specific high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method for the detection of subnanogram concentrations of selegiline and its three principle metabolites, N-desmethylselegiline, methamphetamine, and amphetamine, in human plasma. The assay has a dynamic range of 0.1-20 ng/mL for selegiline and N-desmethylselegiline (norselegiline) and 0.

A liquid chromatographic-electrospray ionization-tandem mass spectrometric method for determination of buprenorphine, its metabolite, norbuprenorphine, and a coformulant, naloxone, that is suitable for in vivo and in vitro metabolism studies.

A liquid chromatographic-electrospray ionization-tandem mass spectrometric method has been developed and validated for determination of the antiabuse medication, buprenorphine, its primary metabolite, norbuprenorphine, and a proposed coformulant, naloxone. The method uses deuterated internal standards and a simple liquid-liquid extraction. Mass spectrometry employed selected reaction monitoring of the transitions of m/z 468 to 396 for buprenorphine, 472 to 400 for [2H4]buprenorphine, 414 to 101 for norbuprenorphine, 423 to 110 for [2H9]norbuprenorphine, 328 to 310 for naloxone, and 345 to 327 for its internal standard, [2H3]naltrexone.