Therapeutic drug monitoring of cefepime with micellar electrokinetic capillary chromatography: Assay improvement, quality assurance, and impact on patient drug levels

The improvement and performance of a micellar electrokinetic capillary chromatography assay for cefepime in human serum and plasma with a 50 μm id fused-silica capillary elongated from 40 to 60 cm is reported. Sample preparation with dodecylsulfate protein precipitation at pH 4.5, the pH 9.1 separation medium and the applied voltage were as reported previously[16]. The change resulted in a significant lower current, higher resolution and increased detection time intervals. The performance of the assay with multi-level internal calibration was assessed with calibration and control samples. Quality assurance data of a two year period assessed under the new conditions demonstrated the robustness of the assay. In serum samples of patients who received both cefepime and sulfamethoxazole, cefepime could not be detected due to the inseparability of the two compounds. The presence of an interference can be recognized by an increased peak width (width > 0.2 min), the appearance of a shoulder or an unresolved double peak. The patient data gathered during a three year period reveal that introduction of therapeutic drug monitoring led to a 50% reduction of the median drug level. The data suggest that therapeutic drug monitoring can help to minimize the risk of major adverse reactions and to increase drug safety on an individual basis. This article is protected by copyright. All rights reserved.

Functional specifications for an advanced chromatography automation system /

Mode of access: Internet.

Ion chromatography of anions /

"March 1980."

User's guide for the gas chromatography automation system /

Mode of access: Internet.

Performance tests for the evaluation of computerized gas chromatography/mass spectrometry equipment and laboratories /

"April 1980"--Cover.

Chromatography, or, A treatise on colours and pigments, and of their powers in painting, &c. /

Color samples on front. hand-colored.

Method of analysis and quality-assurance practices for determination of pesticides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry at the U.S. Geological Survey California District Organic Chemistry Laboratory, 1996-99 /

Mode of access: Internet.

Inorganic chromatography.

Mode of access: Internet.

Development and Application of Improvements to the Tile-based Fisher Ratio Method and Fundamental Instrument Considerations for Non-targeted Analysis using Two-dimensional Gas Chromatography

Thesis (Ph.D.)--University of Washington, 2016-06

Measurement of free drug and clinical end-point by high-performance liquid chromatography-mass spectrometry: Applications and implications for pharmacokinetic and pharmacodynamic studies

Free drug measurement and pharmacodymanic markers provide the opportunity for a better understanding of drug efficacy and toxicity. High-performance liquid chromatography (HPLC)-mass spectrometry (MS) is a powerful analytical technique that could facilitate the measurement of free drug and these markers. Currently, there are very few published methods for the determination of free drug concentrations by HPLC-MS. The development of atmospheric pressure ionisation sources, together with on-line microdialysis or on-line equilibrium dialysis and column switching techniques have reduced sample run times and increased assay efficiency. The availability of such methods will aid in drug development and the clinical use of certain drugs, including anti-convulsants, anti-arrhythmics, immunosuppressants, local anaesthetics, anti-fungals and protease inhibitors. The history of free drug measurement and an overview of the current HPLC-MS applications for these drugs are discussed. Immunosuppressant drugs are used as an example for the application of HPLC-MS in the measurement of drug pharmacodynamics. Potential biomarkers of immunosuppression that could be measured by HPLC-MS include purine nucleoside/nucleotides, drug-protein complexes and phosphorylated peptides. At the proteomic level, two-dimensional gel electrophoresis combined with matrix-assisted laser desorption/ionisation time-of-flight (TOF) MS is a powerful tool for identifying proteins involved in the response to inflammatory mediators. (C) 2003 Elsevier Science B.V. All rights reserved.

The measurement of nicotine in human plasma by high-performance liquid chromatography-electrospray-tandem mass spectrometry

The authors describe a reverse-phase high-performance liquid chromatography-electrospray-tandem mass spectrometry method for the measurement of nicotine in human plasma. Samples (500 muL) with added deuterium-labeled d(3)-nicotine as an internal standard (IS) were treated with a 2-step process of ether extraction (6 mL) followed by back-extraction into 0.1% formic acid (50 muL). Chromatography was performed on a phenyl Novapak column with a mobile phase consisting of 50% 10 mM ammonium fortriate (pH 3.3) and acetonitrile (50:50, vol/vol). A flow rate of 0.2 mL/min resulted in a total analysis time of 5 minutes per sample. Mass spectrometric detection was by selected reactant monitoring (nicotine m/z 163.2 --> 130.2; IS m/z 166.2 --> 87.2). The assay was linear from 0.5 to 100 mug/L (r > 0.993, n = 9). The accuracy and imprecision of the method for quality control sampleswere 87.5% to 113% and < 10.2%, respectively. Interday accuracy and imprecision at the limit of quantification (0.5 mug/L) was 113% and 7.2% (n = 4). The process efficiency for nicotine in plasma was > 75%. The method described has good process efficiency, stabilized nicotine, avoided concentration steps, and most importantly minimized potential contamination. Further, we have established that water-based standards and controls are interchangeable with plasma-based samples. This method was used successfully to measure the pharmacokinetic profiles of subjects involved in the development of an aerosol inhalation drug delivery system.

Determination of binding constants by affinity chromatography

This review summarizes developments in the use of affinity chromatography to characterize biospecific interactions in terms of reaction stoichiometry and equilibrium constant. In that regard, the biospecificity incorporated into the design of the experiment ensures applicability of the method regardless of the sizes of the reacting solutes. By the adoption of different experimental strategies (column chromatography, simple partition equilibrium, solid-phase immunoassay and biosensor technology protocols) quantitatiative affinity chromatography can be used to characterize interactions governed by an extremely broad range of binding affinities. In addition, the link between ligand-binding studies and quantitative affinity chromatography is illustrated by means of partition equilibrium studies of glycolytic enzyme interactions with muscle myofibrils. an exercise which emphasizes that the same theoretical expressions apply to naturally occurring examples of affinity chromatography in the cellular environment. (C) 2004 Elsevier B.V. All rights reserved.