Special Issues-04-01-2011

Special Issues

Many laboratory budgets do not allow the purchase of new ultrahigh-pressure liquid chromatography (UHPLC) systems, and workloads typically are not declining. Fast LC incorporates the use of faster mobile phase flow rates and smaller particles to achieve separations in less time and with equivalent resolution to traditional high performance liquid chromatography (HPLC).

William W. Carson, Ming Zhou, and Tom Kearney

Published methods for the determination of ibuprofen in biological fluids by liquid chromatography (LC)–UV or LC–mass spectrometry (MS)-MS have quantitation ranges consistent with the relatively high but typical ibuprofen dose (200–800 mg), generally having lower limits of quantitation in the low micrograms-per-milliliter range. For the analysis of plasma and synovial fluid samples from preclinical (miniature swine) studies utilizing a novel ibuprofen dosage form, LC–MS-MS methods were developed and validated over the 10–1000 ng/mL range. Ibuprofen undergoes biotransformation to ibuprofen acyl glucuronide and sublimes under routine bioanalytical sample handling conditions. Procedures were implemented to minimize the impact of these potential liabilities.

Special Issues

April 01, 2011

New chromatography technology for the analytical laboratory is being driven by the ever expanding need and challenge to get more and better information faster, all in an economic climate where cost control is a primary concern. At the same time, samples have become more and more complex, detection limits are being driven increasingly lower, and regulatory concerns, particularly for biotherapeutics, are being increasingly scrutinized.

The growing market for biotherapeutic peptides and the development of quantitative methods for those analytes has brought to light the challenges facing the analysis of this broad range of compounds. Market forces and regulatory requirements are encouraging analytical groups to develop methodologies that are time- and cost-effective, while still producing assays that are sensitive enough to cope with biological matrices.

Screening with multiple orthogonal HPLC methods provides a comprehensive alternative to single method drug impurity profiling with their complementary selectivity. One key challenge of the approach is to track the peaks across the orthogonal chromatograms and identify all unique impurities.

High performance liquid chromatography (HPLC) with light absorbance detection (UV) is limited by the dependence of detector response on the structure of the analyte. Some detection techniques based on nebulization of the mobile phase and formation of Aerosol particles demonstrate an analyte independent response that approaches "universal."

A fast, selective, and reproducible high performance liquid chromatography (HPLC) method was developed and validated for the analyses of third-generation cephalosporin antibiotics, namely, ceftriaxone, cefixime, and cefdinir in human plasma. The analysis was carried out on a 150 mm Ã- 4.6 mm, 5.0-µm C18 column. The mobile phase used was 80:20 (v/v) 50 mmM phosphate buffer (pH 5.0)–methanol at a flow rate of 1.0 mL/min with 230-nm UV detection.