A simple, selective and sensitive isocratic HPLC method with triple quadrupole mass spectrometry detection has been developed and validated for simultaneous quantification of zopiclone and its metabolites in human plasma. The analytes were extracted using solid phase extraction, separated on Symmetry shield RP8 column (150 mm x 4.6 mm i.d., 3.5 microm particle size) and detected by tandem mass spectrometry with a turbo ion spray interface. Metaxalone was used as an internal standard. The method had a chromatographic run time of 4.5 min and linear calibration curves over the concentration range of 0.5-150 ng/mL for both zopiclone and N-desmethyl zopiclone and 1-150 ng/mL for zopiclone-N-oxide. The intra-batch and inter-batch accuracy and precision evaluated at lower limit of quantification and quality control levels were within 89.5-109.1% and 3.0-14.7%, respectively, for all the analytes. The recoveries calculated for the analytes and internal standard were > or = 90% from spiked plasma samples. The validated method was successfully employed for a comparative bioavailability study after oral administration of 7.5 mg zopiclone (test and reference) to 16 healthy volunteers under fasted condition.
[Show abstract][Hide abstract] ABSTRACT: Industrial chemicals, pesticides and other similar compounds are all known to be a burden for the environment. In high concentrations they can all affect the biological environment in a manner that is dangerous for organisms. The presence of pharmaceuticals and personal care products (PPCPs) in the environment are of great interest regarding to their potential toxicity. Pharmaceuticals and PPCPs are discovered in soil, sludge, sewage and in the adjacent aquatic environment. The aim of this study was to develop and optimize a hollow fiber liquid- phase microextraction (HF-LPME) method for extraction and pre-concentration of benzodiazepines and its metabolites in sewage water. Different parameters like donor- and acceptor phases, fibers and organic phases were to be tested. The compounds that was to be investigated in this study were chosen by looking at sales statistics for benzodiazepines in Norway over a three years period, 2005-2007. Some metabolites of the compounds were also included. The chosen compounds were zopiclone, zopiclone-d8, zopiclone N-oxide, N-desmethyl zopiclone hydrochloride, zolpidem, zolpidem-d6, alprazolam, alprazolam 5-oxide, 1-hydroxy alprazolam, midazolam, midazolam- d5 and 1`-hydroxy midazolam. Later in the project clonazepam and 7-aminoclonazepam were included. Sewage water samples were collected at Langnes Sewage Treatment Plant (STP), TromsÃ¸, before they were filtered and extracted by hollow fiber liquid phase microextraction and analysed on Ultra Performance Liquid Chromatography- Mass Spectrometry/ Mass Spectrometry (UPLC- MS/MS). Quantifiable amounds of zolpidem was found during the collection in January, midazolam and 1- hydroxyl midazolam were detectable. In April 1- hydroxy midazolam, midazolam and zolpidem were detectable.
[Show abstract][Hide abstract] ABSTRACT: Liquid chromatography coupled to atmospheric pressure ionization tandem mass spectrometry is currently the method of choice for the quantitative determination of drugs in biological matrices. The advantages of this technique include high specificity, sensitivity and throughput. However, co-eluting matrix components, which are not observed in the chromatogram, can have a detrimental effect on the analysis, since they can cause ion suppression or enhancement of the analyte. The evaluation of matrix effects on the quantitative analysis of drugs in biological fluids is an important and sometimes overlooked aspect of assay validation. In this review, the influence of matrix effects on bioanalytical LC-MS/MS methods is discussed and illustrated with some examples. In addition, possible solutions to reduce or eliminate matrix effects are highlighted. A literature overview of validated LC-MS/MS methods published from January till June 2008 is also included. Although matrix effects are investigated in most papers, there is no consensus on how matrix effects should be evaluated during method validation. In addition, the definition of specificity should be changed for LC-MS/MS based methods.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 02/2009; 877(23):2198-207. DOI:10.1016/j.jchromb.2009.01.003 · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Many components in biological matrices influence the result of an analysis, affecting assay sensitivity and reproducibility. Improved matrix management becomes critical as requirements for higher assay sensitivity and increased process throughput become more demanding. There are several robotic laboratory automation systems that are commercially available, which serve to minimize matrix interference by performing purification and extraction protocols. However, there is an unmet need of inline matrix effect reduction solutions to reduce the processing time and cost for automated sample preparation. In microfluidics, effective matrix management is essential for developing fully integrated systems capable of meeting these requirements. This review surveys current biological matrix management techniques for liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods and binding assays with a view toward building automatable processes. For some systems, simple sample-preparation methods, such as dilution and protein precipitation (PPT), are sufficient, whereas other systems require labor-intensive methods, such as liquid-liquid extraction (LLE) and solid-phase extraction (SPE). To achieve high throughput, PPT, LLE, and SPE have been adopted to 96-well-plate format. Online SPE has also been coupled with LC-MS/MS to automate sample preparation and analysis of urine, plasma, and serum matrices. However, offline processing of whole blood is still required to obtain plasma and serum. The ultimate goal of implementing sample preparation to reduce matrix effects within untreated sample is to achieve reproducibility and sensitivity required by the application; therefore, inline sample preparation integrated with molecular analysis will be highly significant for laboratory automation. Electrokinetic methods have the potential of handling whole-blood, urine, and saliva samples and can be incorporated into microfluidic systems for full automation. Optimization of analysis conditions and the use of appropriate standards have likewise assisted in reducing or correcting matrix effects and will also be discussed.
Journal of the Association for Laboratory Automation 06/2010; 15(3):233-242. DOI:10.1016/j.jala.2010.02.001 · 1.50 Impact Factor
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