Liquid chromatography tandem mass instrumentation

Instrumentation Liquid chromatography/tandem mass spectrometry (LC/ MS/MS). 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

Hager, J. W., and Le Blanc, J. C. (2003). High-performance liquid chromatography-tandem mass spectrometry with a new quadrupole/linear ion trap instrument. J. Chromatogr. A 1020 3-9. 

The growing availability of liquid chromatography-tandem mass spectrometry (LC-MS-MS) instruments to life science researchers has sparked an exponential flurry of efforts to discover new possibilities for the detection and quantitation of anabolic steroids in a wide variety of samples. Of all the directions and applications that have been explored to date, the area of greatest potential impact on science focuses on natural androgens in human samples, as opposed to synthetic anabolic steroids or animal samples. 

Thermo Scientific has introduced the 2D (or linear) liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/ MS/MS) ion trap mass spectrometer [11], known as the LTQ. The ion injection efficiency has been improved dramatically in the linear ion trap. In addition, ions in a linear ion trap are distributed along the central axis, rather than concentrated in the ion trap center for a 3D ion trap thus, both charge capacity and sensitivity in a linear ion trap have been increased significantly. Although at the present time there is neither commercial linear ion trap/GC/MS nor commercial linear ion trap/GC/ MS/MS instruments, a commercial version of a linear ion trap/GC/MS is expected to appear in the near future. 

Also, new-generation HPLC instrument which can exceed the pressure limitation of conventional equipment has been developed. This technique is ultra performance liquid chromatography (UPLC), where small particle size columns with 1.7 pm particle size in combination with high flow rates offers increased speed, resolution, and sensitivity [15]. Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has shown to be well suited for support of PK studies [16-19], Often, there is a need to improve the sensitivity of the assay for the determination of PK parameters, especially for very potent compounds, since lower amount is administrated, and also for compounds with low bioavailability. UPLC-MS/MS has shown decreased ion suppression and superior sensitivity, and has been successfully applied to PK studies for compounds with low bioavailability [20-22]. 

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is emerging as the preferred method for the identification and quantitation of illicit drags with many advantages over previous methods (GC and GC-MS). With increases in technology and instrumentation, samples can be measured directly with little or no sample... 

Haloperidol (Haldol), risperidone (Risperdal), loxapine (Loxitane), ziprasidone (Geodon), quetiapine (Seroquel), clozapine (Clozaril), aripiprazole (Abilify), and thioridazine (Mellaril) are targeted in this solid phase extraction (SPE), liquid chromatography— tandem mass spectrometry (LC-MS/MS) method. Both 9-hydroxy-risperidone (Paliperiodone), an equipotent metabolite, and mesoridazine (Serentil) are also included in this method as they are pharmacologically active major metabolites of risperidone and thioridazine, respectively (4). Olanzapine (Zyprexa) can be quantified with this instrument method however, the extraction method is a liquid-liquid basic extraction (see Note 1). Due to the subsequent administration of antidepressants in conjunction with antipsychot-ics, this method can also be used for many of the common antidepressants, including the selective serotonin reuptake inhibitors (SSRIs) (see Note 2). 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

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