Coupling liquid chromatography - mass

Dear GJ, Plumb RS, Sweatman BC et al. (2000) Mass directed peak selection, an efficient method of drug metabolite identification using directly coupled liquid chromatography-mass spectrometry-nuclear magnetic resonance spectroscopy. J Chromatogr B Biomed Sci Appl 748 281-293... 

Detection by on-line coupled liquid chromatography-mass spectrometry (LC-MS) is at present at an experimental stage. The technique and instrumentation in LC-MS is improving rapidly at present, and recent reviews on the subject should be consulted for up-to-date information. 

G. S. Rule, A. V. Moi dehai and J. Henion, Determination of carbofuran by on-line immunoaffinity cliromatography with coupled-column liquid chromatography/mass spectrometiy . Aim/. Chem. 66 230-235 (1994). 

The ion spray liquid chromatography/mass spectrometry (LC-MS) interface coupled via a postsuppressor split with an ion chromatography (IC) has been used in the analysis of alcohol sulfates. The IC-MS readily produces the molecular weight while the tandem mass spectrometric detection IC-MS-MS provides structural information [305]. 

Liquid Chromatography Mass Spectrometry Coupling Limit of Detection... 

Gu, S Du, Y Chen, J., Liu, Z Bradbury, E.M., Hu, C.A., Chen, X. (2004). Large-scale quantitative proteomic study of PUMA-induced apoptosis using two-dimensional liquid chromatography—mass spectrometry coupled with amino acid-coded mass tagging. J. Proteome Res. 3, 1191 1200. 

Opiteck, G.J., Jorgenson, J.W., MacNair, J.E., Moseley, M.A., 3rd (1997). Two-dimensional SEC/RPLC coupled to mass spectrometry for the analysis of peptides. Rapid separation and characterization of protein and peptide mixtures using 1.5 microns diameter non-porous silica in packed capillary liquid chromatography/mass spectrometry. Anal. Chem. 69, 2283-2291. 

Niederlander H.A.G. et al., 2006. High throughtput therapeutic drug monitoring of clozapine and metabolites in serum by online coupling of solid phase extraction with liquid chromatography-mass spectrometry. J Chromatogr B 834 98. 

P.J. Arpino, On-line liquid chromatography/mass spectrometry An odd couple, Trends Anal. Chem., 1 (1982) 154. 

Nowadays, ESI is the leading member of the group of atmospheric pressure ionization (API) methods and the method of choice for liquid chromatography-mass spectrometry coupling (LC-MS, Chap. 12). [10-13] Currently, ESI and MALDI (Chap. 10) are the most commonly employed ionization methods and they opened doors to the widespread biological and biomedical application of mass spectrometry. [5,10,11,13-17] Moreover, ESI serves well for the analysis of ionic metal complexes [18,19] and other inorganic analytes. [20-22]... 

Li C, Hong Y, Tan YX et al. Accurate qualitative and quantitative proteomic analysis of clinical hepatocellular carcinoma using laser capture microdissection coupled with isotope-coded affinity tag and two-dimensional liquid chromatography mass spectrometry. Mo/ Cell Proteomics 2004,3399-409. 

The number of detectors that are sensitive and selective enough to be applied online with LC is limited because the solvents used are not compatible, as in the case of immunochemical detection after reversed- or normal-phase LC. The technology of coupling is still under development and not yet available in a large number of laboratories not specialized in techniques such as LC-MS. Therefore, LC separations are frequently followed by offline detection. Confirmatory analysis of suspected liquid chromatographic peaks can be made possible by coupling liquid chromatography with mass spectrometry. Atmospheric-pressure chemical ionization LC-MS has been employed for the identification of six steroid hormones in bovine tissues (448). 

The system relies upon preliminary fractionation of the microbial crude extract by dualmode countercurrent chromatography coupled with photodiode array detection (PDA). The ultraviolet-visible (UV-Vis) spectra and liquid chromatography-mass spectrometry (LC-MS) of biologically active peaks are used for identification. Confirmation of compound identity is accomplished by nuclear magnetic resonance (NMR). Use of an integrated system countercurrent chromatography (CCC) separation, PDA detection, and LC-MS rapidly provided profiles and structural information extremely useful for metabolite identification (dereplication, Figure 14.1). 

B. Ardrey, Liquid Chromatography-Mass Spectrometry An Introduction (Chichester, UK Wiley, 2003) W. M. A. Niessen. Liquid Chromatography-Mass Spectrometry, 2nd ed (New York Marcel Dekker, 1999) M. S. Lee, LC/MS Applications in Drug Development (New York Wiley, 2002) J. Abian, Historical Feature The Coupling of Gas and Liquid Chromatography with Mass Spectrometry, J. Mass Spectrom. 1999, 34, 157. 

The use of liquid chromatography-mass spectrometry (LC-MS) is becoming more popular because of the increasing number of LC-MS interfaces commercially available thermospray (TSP), particle beam (PB), and atmospheric pressure ionization (API). Coupled with mass spectroscopy, HPLC provides the analyst with a powerful tool for residue determination. 

Corcoran, O., Nicholson, J. K., Lenz, E. M., Abou-Shakra, F., Castro-Perez, J., Sage, A. B., and Wilson, I. D. (2000). Directly coupled liquid chromatography with inductively coupled plasma mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry for the identification of drug metabolites in urine Application to diclofenac using chlorine and sulfur detection. Rapid Commun. Mass Spectrom. 14 2377-2384. 

Figure 4.5 Separation of two trialkyl lead and three organomercury species. Column 1.5mm i.d. x 5cm long flow rate lOOpimirT1 mobile phase 5mM ammonium pentanesulfonate in 20 80 v/v ACN-H20 (pH 3.4) injection volume 2jul, sample size, 40 pg (as Pb) for (Me)3Pb+, 80 pg (as Pb) for (Et)3Pb+ and 2 ng (as Hg) for each of the organomercury species. Taken from Speciation of mercury and lead compounds by microbore column liquid chromatography inductively coupled plasma chromatography mass spectrometry (Shum ef a/. 1992).

Shum, S.C.K., Pang, H. and Houk, R.S. (1992) Speciation of mercury and lead compounds by microbore column liquid chromatography inductively coupled plasma chromatography mass spectrometry. Anal. Chem., 64, 2444—2450. 

They are still the workhorses of coupled mass spectrometric applications, as they are relatively simple to run and service, relatively inexpensive (for a mass spectrometer), and provide unit mass resolution and scanning speeds up to approximately 10,000 amu/s. This even allows for simultaneous scan/ selected ion monitoring (SIM) operation, in which one part of the data acquisition time is used to scan an entire spectrum, whereas the other part is used to record the intensities of selected ions, thus providing both qualitative information and sensitive quantitation. They are thus suitable for many GC-MS and liquid chromatography-mass spectrometry (LC-MS) applications. In contrast to GC-MS with electron impact (El) ionization, however, LC-MS provides only limited structural information as a consequence of the soft ionization techniques commonly used with LC-MS instruments [electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)]. Because of this limitation, other types of mass spectrometers are increasingly gaining in importance for LC-MS. 

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