Liquid chromatography-multiple reaction monitoring

Detection and quantitation of PAH-derived DNA adducts requires authentic synthetic standards to act as internal standards and therefore a knowledge of adduct structure. Adduct structure can often be used to provide information on the mechanism of PAH activation that must have occurred. Unfortunately, this is quite challenging since PAH-DNA adducts can be difficult to detect and quantitate since they may be present in only 1 108 nucleotides. State-of-the art methods requiring stable isotope dilution liquid chromatography/multiple reaction monitoring/mass spectrometry (LC/MRM/MS) are necessary to provide sufficient sensitivity to detect these adducts reliably. Additionally, PAH-DNA adducts have different rates of repair and yield different rates of mutation. Thus, each adduct must be assessed so that it can be ranked according to its half-life and miscoding potential. 

Modern triple quadrupole instruments can rapidly switch between many SRM transitions within a single acquisition cycle (MRM), enabling the measurement of multiple analytes simultaneously. It is critical to choose a unique molecular ion and product ion pair (the SRM transition ) for specific monitoring of the targeted analyte. An example of liquid chromatography-multiple reaction monitoring (LC-MRM) analysis of midazolam and its two major metabolites, T-hydroxymidazolam and 4-hydroxy midazolam, is shown in Figure 6.2 [18]. 

Agger SA, Mamey LC, Hoofnagle AN. Simultaneous quantification of apoUpoprotein A-I and apoUpoprotein B by liquid-chromatography—multiple- reaction-monitoring mass spectrometry. Clin Chem 2010 56 1804-13. 

Yeo, T.H., Ho, M.L., Loke, W.K., 2008. Development of a liquid chromatography-multiple reaction monitoring procedure for concurrent verification of exposure to different forms of mustard agents. J. Anal. Toxicol. 32, 51 6. 

Figure 5.65 LC-UV and LC-MS-MS (multiple-reaction monitoring (MRM)) traces from the analysis of a enzymatically digested solution of 100 p,g salmon testes DNA (for nomenclature, see text). Reprinted by permission of Elsevier Science from Comparison of negative- and positive-ion electrospray tandem mass spectrometry for the liquid chromatography-tandem mass spectrometry analysis of oxidized deoxynucleosides , by Hua, Y., Wainhaus, S. B., Yang, Y., Shen, L., Xiong, Y., Xu, X., Zhang, F., Bolton, J. L. and van Breemen, R. B., Journal of the American Society for Mass Spectrometry, Vol. 12, pp. 80-87, Copyright 2000 by the American Society for Mass Spectrometry.

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

LC/MS/MS. LC/MS/MS is used for separation and quantitation of the metabolites. Using multiple reaction monitoring (MRM) in the negative ion electrospray ionization (ESI) mode, LC/MS/MS gives superior specificity and sensitivity to conventional liquid chromatography/mass spectrometry (LC/MS) techniques. The improved specificity eliminates interferences typically found in LC/MS or liquid chro-matography/ultraviolet (LC/UV) analyses. Data acquisition is accomplished with a data system that provides complete instmment control of the mass spectrometer. 

Gergov M, Ojanpera I, Vuori E. 2003. Simultaneous screening for 238 drugs in blood by liquid chromatography-ionspray tandem mass spectrometry with multiple-reaction monitoring. J Chromatogr B 795 41. 

Fig. 2.2.9 High-performance liquid chromatography-tandem mass spectrometric analysis of AdoMet and AdoHcy. The analytes were evaluated by multiple reaction monitoring with the following transitions m/z 399 -> 250 for AdoMet m/z 402 -> 250 for the internal standard, tridenterated AdoMet (AdoMet +3) m/z 385 -> 135 for AdoHcy m/z 390 ->- 135 for the internal standard, pentadenterated AdoHcy (AdoHcy+5). Mass spectrometric conditions are described in the text. TIC total ion current, SRM selected reaction monitoring (Figure courtesy of Dr. Ries Duran, Amsterdam)...

Homocarnosine is a dipeptide of GABA and L-histidine. After deproteinizing the sample with ethanol, the mixtures are centrifuged. The clear supernatant is evaporated to dryness and derivatized with butanol. The sample is evaporated to dryness and redissolved in the mobile phase. The homocarnosine-butyl derivatives (Fig. 2.3.4) are quantified using liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS) operating in the positive mode. With multiple reaction monitoring (MRM), the transitions of m/z 297.0 to m/z 212.0 for homocarnosine and m/z 299.0 to m/z 212.0 for 2H2-L-homocarnosine are quantified. 

Coupling of liquid chromatography with mass spectrometry can provide unequivocal on-line spectrometric identification of anthelminthic residues in animal-derived foods. Typical applications of such techniques include the confirmation of moxidectin residues in cattle fat by liquid chromatography-thermospray mass spectrometry (352), and the confirmation of eprinomectin residues in bovine liver tissue by liquid chromatography, electrospray ionization, and multiple reaction monitoring in the MS-MS mode with positive ion detection (370). 

DE, two-dimensional gel electrophoresis WB, Western blot MS, mass spectrometry LC, liquid chromatography 2DE DICE, two-dimensional difference gel electrophoresis, SRM, selected-reaction monitoring MRM, multiple reaction monitoring AQUA, absolute protein quantitation SMIM, selected MS/MS ion monitoring. ... 

Gschwend MH, Arnold P, Ring J, Martin W (2006) Selective and sensitive determination of amisulpride in human plasma by liquid chromatography-tandem mass spectrometry with positive electrospray ionisation and multiple reaction monitoring. J Chromatogr B Analyt Technol Biomed Life Sci 831(1-2) 132-139. doi S1570-0232(05)00890-l [pii] 10.1016/j.jchromb.2005.11.042... 

High-performance liquid chromatography-tandem mass spectrometry method for the determination of gemifloxacin in human plasma was based on the protein precipitation of plasma samples with acetonitrile containing [ C Ha] gemifloxacin as an internal standard. The supernatant was injected onto a PLRP-S column without any further clean-up. The mass spectrometer was operated in positive ion mode, and the ions were detected in multiple reaction-monitoring (MRM) mode. The assay requires 50 gl of plasma and is precise and accurate within the range 10-5000 ng/ml [15]. 

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed to detect tumor-promoting diterpene esters of the tigliane and ingenane types within plant extracts. Fractionation on a Cig HPLC column was followed by MS-MS-multiple reaction monitoring (MRM). 

Liquid chromatography, coupled with mass spectrometry and tandem mass spectrometry (LC-MS/MS), is a universal technique for determining toxins in food. The first multiple reaction monitoring (MRM) method for polyether marine toxins was used for the determination of DSP toxins and this technique has been successfully applied to the simultaneous determination of various groups of polyether toxins in shellfish (Draisci et al., 1998, 1999). MRM involves the selection of a precursor ion and its product ion from CID fragmentations and it is highly selective. For azaspiracids, the first validated LC-MS/MS method was developed for the determination of AZAl... 

TISP, turbo ion spray MRM, multiple reaction monitoring UHPLC, ultra-high-pressure liquid chromatography TOP, time-of-flight mass analyzer ISP, ion spray SRM, selected reaction monitoring ESI, electrospray interface APCI, Atmospheric pressure chemical ionization. 

Nakanishi, H., lida, Y., Shimizu, T. and Taguchi, R. (2009) Analysis of oxidized phosphatidylcholines as markers for oxidative stress, using multiple reaction monitoring with theoretically expanded data sets with reversed-phase liquid chromatography/tandem mass spectrometry. J. Chromatogr. B 877, 1366-1374. 

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