Multiple reaction ion monitoring

COWARD L, KIRK M, ALBIN N and BARNES s (1996) Analysis of plasma isoflavones by reversed-phase HPLC-multiple reaction ion monitoring-mass spectrometry. Clin Chim Acta. 247 (1-2) 121-42. 

Fig. 2.73. HPLC-MS-MS analysis of a methanolic extract of hops, peaks 1 = isoxanthohumol 2 = xanthohumol 3 = 2, 4-dihydroxy- chalcone (internal standard) 4 = 8-prenylnaringenin 5 = desmethylxanthohumol 6 = 6-prenylnaringenin 7 = 3 geranylchalconaringenin 8 = 6-geranylnaringenin. Prenylflavomoids were detected in a single HPLC run by multiple-reaction ion monitoring vertical lines in the panels indicate start of a new scanning period. For other details see text. Reprinted with permission from. J. F. Stevens, et al. [191].

Measurement of the isoflavonoids and their metabolites in urine from those consuming a heavy soy diet can be carried out by HPLC-UV analysis (Franke and Custer, 1994) as well as HPLC-MS. In the latter method, multiple reaction ion monitoring (MRM) is used, combining each parent molecular ion with a specific daughter ion produced by CID. The data from the two methods are significantly... 

Figure 5.64 LC-UV and LC-MS-MS (multiple-reaction monitoring (MRM)) traces from the analysis of a synthetic mixture of four native and five oxidized deoxynucleosides (for nomenclature, see text). Reprinted by permission of Elsevier Science from Comparison of negative- and positive-ion electrospray tandem mass spectrometry for the liquid chromalography-landem mass speclrometry 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, Copyrighl 2000 by Ihe American Society for Mass Spectrometry.

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. 

Electrospray (Turbo lonSpray), negative ion mode MS/MS with multiple reaction monitoring (MRM) -4500 V... 

Once the analyte has been identified and characterized, it is possible to determine its quantity. This is important information in a lot of fields and in cultural heritage in particular. There are specific experimental set-ups for quantitative analysis, such as selected ion monitoring (SIM) and multiple reaction monitoring (MRM). By considering that MS is highly sensitive, it is possible to carry out quantitative determinations of compounds at trace level.[7,8]... 

SIM, selected ion monitoring SRM, selected reaction monitoring MRM, multiple reaction monitoring. 

Various analyzers have been used to analyze phenolic compounds. The choice of the MS analyzer is influenced by the main objective of the study. The triple quadrupole (QqQ) has been used to quantify, applying multiple reaction monitoring experiments, whereas the ion trap has been used for both identification and structure elucidation of phenolic compounds. Moreover, time-of-flight (TOF) and Fourier-transform ion cyclotron resonance (FT-ICR) are mainly recommended for studies focused on obtaining accurate mass measurements with errors below 5 ppm and sub-ppm errors, respectively (Werner and others 2008). Nowadays, hybrid equipment also exists, including different ionization sources with different analyzers, for instance electrospray or atmospheric pressure chemical ionization with triple quadrupole and time-of-flight (Waridel and others 2001). 

The LC-MS/MS technique has been used to quantify and identify phenolic compounds. In order to quantify, multiple reaction monitoring (MRM), in which there is a combination of the precursor ion and one of its daughter fragments, is used to characterize a particular compound. This behavior should be as specific as possible in samples with a complex mixture of phenolic compounds. This technique has been largely used to quantify phenolic compound metabolites in urine and plasma (Urpf-Sarda and others 2005, 2007). In this context, LC-ESI-MS/MS with negative mode has been applied for the identification of a variety of phenolic compounds in a cocoa sample (Sanchez-Rabaneda and others 2003 Andres-Lacucva and others 2000). 

FIGURE 1.9 Multiple reaction monitored ion chromatograms for desloratadine (top), 3-hydroxydesloratadine (middle), and phosphatidylcholine monoester (bottom) during post-column infusion and subsequent injection of a SPEC(R) MPl-extracted control blank plasma sample.111 (Reproduced with permission from Elsevier.)... 

MS condition — An API 4000 equipped with a Turbo Ionspray from Applied Biosystems was used as the mass detector and [M + NH4]+ was chosen as the precursor ion for multiple reaction monitoring (MRM) due to the lack of protonated molecular ions. A transition of m/z 434.4 — 273.2 was chosen for paricalcitol and m/z 450.5 —> 379.2 was selected for the structure analog internal standard. 

MS condition — An API 3000 equipped with a Turbo Ionspray from Applied Biosystems was used as the mass detector. [M - II was chosen as the precursor ion for multiple reaction monitoring... 

Selected Reaction Monitoring (SRM) Data acquired from specific product ions corresponding to m/z selected precursor ions recorded via two or more stages of mass spectrometry. Selected reaction monitoring can be preformed as tandem mass spectrometry in time or tandem mass spectrometry in space. The term multiple reaction monitoring is deprecated [1],... 

Note SRM is preferably performed on triple quadrupole, quadrupole ion trap, and Q-TOF hybrid instruments due to their ease of setting up the experiment and to their speed of switching between channels if monitoring of multiple reactions plays a role. 

Skutlarek D, Faerber H, lippert F, Ulbrich A, Wawrzun A, Buening-Pfaue H (2004) Determination of glucosinolate profiles in Chinese vegetables by precursor ion scan and multiple reaction monitoring scan mode (LC-MS/MS). Eur Food Res Technol 219 643-649... 

GC/MS(/MS) is also popular for quantifying DBFs. Selected ion monitoring (SIM) or multiple reaction monitoring (MRM) mode are used with GC/MS and GC/ MS/MS, respectively, to maximize the sensitivity and provide low detection limits. Some EFA Methods utilize GC/MS, including EFA Method 524.2, which uses GC/ EI-MS for THM analysis [155], and EFA Method 521, which uses for GC/CI-MS/ MS for nitrosamine analysis [55]. In addition, many priority unregulated DBFs have been measured using GC/MS in a U.S. Nationwide Occurrence Study [11,12]. 

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