Selected reaction monitoring. SRM

The MS-MS equivalent of this technique is known as selected-decomposition monitoring (SDM) or selected-reaction monitoring (SRM), in which the fragmentation of a selected precursor ion to a selected product ion is monitored. This is carried out by setting each of the stages of mass spectrometry to transmit a single ion, i.e. the precursor ion by MSi and the product ion by MS3 (see Figure 3.8 above). 

Table 5.2 Selected-reaction monitoring (SRM) transitions nsed for MS-MS detection of the pesticides studied in the systematic investigations on APCI-MS signal response dependence on eluent flow rate. Reprinted from J. Chro-matogr.. A, 937, Asperger, A., Efer, J., Koal, T. and Enge-wald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science...

The instrument scan mode called selected reaction monitoring (SRM) is generally used for quantitative applications. SRM is similar to selected ion monitoring (SIM) in single quadrupole MS. The difference is that a product ion from the decomposition reaction in the collision cell is measured instead of a single ion formed in the... 

Water samples, received from the respective groundwater trials, are analyzed by direct aqueous injection (DAI) by LC/ESI-MS/MS. A 1-mL volume of the water is pipetted into a 1.8-mL autosampler vial. The internal standard solution is added (200 qL) and mixed. The vials are capped and analyzed by LC/ESI-MS/MS using the selected reaction monitoring (SRM) mode. 

The software tools accompanying the QTRAP MS/MS allow set-up of multiple selected reaction monitoring (SRM) transitions for all likely metabolites after the major product ion transitions for the dosed compound are known. Because QTRAP MS/MS can monitor up to 100 SRM transitions during a single assay, the SRM transitions required for quantitation of the dosed compound and internal standard are obtained along with the possible metabolite transitions. During sample analysis, when a possible metabolite transition exceeds a preset threshold value, the QTRAP MS/MS performs an enhanced product ion (EPI) scan. When the assay is complete, the EPI scans can be used to determine whether the hits are metabolites, and if they are metabolites, what part of the molecule has changed. Thus, one analytical run provides both quantitative and metabolite information. 

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],... 

The standard addition procedure is another method for recognising and overcoming potential matrix effects in quantification. Both alternatives, FIA—MS or FIA—MS—MS, can be performed using this procedure. Despite the increased expenditure because of a multiplication in analyses, the FIA approach combined with standard addition remains the faster technique even with the application of specific analytical MS—MS techniques such as product-, parent- or neutral loss scans applying selected reaction monitoring (SRM). The greatest drawback of this technique is that the compounds to be quantified must... 

LC/MS/MS with selected reaction monitoring (SRM) offers a fast and simple means to analyze biological matrices, which is a key factor in high-throughput CYP inhibition screens using liver microsomes. Potentially, the LC/MS/MS technique is suitable for analyses of cocktail substrates in other in vitro drug metabolism evaluations such as CYP induction/activation assays, rapid analysis of pooled liver microsomes, rapid reaction phenotyping of tissue (hepatic and extrahepatic) samples, as well as evaluation of hepatocytes/tissue slice CYP activity. ° ... 

The use of MALDI for the analysis of small molecules was recently reported. Particularly attractive is the coupling of a MALDI source with a triple quadrupole mass analyzer for quantitative analysis in the selected reaction monitoring (SRM) mode due to very high analysis speed. 

Secondary ozonides see Final ozonides Selected reaction monitoring (SRM), mass spectrometry, 693 Selenides... 

There is also one other type of scan that is actually a subset of all of the above scans. These are known as selected reaction monitoring (SRM) scans. These scans pick one precursor ion and one product ion and monitor that signal. You can add as many SRM scans as the software allows. 

Selected Reaction Monitoring (MS/MS) Selected reaction monitoring (SRM) is the process by which the first mass analysis selects a specific m/z (the precursor ion) to be fragmented in the collision cell and the second mass analysis selects and detects a specific product ion. Most commonly used in the quantitative analysis of well-characterized, targeted species for which optimized precursor-product pairs can be established. In SRM-based LC-MS assays no qualitative information can be obtained. However, SRM can be used to trigger product ion, neutral loss, or precursor ion scans. 

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