Multiple reaction monitoring validation

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... 

Quality control methods for each protocol are also presented. Applications and representative data are presented for the sensor controlled aerosol and matrix microinjection, whereas representative data for matrix solution fixation are reported elsewhere (8). Sensor controlled aerosol is applied to multimodal cell tracking by fluorescence and multiple reaction monitoring (MS/MS) of a fluorescent dye incorporated into stem cells and tumor cells surgically implanted into a mouse brain. This protocol enables validation of MSI using confocal microscopy for the tracking of implanted cells, and potentially the effect of a given cell s microenvironment upon its molecular composition. Matrix microinjection is used to acquire a MALDI mass spectrum of a single motor neuron from layer V of a mouse motor cortex. 

An LC-MS-MS method to monitor lonafarnib (a novel anticancer drug that inhibits farnesyl transferase) in human plasma. Deuterated internal standard is used proteins are precipitated by acetonitrile. Reverse-phase chromatographic separation is performed using acetonitrile/water/formic acid (50 50 0.05, v/v/v) mobile phase. Time of analysis 8 min. A triple quadrupole tandem mass spectrometer in the positive-ion mode with multiple reaction monitoring is used for detection. The cahbration curve has been established in the 2.5-2500 ng/ml concentration range. The validated method was successfully used in phase I trials of the drug. 

It is not possible to test for all potential interferences, and there is a possibility that an interfering substance will subsequently be encountered in analysis of field samples from diverse sources. Detection using tandem mass spectrometers, with multiple- or selected-reaction monitoring (MRM or SRM see Chapters 6 and 7), reduces the probability of encountering unexpected interferences, but does not totally eliminate the possibility. When interference is discovered once a validated method has been put into routine use, it may be necessary to modify the method (clean-up or chromatography) to eliminate the interference. Such modifications, if they involve significant change, may require re-validation of the method. 

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