| Mass spectrometry coupled with liquid chromatography has become a widelyused analytical technique due to its high sensitivity and high specificity. The mainapplication areas of LC-MS are currently in the field of pharmaceutical,environmental and biochemical analysis. Even though LC-MS has many excellentfeatures, it also suffers from signal instability caused by the gradual fouling of the ionsource, vacuum instability, and aging of the ion multiplier, etc. Continuous signalvariations could invalid the calibration models established for quantitative LC-MSanalysis, if no proper measures have been taken to correct its detrimental effects. Thisthesis focuses on the development of a novel quantitative theory for massspectrometry to eliminate the influence of signal instability in quantitative assays atminimum cost. The main contents of this thesis include the following aspects:In Chapter2, the influence of ionization efficiency on the signal intensity inLC-MS measurements was investigated, and a unique calibration model–multiplicati-ve effects model with internal standard in mobile phase (MEMIS) was proposed forquantitative LC-MS analysis. In the proposed model, a multiplicative parameter wasintroduced to account for the MS signal contributions caused by variations inmeasurement conditions and/or the instrument itself. A “dual calibration” strategy wasthen adopted to eliminate the detrimental effects of multiplicative parameters. Theproposed method was successfully applied to the accurate quantitative analysis ofboth tryptophane and tyrosine in ultrapure water using LC-MS.In Chapter3, the calibration model proposed in Chapter2has been applied to thequantitative analysis of cryptotanshinone, tanshinone IIAand dihydrotanshinone I indanshen tablets and salvia miltiorrhiza. Experimental results showed that the proposedmodel could accurately determine the contents of analytes of interest in systems withcomplex matrices.In Chapter4, Another advanced calibration model–multiplicative effects modelfor mass spectrometry (MEMMS) was applied to the determination of amlodipine andnifedipine in both plasma samples and Duzhong Pingya Tablet. Experimental resultsdemonstrated that MEMMSmodel could effectively eliminate the influence of signalinstability, and therefore realize accurate quantitative analysis of amlodipine andnifedipine in both plasma samples and Duzhong Pingya Tablet. |
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