Optimizing mass spectrometric detection for ion chromatographic analysis. I. Common anions and selected organic acids

摘要

We describe a systematic method of optimizing mass spectrometric (MS) detection for ion chromato-graphic (IC) analysis of common anions and three selected organic acids using response surfacemethodology (RSM). RSM was utilized in this study because it minimized the number of exper-iments required to achieve the optimum MS response and included the interactions betweenindividual parameters for multivariable optimization. Five MS parameters, including probe tempera-ture, nebulizer gas, assistant makeup flow, needle voltage and cone voltage, were screened andsystematically optimized by two steps. Central composite design (CCD) was used to design theexperiment points and a quadratic model was applied to fit the experimental data. Analysis ofvariance (ANOVA) was carried out to evaluate the validity of the statistical model and to determinethe most significant parameters for MS response. The optimum MS conditions for each analyte weresummarized and the method optimum condition was achieved by applying desirability function.Our observation showed good agreements between statistically predicted optimum response and theresponses collected at the predicted optimum condition. Operable range of each parameter (withnormalized MS response greater than 0.8 for each analyte) was provided for general anionic IC/MSapplications.