Quantitative Application Of Chemical Multivariate Analysis Combined With Spectroscopy And Chromatography Instruments For Small Molecule

All kinds of new analytical instruments that can produce multivariate data provide abundant measurement data for analysts.Extracting useful information from these measurement data to solve practical problems in analytical chemistry is one of the research focuses in the field of analytical chemistry.The main goal of chemometrics is to extract useful information from these complex data and to solve the problems of qualitative and quantitative analysis quickly and accurately,which is one of the frontier research fields.The research work of this thesis is mainly based on spectroscopic and chromatographic instrument data,using chemical multivariate analysis method for accurate and anti-interference quantitative analysis of target components in complex system,mainly including the following contents:In Chapter 2,waste tobacco leaves were used as the carbon source for synthesizing a novel carbon dots（CDs（WTL））through a facile hydrothermal method.The CDs（WTL）possess a series of excellent properties,including good water solubility,well stability,and high fluorescence quantum yield.The fluorescent intensity of the CDs（WTL）can be quenched by tetracycline（TC）obviously,but there is a spectrum shift.In order to use the CDs（WTL）as fluorescent probes to quantify TC with higher accuracy,a quantification fluorescence model（QFM）was introduced to overcome this spectrum shift effect that often occurs.The coefficient of determination（R²）of traditional quantification model（TQ）,partial least squares（PLS）,and QFM are 0.9672,0.9834,and 0.9991,respectively;the average relative predictive error（ARPE）of TQ,PLS,and QFM are 8.8%,4.5%,and 3.9%for the spiked water samples,and 21.9%,22.0%,and 2.9%for spiked tablet samples,respectively.The obtained results suggest that QFM is more accurate than PLS and TQ for the TC detection.By utilizing QFM,the spike recoveries（mean±standard deviation）in three kinds of real tablet samples produced by different manufacturers are 98.9±3.6%,102.5±6.2%,and 98.5±2.7%,respectively;the spike recovery in river water samples is 99.4±5.0%.In addition,high performance liquid chromatography（HPLC）was used as a reference method,the F and t tests suggested that there are no significant differences on the precision and accuracy between QFM and HPLC methods at the 5%significance level.In Chapter 3,a second-order calibration method based on alternating trilinear decomposition（ATLD）algorithm assisted HPLC-DAD method was established,which for rapid and simultaneous the determination of adenosine-5’-monophosphoric acid（AMP）,guanosine-5’-monophosphoric acid（GMP）,cytidine 5’-monophosphoric acid（CMP）,5’-uridine acid（UMP）and inosine-5’-monophosphoric acid（IMP）in infant formula samples.Even if there are complex unknown interference,serious chromatographic peak overlap and a certain degree of retention time drift,this method still realizes the quantitative analysis of these five nucleotide substances.The analysis results of calibration set,validation set and prediction set of CMP,UMP,GMP,IMP and AMP were very satisfactory,and the average spike recoveries（mean±standard deviation）were 97.4±4.2%,87.9±1.2%,96.2±3.9%,99.7±5.9%and 92.4±1.1%,respectively.The predicted total nucleotide content in the predicted sample（real sample）was consistent with the allowable addition amount specified in infant formula by national regulations.The limit of detection（LOD）of CMP,UMP,GMP,IMP and AMP were 0.03,0.09,0.22,0.30 and 0.15μg m L^-1,respectively.The limits of quantitation（LOQ）were 0.08,0.28,0.66,0.91 and 0.46μg m L^-1,respectively.In addition,the standard curve method based on high performance liquid chromatography（HPLC）was used as a reference method for quantitative analysis of AMP,the F and t tests showed that there was no significant difference between the predicted results of the two methods at the significance level of 5%.The satisfactory results in this study indicated that the second-order calibration method assisted HPLC-DAD analysis was a promising analytical method,which could not only reduce the elution time but also improve the selectivity of HPLC-DAD.In Chapter 4,a three-way calibration method based on Ultraviolet-visible absorption spectrometry was proposed for the direct quantitative analysis of nucleic acid monomers in cell samples,namely AMP,GMP,CMP and UMP nucleotides.First,spectral p H data for each sample were constructed by introducing a p H dimension from Ultraviolet-Visible absorption spectroscopy（UV-Vis）.Then,the spectrum-p H data of calibration sample,validation sample and prediction sample were stacked to construct three-way data array,and pure signals of AMP,GMP,CMP and UMP were extracted from the mixed signals by trilinear decomposition.In this work,a new three-way calibration method was established for the direct quantitative analysis of four nucleotides in cell samples.Even in the presence of uncalibrated interferents,the average spike recoveries（mean±standard deviation）of AMP,GMP,CMP and UMP were 104.5±4.2%,96.7±8.0%,99.8±1.4%and 95.9±4.5%,respectively.These results show that the spectrum-p H three-way calibration method established in this work has high mathematical selectivity,and can enhance the ability of UV-Vis to achieve direct quantitative analysis in complex analysis system.