Preparation Of Deuterium Aromatic Acid And Its Application In Paper Spray-mass Spectrometry

Many analytes could be determined by paper spray-mass spectrometry(PS-MS)without preparation or with less preparation.PS-MS has many advantages,such as fewer reagents,low cost,fast and high-through analysis.PS-MS has been used in biology,chemistry,food and Chinese medicinal materials.However,due to the influence of ion suppression,these applications for PS-MS have been limited to qualitative and semi-quantitative analysis.Researchers have found that less ion suppression can be obtained by using isotope internal standards and quantitative analysis can be achieved by PS-MS.And deuterated internal standard(DIS)is the most appropriate isotopeinternal standard.Therefore,the synthesis of DIS is a hot topic of researchers.In general the methods for synthesis of DIS are heterogeneous H/D exchange,homogeneous H/D exchange and microwave assisted H/D exchange.The four aromatic acids studied in this paper are applied in food,pharmaceutical clinical,chemical and traditional Chinese medicine.The methods of analyzing the acids generally are HPLC,GC,CE and SFC.This thesis focuses on the synthesis of the DIS of four aromatic acids and their application in PS-MS,and the main contents are summarized as follows:1.In Chapter 2,based on using heterogeneous metal catalyst,a simple and low cost method of preparation deuterated benzoic acid has been developed.A H/D exchange reaction of benzoic acid(BA)consisiting of Pt/C(10%on carbon),NaOD in D2O was produced at the temperature of 200?for 12 h.The product was confirmed as d5-BA by IR,MS and NMR.The mechanism of benzoic acid H/D exchange reaction is electrophilic substitution.The carbon atomic charge distribution of BA benzenering was calculated using density functional theory(DFT)B3LYP method.The results agree with the experimental results.The meta-hydrogen atoms of carboxyl have the fastest reaction speed.The second is the para-H,and the slowest is ortho-H.2.In Chapter 3,we reported a simple,cost-effective,rapid PS-MS method based on using d5-BA as IS for the quantitative detection of BA in beverages.It requires less sample preparation,analysis time,and solvent than HPLC method.The linearity was obtained range of 0.3-100?g/mL,giving a correlation efficient of 0.9996.The limit of quantitation was 0.3?g/mL and the recovery ranged from 91.1 to 106.7%.This method was successfully applied to blind samples for BA.PS-MS can be well applied to high-throughput screening of BA in beverages.3.In Chapter 4,we reported a simple,fast,low-cost microwave assisted homogeneous K2PtCl4 metal catalytic H/D exchange method.Good deuterium incorporation of salicylic acid(SA)could be attained using the best reasonable experimental parameters,such as microwave irradiation,the temperature of 150?,K2PtCl4 catalyst,and the reaction time of 60 min using only NaOD as an alkaline environment.The product was confirmed as d4-SA by MS,1H-NMR and 13C-NMR.We assume that the mechanism of SA H/D exchange reaction is dissociative mechanism with a reversible?-?conversion under acidic condition and that is dissociative mechanism based on only ? bond under alkaline condition.4.In Chapter 5,we have established a simple,rapid,high-throughput quantitative analysis of salicylic acid in the urine and medicaments using paper spray-mass spectrometry.The method needs no sample preparation and the whole sample detection was finished within less than one minute.The method is based on using d4-SA prepared as IS.We got very good results.Firstly,the linear range of 1.5-100?g/mLof PS-MS was studied using d4-SA as internal standard and the correlation efficient is 0.9998.LOD and LOQ are 0.5?g/mL and 1.5?g/mL respectively.The recovery ranged from 90.4%to 108.9%.For actual sample analysis,the accuracy rate was from 96.67%to 113.0%.These results indicate that PS-MS can quantitatively analyze the content of salicylic acid in complex samples in real time,with many advantages of without destroying samples,rapid and high-through features.5.In Chapter 6,we mainly studied the reaction conditions of H/D exchange for 4-methyl salicylic acid(4-MSA)and the kinetics of H/D exchange due to the change of proton integral signal of 1H-NMR.We found that the H/D exchange reaction rate of different hydrogen in benzene ring for 4-MSA under the conditions of 200? and Pd/C catalyst was ks>k3>k6.In this assay,the linear for the quantitative analysis of PS-MS using deuterated 4-MSA as IS was significantly better than using SA as IS.The results of this study proved that PS-MS can be well applied to quantitative analysis of 4-MSA in actual samples.6.In Chapter 7,we have reported a simple,fast and low cost microwave homogeneous metal-catalyzed method for preparation deuterium ginkgolic acid(GA)(13:0).Microwave assisted H/D exchange reaction of GA(13:0)lasted 30 min with Rh salt catalyst,at 200? and under alkaline condition.Compared with the traditional heating method,microwave assisted H/D exchange reaction of GA(13:0)has many merits,such as short reaction time,the ginkgolic acid less decomposition,fewer byproducts and dimers.The main product was d3-GA(13:0)and some d4-GA(13:0)confirmed by MS,IR,1H-NMR.In this assay,we used deuterated product as IS of PS-MS and satisfactory results for the quantitative analysis were obtained.