Analysis Of Several Organic Acids By Array Paper Chip-Desorption Corona Beam Mass Spectrometry

Desorption corona beam ionization mass spectrometry（DCBI-MS）is a new type of ambient mass spectrometry method that is widely used in many fields such as food quality control,environmental monitoring,and biomedicine.Compared with other ambient ionization technologies,DCBI technology has unique advantages and value.The visible corona beam facilitates surface positioning of samples,which is beneficial for applications such as mass spectrometry imaging and chemical profile characterization.In addition,DCBI matches the working mode of electrospray ion sources or atmospheric pressure chemical ionization sources equipped with most current commercial mass spectrometers,and can be easily installed on existing commercial mass spectrometers.However,due to the limited ionization capability of DCBI,the thermal desorption ionization mechanism limits the detection object,and the open working environment is susceptible to external factors.Like other open mass spectrometers,DCBI-MS has the problems of low sensitivity and poor reproducibility.As a chemical analysis device,microfluidic paper-based analytical devices（μPADs）has the dual characteristics of a microfluidic platform and a paper base,and has the advantages of low energy consumption,high integration,and pollution-free subsequent processing.In this paper,an array paper-based analytical devices with stable affinity/hydrophobicity is designed and prepared.The introduction of the paper-based analytical devices for desorption of corona beam mass spectrometry samples can effectively improve the detection sensitivity and reproducibility of DCBI-MS.This article discusses the feasibility and applicability of the combination of array paper-based analytical devices technology and desorption corona beam mass spectrometry technology.The practical application of this method in the qualitative and quantitative analysis of targets in complex samples is also discussed.The details are as follows:1.μPADs-DCBI-MS to determine the activity of lipase.TheμPADSs was prepared by silanization reagent and plasma etching technology,and the analysis performance and specifications of it were investigated.The results show that the injection ofμPADs can not only improve the detection sensitivity,but also reduce the interference of background ions.Establish a method to determine the activity of lipase by combining theμPADs and DCBI-MS.Tributyrin was used as a substrate,and butyric acid made in the laboratory was used as an internal standard.The activity of lipase was evaluated by measuring the amount of the enzymatic reaction product—n-butyric acid.The factors affecting the enzymatic reaction were investigated,and the mass spectrometry detection conditions were optimized.The linear correlation coefficient of n-butyric acid is 0.9996 in the concentration range of 0.5-25 mg/L,the relative standard deviation（RSD）is 1.5%-6.7%,and the recovery rate of the three concentration levels is 103.1%-107.3%.The experimental measurement of the purchased porcine pancreatic lipase activity value is 9056.0 U/g.The result is compared with the measurement result of the gas chromatography external standard method.According to the significance test,there is no significant difference in the precision and value of the two.In addition,the half-inhibitory concentration(IC₅₀ value)of the lipase inhibitor orlistat was determined to be 0.0971 mg/m L using the established method.2.μPADs-DCBI-MS for rapid analysis of Ginkgolic Acid（GA）.The factors affecting the ionization efficiency of the sample were investigated,and the methodology was investigated under the best measurement conditions.The linear correlation coefficient of ginkgolic acid in the concentration range of 2-50 mg/L is greater than 0.998,the RSD value is2.6%-19%（n=3）,and the standard addition recovery rate of the three concentration levels is 86.9%-133.2%.The total ginkgolic acid content of ten batches of Ginkgo biloba medicinal materials was actually measured to be 16.39 mg/g-29.15 mg/g,and there is no significant difference between this result and the measurement result of liquid chromatography..3.μPADs-DCBI-MS for rapid analysis of caffeic acid and ferulic acid.The instrument parameters were optimized,and the methodology was investigated under the best measurement conditions.CA has a linear correlation coefficient of 0.9919 in the concentration range of 2-25 mg/L,the RSD value is 11%-15%（n=3）,the recovery rate under the three concentration levels is 90.2%-116.5%;The linear correlation coefficient of FA in the concentration range of 1-10 mg/L reaches 0.9997,the RSD value is 3.6%-15%（n=3）,and the recovery rate of standard addition at 3concentration levels is 84.3-113.2%.The caffeic acid content of ten batches of dandelion medicinal materials was measured to be 0.160 mg/g-0.655mg/g,and the ferulic acid content was 0.046 mg/g-0.074 mg/g.Comparing the results with the detection results of high performance liquid chromatography,there is no significant difference between the two.Caffeic acid was derivatized with the isotope-encoded light/heavy derivatization reagent methanol/deuterated methanol,and the content of caffeic acid in the caffeic acid solution of unknown concentration was determined.The linear range of the derivatization method is 5-50 mg/L,the R² is 0.9992,the RSD value is 3.3%-16%（n=3）,and the standard addition recovery rate of the three concentration levels is 95.8%-106.0%.