Research on accurate quantitation technique using liquid chromatography coupled with triple quadrupole mass spectrometry and experiment optimization—take a novel diuretic as an example

Liquid chromatography coupled with the triple quadrupole mass spectrometry(LC-QQQ MS)technique is the most commonly used technique for quantitative analysis.It is widely used in pharmacology,targeted metabolomics,Chinese medicine quality control,and other research fields.The technique monitors only characteristic precursors and product ions through multiple reaction monitoring(MRM)mode and can detect targeted molecules in complex matrix with high specificity and sensitivity.In the present study,a diarylamide derivative diuretic was used as an example to introduce the method establishment and parameter optimization of this liquid chromatography-mass spectrometry technique.Diuretic and its internal standard could be completely separated within a 5-min gradient,and the quantitative linear range was 1–1000 ng/mL with R2=0.9996 in practical samples.This study showed that the key to the method development for LC-QQQ MS was the selection of the LC mobile phase,the elution gradient,the declustering potential,and the collision energy of compounds in MS.

Influences of Various Environmental Factors on the Degradation of Deoxynivalenol in Wheat Grains

In this study, the influences of various environmental factors on the degradation of deoxynivalenol （DON） in wheat grains were investigated using a triple quadrupole LC-MS/MS system. After being treated under different conditions for 150 d, DON toxin in wheat grains exhibited the degradation rate of 78.85%-87.00% and degradation half-life of 54.57-71.44 d. According to the accelerating effects of different conditions on DON degradation, natural light 〉 strong light （10 000 lx） 〉 darkness, 90% humidity 〉50% humidity, but high temperature could not accelerate the degradation of DON toxin.

In situ Rb-Sr dating of mica by LA-ICP-MS/MS

Mica exhibits a relatively high Rb/Sr ratio and possesses a closure temperature for the Rb-Sr isotope system that is higher than the ore-forming temperature range of low-to medium-temperature deposits.Consequently,utilizing the laser ablation(LA)technique for in situ Rb-Sr dating in mica constitutes a significant methodology for resolving the mineralization chronology of low-to medium-temperature hydrothermal ore deposits.In this study,we employed a combination of a triple quadrupole inductively coupled plasma mass spectrometer(ICP-MS/MS)and 193 nm LA system with SF_6as the reaction gas to achieve interference removal of~(87)Rb~+on~(87)Sr~+.We then developed an in situ Rb-Sr dating method for mica.In addition,an investigation was conducted to identify the factors that could influence the analytical accuracy of the method.Subsequently,we applied the developed method to carry out in situ Rb-Sr dating for the ZBH-25 biotite,a national primary reference material(GBW04439)for K-Ar dating,and yielded a younger age(ca.12%,relative standard deviation,RSD)than the reference K-Ar age when using NIST SRM 610 as the reference material for external calibration.This finding indicated that in the process of determining Rb-Sr ages for mica by LA-ICP-MS/MS,there are significant matrix effects between the NIST SRM 610 and the mica samples,resulting in inaccurate Rb-Sr ages.In response to this issue,a two-step calibration method is proposed here.Based on external calibration using NIST SRM 610,ZBH-25 biotite is employed as a second external reference material to perform a second calibration of the sample data to correct the matrix effect between the glass standards and the natural mica samples,thereby improving the accuracy of Rb-Sr dating by LA-ICP-MS/MS.Using the proposed method,in situ Rb-Sr dating by LA-ICP-MS/MS was performed on mica samples from monzonite exposed in Mt.Dromedary,New South Wales,Australia,porphyritic granodiorite in Fangshan pluton and albionite granite in the Gyirong area of Tibet.The obtained Rb-Sr age results show agreement with the recommended values within the analytical uncertainty,which serves to validate the accuracy and effectiveness of the proposed method.

Simultaneous quantification of eighteen constituents in traditional Chinese medicine XiaoShuanTongLuo by UPLCMS/ MS

XiaoShuanTongLuo （XSTL） is an important multi-herbal formula widely used as a traditional Chinese medicine （TCM）. In this paper, an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometric method （UPLC-ESI-MS/MS） was developed for the simultaneous identification and quantification of 18 chemical constituents in the extract of XSTL. The analysis was performed in multiple-reaction monitoring （MRM） mode using positive and negative electrospray ionization （ESI）. A BEH C18 （2.1 mm× 100 mm, 1.7 μm） column with a gradient mobile phase of methanol-0.1% aqueous formic acid solution at a flow rate of 0.2 mL/min was used for separation. The standard curves of most components showed good linearity over the concentration range of 0.001-0.5 μg/mL with r = 0.9896-0.9996. The relative standard deviations （RSD） of intra-day and inter-day precision were all lower than 15% at low, middle, and high concentration levels. The RSD of stability analysis in 24 h were also lower than 15%. The validated method was employed to quantify 18 active components simultaneously in four different commercial brands of XSTL products in various dosage forms. The developed method was rapid, accurate, sensitive, and reproducible for the quality control of XSTL.

Characterization and quantitation of aristolochic acid analogs in different parts of Aristolochiae Fructus, using UHPLC-Q/TOF-MS and UHPLC-Qq Q-MS

Aristolochiae Fructus, a Chinese herbal medicine derived from the fruit of Aristolochia contorta Bge., contains nephrotoxic aristolochic acid analogues(AAAs). According to ancient medical texts, various medicinal parts of the fruit of A. contorta were ever used. In order to reveal which part could be safely and effectively used, it is necessary to analyze the chemical profiles of different medicinal parts. Herein we compared the chemical compositions and determined aristolochic acid I(AA-I) and aristolochic acid II(AA-II) in the four parts viz. outer pericarp, inner pericarp, septum, and seed. Ultra-high performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry(UHPLC-QTOF-MS) was applied for chemical profiling. Ultra-high performance liquid coupled with triple quadrupole mass spectrometry(UHPLC-Qq Q-MS) was employed to quantify AA-I and AA-II in different parts. It was found that the chemical compositions of the four parts varied both qualitatively and quantitatively. A total of 10 AAAs, including 5 aristolochic acids and 5 aristolactams, together with 3 alkaloids, were unambiguously or tentatively identified by UHPLC-QTOF-MS. The quantitatively analytical results obtained by UHPLC-Qq Q-MS showed that AA-I and AA-II exclusively accumulate in the seeds of A. contorta. These findings provide supporting data for the rational selection of medicinal parts.