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.

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.