• Analytical Science and Technology
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• v.10 no.1
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• pp.9-17
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• 1997

Nitrophenols are a group of important priority pollutants classified by the US Environmental Protection Agency. Reverse-phase liquid chromatographic method combined with mass spectromethy employing atmospheric pressure chemical ionization(APCI) interface is utilized to determine a mixture of nitrophenols in water matrix without any pretreatment. The sensitivity and selectivity for the identification of different kind of nitrophenols is enhanced by the use of selected ion monitoring and cone voltage fragmentation. The fragmentation patterns of nitrophenols are compared with those obtained from the collision induced dissociation(CID) MS/MS technique.

• Analytical Science and Technology
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• v.30 no.6
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• pp.379-389
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• 2017

In this study, we set up an analytical method that can be used for rapid and accurate determination of representative isoquinoline alkaloids in medicinal plants using UPLC-ESI-Q-TOF MS (ultra pressure liquid chromatography-electrospray ionization-quadrupole-time-of-flight mass spectrometry). The compounds were eluted on a C18 column with 0.1 % formic acid and acetonitrile, and separated with good resolution within 13 min. Each of the separated components was characterized by precursor ions (generated by ESI-Q-TOF) and fragment ions (produced by collision-induced dissociation, CID), which were used as a reliable database. We also performed method validation: analytes showed excellent linearity ($R^2$, 0.9971-0.9996), LOD (5-25 ng/mL), LOQ (17-82 ng/mL), accuracy (91.6-97.4 %) as well as intra- and inter-day precisions (RSD, 1.8-3.2 %). In the analysis of Chelidonium majus L., magnoflorine, coptisine, sanguinarine, berberine and palmatine were detected by matching retention times and characteristic fragment ion patterns of reference standards. We also confirmed that, among the quantified components, coptisine was present in the highest quantity. Furthermore, alkaloid profiling was carried out by analyzing the fragment ion patterns corresponding to peaks of unknown components. In this manner, protopine, chelidonine, stylopine, dihydroberberine, canadine, and nitidine were tentatively identified. We also proposed the molecular structure of the fragment ions that appear in the mass spectrum. Therefore, we concluded that our suggested method for the determination of major isoquinoline alkaloids by UPLC-Q-TOF can be useful not only for quality control, but also for rapid and accurate investigation of phytochemical constituents of medicinal plants.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1684-1688
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• 2013

A rapid and sensitive method for determining usnic acid of Lethariella cladonioides in rat was established using high performance liquid chromatography (HPLC) quadrupole time-of-flight (QTOF) tandem mass (MS/MS). Rat plasma was pretreated by mixture of acetonitrile and chloroform to precipitate plasma proteins. Chromatographic separation was achieved on a column ($50{\times}2.1$ mm, $5{\mu}m$) with a mobile phase consisting of water (containing $5{\times}10^{-3}$ M ammonium formate, pH was adjusted to 3.0 with formic acid) and acetonitrile (20:80, v/v) at a flow rate of 0.3 mL/min. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via collision induced dissociation (CID) under negative ionization mode. The MS/MS transitions monitored were m/z 343.0448 ${\rightarrow}$ m/z 313.2017 for usnic acid and m/z 153.1024 ${\rightarrow}$ m/z 136.2136 for protocatechuic acid (internal standard). The linear range was calculated to be 2.0-160.0 ng/mL with a detection limit of 3.0 pg/mL. The inter- and intra-day accuracy and precision were within ${\pm}7.0%$. Pharmacokinetic study showed that the apartment of usnic acid in vivo confirmed to be a two compartment open model. The method was fully valid and will probably be an alternative for pharmacokinetic study of usnic acid.