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In this study, we developed a method of liquid chromatography with fluoresce detector (LC-FLD) and on-line mass spectrometry identification (MSI) using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as pre-column derivatisation reagent for determination of the amino acids (AAs) in <i>Potentilla anserina</i> L<i>.</i> Separation of the derivatised AA exhibited a good baseline resolution in combination with a gradient elution. All AA derivatives give excellent linear responses with correlation coefficients of >0.9992. The detection limits of each AA were 2.60-24.3 fmol. Eighteen AAs, involving seven essential AAs, were detected in <i>Potentilla anserina</i> L<i>.</i> Quantitative recoveries of the AAs from the <i>Potentilla anserina</i> L<i>.</i> were 84-107%, and the relative standard deviation values were <1.45%. The established method in this study was sensitive and precision enough to separate and quantify AA composition of <i>Potentilla anserina</i> L. Good compositional data were obtained from the analysis of the AAs obtained from <i>Potentilla anserina</i> L<i>.</i> root.

• A new low toxic dual-UADLLME coupled with microwave-assisted derivatization was proposed. • 4′-Carboxy-substituted rosamine was firstly used as derivatization reagent. • Simultaneous determination of PPD and PPT in rat plasma was achieved by UHPLC-MS/MS. • This method was successfully applied to pharmacokinetics study.<br>This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20(<b>S</b>)-protopanaxadiol (PPD) and 20(<b>S</b>)-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4′-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015 ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma.

Recent researches shows that amino acids (AA) are not only cell signaling molecules but are also regulators of gene expression and the protein phosphorylation cascade. More precise analysis of AA composition is reckoned to be one of the most important applications in the biomedical and pharmaceutical fields. In this paper, we develop a sample, sensitive and mild method using 2-[2-(7H-dibenzo[a,g]carbazol-7-yl)-ethoxy]ethyl chloroformate (DBCEC) as A labeling reagent for AA determination by high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) and identification with mass spectroscopy. The maximum excitation and emission wavelengths for DBCEC-AA derivatives were 300 and 395 nm, respectively. This method, in conjunction with a gradient elution, offered a baseline resolution of 20 AA on a reversed-phase Hypersil BDS C<sub>18</sub> column. LC separation for the derivatized AA showed good reproducibility, and all AA were found to give excellent linear responses with correlation coefficients > 0.9993. The calculated detection limits with a 25.0 fmol injection of each AA (at a signal-to-noise ratio of 3:1) ranged from 2.62 to 22.6 fmol. This method was applied to determine the AA composition in <i>Saussurea involucrate</i> and <i>Artemisia capillaris</i> Thunb. Meanwhile, this method exhibits a powerful potential for trace analysis of AA from biomedicine, foodstuff and other complex samples. Copyright © 2010 John Wiley & Sons, Ltd.

A sensitive and inexpensive method involving ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and pre-column derivatization followed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed for the analysis of glycyrrhetinic acid. In this work, glycyrrhetinic acid could be obtained by hydrolyzing glycyrrhizic acid to remove glucuronic acid and subsequently extracted by UA-DLLME using chloroform and acetone as the extraction and disperser solvents, respectively. The sample extraction was firstly concentrated to dry under nitrogen and then rapidly derivatized with 2-(12-oxobenzo[b]acridin-5(12H)-yl)-ethyl-4-toluenesulfonate (BAETS) after the UA-DLLME. The prime parameters influencing the UA-DLLME and derivatization procedure were optimized using response surface methodology. Under the optimum conditions, the proposed method has a better linearity in a wider range of 6-300 ng mL<sup>−1</sup> and a high square of correlation coefficient (<i>R</i> <sup>2</sup>) at 0.9994. Limit of detection and limit of quantification were found to be 1.7 ng mL<sup>−1</sup> and 5.8 ng mL<sup>−1</sup>, respectively. The proposed method was applied to the analysis of glycyrrhetinic acid in liquorice, liquorice apricot and sugar plum samples. For the analysis of the spiked samples, the spiked recoveries were in the range of 90.4-103.0 % with RSD less than 5.18 %. All results demonstrated that the UA-DLLME-HPLC-FLD (ultrasound-assisted dispersive liquid-liquid microextraction-high-performance liquid chromatography with fluorescence detection) was a sensitive, accurate, efficient analytical method for the determination of glycyrrhetinic acid.