Shijuan Zhang

Analysis of estrogenic compounds in environmental and biological samples by liquid chromatography-tandem mass spectrometry with stable isotope-coded ionization-enhancing reagent

A sensitive and reliable stable isotope labeling technology was developed for the determination of estrogenic compounds in environmental and biological samples based on the derivatization of estrogenic compounds with 10-methyl-acridone-2-sulfonyl chloride (d(0)-MASC) and its deuterated counterpart d(3)-MASC. The labeling reaction of MASC with estrogenic compounds is simple and robust and can be carried out under mild conditions within 5 min. Internal standard-based quantification was achieved by this labeling strategy without the need of using expensive internal standard analogy to every analyte of interest. Meanwhile, the sensitivity obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was enhanced by 2-3 orders of magnitude compared to the underivatized counterparts. Application of the stable isotope labeling technology in relative and absolute quantification of estrogenic compounds in complicated samples indicated that the labeling strategy was effective in overcoming matrix effects. The proposed method was successfully applied to the analysis estrogenic compounds in different environmental and biological samples with high sensitivity and accuracy.

Analysis of free fatty acids in Notopterygium forbesii Boiss by a novel HPLC method with fluorescence detection

A new labeling reagent for fatty acids, 1-(9H-carbazol-9-yl) propan-2-yl-methanesulfonate (CPMS), has been synthesized and successfully applied to the HPLC determination of fatty acids in traditional Chinese herb Notopterygium forbesii Boiss. The reaction of CPMS with fatty acids could proceed easily and quickly in the presence of K(2)CO(3) catalyst within 30 min. The derivatives exhibit excellent fluorescence property with excitation and emission wavelengths of 293 nm and 360 nm respectively. The 34 derivatives of fatty acids were separated on a BDS C8 reversed-phase column with gradient elution. Good linear correlations were observed for all fatty acids with correlation coefficients of >0.996. The detection limits at a signal-to-noise ratio of 3 were in the range 0.032-0.312 μg g(-1). Free fatty acids in the roots, stem, leaves and petioles of N. forbesii Boiss from different places were analyzed by the developed method. This is the first time that the fatty acids composition of N. forbesii Boiss has been reported. This method also shows powerful potential for the trace analysis of fatty acids or other carboxylic acids from complex samples.

Studies of crude chloroform extract of roots ofPodophyllum emoddii var. chinesis Sprague by micellar electrokinetic chromatography

SummaryA crude chloroform extract of the roots ofPodophyllum emoddii var. chinesis Sprague was studied by micellar electrokinetic chromatography. Four peaks belonging to podophyllotoxin, 4′-desmethyl-podophyllotoxin, kaempferol and quercetin were identified by known standards. The four substances are valuable pharmaceutical ingredients of the plant.

Sensitive, accurate and rapid detection of trace aliphatic amines in environmental samples with ultrasonic-assisted derivatization microextraction using a new fluorescent reagent for high performance liquid chromatography

A new fluorescent reagent, 1-(1H-imidazol-1-yl)-2-(2-phenyl-1H-phenanthro[9,10-d]imidazol-1-yl)ethanone (IPPIE), is synthesized, and a simple pretreatment based on ultrasonic-assisted derivatization microextraction (UDME) with IPPIE is proposed for the selective derivatization of 12 aliphatic amines (C1: methylamine-C12: dodecylamine) in complex matrix samples (irrigation water, river water, waste water, cultivated soil, riverbank soil and riverbed soil). Under the optimal experimental conditions (solvent: ACN-HCl, catalyst: none, molar ratio: 4.3, time: 8 min and temperature: 80°C), micro amount of sample (40 μL; 5mg) can be pretreated in only 10 min, with no preconcentration, evaporation or other additional manual operations required. The interfering substances (aromatic amines, aliphatic alcohols and phenols) get the derivatization yields of <5%, causing insignificant matrix effects (<4%). IPPIE-analyte derivatives are separated by high performance liquid chromatography (HPLC) and quantified by fluorescence detection (FD). The very low instrumental detection limits (IDL: 0.66-4.02 ng/L) and method detection limits (MDL: 0.04-0.33 ng/g; 5.96-45.61 ng/L) are achieved. Analytes are further identified from adjacent peaks by on-line ion trap mass spectrometry (MS), thereby avoiding additional operations for impurities. With this UDME-HPLC-FD-MS method, the accuracy (-0.73-2.12%), precision (intra-day: 0.87-3.39%; inter-day: 0.16-4.12%), recovery (97.01-104.10%) and sensitivity were significantly improved. Successful applications in environmental samples demonstrate the superiority of this method in the sensitive, accurate and rapid determination of trace aliphatic amines in micro amount of complex samples.

Determination of triterpenic acids in fruits by a novel high performance liquid chromatography method with high sensitivity and specificity

A novel and interesting pre-column derivatisation method was developed for the analysis of triterpenic acids by high-performance liquid chromatography (HPLC) with fluorescence detection. Each triterpenic acid produced two HPLC peaks with similar peak areas after derivatising with chiral 1-(9H-carbazol-9-yl) propan-2-yl-methanesulfonate (CPMS), while the fatty acid derivative of CPMS had only one peak. This phenomenon greatly increased the confidence in analyte confirmation. Compound with only one peak or two peaks differing greatly in their peak areas could be excluded from the target compound list. CPMS was compared with five other derivatising reagents, four of which produced only one peak for one triterpenic acid, to study the possible mechanism. Analytes with different behaviours were also studied to better interpret the mechanism. The proposed method also showed the merits of high sensitivity and less sample consumption. It was successfully applied to the analysis of triterpenic acids in fruit peels and flesh. There is no prior report on the two peak phenomenon of triterpenic acids. The information provided in this study will be helpful for those who are also engaged in derivatisation study.

Rapid and sensitive ultrasonic-assisted derivatisation microextraction (UDME) technique for bitter taste-free amino acids (FAA) study by HPLC–FLD

Amino acids, as the main contributors to taste, are usually found in relatively high levels in bitter foods. In this work, we focused on seeking a rapid, sensitive and simple method to determine FAA for large batches of micro-samples and to explore the relationship between FAA and bitterness. Overall condition optimisation indicated that the new UDME technique offered higher derivatisation yields and extraction efficiencies than traditional methods. Only 35min was needed in the whole operation process. Very low LLOQ (Lower limit of quantification: 0.21-5.43nmol/L) for FAA in twelve bitter foods was obtained, with which BTT (bitter taste thresholds) and CABT (content of FAA at BTT level) were newly determined. The ratio of CABT to BTT increased with decreasing of BTT. This work provided powerful potential for the high-throughput trace analysis of micro-sample and also a methodology to study the relationship between the chemical constituents and the taste.

Determination of the carbohydrates from Notopterygium forbesii Boiss by HPLC with fluorescence detection

A sensitive pre-column derivatization method was developed for analysis of carbohydrates by HPLC with fluorescence detection. The introduction of 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) with excellent fluorescence property into the molecules of monosaccharides greatly enhanced the HPLC sensitivity of the analytes. Meanwhile, derivatization with BAAH also greatly increased the hydrophobicity of the monosaccharides and made them elute at increased retention times. The monosaccharides with similar properties therefore could be completely separated due to the increased interaction between the analytes and the column. Component monosaccharides of the polysaccharides obtained from the roots, stems and leaves of Notopterygium forbesii Boiss (NF) were analyzed by the developed method. The results indicated that the polysaccharides of NF were mainly composed of d-galactose and d-glucose. This is the first systematic study of the sugar composition of the polysaccharides of NF. It will be helpful for the quality control of NF.

Development of ultrasonic-assisted closed in-syringe extraction and derivatization for the determination of labile abietic acid and dehydroabietic acid in cosmetics.

Two resin acids, abietic acid (AA) and dehydroabietic acid (DHAA), in cosmetics may cause allergy or toxicoderma, but remain inaccurately investigated due to their lability. In this work, an accurate, sensitive, efficient and convenient method, utilizing the ultrasonic-assisted closed in-syringe extraction and derivatization (UCSED) prior to high performance liquid chromatography (HPLC) coupled with fluorescence detection (FLD) and on-line tandem mass spectra (MS/MS), has been developed. Analytes are extracted by acetonitrile (10/1, v/m) in a sealed syringe under safe condition (60°C; 15 min; nitrogen atmosphere) and then in-syringe derivatized by 2-(2-(anthracen-10-yl)-1H-naphtho[2,3-d]imidazol-1-yl) ethyl-p-toluenesulfonate (ANITS) (8-fold, 93°C, 30 min, DMF as co-solvent, K2CO3 as catalyst). In UCSED, derivatization contributes to increase both analytical sensitivity and stability of analytes. Excellent linearity (r2≥0.9991) is achieved in wide range (75-3000 ng/mL (AA); 150-4500 ng/mL (DHAA)). Quite low detection limits (AA: 8.2-10.8 ng/mL; DHAA: 19.4-24.3 ng/mL) and limits of analyte concentration (LOAC) (AA: 30.0-44.5 ng/mL; DHAA: 70.9-86.7 ng/mL) ensure the trace analysis. This method is applied to the analysis of cosmetic samples, including depilatory wax strip, liquid foundation, mascara, eyeliner, eyebrow pencil and lip balm. No additional purification is required and no matrix effect is observed, demonstrating obvious advantages over conventional pretreatment such as solid phase extraction (SPE). Accuracy (RE: -3.2% to 2.51%), precision (RSD: 1.29-2.84%), recovery (95.20-103.63%; 95.51-104.22%) and repeatability (<0.23%; <2.87%) are significantly improved. Furthermore, this work plays a guiding role in developing a reasonable method for labile analytes.

A sensitive and efficient method to systematically detect two biophenols in medicinal herb, herbal products and rat plasma based on thorough study of derivatization and its convenient application to pharmacokinetics with semi-automated device

A sensitive and efficient method using a semi-automated pretreatment device, pre-column derivatization, multivariate optimization and high performance liquid chromatography with fluorescence and mass spectrometric detection was developed and validated for the systematic determination of two biophenols in four herb-related samples (medicinal herb; herbal products in tablet, capsule and oral liquid forms) and plasma samples after oral administration to rat. Only micro-sampling of 20 μL blood was needed for the analysis, and the pretreatment procedure including blood collection, derivatization by 10-ethyl-acridine-3-sulfonyl chloride (EASC) and injection to the sampling vials was efficiently finished in 10 min with no cumbersome and complicated operation. The novel application of artificial neural network (ANN) coupled with genetic algorithm (GA) to optimization of derivatization condition was executed and compared with the classical response surface methodology (RSM). The optimal condition for derivatization was validated by multi-criteria and nonparametric tests and used successfully to achieve the higher sensitivity (limit of detection: 0.6 and 0.8 ng/mL). The limit of reactant concentration (LORC) was put forward for derivatization method for the first time, and the lower values (2.0-2.7 ng/mL) provided the guarantee for the trace detection with the micro samples (<50 μL) required. The results of validation including selectivity, sensitivity, linearity, accuracy, precision, recovery, matrix effect and stability demonstrated the advantages of this method. The pharmacokinetic study of major bioactive components salidroside and p-tyrosol in herb Rhodiola crenulata and its products was more conveniently performed in 25 min. The established method could be the sensitive and efficient alternative method for the systematic detection of bioactive components in series of drug carriers from raw herb to herbal products and to blood in medical research. And the approaches of the thorough study played the guiding role in seeking a novel analytical method.

Improved Method for the Extraction and Determination of Bromophenols in Seafoods by High-Performance Liquid Chromatography with Fluorescence Detection

A sensitive precolumn derivatization method using 10-methylacridone-2-sulfonyl chloride (MASC) as derivatizing reagent followed by high-performance liquid chromatography (HPLC) with fluorescence detection has been developed for the determination of naturally occurring bromophenols in seafoods. Instead of using a traditional complex steam distillation solvent extraction method, the extraction method was modified by using sulfuric acid hydrolysis followed by hexane extraction and subsequent alkaline back extraction to obtain good recoveries and fewer interferences. Batch analysis of bromophenols thus became more performable because the sample amount and analysis time were greatly reduced. The recoveries of the five bromophenols were >80% with a noticeable improvement for 4-BP, the recoveries of which were usually <40% when analyzed by traditional methods. The HPLC sensitivity for the determination of bromophenols was greatly enhanced through derivatization. Under optimal conditions, the quantification limits obtained by using 4.0 g of sample were in the range of 0.60-1.0 ng/g. This is the first time that derivatization was applied to enhance the HPLC sensitivity of bromophenols. The proposed method was successfully applied to the determination of the target compounds in seafoods with a much higher sensitivity than traditional HPLC method.