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This study aimed to develop a chromatographic method to quantitatively determine phenol in fish tissues. This method involves solvent extraction of acidified samples, followed by derivatization to phenyl acetate and analysis with gas chromatography coupled with mass spectrometry (GC–MS). Phenol in a representative tissue sample (belly, gill, or renal tubules), which was homogenized with 2 N sulfuric acid, was extracted with ethyl acetate and derivatized to phenyl acetate using acetic anhydride and K2CO3 in water. An n-butyl acetate extract was injected into the GC–MS. The linearity (r 2) of the calibration curve was greater than 0.996. The analytical repeatability, which is expressed as the relative standard deviation, was less than 6.14%, and the recovery was greater than 96.3%. The method detection limit and the limit of quantitation were 8.0 μg/kg and 26 μg/kg, respectively. The proposed method is also applicable to the analysis of other biological tissues for phenol and its analogs, such as pentachlorophenol.

Open access
Pharmacokinetic UPLC–MS/MS studies on byakangelicol after oral and intravenous administration to rats
Authors: Xi Bao, Bingge Huang, Yiting Mao, Zhiguang Zhang, Yunfang Zhou, Congcong Wen and Quan Zhou

Byakangelicol is one of coumarins from Baizhi and has been shown to inhibit the release of PGE2 from human lung epithelial A549 cells in a dose-dependent manner. A sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and full validated for the quantification of byakangelicol in rat plasma. The pharmacokinetics of byakangelicol after both intravenous (5 mg/kg) and oral (15 mg/kg) administrations were studied. Chromatographic separation was performed on an ultra-performance liquid chromatography ethylene bridged hybrid (UPLC BEH) C18 column with acetonitrile and 0.1% formic acid as the mobile phase at a flow rate of 0.4 mL/min; fargesin was used as the internal standard (IS). The following quantitative analysis of byakangelicol was utilized in the multiple reaction monitoring mode. The samples were extracted from rat plasma via protein precipitation using acetonitrile. In the concentration range of 1–2000 ng/mL, the method correlated linearity (r > 0.995) with a lower limit of quantitation (LLOQ) of 1 ng/mL. Intra-day precision was less than 11%, and inter-day precision was less than 12%. The accuracy was between 92.0% and 108.7%, the recovery was better than 89.6%, and the matrix effect was between 85.9% and 98.6%. The method was successfully applied to a pharmacokinetic study of byakangelicol after intravenous and oral administration, and the absolute bioavailability was 3.6%.

Open access
Pharmacokinetics and bioavailability of hapepunine in mice by ultra-performance liquid chromatography–tandem mass spectrometry
Authors: Lianguo Chen, Qingwei Zhang, Yijing Lin, Xiaojie Lu, Zuoquan Zhong, Jianshe Ma, Congcong Wen and Cheng Ding

An ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was established to determine the hapepunine in mouse blood, and the pharmacokinetics of hapepunine after intravenous (1.0 mg/kg) and intragastric (2.5, 5, and 10 mg/kg) administrations was studied. Delavinone was used as an internal standard. The UPLC ethylene bridged hybrid (BEH) C18 column was used for chromatographic separation. The mobile phase consisted of acetonitrile and 0.1% formic acid with a gradient elution flow rate of 0.4 mL/min. Multiple reaction monitoring (MRM) mode was used for quantitative analysis of hapepunine in electrospray ionization (ESI) positive interface. Proteins from mouse blood were removed by acetonitrile precipitation. The verification method was established in accordance with the US Food and Drug Administration (FDA) bioanalytical method validation guidelines. In the concentration range of 1–1000 ng/mL, the hapepunine in the mouse blood was linear (r 2 > 0.995), and the lower limit of quantification was 1.0 ng/mL. In the mouse blood, the intra-day precision coefficient of variation (CV) was less than 12%, the inter-day precision CV was less than 14%. The accuracy ranged from 91.7% to 109.3%. The average recovery was higher than 76.7%, and the matrix effect was between 86.0% and 106.4%. The UPLC–MS/MS method was sensitive, rapid, and selective and was successfully applied to the pharmacokinetic study of hapepunine in mice. The absolute bioavailability of hapepunine was 22.0%.

Open access
Quality assessment of Moringa seed shells based on fingerprinting using HPLC-DAD
Authors: Yanqin Zhu, Ping Du, Shaojun Huang, Qinhong Yin and Yaling Yang

A fingerprint analysis method was established for the quality control of Moringa seed shells by high-performance liquid chromatography with diode array detection (HPLC–DAD). The HPLC–DAD separation was performed on a Thermo Hypersil Gold C18 (4.6 mm × 250 mm, 5 μm) column by gradient elution with acetonitrile–water as mobile phase. The fingerprint of Moringa seed shells was established with good precision, reproducibility, and stability obtaining within 60 min, and 13 common peaks in the fingerprint were designed. Similarity analysis, principal component analysis (PCA), and hierarchical clustering analysis (HCA) were carried out to analyze the obtained fingerprints. The similarity among 11 batches of samples in addition to No. 5 and 6 was no less than 0.92. Eleven samples could be classified into 2 clusters. The HPLC fingerprint technology and application of chemical pattern recognition can provide a more comprehensive reference for the quality control of medicinal plants.

Open access
Rapid RP-HPLC method for simultaneous estimation of metformin, pioglitazone, and glimepiride in human plasma
Authors: Mahmoud M. Sebaiy, Sobhy M. El-Adl, Mohamed M. Baraka and Amira A. Hassan

An isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed for rapid and simultaneous separation and estimation of 3 antidiabetic drugs, namely, metformin, pioglitazone, and glimepiride, in human plasma within 3 min. Separation was carried out on a MAGELLEN 5U C18 (5 μm, 150 mm × 4.60 mm) using a mobile phase of MeOH–0.025 M KH2PO4 adjusted to pH 3.20 using ortho-phosphoric acid (85:15, v/v) at ambient temperature. The flow rate was 1 mL/min, and the maximum absorption was measured at 235 nm. The retention time of metformin, pioglitazone, and glimepiride was noted to be 1.24, 2.32, and 2.77 min, respectively, indicating a very short analysis time compared to that of other reported methods. Also, limits of detection were reported to be 0.05, 0.26, and 0.10 μg/mL for metformin, pioglitazone, and glimepiride, respectively, showing a high degree of method sensitivity. The method was then validated according to the FDA guidelines for the determination of the three drugs clinically in human plasma, in particular, regarding pharmacokinetic and bioequivalence simulation studies.

Open access
Solid phase microextraction techniques used for gas chromatography: a review
Authors: Stefano Dugheri, Nicola Mucci, Alessandro Bonari, Giorgio Marrubini, Giovanni Cappelli, Daniela Ubiali, Marcello Campagna, Manfredi Montalti and Giulio Arcangeli

In the last decade, the development and adoption of greener and sustainable microextraction techniques have been proved to be an effective alternative to classical sample preparation procedures. In this review, 10 commercially available solid-phase microextraction systems are presented, with special attention to the appraisal of their analytical, bioanalytical, and environmental engineering. This review provides an overview of the challenges and achievements in the application of fully automated miniaturized sample preparation methods in analytical laboratories. Both theoretical and practical aspects of these environment-friendly preparation approaches are discussed. The application of chemometrics in method development is also discussed. We are convinced that green analytical chemistry will be really useful in the years ahead. The application of cheap, fast, automated, “clever”, and environmentally safe procedures to environmental, clinical, and food analysis will improve significantly the quality of the analytical data.

Open access
Stability-indicating RP-HPLC method for simultaneous determination of metformin hydrochloride and vildagliptin in tablet and biological samples
Authors: Abdul Shakoor, Mahmood Ahmed, Rabia Ikram, Sajad Hussain, Arifa Tahir, Badrul Mohamed Jan and Ahmad Adnan

The present work aimed to develop and validate a simple, rapid, sensitive, accurate, and precise method for simultaneous determination of metformin hydrochloride and vildagliptin in tablet and biological samples. Isocratic elution of both the analytes was performed at 35 °C by injecting 20 μL into Thermo Hypersil ODS C18 column (5 μm, 4.6 mm× 250 mm), while the flow rate was set to 0.8 mL/min. The mobile phase comprised of methanol, acetonitrile, and phosphate buffer (5:30:65, v/v, pH 3.5), and wavelength was selected at 212 nm. The overall run time per sample was 7.0 min with a retention time of 3.36 and 5.41 min for metformin hydrochloride and vildagliptin, respectively. The calibration curve was linear from 10–140 μg/mL for metformin and 1–14 μg/mL for vildagliptin with a coefficient of determination (R 2) ≤ 0.9919, while repeatability and reproducibility (expressed as relative standard deviation) were lower than 1.13 and 0.97%, respectively. Force degradation studies indicated a complete separation of the analytes in the presence of their degradation products providing a high degree of method specificity. The proposed reversed-phase high-performance liquid chromatography (RP-HPLC) method was demonstrated to be simple and rapid for the determination of metformin hydrochloride and vildagliptin in commercially available tablet and biological samples providing recoveries ranged between 100.13–100.29%.

Open access
Extraction of soluble sugars from green coffee beans using hot water and quantification by a chromatographic method without an organic solvent
Authors: Leonel Vinicius Constantino, Douglas Mariani Zeffa, Alessandra Koltun, Mariana Ragassi Urbano, Alisson Wilson Santos Sanzovo and Suzana Lucy Nixdorf

An optimal condition for extraction of soluble sugars from green coffee using water and a validated chromatographic method for its separation and quantification were proposed in this research. An orbital incubator shaker (OIS) and microwave-assisted extraction (MAE) were the 2 techniques used to extract soluble sugars. In such experiments, the variables: sample amount (300, 400, and 500 mg), time (30, 60, and 90 min), and temperature (30, 45, and 60 °C) were tested. The separation of sugars was performed in a chromatographic system (high-performance liquid chromatography refractive index detector [HPLC-RID]), which presented the selectivity for the analytes, a limit of detection of 0.020 g/L, a limit of quantification of 0.0625 g/L, and recovery rates greater than 95%. The repeatability and inter-day precision had low dispersion, RSD < 2.0% and < 3.0%, respectively. Sucrose content ranged from 0.65 to 2.39 g/L using an OIS and from 1.19 to 2.72 g/L by MAE, while glucose and fructose concentration varied from 0.08 to 0.12 g/L using both methods. The OIS technique is preferably indicated for extraction of soluble sugars at the following conditions: 500 mg of grounded green coffee, 90 min, and 60 °C. The proposed method for soluble sugar extraction and quantification may be applied in research laboratories and food industries since it is a low-cost and environment-friendly technique.

Open access
HPLC–DAD method for investigating pantoprazole for its stress-dependent degradation by photolysis and oxidation
Authors: Mohammad Al Bratty, Neelaveni Thangavel, Ramalingam Peraman, Vinod Kumar, Padmanabha Reddy, Krishna Veni Nagappan and Hassan Al Hazmi

A reversed-phased high-performance liquid chromatography–diode-array detection (HPLC–DAD) method has been developed for investigating the stress-dependent degradation of pantoprazole (PTZ) by a photolytic and oxidative mechanism. The developed method separated PTZ from its degradation products on a C18 column with a mobile phase consisted of methanol and water (60:40, v/v; pH 3.0) at a flow rate of 1 mL/min. The linear regression coefficient of 0.9995 was obtained for a concentration range from 5 to 25 μg/mL. The % relative standard deviation for repeatability and intermediate precision were below 0.5% and 1.5%, respectively, while the sensitivity of the method was demonstrated by a limit of detection value of 0.25 μg/mL. The stress sample analyses for PTZ results revealed the formation of a total of 18 degradation products, and out of them, 9 degradation products were common for both photolytic and oxidative degradations. Further, the oxidation by azobisisobutyronitrile produced the highest number of degradation products (11 impurities), 3 of which are more hydrophobic than PTZ. In photolytic degradation, 8 and 7 degradation products were observed with UV radiation and sunlight exposure, respectively. Furthermore, the degradation of pantoprazole sodium injection formulation was carried out under the same stress conditions, and it revealed the formation of 3 common impurities under both stress conditions, but other impurities were not detected in the formulations. Finally, 3 common impurities formed in formulations of PTZ injections, viz., sulfone, N-oxide, and N-oxide sulfone impurities, were identified by spike analyses.

Open access

Phyllostachys edulis (PES), the most important bamboo species in China, is widely distributed in East Asia. Flavonoids, which are important bioactive natural compounds, often have similar structures, making their structural elucidation difficult. The aim of this study was to represent valuable, reliable mass spectral data for the identification of flavonoids in plant leaves. Ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–Q-TOF-MS/MS) method was established for characterization and identification of the major flavonoids in PES leaf extract. A total of 13 flavonoids were simultaneously characterized, and their proposed characteristic product ions and fragmentation pathways were investigated. Thirteen compounds were separated on an Agilent Zorbax RRHD SB-C18 column (150 mm × 2.1 mm, 1.8 μm). On the basis of comparing with the 4 reference standards and the literature data, the other 9 flavonoids were identified by tandem mass spectrometry (MS/MS). Eight compounds (compounds 1, 4, 5, 8, 9, 10, 11, and 12) were found in PES leaves for the first time. An efficient UPLC–QTOF-MS/MS method was successfully applied for the structural identification of flavonoids in PES leaves. These results have practical applications for the rapid identification and structural characterization of these compounds in crude bioactive extracts or mixtures.

Open access