Abstract 2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside is the main compound of Polygonum multiflorum . There are two geometrical isomers of 2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside. Several studies have shown that cis ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside may be the risk compound of hepatotoxicity in Polygonum multiflorum Thunb. and there are few comprehensive comparisons on the different impacts of cis ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside and trans ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside about metabolic characteristics. This paper aimed to provide a comprehensive assessment of the metabolomics and lipidomics studies of the differences in metabolic characteristics of cis ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside and trans ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside. The results showed that trans ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside and cis ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside significantly affected 47 metabolites. The main interfering pathways included alpha‐linolenic acid, linoleic acid (LA) metabolism, arachidonic acid (AA) metabolism, and fatty acid metabolism. According to the transcriptomics study, the altered genes were mainly enriched in LA metabolism, AA metabolism, and fatty acid metabolism. Two genes ( Runx3 and Scd1 ) were mainly involved in the cell cycle and fatty acid metabolism in the cis ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside group, and one enzyme (Phospholipase B1) was related to alpha‐linolenic acid, LA metabolism and AA metabolism in the trans ‐2,3,5,4′‐tetrahydroxy stilbene‐2‐ O‐β ‐D‐glucoside group. These would provide useful information for further investigation on therapeutic and hepatotoxic mechanisms of Polygonum multiflorum Thunb.

Abstract Doxycycline hyclate (DOXH) is very important to treat acne and prevent infections caused by bacteria, so quantifying doxycycline hyclate and its related substances is crucial. In this work, All analytes of doxycycline and its related substances, including methacycline, 4‐epi doxycycline, 6‐epi doxycycline, and 2‐acetyl‐2‐carbamoyl doxycycline, were successfully separated at low concentrations in a single run utilizing the suggested isocratic high‐performance liquid chromatography method with a mobile phase comprising water:acetonitrile:perchloric acid (75:25:0.2, v/v), Phenomenex Luna C18 column (50 × 4.6 mm, 3 μm i.d.) maintained at 30°C with a flow rate of 0.7 mL/min, injection volume of 25 μL, and photodiode array detector at 269 nm. DOXH and its related substances were linear in the range of 0.25–50, 0.1–30, 0.2–35, 0.5–50, and 0.6–20 μg/mL, respectively, with correlation coefficients greater than 0.999 and good accuracy results between 98% and 102%. The method has been successfully used to determine the drug's comparative study in both generic and reference products, demonstrating the similarity between the two products. According to the International Council for Harmonization requirements, the proposed approach was validated. Additionally, the technique has effectively studied in vitro dissolution, Six Sigma, and content uniformity.

Abstract Herein, the zeolitic imidazolate framework‐8 template was accommodated onto the surface of a pencil graphite substrate through the electrodeposition system. Then, Zn in the zeolitic imidazolate framework‐8 was replaced with Cu atoms via the galvanic replacement procedure. The modified template was used for the synthesis of another metal‐organic framework (copper‐benzene di carboxylic acid) by a solvothermal method. The prepared fiber was characterized by field emission‐scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction technique. Then, it was employed for direct immersion solid‐phase microextraction of methyl, ethyl, and butyl parabens. Various factors, such as the pH of the sample solution, stirring rate, desorption volume, the concentration of salt, extraction time, and desorption time, were selected and optimized. Under the optimized condition (extraction time = 30 min, desorption time = 2 min, desorption volume = 200 μL, salt concentration = 0% w/v, sample solution pH = 3.0, and stirring rate = 700 rpm), the linearity of the method was in the range of 1–200 μg/L ( r 2 > 0.9926). The limits of detection and quantification fall between 0.28–0.65 μg/L and 0.91–1.98 μg/L, respectively. The analysis of selected parabens in toothpaste and hand and face lotion, were also done using the suggested methodology.

Abstract According to the concept of green analytical chemistry, the analytical method development should be carried out by avoiding or minimizing the usage of toxic organic solvents for the safety of human and aquatic animal life and the protection of the environment. Hence, the green analytical chemistry (GAC)‐assisted robust liquid chromatographic method has been developed for chromatographic analysis of azilsartan medoxomil and cilnidipine (CIL) using safe organic solvents. The chromatographic method was developed by the implementation of analytical quality by design using chemometrics and response surface modeling. The chromatographic separation was carried out using Shim‐Pack C18 (250 × 4.6 mm, 5.0 μm) column as stationary phase and ethanol: 0.1% V/V ammonia solution (45:55, %V/V) as mobile phase. The chromatographic peak of AZL and CIL was found to be at the retention time of 3.5 and 4.5 min, respectively. The flow rate was kept at 1.0 mL/min and the column oven temperature was set to 40˚C. The developed method was found to be validated as per the International Council for Harmonization Q2 (R1) guideline. The method was applied for the assay of fixed‐dose combination and results were found in compliance with the labeled claim. The greenness of the method was evaluated using GAC tools.

Abstract A polypyrrole‐coated rubber foam sorbent with a steel wire insert was developed for the magnetic solid phase extraction of fipronil and fipronil sulfone from tea samples for analysis by a gas chromatography‐electron capture detector. Under the optimum conditions, the method linear ranges were 0.05–100 μg/L for fipronil and 0.01–100 μg/L for fipronil sulfone. The limits of detection were 0.01 and 0.005 μg/L while limits of quantitation were 0.05 and 0.01 μg/L for fipronil and fipronil sulfone, respectively. The preparation procedure of the developed sorbent exhibited good reproducibility with a relative standard deviation in the range of 1.9%–2.4% spiked at 50 μg/L. Good precision was obtained with a relative standard deviation below 6.7% in four concentrations ranging from 0.0 to 50 μg/L. Fipronil sulfone was detected in two tea samples at concentrations of 1.79 ± 0.05 and 2.64 ± 0.03 μg/L with recoveries ranging from 80.4 ± 1.5% to 110.0 ± 2.0%. Thus, the developed sorbent exhibited high extraction efficiency with good selectivity towards the target analytes in real samples.

Abstract Polyvinylpyrrolidone (PVP) is known as a polymer with special adsorption properties for polyphenolic compounds. In this paper, chemical‐bonded stationary phase (PVP@Silica) was prepared and applied to the separation of flavonoids. System constants determined by linear solvation energy relationships with methanol–water mixtures as the mobile show that the column can provide stronger hydrogen bonding and π–π interaction than C18 column. Under reversed‐phase conditions, traditional flavonoids have much longer retention on PVP@Silica than on C18 column with methanol–water mobile phase due to multimodal retention mechanism, including hydrogen bonding and π–π interaction. In addition, a U‐shaped retention curve was observed in acetonitrile–water mobile phase because of the enhanced hydrogen bonding under the high proportion of acetonitrile. The selectivity to polyhydroxy structure gives the stationary phase unique separation ability for flavonoids. The separation orthogonality was further investigated by a sample set containing 33 flavonoids with different substitution structures. The (RP‐PVP@Silica)‐(RP‐C18) system exhibited 60% orthogonality metric (OM) for these flavonoids with methanol–water mobile phase. A high OM of 63.5% was achieved in (RP‐PVP@Silica)‐(HILIC‐PVP@Silica) system. Finally, PVP@Silica was applied to the purification of total flavonoids in Ginkgo biloba extract (GBE). The offline (RP‐PVP@Silica)‐(RP‐C18) two‐dimensional separation system was used for the analysis of flavonoids in GBE.

Abstract Benzodiazepines are one of the most prescribed for therapeutic purposes and the most abused drugs. Therefore, liquid chromatography–tandem mass spectrometry–based methods that analyze several benzodiazepines simultaneously are required. In this study, we developed a simple, full validated in‐house method in a single‐triple quadrupole platform SCIEX QTRAP 4500 system for the simultaneous detection and quantification of the 10 most prescribed benzodiazepines within a 10‐min run time. The linear range was 12.5–500 ng/mL. All limits of detection were below 4.03 ng/mL and limits of quantitation below 12.22 ng/mL, except clobazam (7.27 and 22.04 ng/mL, respectively). Both the limit of detection and quantitation were lowest for diazepam (0.95 and 2.89 ng/mL, respectively). The method was evaluated for accuracy, precision, carry‐over, recovery, stability, and matrix effects, and all validation studies met internationally acceptable criteria. The applicability of the method was proven by analyzing authentic urine samples, internal, and third‐party external quality samples. This precise, accurate, shorter total run time and ease of urine sample analysis method is applicable in detecting most prescribed benzodiazepines and their metabolites even in glucuronide forms.