Vitamin D is a lipid-soluble compound that plays a key role in bone mineral metabolism. The commercial current kits and several published assay methods (High-performance liquid chromatography (HPLC) and Immunoassay) are complicated due to the use of multiple reagents, larger sample volume, high backpressure, longer extraction time, evaporation under nitrogen after extraction, significant interference and antibody cross-reactivity. Here we report a new HPLC method for the determination of 25-hydroxyvitamin D2 (25-OHD2) and 25-hydroxyvitamin D3 (25-OHD3) that is simple (no evaporation), rapid (10-minute run time) and robust. Serum sample (300μl) is mixed with 300μl acetonitrile containing lauraphenone as internal standard. After vortexing and centrifugation, the supernatant was loaded into C18 extraction cartridges, washed with 70% methanol and then eluted with 200μl of a mixture of 70% ethanol and 30% isopropyl alcohol (IPA). The eluent was mixed with 50μl of water and injected into the HPLC-UV system for analysis. The method proved to be linear in the range of 10-750nmol/L of 25-OHD2 and 25-OHD3. The intra- and inter-assay precision was less than 10 for both compounds at four different concentrations. The method was compared with (LC-MS/MS) and the correlation coefficients (R2) were 0.9454 and 0.9673 for 25-OHD2 and 25-OHD3 respectively. The proposed HPLC method is simple, rapid, robust and free from the most common problems encountered with commercial kits. It can be used in a high-volume laboratory that uses the HPLC method for the simultaneous determination of 25-OHD2 and 25-OHD3 in serum samples.

In this research, eight natural deep eutectic solvents (NaDESs) consisting of food-grade ingredients were screened for the extraction of four bioactive compounds (acteoside, cinnamic acid, angoroside C and harpagoside) from radix scrophulariae (RS). Among these NaDESs, Proline-Glycerol NaDES with higher comprehensive score was selected. The Criteria Importance Through Intercriteria Correlation (CRITIC) was applied to calculate the information entropy and the weight of indexes, and figured out a comprehensive score. The weights of acteoside, cinnamic acid, angoroside C and harpagoside were 0.369, 0.172, 0.241 and 0.218, respectively. Response surface methodology (RSM) mathematical model was used to optimize the extraction parameters. The optimal extraction parameters were as follows: extraction time with 42.21min, NaDES concentration with 52.89%, solid-to-liquid ratio with 1 : 37.05g/mL and the predicted value of comprehensive score was 0.885. Under the optimal condition, the comprehensive score was 0.903 ± 0.005. Finally, the antioxidant activity experiment revealed that the 1,1-Diphenyl-2-picrylhydrazyl · radical scavenging activity and hydroxyl radical scavenging activity of the extract at 2.0mg/mL and 1.5mg/mL were approximately equal to those of ascorbic acid, respectively. The results showed that the extraction condition optimized by RSM combined with CRITIC was reasonable and dependable, and the extract of radix scrophulariae exhibited good antioxidant activity.

With the widespread application of mixed-mode chromatography in separation analysis, it is becoming increasingly important to study its retention mechanism. The retention behavior of acidic compounds on mixed-mode octyl-quaternary ammonium (Sil-C8-QA) columns was investigated by computer simulation. Firstly, the benzoic acid homologues were used as the analytes, and the simulation model was constructed by the Materials Studio. Geometric optimization, annealing and molecular dynamics (MD) simulation of these complexes resulted in optimized conformations. The binding energy, mean square displacement (MSD) and torsion angle distribution generated by MD simulation were then analyzed. The results showed that the more negative binding energy, the greater the MSD and the narrower the torsion angle distribution, indicating that the stationary phase behaves with stronger interaction and retention. The retention behavior of five acidic drugs on the Sil-C8-QA column was then successfully explained by simulation. Acidic drugs are more retentive on the mixed-mode column due to the more substantial interaction brought by the reversed-phase/ion-exchange mixed-mode mechanism compared to other single-mode columns. This simulation method is expected to provide ideas for studying the separation mechanism and predicting the retention behavior of more complex samples.

In the present study, metal-organic frameworks, MIL-101(Fe) and MIL-53(Al), were synthesized under solvothermal conditions and were characterized by Fourier transform infrared spectroscopy, X-ray energy diffraction spectroscopy and scanning electron microscopy. The synthesized metal-organic frameworks were utilized for the purpose of dispersive micro-solid phase extraction of sorafenib in both human plasma and wastewater, which was subsequently followed by high performance liquid chromatography with ultraviolet determination. Parameters affecting extraction efficacy including adsorbent amount, ionic strength, pH, type of elution solvent, adsorption and desorption time were optimized. Under optimal experimental conditions, the linearity in human plasma and wastewater was achieved in the range of 0.25-5.00 and 0.01-0.20μg/mL, respectively. The extraction recovery for MIL-101(Fe) and MIL-53(Al), respectively, was calculated in human plasma and wastewater and found to be in the range of 86.27-99.47%.

2-hydroxyglutarate has limited abundance in normal tissues but a high level under certain pathologic conditions. To clarify the diagnostic value of two chiral isomers of 2-hydroxyglutarate in plasma and urine of Chinese cancer patients, an ultra-high performance liquid chromatography-tandem mass spectrometric method was developed for simultaneous quantification of D-/L-2-hydroxyglutarate. The selected D-/L-2-hydroxyglutarate-d5 as internal standards were added to samples before the SPE on Waters Oasis® MAX 96-Well plate (30μm, 60mg). A derivatization step with (+)-O,O'-diacetyl-L-tartaric anhydride permitted the chromatography separation of D-/L-2-hydroxyglutarate on an ACQUITY UPLC-HSS T3 column (50 × 2.1mm, i.d. 1.8μm) with acetonitrile and water (containing 0.1% formic acid and 10mmol ammonium acetate) as the mobile phase. The calibration curves showed good linearity (R ≥ 0.99) over the concentration ranges of 200-5,000ng/mL and 500-20,000ng/mL for analysis of D-/L-2-hydroxyglutarate in plasma and urine samples, respectively. Intra- and inter-run precision were ≤ 12.33%, and the accuracy was within the range of -10.44 to 13.90%. This method was further successfully applied to clinical sample analysis in isocitrate dehydrogenase 1/2 mutated Chinese cancer patients.

Green, selective and accurate high-performance liquid chromatography (HPLC) chromatographic method is presented for simultaneous separation and quantitation of the co-prescribed drugs in chemotherapy omeprazole, ondansetron and deflazacort in spiked human plasma. An isocratic HPLC separation was performed on X Bridge C18 (4.6 × 250mm) column with 5μm particle size using mobile phase consisting of methanol: ammonium acetate buffer pH4 adjusted by acetic acid (60: 40, v/v). The injection volume was 20μL with UV detection wavelength at 237nm at room temperature. Flow rate of the mobile phase was adjusted to be 2.0ml/min. Dexamethasone was used as internal standard to correct the variation during sample pretreatment. FDA guidelines were followed to validate the developed method. Successful application of the developed method was revealed by simultaneous determination of omeprazole, ondansetron and deflazacort in spiked human plasma in ranges of 1-20, 0.1-8 and 0.2-8μgmL-1 for omeprazole, ondansetron and deflazacort, respectively. Four greenness assessment tools were used to evaluate the greenness of the developed method and the results were accepted. This method permitted the accurate simultaneous determination of the studied drugs, thus it can be used during therapeutic drug monitoring in daily clinical practice.

A stability indicating RP-HPLC method is suggested for determination of Glycopyrrolate-Neostigmine (GLY/NEO) in bulk drugs and injection formulation. GLY/NEO were eluted from a Chromolith High Resolution RP-18e (100 mm×4.6mm) with buffer solution (pH3.0) as mobile phase A and a mixture of HPLC grade acetonitrile and water mixture (90:10) as mobile phase B. The gradient was optimized with a flowrate of 0.5mL/min and wavelength of 222nm. A complete analytical method validation was effectively carried out as per ICH Q2 (R1) guidelines. Recovery studies were performed at 50-150% level of working concentrations, and results were in the range of 99-101%. The linearity was detected in the range of LOQ to 200% of the specification limits i.e., 0.5% each for NEO and GLY, 0.01% for NEO Impurity B and 1.0% for rest of the impurities with respect to the test concentration of the respective components. For stability study, various stress conditions such as acid, base, oxidation and thermal as per ICH guidelines were studied. The high recovery and low relative standard deviation confirm the suitability of proposed method that can be employed for the routine analysis in bulk and pharmaceutical formulation.

Elagolix sodium is a gonadotropin-releasing hormone (GnRH) receptor antagonist that inhibits endogenous GnRH signaling by competitively binding to GnRH receptors in the pituitary gland to treat moderate to severe pain associated with endometriosis. To keep the safety and quality of the drug, a fast quantitative method by reversed-phase ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry has been developed and validated for the identification, assay and estimation of potential genotoxic impurities trimethyl phosphate and triisopropyl phosphate in commercial batches of this active pharmaceutical ingredient in accordance with International Conference on Harmonization guidelines Q2 and M7. The method was validated by assessing specificity, sensitivity, linearity, the limit of quantification and detection, accuracy, precision and robustness for above analytes at a very low concentration, whose quantification and detection limits reached to 24 and 4.8pg/ml, respectively, and the total run time for a single injection was 6min.

A rapid, simple and highly sensitive stability-indicating reverse-phase high-performance liquid chromatographic technique, coupled with a photodiode array detector, was developed and validated for the estimation of Deferasirox (DFS). The chromatographic separation was achieved using a C-18 (250 × 4.6 mm, 5μm) stationary phase and a mobile phase composed of 0.1% orthophosphoric acid and acetonitrile at a flow rate of 1mL/min. The detection was carried out at a wavelength of 245nm with a constant injection volume of 10μL throughout the analysis. With an R2 value of 0.9996, the calibration curve was determined to be linear over an appropriate concentration range of 50-500ng/mL. According to the International Conference on Harmonization (ICH) Q1 (R2) guideline, DFS was evaluated under stress conditions that included hydrolytic (acid, alkali and neutral), oxidative and thermal degradation. The findings demonstrated that significant degradation was observed in acidic degradation conditions, whereas drug substance was found to be stable when exposed to neutral, basic, oxidative and thermal degradation. The developed method was validated as per ICH guidelines. The developed method was employed successfully to estimate the amount of DFS in bulk and pharmaceutical formulation.

Anlotinib and osimertinib are a class of tyrosine kinase inhibitors for the treatment of malignant tumor. The combination of anlotinib and osimertinib is currently used for treating non-small cell lung cancer (NSCLC) patients. This study aimed to develop a simple and rapid isotope-labeled UHPLC-MS/MS method for the simultaneous determination of anlotinib and osimertinib in human plasma. The analytes were extracted by protein precipitation with acetonitrile and were then separated on a Shim-pack GIST C18 column. The detection was performed on Shimadzu 8050 triple quadruple mass spectrometer in the positive electrospray ionization mode with multiple reaction monitoring. The precursor-to-product ion transitions were m/z 408.10→339.75, 500.25→72.20 and 413.50→344.50 for anlotinib, osimertinib and D5-anlotinib, respectively. Validation is based on US Food and Drug Administration guidelines. The linearity ranges were 0.5-100ng/mL for anlotinib and were 1-500ng/mL for osimertinib with the correlation coefficients (r 2) ≥ 0.99. Accuracy and precision, matrix effect, extraction recovery and stability of anlotinib and osimertinib were acceptable after validation. The UHPLC-MS/MS method was successfully validated and was applied to monitor the concentration of anlotinib and osimertinib in NSCLC patients.