A method was developed to determine glyphosate and their metabolites in water. The widespread use of this herbicide in agricultural activities worldwide, despite the reported adverse effects on both the environment and health, is a cause for concern and makes it necessary to monitor its presence through a method that guarantees the determination at trace levels. A direct extraction of the analytes with phosphate buffer was performed with subsequent derivatization with 9-fluorenylmethyl chloroformate. The quantification was determined by Ultra Performance Liquid Chromatography-tandem mass spectrometer. The method was validated through the following parameters: selectivity, detection and quantification limits, linearity, accuracy, precision and uncertainty. The average recoveries ranged between 94.08 and 103.31%. Additionally, detection limits from 0.396 to 0.433 μg/L, and the quantification limit was 5.0 μg/L for all the analytes evaluated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R2 ≥ 0.99 and CV ≤ 20%), the estimated expanded uncertainty was 12.95, 11.15 and 13.83% for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. This method was successfully applied for the determination of the target analytes in irrigation water samples, detecting concentrations of aminomethylphosphonic acid over limit detection for some sampling sites.

An applicable method for the precise measurement of major carboxylesterase (CESs) activity in liver still limited. Clopidogrel and irinotecan are specific substrates for CES1 and CES2, respectively. Clopidogrel is metabolized to the inactive metabolite clopidogrel carboxylate (CCAM) by CES1. Irinotecan is metabolized to the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38) by CES2. In the present study, the LC-MS/MS method for the determination of CCAM and SN-38 were separately developed to characterize the metabolic activities of CES1 and CES2 in mouse liver microsomal. CCAM was separated on a Ecosil ODS column with an isocratic mobile phase consisted of 5 mmol/L ammonium formate and 0.1% formic acid in water and acetonitrile (15:85, V:V) at a flow rate of 0.4mL/min. SN-38 was separated on a Waters symmetry C18 column with an gradient mobile phase consisted of 5 mmol/L ammonium formate and 0.1% formic acid in water and acetonitrile at a flow rate of 0.3 mL/min. Calibration curves were linear within the concentration range of 100-20,000 ng/mL for CCAM and 1-200 ng/mL for SN-38. The results of method showed excellent accuracy and precision. The recovery rate, matrix effect and stability inspection results were within the acceptance criteria. The optimized incubation conditions were as follows: protein concentration of microsomes were all 0.1 mg/mL, incubation time was 60 min for clopidogrel and 30 min for irinotecan, respectively. This method was sensitive and applicable for the determination of the activity of CESs in the mouse liver microsomes.

In view of the adsorption performance of polyvinylpolypyrrolidone (PVPP) to flavones, the adsorption and purification of bamboo leaf flavones (BLFs) by PVPP were studied. The flavones solution was adsorbed by PVPP column chromatography, and then establish a relatively effective method for elution and purification of flavones from bamboo leaf. The optimal separation conditions of column chromatography were determined as the following: the feed concentration of 10 mg/mL, the ratio of diameter to height of 1:1.9, eluents of deionized water (21 mL) and 70% ethanol (800 mL) with a flow rate of 0.33 mL/min. The purity of flavones obtained from ethanol eluents (80–480 mL) was 96.2%. This showed that the PVPP had an ideal adsorption and purification effect on BLFs.

A reversed-phase high-performance liquid chromatography method was developed and validated for the simultaneous determination of pridinol, diclofenac and diclofenac-related compounds in tablet formulations. The proposed method is also suitable for content uniformity determination, for dissolution test and for stability studies. Separation was achieved on a base-deactivated silica C8 column, using 50 mM phosphate buffer (pH 2.5) and methanol (40:60 v/v) as mobile phase, at a flow rate of 1.0 mL/min and column temperature of 40°C. Ultraviolet detection was made at 225 nm. The method was validated for specificity, accuracy, precision (intraday and interday levels) and linearity for each analyte. For diclofenac impurity A, sensitivity was also studied. The method showed specificity and linearity (R2: 0.999 for the three analytes) over the assessed concentration range (diclofenac: 2.5–75.0 μg/mL, pridinol: 2.0–60.0 μg/mL and impurity A: 1.25–5.0 μg/mL) and demonstrated good precision as reflected by the low coefficient of variation in all cases. Recovery rates obtained were 99.81, 100.58 and 100.96% for diclofenac, pridinol and impurity A respectively, and for all three analytes, the variances of the concentrations tested were equivalent. The detection and quantitation limits for impurity A were 0.078 and 0.261 μg/mL, respectively.

Clobetasol Propionate is a highly strong corticosteroid that is used in a variety of topical medication formulations, including foam, ointment, lotion, spray and shampoo; with a dosage strength of 0.05% (w/w). The goal of this research was to identify and characterize a substantial unknown impurity (UK) detected during the stability testing of a Clobetasol Propionate foam pharmaceutical product in accelerated conditions (40°C and 75% relative humidity). Developing a single, robust and accurate HPLC method that is LC-MS compatible for quantifying all 14 potential Clobetasol Propionate impurities in therapeutic drugs is another goal. Preparative column chromatography was used to separate the impurity, and spectroscopic techniques like IR, NMR and MS were used to characterize its structure. The structure of isolated UK was effectively characterized and defined using spectroscopic data evaluation. The chromatographic method has also been validated according to the International Conference on Hominization's Q (2) quality guidelines. The isolated and characterized impurity had the same equivalence as the impurity found during stability testing. Precision, accuracy, linearity, robustness and ruggedness are all met in the method validation data.

The aim of this study is to examine the interactions of composite materials obtained by adding single-walled carbon nanotubes (SWCNT) to polyetherimide (ULTEM) in different weight ratios with various organic solvents, and to evaluate the solubility of composites in these organic solvents. The characterization of prepared composites was performed with SEM analysis. Thermodynamic properties of ULTEM/SWCNT composites were determined by the inverse gas chromatography (IGC) method at 260–285°C in infinite dilution. According to the IGC method, the retention behaviors were examined by passing different organic solvent vapors over the composites used as stationary phase, and retention diagrams were drawn using the obtained retention data. Thermodynamic parameters including Flory–Huggins interaction parameters (${\chi}_{12}^{\infty }$), equation of state interaction parameters (${\chi}_{12}^{\ast }$), weight fraction activity coefficients in infinite dilution (${\Omega}_1^{\infty }$), effective exchange energy parameters (${\chi}_{\mathrm{eff}}$), partial molar sorption enthalpies ($\Delta{\overline{H}}_1^S$), partial molar dissolution enthalpies in infinite dilution ($\Delta{\overline{H}}_1^{\infty }$) and molar evaporation enthalpies ($\Delta{\overline{H}}_v$) were calculated using the linear retention diagrams. According to ${\chi}_{12}^{\infty }$, ${\chi}_{12}^{\ast }$, ${\Omega}_1^{\infty }$ and ${\chi}_{\mathrm{eff}}$ values, organic solvents were found to be poor solvents for composites at all temperatures. Besides, the solubility parameters of composites were determined by IGC method at infinite dilution.

The goal of this study is to provide a single, widely applicable high-performance liquid chromatographic (HPLC) technique for the determination of related substances in multicomponent oral solution of promethazine hydrochloride and dextromethorphan hydrobromide. For the assessment of impurities of promethazine hydrochloride and dextromethorphan hydrobromide in oral solution, a unique, sensitive, quick, stability-indicating gradient HPLC technique has been created. For chromatographic separation, an Agilent Eclipse XDB-C18, 250 mm × 4.6 mm, 5 μm column was used with a buffered mobile phase consisting of a mixture of potassium dihydrogen phosphate pH 3.0:acetonitrile (80:20) v/v as mobile phase A and potassium dihydrogen phosphate pH 3.0:acetonitrile:methanol (10:10:80) v/v/v as mobile phase B. The separation was performed at a flow rate of 1.2 mL/min and a detection wavelength of 224 nm. The temperature of the column oven was regulated at 40°C. With good sensitivity and resolution, all compounds were effectively separated on a reverse-phase HPLC column. Acid, base, photolytic, thermal, oxidative and humidity stress conditions significantly degraded dextromethorphan hydrobromide and promethazine hydrochloride. The developed technique was validated according to the criteria of the International Conference on Harmonization for all validation parameters such as specificity, accuracy, linearity, precision, the limit of detection, the limit of quantitation and robustness.

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×4.6 mm) with buffer solution (pH 3.0) 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 0.5 mL/min and wavelength of 222 nm. 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.

Tecoma stans (Fam. Bignoniaceae) is also popularly known as yellow bells and yellow trumpet bush in vernacular terminology. Limited and variable data are available from the literature regarding the quantification of luteolin, apigenin and chrysoeriol, which are considered as the most active pharmacological active constituents. High-performance liquid chromatography-photodiode array detection has been developed for the determination of the bioactive flavonoids, luteolin, apigenin and chrysoeriol, from the methanolic extract of the leaves of T. stans. A column packed with a pentafluorophenyl-based stationary phase was used for the separation of the analytes under gradient elution. The detection wavelength was 345 nm. The validation of the method as per the International Council on Harmonisation (ICH) guidelines (ICH 2005) for linearity, accuracy and precision was investigated and found within limits specified by the ICH guidelines. The method was linear over with a good regression coefficient of more than 0.99. The limit of detection of the method was 0.68, 2.97 and 1.76 μg/mL for luteolin, apigenin and chrysoeriol, respectively. In conclusion, a reliable and reproducible method was devised that can be used for the estimation of the said components from T. stans.

An optimized method employing chiral supercritical fluid chromatography with diode array UV-VIS detection has been developed for the quantitative analysis of nicotine and nornicotine enantiomer distributions. The method parameters that were optimized included: column type (stationary phases, Chiralpak IG-3), column temperature (40°C), modifier types and concentration (isopropyl alcohol, 10%), additive types and concentrations (diethylamine, 0.2%), elution times (1.2). These optimized conditions led to nicotine and nornicotine enantiomer detection limits of ~5 ng/μL with accompanying %RSD values of <2% from the analyses of commercially available nicotine-containing formulations.

Using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as a pre-column derivatization reagent, optimized derivatization and chromatography parameters, a simple high-performance liquid chromatography fluorescence detector (HPLC–FLD) method was developed and validated to determine 23 related amines in plasma and cortex of C57BL/6 mice with cerebral ischemia–reperfusion injury. The prepared samples were separated on a ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm) with 60% acetonitrile (ACN) and 20 mM sodium acetate solution (pH adjusted to 5.0 by phosphoric acid). All analytes achieved good separation within 1.2 h at a flow rate of 1 mL/min. The limits of detection and limits of detection quantitation of the method were ranged from (0.1–9.2) to (0.3–30.6) ng/mL, respectively. The analytical method was apt for simultaneously determining 23 amino acids in plasma and cortex. Our results revealed that the relevant amino acids were significantly altered (P < 0.05) in C57BL/6 mice.

An analytical method coupling pressurized liquid extraction (PLE), pre-concentration by thermal desorption (ATD) and analysis by GC/MSMS was developed for the quantification of pesticides in air and dust near vineyards crops to evaluate potential exposure of residents living near these crops. PLE was done using acetonitrile and extracts were concentrated under fume hood to 1 mL. 100 μL of the extract was spiked in a Tenax TA tube and internal standards and N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide were added before thermal desorption at 300°C for 30 min. GC/MSMS analysis was done in MRM mode and limits of quantification and limits of detection were determined for each matrix (passive air sample, active air sample and dust). The method was applied in the field and shows good sensitivity and accuracy.

An innovative RP-HPLC technique was devised to simultaneously quantify thymoquinone (TQ) and capecitabine (CAP) in newly designed polymeric nanoparticles. A unique chromatographic approach was created, optimized and validated using Design-Expert® (design of experiment) in compliance with ICH requirements. A 24 factorial design examined the influence of variables on method responses. The method found linear between 0.25 and 16 μg/mL, with an R2 value of 0.999. The detection and quantification limits for CAP were 0.05 and 0.16 μg/mL, respectively, and 0.12 and 0.38 μg/mL for TQ, respectively, and 97-100% recovery in plain drug solution and 100-102% in nanoformulation were achieved. A purposeful modification examined by analysis of variance revealed that the experimental model was significant (P = 0.0001). The total drug content in nanoformulation was 8.68 mg, and the entrapment efficiency was 84.79%. Based on the findings, it is possible to infer that the use of the Quality by Design methodology resulted in the development of a more accurate technique capable of producing consistent, dependable, high-quality data and precise in quantifying CAP and TQ in bulk and nanoparticulate systems.

Two rapid, smart and validated stability indicating HPLC and TLC techniques were developed to determine atenolol (ATE) and lercanidipine HCl (LER) simultaneously in their pharmaceutical formulation. HPLC chromatographic separation was implemented by using Microsorb C18 (250 × 4.6 mm, 5 μm) column, with mobile phase of acetonitrile and 20 mM potassium dihydrogen phosphate buffer pH 3.5 adjusted by orthophosphoric acid in the ratio of (65:35, v/v) at a flow rate of 1.2 mL/min at 240 nm also the injection volume adjusted to be 30 μL. These selected conditions effectively separated ATE and LER at a retention time of 2 and 6.7 min, respectively, by isocratic elution mode without any interference from the obtained degradation products of LER. The densitometric determination was performed by using precoated silica gel 60F254 aluminum plates and chloroform, methanol and triethylamine (11.3:1.3: 0.3, by volume) as a developing system. The detection wavelength for simultaneous estimation of both drugs was 240 nm in the presence of the oxidative product of LER. The RF values for ATE and LER were 0.22 and 0.78, respectively. The calibration curves of both techniques were constructed with linearity ranges of (5–55) μg.mL−1 and (1–55) μg.mL−1 for both ATE and LER, respectively, for HPLC determination. While for TLC, the linearity ranges were (1–4) μg/band and (0.2–1.4) μg/band for ATE and LER, respectively. LER degradation products were characterized using UPLC/MS and the suggested mechanisms and degradation pathways were introduced.

Ophthalmic pharmaceutical preparation containing antazoline (ANT) and tetryzoline (TET) is prescribed widely as an over the counter medication for allergic conjunctivitis treatment. Development of a selective, simple and environmentally friendly thin-layer chromatographic method established to determine both ANT and TET in their pure forms, pharmaceutical formulation and spiked aqueous humor samples. By using silica gel plates and means of a developing system consists of ethyl acetate:ethanol (5:5, by volume), the studied drugs separation was achieved, and scanning was carried out at 220.0 nm for the separated bands with a 0.2–18.0 μg/band concentration range for each of ANT and TET. Standard addition technique application was carried out to determine the proposed method validity. Statistical comparison was made between the proposed method and the official methods ANT and TET showing no significant difference concerning accuracy and precision. Furthermore, greenness profile assessment was accomplished by means of four metric tools, namely, analytical greenness, green analytical procedure index, analytical eco-scale and national environmental method index. Highlights

A method has been designed based on gas chromatography with flame ionization detection (FID) for the separation and analyses of ranitidine, famotidine and metformin after pre-column derivatization with trifluoroacetylacetone and ethyl chloroformate. DB-1 (30 m × 0.32 mm id) column with film thickness 0.25 μm was used for the separation at an initial temperature of column was 100°C for 2 min, and ramping at 20°C/min up to 250°C, with a hold time of 3 min. The rate of nitrogen flow was 2.5 mL/min and FID was used for detection. Complete separation was obtained between all the three drugs including excess of derivatization reagents. Linear calibration curves and detection limits were obtained in the ranges 0.1–30 μg/mL and 0.011–0.015 μg/mL. The procedure was repeatable in terms of peak heights/peak areas and retention time (n = 5) for derivatization, quantitation and separation with relative standard deviations (RSDs) within 2.0–3.0%. The approach was examined for the analyses of drug products and serum after the intake of the drugs by healthy volunteers, and recoveries were obtained within 95–98% with RSDs 2.4–3.1%.

A reverse phase high-performance liquid chromatography (HPLC) method has been developed for the quantification of a typical drug Dasatinib (DST) and its related impurities in pharmaceuticals. Kinetex C18 (4.6 × 150 mm, 5 μm) column was used in the chromatographic separations, using buffer (1.36 g of KH2PO4 in 1000 mL of water, pH = 7.8; adjusted with diluted KOH solution) with solvent as acetonitrile and mode of elution as the gradient. The flow rate is 0.9 mL/min, column oven temperature as 45°C and the overall gradient run time as 65 min. The developed method was found to produce symmetric and good separation between the process-related and degradation impurities. Method optimization is achieved with photodiode array at 305 nm over the concentration range of 0.5 mg/mL and degradation studies were carried out under acidic, alkaline, oxidative, photolytic and thermal conditions to demonstrate the stability indicating capability of the method. Two major impurities were found in forced degradation studies in the HPLC analysis, the unknown, acid degradants were enriched and isolated by preparative HPLC, then characterized through high-resolution mass spectrometry, nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The unknown acid degradation impurity was showing Exact Mass of 521.11, molecular formula C22H25Cl2N7O2S and its chemical name as 2-(5-chloro-6-(4-(2-hydroxyethyl) piperazin-1-yl)-2-methylpyrimidin-4-ylamino)-N-(2-chloro-6-methylphenyl) thiazole-5-carboxamide. Another impurity (oxidative degradant) found as known DST N-oxide Impurity-L and its chemical name as 4-(6-((5-((2-chloro-6-methylphenyl) carbamoyl) thiazol-2-yl) amino)-2-methylpyrimidin-4-yl)-1-(2-hydroxyethyl) piperazine 1-oxide. The analytical HPLC method was further validated as per ICH guidelines.

A new stability-indicating liquid chromatography method was developed for the quantification of empagliflozin and two synthetic impurities. The chromatographic conditions included Spherisorb® RP-18 column (150 × 4.6 mm, 5 μm) with a PDA detector, using acetonitrile and formic acid (pH 4.0) as mobile phase in gradient elution and flow-rate of 1.2 mL·min-1. The gradient increasing from 51 to 100% acetonitrile until 11.00 min, followed by decreasing the solvent from 100% to the initial ratio from 11.01 to 15.00 min. The method was validated according to International Council of Harmonization guidelines. The LOD and LOQ values for impurities A and B were 35 and 15 ng·mL-1, respectively, (for LOD) and 115 and 35 ng.mL-1, respectively (for LOQ). The method was linear in the range of 80-140, 115-1150 and 35-350 ng·mL-1 for EMPA, impurities A and B, respectively, and the correlation coefficient were > 0.999 in all situations, indicating the method good linearity. The developed method showed a good recovery for empagliflozin and added impurities. The method has proven to be precise, demonstrated values less than 2.0% to empagliflozin and 5.0% to synthetic impurities, robust and selective with no interference from other products in the determination of analytes. The in silico toxicity prediction suggested that the impurities do not present any toxicity risk for the parameters evaluated.

Prednisolone (PDS) has recently been utilized to treat a variety of medical disorders, including autoimmune illnesses and cancer. It is also used to treat coronavirus disease 2019 infection-related respiratory problems. Because it may induce health problems including gastrointestinal lesions and ulceration, it has to be used alongside other drugs like esomeprazole (ESM), which acts as a proton pump antagonist to reduce the probability of ulceration. As a result, the goal of this research is to create an environmentally safe and sensitive high-performance liquid chromatography (HPLC) approach for determining PDS and ESM in their binary combination and spiked human plasma. C8 column (100 × 4.6 mm, 5 μm) and gradient mobile phase elution were used to separate the studied drugs with ultraviolet recognition at 290 nm. Caffeine was utilized as an internal standard to adjust the sample variance. Plasma, caffeine, ESM and PDS all had tR values of 1.4, 3.5, 6.3 and 7.3, respectively. The suggested method’s greenness features were evaluated using three greenness evaluation tools: green analytical procedure index, analytical greenness metric approach and analytical eco-scale, and the findings were approved and satisfied. Validation parameters were evaluated in accordance with US-FDA recommendations in order to meet the global desires for biological analysis technique, acceptable limits were obtained.

Recently, the aim of analytical community is to reduce the usage of hazardous chemicals; so eco-friendly, rapid, selective and cost-effective methods were developed for simultaneous determination of montelukast sodium (MKT) and loratadine (LRT). The first method was based on chromatographic separation performed on precoated silica gel 60 GF254 plates with ethyl acetate–ethanol 9: 1 (v/v) as the mobile phase. The developed plates were scanned and quantified at 260 nm. The method gives linear correlation over concentration ranges of 0.3–3.6 μg/spot and 0.2–4.0 μg/spot for MKT and LRT, respectively. It was also successfully applied to analysis of both drugs in their pharmaceutical preparation and human plasma. The other methods are UV-spectrophotometric methods based on smart spectra manipulating to zero order spectrum of each drug. These methods are named response correlation (RC), a-centering and ratio derivative methods. RC and a-centering methods were dependent on the presence of an isosbestic point between the overlapped spectra of both drugs. While ratio derivative method based on manipulation of the ratio spectra of both drugs. The two drugs obey Beer–Lambert law over the concentration ranges of 3.0–30.0 μg/mL in the three spectrophotometric methods. Moreover, the greenness of the developed methods is assessed using suitable analytical Eco-Scale and Green Analytical Procedure Index.