C18 Column Research Articles

Utilizing experimental design and desirability function in optimizing RP-HPLC method for simultaneous determination of some skeletal muscle relaxants and analgesics

An experimental design and response surface methodologies using Plackett–Burman and Box-Behnken designs were applied for selecting and optimizing the most appropriate parameters which significantly affect the separation and quantitative estimation of five skeletal muscle relaxants and four analgesic drugs (baclofen, methocarbamol, dantrolene sodium, orphenadrine citrate, cyclobenzaprine hydrochloride, ketoprofen, etoricoxib, ibuprofen, and mefenamic acid) with a relatively short duration of analysis in a single run. For the separation of the nine drugs, an INERTSIL ODS-V3-5 µm C18 column (250 × 4.6 mm I.D.) was used with the optimum mobile phase conditions (45.15 mM ammonium acetate buffer pH 5.56 adjusted with acetic acid, acetonitrile, and methanol in a ratio of 30.5:29.5:40, v/v/v with a flow rate of 1.5 mL/min) and UV-detection at 220 nm. The optimized method was successfully subjected to the validation steps as described in ICH guidelines for linearity, precision, accuracy, robustness, and sensitivity. The optimized and validated method was effectively applied to determine the content of the studied drugs in their pharmaceutical preparations and to expand its applicability to the counterfeit estimation of etoricoxib in different brands of tablet dosage forms.

Development of Response Surface Approach for Determination of Paracetamol, Chlorpheniramine Maleate, Caffeine and Ascorbic Acid by Green HPLC Method: A Desirability-Based Optimization.

Design of experiment is an efficient and cost-effective tool to optimize the chromatographic separation of a multicomponent mixture. The central composite design was conducted to develop and optimize a green high performance liquid chromatography (HPLC) method for simultaneous quantitation of a quaternary mixture of paracetamol, chlorpheniramine maleate, caffeine and ascorbic acid in their pharmaceutical dosage form as well as the determination of their dissolution profile. A five-level three-factor model was performed to investigate the effect of mobile phase composition, pH and flow rate on enhanced resolution and short run time. Analysis was performed using a Kinitex EVO C18 column and a mobile phase composed of methanol: 0.02M phosphate buffer pH3.3 (34:66, v/v) at 1.0mL/min using photodiode array detection. Optimum chromatographic separation was achieved in <6min with a desirability of 0.999. Linearity was achieved over a range of 1.00-300.00, 1.00-50.00, 2.00-50.00 and 2.00-100.00μg/mL for paracetamol, chlorpheniramine maleate, caffeine and ascorbic acid, respectively, with a limit of detection (<0.1μg/mL). The greenness profile was evaluated using the analytical eco-scale and Analytical GREEnness Metric Approach with values of 81 and 0.77, respectively.

Two chromatographic methods for determination of cytarabine and dexamethazone; two co-administered drugs for the treatment of leukemia: green analytical perspective

Two sensitive, straightforward and repeatable chromatographic techniques were developed for the determination of Cytarabine HCl and Dexamethazone in their pure form and spiked human plasma without prior separation. The drugs are used co-administered for the treatment of Leukemia, a certain type of blood cancer. Method (A) is an isocratic chromatographic HPLC method; separation was accomplished on C18 column using the eluting mixture of 6.9 g/L Monobasic Sodium Phosphate pH 3: methanol (70:30, v/v) and detection was at 275 nm. Concentrations were in the range of 0.2–15 μg/mL for both CYT and DEX. Method (B) is a HPTLC method in which separation was attained on HPTLC F254 plates using methanol: ethyl acetate: ammonia, (7.8:2:0.2, by volume) as eluting solvents and detection was at 275 nm. Concentrations were in the range of 0.1–4 μg/band for both CYT and DEX. The parameters for system suitability testing were evaluated to determine the effectiveness of the developed chromatographic procedures in terms of performance. The recently developed techniques were applied for the determination of the drugs under investigation in spiked human plasma. Validation parameters were examined in accordance with US-FDA criteria. All results were found to be within the acceptable ranges. To evaluate the greenness characters of the proposed methods to the environment; three greenness assessment tools including eco-scale assessments (ESA), green analytical procedure index (GAPI), and Analytical Greenness calculator (AGREE) were used. Acceptable and satisfying results that demonstrated the greenness characteristics of the suggested methods were attained.

Validated chromatographic methods for determination of teriflunomide and investigation of its intrinsic stability

Two rapid, precise, and sensitive stability-indicating high performance chromatographic methods for the measurement of Teriflunomide in its degradation products’ existence were developed. These were RP-HPLC and HPTLC using UV detector. HPLC separation was accomplished utilizing Thermo BDS hypercil C18 column (250 × 4.6 mm, 5 μm) and acetonitrile: 0.03 M potassium dihydrogen phosphate: triethylamine (50:50:0.1%, by volume) as mobile phase at flow rate of 1mL/min. The separated peaks were detected at 250.0 nm. The densitometric approach was conducted utilizing HPTLC 60 F254 silica gel plates, and a developing system of benzene: ethanol: acetic acid (7.5:1:0.25, by volume) and detection was done at 250.0 nm. The developed approaches were evaluated regarding the International Conference on Harmonization (ICH) instructions. The calibration curves of both techniques were constructed with linearity ranges of (5-100) µg/mL and (2–10) µg /band, for HPLC and densitometric determination, consecutively. Teriflunomide was exposed to base and acid hydrolysis, oxidation using H2O2 and finally, thermal degradation as stated in ICH guidelines. The degradation product structures’ elucidation was achieved through LC-MS.

A Fully Automated Online Enrichment and Separation System for Highly Reproducible and In-Depth Analysis of Intact Glycopeptide.

A fully automated online enrichment and separation system for intact glycopeptides, named AutoGP, was developed in this study by integrating three different columns in a nano-LC system. Specifically, the peptide mixture from the enzymatic digestion of a complex biological sample was first loaded on a hydrophilic interaction chromatography (HILIC) column. The nonglycopeptides in the sample were washed off the column, and the glycopeptides retained by the HILIC column were eluted to a C18 trap column to achieve an automated glycopeptide enrichment. The enriched glycopeptides were further eluted to a C18 column for separation, and the separated glycopeptides were eventually analyzed by using an orbitrap mass spectrometer (MS). The optimal operating conditions for AutoGP were systemically studied, and the performance of the fully optimized AutoGP was compared with a conventional manual system used for glycopeptide analysis. The experimental evaluation shows that the total number of glycopeptides identified is at least 1.5-fold higher, and the median coefficient of variation for the analyses is at least 50% lower by using AutoGP, as compared to the results acquired by using the manual system. In addition, AutoGP can perform effective analysis even with a 1-μg sample amount, while a 10-μg sample at least will be needed by the manual system, implying an order of magnitude better sensitivity of AutoGP. All the experimental results have consistently proven that AutoGP can be used for much better characterization of intact glycopeptides.

New methods for resolution of hydroxychloroquine by forming diastereomeric salt and adding chiral mobile phase agent on RP-HPLC.

Hydroxychloroquine (HCQ), 2-([4-([7-Chloro-4-quinolyl]amino)pentyl]ethylamino)ethanol, exhibited significant biological activity, while its side effects cannot be overlooked. The RP-HPLC enantio-separation was investigated for cost-effective and convenient optical purity analysis of HCQ. The thermodynamic resolution of Rac-HCQ, driven by enthalpy and entropy, was achieved on the C18 column using Carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral mobile phase agent (CMPA). The effects of CCM-β-CD, pH, and triethylamine (TEA) V% on the enantio-separation process were explored. Under the optimum conditions at 24°C, the retention times for the two enantiomers were and , resulting in . The resolution via diastereomeric salt formation of Rac-HCQ was developed to obtain the active pharmaceutical ingredient of single enantiomer S-HCQ. Di-p-Anisoyl-L-Tartaric Acid (L-DATA) was proved effective as the resolution agent for Rac-HCQ. Surprisingly, it was found that refluxing time was a key fact affecting the resolution efficiency, which meant the kinetic dominate during the process of the resolution. Four factors-solvent volume, refluxing time, filtration temperature, and molar ratio-were optimized using the single-factor method and the response surface method. Two cubic models were established, and the reliability was subsequently verified. Under the optimal conditions, the less soluble salt of 2L-DATA:S-HCQ was obtained with a yield of 96.9% and optical purity of 63.0%. The optical purity of this less soluble salt increases to 99.0% with a yield of 74.2% after three rounds recrystallization.

Chemical fingerprinting and multicomponent quantitative analysis for quality control of Cinnamomum tamala collected from Western Himalaya by HPLC-DAD

Cinnamomum tamala, commonly known as “Indian bay leaf” or “Tejpat”, is an economically important plant widely used in medicine, food and cosmetic industries. Growing demand for its leaf and bark in the herbal trade and non-availability of quality materials lead to large-scale species admixture and adulteration in the global market. The present study aims at developing a validated HPLC-DAD (High-performance liquid chromatography coupled with diode array detection) method and multiple markers-based chemical fingerprints for quality evaluation of C. tamala leaf extracts. Five bioactive compounds, viz., coumarin, cinnamyl alcohol, cinnamic acid, cinnamaldehyde and cinnamyl acetate, were identified and quantified in 28 samples collected from the western Himalayan region of India. The chromatographic separation was achieved on Shimadzu Shimpak C18 column (dimension 250×4.6 mm, pore size 5 μm) with a gradient elution of mobile phase using acetonitrile and 0.1 percent phosphate buffer and the chromatograms were obtained at a wavelength of 265 nm. The method validation was done by analyzing the linearity, LOD, LOQ, precision, stability, repeatability and recovery rates of standard compounds for quantitative analysis. The values of coefficient of correlation (R2) and standard deviation were found to be close to 1 for linearity and similarity analysis; and less than 3 percent in case of precision, stability, repeatability and recovery. The content of target compounds such as coumarin, cinnamyl alcohol, cinnamic acid, cinnamaldehyde and cinnamyl acetate varied in the range of 0-1.09, 0-0.05, 0.07-0.51, 0.39-1.27 and 0-0.27percent, respectively. In the chemical fingerprint of C. tamala leaves, a total of 13 peaks were assigned as common peaks. The results of the study indicated that the HPLC method now developed combining chemical fingerprint with quantification of analytes could serve as a useful tool for quality evaluation of herbal raw materials of C. tamala and a valuable reference for further study.

Magnetic molecularly imprinted polymers are used to selectively extract cephalosporins from milk samples and analyze by LC-MS/MS

Cephalosporins were extracted from milk samples by using magnetic molecularly imprinted polymers (MMIP). To characterize the physical properties of MMIP, an experiment was conducted involving both static and dynamic adsorption. Samples were analyzed with LC-MS/MS to identify cephalosporin residues. The quantitative technique employed was the use of an isotope as an internal standard. Analysis was conducted using an Ascentis C8 column with a mobile phase consisting of a 0.1% aqueous solution of formic acid and acetonitrile. The determination coefficients varied between 0.9945 and 0.9995, as indicated by the linear equations. Cephalosporins exhibited a diverse spectrum of recovery rates, varying between 80.7% and 118.3%, accompanied by a range of relative standard deviations spanning from 3.8% to 13.5%. The detection limits for 9 kinds of cephalosporins in milk samples varied from 1 μg kg−1 to 20 μg kg−1, while the quantification limits ranged from 3 μg kg−1 to 60 μg kg−1. The successful implementation of the validated technique has been applied to detect 9 different kinds of cephalosporins in real milk products.

Rp-HPLC method development and validation of finerenone in bulk drug and its formulations

I have done research and achieved the method development &amp; validation of highly accurate, sensitive, precise, rapid gradient system RP-HPLC method of finerenone in both bulk drug &amp; pharmaceutical fixed dosage forms. The separation was achieved on (Agilent) C18 column (4.6 mm*250 mm, 5µm) having this configuration with particle size 5µm &amp; using mobile Methanol: 10 Mm Citric Acid with ratio (38:62) having flow rate 1.0 ml/min. Detection of finerenone was carried out at 258nm. The total chromatographic analysis time per sample was about 15min and retention time of overall analysis is 6.9 min. The response exhibited a linear relationship with concentration in range 98-102 mcg/ml for finerenone correlation coefficient is 0.999 and %RSD is 0.126. The method was validated for accuracy, precision, specificity, linearity &amp; sensitivity. Validation studies demonstrated that the method is simple, specific, rapid, reliable &amp; reproducible.

Validated Stability Indicating UHPLC Method for the Quantification of Escitalopram and Flupentixol in Pharmaceutical Formulation

To assess Escitalopram and flupentixol simultaneously, a verified method for ultra-phase high-performance liquid chromatography (UHPLC) has been developed to indicate stability. The method was thoroughly evaluated and met satisfactory criteria for precision, linearity, accuracy, limits on detection, robustness, and quantitation. The quantitation wavelength of 235 nm was determined. Linearity was successfully demonstrated across concentration ranges of 1–5 µg/ml of Escitalopram and 20-100 µg/ml of Flupentixol. UHPLC separations were conducted employing a Phenomenex L. C18 column measuring 100 x 4.6 mm and containing particles as small as 2.5 µm. To create the mobile phase, the 1% OPA and methanol (a pH of 4.2 with TEA) were combined in a volumetric ratio of 65:35v/v. Escitalopram and Flupentixol were effectively eluted at retention durations of 3.044 and 4.118 minutes, respectively, with the flow rate adjusted at 1.0 ml. The stability-indicating nature of the method was established through validated forced degradation studies. Which included hydrolysis under acidic and basic conditions, exposure to H2O2, thermal degradation, and photo-degradation. Escitalopram and Flupentixol exhibited 10 to 20% degradation under the specified conditions. Importantly, the process evaluated the two prescription drugs in detail with all degradation products generated during the forced degradation experiments. This developed method is characterized as straightforward, specific, and cost-effective, making it suitable for simultaneous estimating Escitalopram and Flupentixol in tabs dose forms.

Pharmacokinetic Studies of Gypenoside XLVI in Rat Plasma using UPLC-MS/MS Method

Background: Gynostemma pentaphyllum (Thunb.) Makino has been linked to a number of pharmacological benefits, including hepatoprotective, anti-inflammatory, antioxidative, and antihyperlipidemic activities. Gypenoside XLVI (Gyp XLVI) was a significant triterpenoid saponin reported from a sweet-taste varietas G. pentaphyllum, which has inhibitory effects and causes apoptosis on human hepatocytes and hepatoma cells. Methods: A quick, precise, and sensitive method for the quantification and pharmacokinetic research of Gyp XLVI in rats was developed utilizing UPLC-MS/MS. When extracting blood samples, protein was precipitated using methanol. An internal standard (IS) was employed, which was tolbutamide. For the chromatographic separation, a C18 column (Waters Acquity) was used with mobile phases as 0.1% formic acid and acetonitrile. Multiple reaction monitoring was used as MS detection manner with electrospray ionization in negative mode. Results: Gyp XLVI had good linearity in the 1.36‒1000.00 ng/mL concentration range. The intra- day and inter-day precisions (RSD%) and accuracy (RE%) were less than 12.7% or 8.29%, respectively. Gyp XLVI’s extraction recovery ranged from 89.5% to 104.2%. The matrix effects ranged from 75.3%‒94.3%. The outcomes of matrix interference and recovery investigations complied with the necessary variability limitations. After three hours at room temperature (25°C), 24 hours in an auto-sampler (4°C), three freeze-thaw cycles, and 30 days of storage at -20°C, the analyte in rat plasma remained stable. Gyp XLVI pharmacokinetic investigations and quantification were conducted using the validated method. The AUC0-∞ values for intravenous administration (1 mg/kg) and oral administration (10 mg/kg) were 2213.9 ± 561.5 ng·h/mL and 1032.8 ± 334.8 ng·h/mL, respectively. Gyp XLVI had a half-life (t1/2z) of 2.5 ± 0.4 h in the rats after intravenous injection and 4.2 ± 0.9 h after oral administrations. Gyp XLVI had a comparatively low oral bioavailability of 4.56%. Conclusion: This is the first time that Gyp XLVI’s pharmacokinetic properties have been investigated through various administration routes. These findings will aid in our understanding of how Gyp XLVI was metabolized in rats and how it behaved pharmacologically in vivo.

Validation of HPLC-DAD method for analysis of paracetamol and potassium sorbate in liquid oral formulations and its application to forced degradation study

AbstractDue to the frequent use of paracetamol formulations, it is useful to develop an analytical technique for the determination of intact paracetamol in presence of other drugs and excipients or the degradation products. In this study, a simple, isocratic, fast, specific, accurate and precise stability-indicating high performance liquid chromatography (HPLC) method has been developed and validated for simultaneous quantitative determination of paracetamol (PCM) and potassium sorbate (PS) in oral liquid formulations. The chromatographic separation was achieved on Zorbax SB C18 column (150 × 4.6 mm, 5 µm) with Zorbax SB C18 precolumn (12.5 × 4.6 mm, 5 µm) using distilled water pH 2 with ortho-phosphoric acid and acetonitrile (70:30, v/v) as a mobile phase, and UV detection at 235 nm. The temperature of the column was kept constant at 25 °C. The method was validated according to International Conference on harmonization (ICH) guidelines. The method demonstrated excellent linearity, with a correlation coefficient of 0.9996 and 0.9998 for PCM and PS, respectively, over the concentration ranges of 10–600 μg mL−1 (PCM) and 6–500 μg mL−1 (PS). The retention time was found to be 1.98 and 4.86 min for PCM and PS, respectively. Oral liquid formulation samples were subjected to various stress conditions (acidic and alkaline hydrolysis, as well as oxidative, heat and photolytic degradation) for the purpose of forced degradation study. The major degradation of paracetamol was achieved in acidic and basic stress conditions, while thermal and photolytic degradation generally had the least influence. On the other hand, potassium sorbate was highly susceptible to photolytic degradation. It was also shown that the formulation has strong influence on stability of tested compounds. Forced degradation studies demonstrated the stability-indicating power of the method and can be used to assess the stability of paracetamol and potassium sorbate in oral liquid formulations.

Simultaneous Determination of Fipronil, Permethrin and their Key Related Substances in a Topical Drug Product by a Single Stability Indicating High Performance Liquid Chromatography Method.

The topical veterinary drug product containing fipronil and permethrin provides an effective repellent protection and high insecticidal efficacy for dogs. The objective of this study was to develop a stability indicating high performance liquid chromatography (HPLC) method for simultaneous detection and quantification of fipronil, permethrin, their key degradation products and butylated hydroxytoluene (BHT) in a topical drug product. The two active ingredients, their degradation products, and the antioxidant (BHT) were separated by a gradient elution on a Phenomenex Kinetex C18 column (150 × 3 mm, 2.6 µm particle size) maintained at 37 °C with H2O/acetonitrile/isopropyl alcohol/85% H3PO4 (65.5 + 32.5 + 4/0.0053, v/v/v/v) as mobile phase-A and acetonitrile (100%) as mobile phase-B. The flow rate was 0.9 mL/min and analytes were detected and quantified at 235 nm. Specificity of the method was demonstrated by adequate separation of fipronil, permethrin, their degradation products, and BHT in the forced degraded finished product. Linearity of the method was demonstrated in the range of 0.2% to 150% of target analytical concentration of both active ingredients and 50% to 150% for BHT. Excellent recoveries of fipronil, permethrin and BHT in placebo spiked active ingredient solutions in the linearity range showed sufficient accuracy of the method. LOQ and LOD of the method were determined to be 0.2% and 0.07% of the analytical concentration. A robustness study did not identify any critical parameter that adversely effected the separation and quantification. Here, we report the development and validation of a robust, stability indicating HPLC method for identification and assay of fipronil, permethrin, and BHT, including estimation of fipronil's and permethrin's degradation products in a topical drug product for dogs. The new HPLC method permits the acquisition of data for all analytes of interest for a topical finished drug product containing fipronil, permethrin, and BHT.

Chitin quantitation (as glucosamine) in food raw materials by HPLC[sbnd]C18-DAD with off-line derivatization

This HPLC method is suitable for chitin quantitation (reported as glucosamine) in food raw materials like insects (mealworm larvae, crickets), shrimps, mushrooms and fungi in a research (non-routine) laboratory using a C18 column with HPLC system <600 bar with UV detection capability (at 265 nm). To remove interferences, the sample is defatted (Soxhlet) and deproteinized (by alkali) prior to acid hydrolysis in 6 M HCl. A five-point linear calibration (5–100 µg/mL) is used. The use of fluorescence detection (λex = 260 nm, λem = 350 nm) is also possible with this method [1].•18 min HPLC run time•LOD = 0.05 µg/mL and LOQ = 5 µg/mL

Novel RP-HPLC method for estimation of a newly developed combination of tizanidine and etoricoxib in rat plasma: Eight criteria for greens evaluation.

A novel environmentally friendly reversed-phase high-performance liquid chromatography (RP-HPLC) method has been effectively validated for simultaneously measuring a prospective conjunction of tizanidine (TIZ) and etoricoxib (ETC), the combined medicine, in rat plasma. The technique employs diclofenac potassium as the internal standard, guaranteeing dependable and precise outcomes. This study aimed to assess the impact of the suggested combination therapy on treating inflammation resulting from rheumatoid arthritis (RA) in a rat model. The procedure was performed using an Agilent series 1200 model HPLC apparatus. The chromatographic conditions consist of isocratic elution mode, C18 column with dimensions of 150 mm × 4.6 mm × 5 µm, flow rate of 1.5 mL/min, wavelength of 230 nm, temperature of 50°C, and injection volume of 10 µL. The elution was performed using a mobile phase consisting of a phosphate buffer with a pH of 3.5 and acetonitrile in a ratio of 80:20 v/v. Calibration curves were conducted for TIZ and ETC within the 1-50 µg/mL range, demonstrating linear trends with R2 values over 0.999. The effectiveness and eco-friendliness of the proposed method were evaluated using eight separate environmentally conscious metrics. The addition of TIZ and ETC to arthritic rodents amplified these effects significantly. Furthermore, TIZ and ETC significantly reduced serum levels in arthritic rodents, and safety investigations revealed normal complete blood count, liver, and renal functions. TIZ and ETC appear to have antiarthritic, anti-inflammatory, and safe combinations, making them viable future treatment options for RA that are also safe and efficacious. Following validation by United States Food and Drug Administration(US-FDA) rules, all goods met the criteria.

Non-covalent interactions of roselle anthocyanins with milk proteins and egg white protein

Roselle (Hibiscus sabdariffa L.) anthocyanins (RA) provides limited stability against hydration and pH changes during digestion which limit their bio-accessibility. The formation of protein-anthocyanin complexes offers a promising strategy for maintaining the stability of RA. Animal proteins are potential candidates for these interactions due to their high digestibility and balanced essential amino acid profile. In this study, we investigated the interactions of RA with animal proteins, specifically whey protein (WHEY) and casein (CAS) from milk, as well as ovalbumin (OVA) from egg white. Highly purified RA was obtained using XAD-7HP, SCX, and C18 column chromatography to facilitate the study of protein-anthocyanin interactions. Fluorescence spectra indicate that RA bound to the three proteins, leading to the quenching of their intrinsic fluorescence. UV–visible absorption spectra reveal changes in the polypeptide skeletons of the proteins after interacting with RA. Circular dichroism (CD) spectra show alterations in the secondary structure contents of α-helix, β-sheet, β-turn, and random coil upon interaction with RA. Molecular docking studies elucidate the docking active sites of proteins with RA. These interactions resulted in enhanced stability of RA during in vitro simulated digestion for all three proteins. Whey protein emerges as the most promising candidate for enhancing the stability of RA, thereby contributing to the potential application of RA in various food products. Our research provides a theoretical foundation for the utilization of WHEY-RA complexes in beverages and dairy products.

Enhanced oral bioavailability of levormeloxifene and raloxifene by nanoemulsion: simultaneous bioanalysis using liquid chromatography-tandem mass spectrometry.

Aim & objective: Levormeloxifene (L-ORM) and raloxifene (RAL) are selective estrogen receptor modulators used in the treatment of postmenopausal osteoporosis and breast cancer. Here, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous estimation of both drugs. Materials & methods: A quality-by-design (QbD) approach was used for the optimization of the nanoemulsion, and US FDA guidelines were followed for method validation. Results: Multiple reaction monitoring transitions were used for L-ORM (459.05→98.50), RAL (475.00→112.02) and internal standard (180.10→110.2). Analytes were resolved in a C18 column with 80:20 v/v% acetonitrile (ACN), 0.1% formic acid in triple-distilled water as a mobile phase. The developed method was linear over a concentration range of 1-600ng/ml. Pharmacokinetic results of free L-ORM-RAL and the L-ORM-RAL nanoemulsion showed Cmax of free L-ORM- 70.65±16.64, free RAL13.53±2.72, L-ORM nanoemulsion 65.07±14.0 and RAL-nanoemulsion 59.27±17.44ng/ml. Conclusion: Future findings will contribute to the treatment of postmenopausal osteoporosis and breast cancer using L-ORM and RAL.

Development of a method for the determination of alkylpyrazine in traditional vinegar and its formation kinetics

Alkylpyrazine (APZ), as one of the crucial components in food flavor, are extremely important for the sensory evaluation of foods. For the purpose of simultaneously identifying multiple APZ in food items, a HPLC analytical method was created. The chromatography was carried out on an XBridge C18 column at a flow rate of 1 mL/min, with a detection wavelength of 275 nm. The ratio of mobile phase A (acetonitrile) to mobile phase B (0.1% formic acid and 0.1% aqueous trifluoroacetic acid) was 1:99. Compared to the conventional assay, RSD of precision less than 3%, average recoveries ranged from 96% to 110%, quantification limits were between 0.052 and 0.278 mg/L, detection limits were between 0.016 and 0.084 mg/L, and total analysis time is 35 min in the HPLC method. Meanwhile, we found that prolonging the aging time could increase the flavor characteristics of vinegar by analyzing the composition of APZ in vinegar and its formation pattern during the brewing process. The above results demonstrated that HPLC is an effective method for the rapid determination of pyrazines in vinegar. This study provides a technical way for further focusing on the characteristic flavor components of vinegars or other fermentation products.

Development and validation of UPLC-MS/MS method for 5-Fluorouracil quantification in dried blood spot

5-Fluorouracil is an antimetabolite drug indicated for cancer treatment. Therapeutic drug monitoring of 5-Fluorouracil is necessary because 5-Fluorouracil has narrow therapeutic window and its concentration in blood is affected by individual conditions, like gene polymorphisms. Dried Blood Spot (DBS) is one of the biosampling methods used for therapeutic drug monitoring. Asides from reducing patients’ discomfort, the use of DBS can increase 5-Fluorouracil stability by stopping the enzymes activity in blood. Therefore, this research developed a method to monitor 5-Fluorouracil levels in DBS using ultra-high performance liquid chromatography-tandem mass spectrometry. Sample preparation was carried out by extracting DBS using 2-Propanol: ethyl acetate (16:84). Reconstituted samples were analyzed using ultra high performance liquid chromatography equipped with Acquity® UPLC BEH C18 column (2.1 × 100 mm; 1.7 μm). The ionization process was carried out in negative electrospray ionization mode. Multiple Reaction Monitoring (MRM) values were set at m/z 128.97 > 41.82 for 5-Fluorouracil and 168.97 > 57.88 for propylthiouracil as the internal standard. Optimum analytical conditions were obtained with acetonitrile-ammonium acetate 1 mM (95:5) as mobile phase, flow rate of 0.15 mL/min, and column temperature of 40 °C. The lowest level of quantification obtained from this method was 0.1 μg/mL with a calibration curve range of 0.1 μg/mL-60 μg/mL. This method was proven to be valid according to the requirements set by the US Food and Drug Administration and the European Medicines Agency.

Targeted and untargeted screening for impurities in losartan tablets marketed in Germany by means of liquid chromatography/high resolution mass spectrometry

Technical advances in the field of quality analysis allow an increasingly deeper look into the impurity profile of drugs. The ability to detect unexpected impurities in addition to known impurities ensures the supply of high-quality drugs and can prevent recalls due to the detection of harmful unexpected impurities, as has happened recently with the N-nitrosamine and azido impurities in losartan (LOS) drug products. In the present study, the LC-MS/HRMS approach described by Backer et al. was applied to an even more complex system, being the investigation of 35 LOS drug products and combination preparations purchased in 2018 and 2022 in German pharmacies. The film-coated tablets were analysed by means of four LC-MS/HRMS method variants. For the separation a Zorbax RR StableBond C18 column (3.0 ×100 mm, particle size of 3.5 µm, pore size of 80 Å), a gradient elution and for mass spectrometric detection a qTOF mass spectrometer with electrospray ionization in positive and negative mode was used. An information-dependent acquisition method was applied for the acquisition of high-resolution mass spectrometry data. The combination of an untargeted and a targeted screening approach revealed the finding of eight impurities in total. Beside the five LOS related compounds, LOS impurity F, J, K, L, M, and related compound D from amlodipine besilate, LOS azide and an unknown derivative thereof were detected. Identification and structure elucidation, respectively, were successfully performed using in silico fragmentation. Differences in the impurity profiles of drug products from 2018 and 2022 could be observed. This study shows that broad screening approaches like this are applicable to the analysis of drug products and can be an important enhancement of the quality assurance of medicinal products.