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Background: The analysis of vitamins in baby food is a challenging task given the complexity of the food matrix, vitamin stability, and strict regulations of the European Union regarding permissible deviations from declared values. Vitamins in food exist in different concentrations and forms and have different stabilities; thus, the preparation of samples for a reliable analysis using the same procedure is not straightforward. Therefore, significant attention has been devoted to optimizing sample preparation in the analysis of vitamins. Methods: This study aims to determine which of the sample preparation and extraction methods is the most efficient for the simultaneous determination of vitamins A, D, E, and K in milk and baby food using high-performance liquid chromatography (HPLC). Different samples of baby food were prepared in seven different ways based on four methods (saponification, enzymatic hydrolysis, solvent extraction, and solid-phase extraction). Results and Conclusions: According to the validation parameters, the optimal preparation method proved to be solid-phase extraction with a C18 stationary phase, with recoveries of 97.4%, 96.1%, 98.3%, and 96.2% for vitamins A, D, E, and K, respectively, and HPLC with a UV–Vis detector was identified as a sufficiently sensitive technique for the identification and quantification of fat-soluble vitamins in milk and baby food. [ABSTRACT FROM AUTHOR]

Mobile phase composition remains the major experimental parameter influencing the separation process in reversed-phase high-performance liquid chromatography (RP-HPLC). Its influence on the retention of solutes is explained by the Hildebrand solubility parameter and solvophobic theory, which also considers molecular characteristics of the participants in a separation process. The main empirical dependences (linear and polynomial) between the retention factor and the composition of mobile phase (retention function) are discussed taking into consideration a wide range of mobile phase compositions. Two direct chromatographic indices are resulting from these equations: the extrapolated value of retention factor for zero organic content in mobile phase composition (log kw) and the solvent strength parameter (S), which for a linear retention function is its slope being constant over the entire mobile phase compositions. Another chromatographic index could result from the retention function for zero content of water in mobile phase, but this situation can be applied only for very hydrophobic solutes. For large domains of mobile phase composition, the retention function cannot be described by a single type of dependence. This explains the paradox of generating by extrapolation different logkwvalues for different organic components. For the mobile phase close to pure water the retention function is different from that at average water concentration.

Background: Recurrent approximation of retention parameters in reversed-phase HPLC is effective for revealing anomalies that are otherwise difficult to detect, namely, the reversible hydration of analytes. This was demonstrated previously for restricted sets of analytes with acetonitrile–water eluents. Expanding the number of analytes and eluents seems to be a topical problem. Two kinds of derivatives of aromatic carbonyl compounds were characterized: unsubstituted hydrazones and oximes. Methods: If analyte demonstrates no anomalies in dependences of retention times vs. concentration of organic modifier, the recurrent approximations of these dependences are linear. To explain the features of recurrent approximations, the numerical experiments were proposed and considered. The artificial shifting of one, two, or more points allows for the modeling the different kinds of deviations of approximations from linearity. Results: It was shown that hydrazones are the class of analytes having no anomalies of retention parameters. On the contrary, several anomalies were detected for oximes. Downward deviations of points in the plots of recurrent approximations of retention times are the signs of reversible hydration. This effect for methanol–water eluents was detected for the first time. Some of oximes underwent hydrolysis. Conclusions: Recurrent approximation of retention times allows detecting chemical transformations of analytes during RP HPLC analysis. [ABSTRACT FROM AUTHOR]

A tandem-column liquid chromatographic method was developed to separate ten non-steroidal anti-inflammatory drugs (Aceclofenac, Aspirin, Carprofen, Celecoxib, Diclofenac, Flurbiprofen, Ibuprofen, Ketoprofen, Naproxen, Salicylic Acid) using an achiral tandem-column configuration under reversed-phase conditions. An NSAID test mix was prepared with 0.5 mg/mL thiourea as a t0 marker and 0.5 mg/mL of the above NSAIDs in 1:1 acetonitrile: 0.2% formic acid. Three different 5-cm columns were investigated individually and in two different tandem-column configurations: an octyl (C8) column, a perfluorophenyl (PFP) column, and a biphenyl (BP) column. The two tandem configurations investigated were a PFP column followed by either a BP or C8 column. While none of the individual columns provided the selectivity needed to separate two sets of critical pairs (Ketoprofen and Naproxen; Flurbiprofen and Ibuprofen), the unique selectivity provided by the two tandem-column combinations enabled both critical pairs to be separated. The PFP + BP tandem column combination was able to separate the 10 NSAIDs with baseline or greater resolution in less than 25 min. [ABSTRACT FROM AUTHOR]

Saffron (Crocus sativus L.) is the most expensive spice in the world and rich in a variety of bioactive compounds including phenolic acids, flavonoids, and vitamins. Saffron is used in food, cosmetics, perfumery, and dye industries due to its color, taste, aroma, and medicinal properties. The extraction of bioactive compounds imposes a constant search for economically and environmentally viable extraction strategies for higher yields including the solvent type. The research was carried out to evaluate total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of C. sativus L. anthers using different extraction solvents including ethanol, methanol, and distilled water. The results showed that ethanol was the most effective extraction solvent type exhibiting the highest TPC (7.29 mg GAE g-1 DW), TFC (3.77 mg QE g-1 DW), and antioxidant activity of flavonoids (88%) and ascorbic acid (76.07%). Flavonoids proved to be stronger antioxidants than ascorbic acid, irrespective of solvent type, however the ethanolic extracts showed significantly higher antioxidant activity. A Reverse Phase High-Performance Liquid Chromatography method revealed that gallic acid (3.1 mg g-1), syringic acid (0.2 mg g-1), and vanillic acid (0.13 mg g-1) were the main phenolic compounds detected in the dried anther ethanolic extracts, while quercetin (2.13 mg g-1), pyrogallol (1.73 mg g-1), kaempferol (1.2 mg g-1), rutin (0.2 mg g-1), and tricin (0.1 mg g-1) the main flavonoid compounds. Thus, apart from the spice, constituted by the red stigmas, the production of other flower parts such as the anthers, so far considered agricultural waste can constitute a rich source of bioactive compounds of high antioxidant potential by setting quality standards for new products’ development and ensuring better valorization of saffron’s bioresidues in Mashhad region of Iran.

Saffron (Crocus sativus L.) is the most expensive spice in the world and rich in a variety of bioactive compounds including phenolic acids, flavonoids, and vitamins. Saffron is used in food, cosmetics, perfumery, and dye industries due to its color, taste, aroma, and medicinal properties. The extraction of bioactive compounds imposes a constant search for economically and environmentally viable extraction strategies for higher yields including the solvent type. The research was carried out to evaluate total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of C. sativus L. anthers using different extraction solvents including ethanol, methanol, and distilled water. The results showed that ethanol was the most effective extraction solvent type exhibiting the highest TPC (7.29 mg GAE g-1 DW), TFC (3.77 mg QE g-1 DW), and antioxidant activity of flavonoids (88%) and ascorbic acid (76.07%). Flavonoids proved to be stronger antioxidants than ascorbic acid, irrespective of solvent type, however the ethanolic extracts showed significantly higher antioxidant activity. A Reverse Phase High-Performance Liquid Chromatography method revealed that gallic acid (3.1 mg g-1), syringic acid (0.2 mg g-1), and vanillic acid (0.13 mg g-1) were the main phenolic compounds detected in the dried anther ethanolic extracts, while quercetin (2.13 mg g-1), pyrogallol (1.73 mg g-1), kaempferol (1.2 mg g-1), rutin (0.2 mg g-1), and tricin (0.1 mg g-1) the main flavonoid compounds. Thus, apart from the spice, constituted by the red stigmas, the production of other flower parts such as the anthers, so far considered agricultural waste can constitute a rich source of bioactive compounds of high antioxidant potential by setting quality standards for new products' development and ensuring better valorization of saffron's bioresidues in Mashhad region of Iran. [ABSTRACT FROM AUTHOR]

Objective: This work aimed to develop a simple HPLC method for the simultaneous quantitative determination of the ultraviolet (UV) filters, hydrophilic benzophenone‐4 and lipophilic octocrylene, in the presence of three other commonly used UV filters, avobenzone, octisalate and homosalate. Methods: Reverse‐phased HPLC was performed on a C18 column. A scouting gradient was initially used to determine the approximate mobile phase composition required for efficient analyte elution and separation before further optimization. The assay was validated with regard to specificity, linearity, intra‐ and inter‐day accuracy and precision, limits of detection and limits of quantification. An ultrasound dispersion extraction method for the UV filters from a commercial sunscreen was developed, and the extraction efficiencies from spiked samples were calculated. Results: An acetonitrile‐methanol‐water mixture (20:67:13, v/v/v), where the water component contained 0.2% trifluoroacetic acid (v/v), was found to be the optimal mobile phase at a flow rate of 1.0 mL/min. The assay was linear between 1.0–100 μg/mL for both benzophenone‐4 and octocrylene (both correlation coefficients were above 0.999). There was no interference from the excipients of the sunscreen nor from the three other UV filters. The intra‐ and inter‐day accuracy was between 90.0–104.6% for both analytes. Extraction recoveries from a spiked commercial sunscreen were between 95.4 ± 2.1% to 98.5 ± 2.1% for benzophenone‐4, and between 87.3 ± 2.3% and 98.9 ± 3.1% for octocrylene. All validation parameters were within the acceptance criteria set out in the International Council for Harmonization (ICH) guidelines. The HPLC assay showed the extracted quantities of benzophenone‐4 and octocrylene from the commercial sunscreen closely matched claimed quantities. Conclusion: The developed isocratic HPLC method was suitable for simultaneously determining the hydrophilic benzophenone‐4 and lipophilic octocrylene in the presence of other commonly used UV filters. Additionally, the extraction method was simple and effective for accurately quantifying the UV filters in a commercial sunscreen. [ABSTRACT FROM AUTHOR]

Background: Recurrent approximation of retention parameters in reversed-phase HPLC is effective for revealing anomalies that are otherwise difficult to detect, namely, the reversible hydration of analytes. This was demonstrated previously for restricted sets of analytes with acetonitrile–water eluents. Expanding the number of analytes and eluents seems to be a topical problem. Two kinds of derivatives of aromatic carbonyl compounds were characterized: unsubstituted hydrazones and oximes. Methods: If analyte demonstrates no anomalies in dependences of retention times vs. concentration of organic modifier, the recurrent approximations of these dependences are linear. To explain the features of recurrent approximations, the numerical experiments were proposed and considered. The artificial shifting of one, two, or more points allows for the modeling the different kinds of deviations of approximations from linearity. Results: It was shown that hydrazones are the class of analytes having no anomalies of retention parameters. On the contrary, several anomalies were detected for oximes. Downward deviations of points in the plots of recurrent approximations of retention times are the signs of reversible hydration. This effect for methanol–water eluents was detected for the first time. Some of oximes underwent hydrolysis. Conclusions: Recurrent approximation of retention times allows detecting chemical transformations of analytes during RP HPLC analysis.

Specific features of chromatographic determination of xanthophyll esters are studied using an example of marigold flower lutein diesters under reversed-phase HPLC conditions. The developed two-column method made it possible to establish that, in samples with a low solubility of carotenoids in the used solvent and on a chromatography column in using a mobile phase with a low solubility of carotenoids, the precipitation of diesters is possible, which detrimentally affects the accuracy of the chromatographic determination. A critical factor in this case isì temperature: the storage of samples (solutions) in a refrigerator is not always advisable, because freezing of the main components is possible. It was shown that the use of a mobile phase containing from 0 to 10 vol % acetonitrile in acetone at a temperature not lower than 20°C is acceptable for the separation of all-trans-lutein diesters from cis-derivatives of lutein and zeaxanthin derivatives on "monomeric" C18-phases. [ABSTRACT FROM AUTHOR]

The aim of this research work was to develop and validate a stability‐indicating, single reversed‐phase HPLC method for the separation of five impurities, including enantiomers, diastereomers, and degradation products in sacubitril–valsartan tablets. The method was developed using a Chiralcel OJ‐RH column (150 × 4.6 mm, 5 μm) at 45°C with a gradient program of (T/%B) 0.01/25, 10.0/25, 25/38, 37.0/45, 39.0/25, and 45.0/25 at a flow rate of 0.8 ml/min. Mobile phase A consisted of 1 ml of trifluoroacetic acid in 1000 ml of Milli‐Q water. Mobile phase B consisted of 1 ml of trifluoroacetic acid in a mixture of acetonitrile and methanol in the ratio of 950:50 (v/v). Sacubitril, valsartan, and their five impurities were monitored at 254 nm. Degradation was not observed when sacubitril–valsartan was subjected to heat, light, hydrolytic, and oxidation conditions. In acid degradation study (1 N HCl/60°C/2 h) impurity 1 (m/z 383.44) was formed, and in base degradation study (0.1 N NaOH/40°C/1 h) impurities 1 and 5 (m/z 265.35) were formed; both impurities were confirmed using LC–MS. The degradation products, enantiomers, and diastereomers were well separated from sacubitril and valsartan, proving the stability‐indicating power of the method. The developed method was validated per the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. The inter‐ and intra‐day percentage relative standard deviation for sacubitril, valsartan, and their five impurities was less than 5.2%, recovery of the five impurities was between 93 and 105%, and linearity was ≥0.999. The limit of detection was 0.030–0.048 μg/ml, and the limit of quantification was 0.100–0.160 μg/ml. [ABSTRACT FROM AUTHOR]

It was found experimentally that the replacement of acetonitrile with ethanol upon the acidification of the mobile phase with phosphoric acid is an effective version for replacing acetonitrile. At that, the order of elution of glycosides of the same type of the five main anthocyanidins (delphinidin, cyanidin, petunidin, peonidin, and malvidin) does not change in eluents convenient for analysis, and the range of retention times for a complete set of such anthocyanins becomes noticeably narrower in going from acetonitrile to ethanol. To determine the effect of aglycone structure on the retention of derivatives of the same anthocyanidin (cyanidin), a mixture of six glycosides was used: one monoglycoside (3-glucoside), two 3-diglycosides (sophoroside and sambubioside), and two 3-triglycosides (2"-glucosylrutinoside and 2"-xylosylrutinoside). This mixture is a real set of anthocyanins, requiring the careful selection of the mobile phase for separating all components. In this work, based on an analysis of separation maps, the composition of a mobile phase based on ethanol is determined that ensures the achievement of the effective separation of these anthocyanins. [ABSTRACT FROM AUTHOR]

The physicochemical regularities of the sorption of some derivatives of benzimidazole on hyper-cross-linked polystyrene (HPS) from a water–acetonitrile eluent with imidazolium ionic liquids (ILs) by reversed-phase high performance liquid chromatography (RP HPLC) are studied in the work. The thermodynamic characteristics of sorption of the compounds under study in systems with 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BdMIM][BF4]) and 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) are calculated, and a comparative analysis of them is performed. It is shown that the structure of the imidazolium IL substantially affects the process of sorption of benzimidazoles under study on HPS. The enthalpy–entropy compensation dependences in the sorption systems under study are analyzed, and some characteristic features of the mechanism of sorption of benzimidazole derivatives are found. [ABSTRACT FROM AUTHOR]

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed to assay tonabersat and assess its stability in pharmaceutical formulations. Chromatographic separation was achieved using a Kinetex® C18 column (2.6 µm, 150 x 3 mm, 100 Å) at 50 °C, with a 20 µL injection volume. A linear gradient of acetonitrile in water (5 - 33.5 %) was applied for 1 min, followed by a gradual increase to 100 % over 26 min at a flow rate of 0.5 mL/min. Tonabersat and its degradation products were detected at 275 nm and 210 nm, respectively. The optimized method was used to evaluate the stability of tonabersat in lipid-based pharmaceutical formulations at 5 ± 3 °C, 25 ± 2°C/60 ± 5 % RH, and 40 ± 2 °C/75 ± 5 % RH over 3 months. The method was validated as per ICH guidelines and demonstrated linearity in the range of 5 - 200 µg/mL (R 2  = 0.99994) with good accuracy (98.25 - 101.58 % recovery) and precision (% RSD < 2.5 %). The limits of detection and quantitation were 0.8 µg/mL and 5 µg/mL, respectively. Forced degradation studies showed significant degradation on exposure to alkaline (90.33 ± 0.80 %), acidic (70.60 ± 1.57 %), and oxidative stress (33.95 ± 0.69 %) at 70 °C, but no degradation was observed on exposure to thermal or photolytic stress. No chemical degradation was observed in either formulation on storage. Thus, the method was sensitive, specific, and suitable for stability testing of tonabersat in pharmaceutical formulations., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Priyanka Agarwal reports a relationship with TheiaNova Ltd. that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The study aimed to investigate extracts of un-ripe pods of Vinca rosea cv. Pink for antidiabetic activity and polyphenol-based characterization of extracts using HPLC. Moreover, the molecular interaction of the identified markers with the antidiabetic targets was explored using molecular-docking software. Different extracts of un-ripe pods were prepared and investigated using antidiabetic models such as glucose uptake by yeast cells, alpha amylase inhibition and haemoglobin-glycosylation inhibition assays. The most active extract was characterized by HPLC using chlorogenic, caffeic and ferrulic acids as an analytical markers. The identified markers were taken as ligands for molecular docking with pancreatic α-amylase, glycogen phosphorelase and hexokinase-Ι using 1-Click Docking Mcule Software, and finding hydrogen-bonding affinities by UCSF Chimera 1.12. Methanol extracts showed higher antidiabetic activity of 37.77, 71.16 and 53.52% inhibition of α-amylase assay, increase in glucose-uptake by yeast cells, and inhibition of Hb-glycosylation assay, respectively. The extract was found to contain 0.25 mg/g of chlorogenic and 0.11 mg/g caffeic acids. These markers were found to be good ligands of diabetes related targets. The results indicate that methanol extract has antidiabetic activity, which may be assigned to chlorogenic and caffeic acids. These compounds may be used as pharmacological markers to standardize the extracts. [ABSTRACT FROM AUTHOR]

A novel, validated, reversed-phase (RP), chiral high performance liquid chromatography (HPLC) method was developed for the enantiopurity control analysis of naproxen, a frequently used non-steroidal anti-inflammatory agent using polysaccharide-type chiral stationary phase (CSP). In the screening phase of method development, seven columns were tested in polar organic (PO) mode using mobile phases consisting of 0.1% acetic acid in methanol, ethanol, 2-propanol, and acetonitrile. Enantiorecognition was observed only in five cases. The best enantioseparation was observed on a Lux Amylose-1 column with 0.1% (v/v) acetic acid in ethanol with a resolution (Rs) of 1.24. The enantiomer elution order was unfavorable, as the distomer eluted after the eutomer. When the ethanolic mobile phase was supplemented with water, enantiomer elution order reversal was observed, indicating a difference in the enantiorecognition mechanism upon switching from PO to RP mode. Furthermore, by changing ethanol to methanol, not only lower backpressure, but also higher resolution was obtained. Subsequent method optimization was performed using a face-centered central composite design (FCCD) to achieve higher chiral resolution in a shorter analysis time. Optimized parameters offering baseline separation were as follows: Lux Amylose-1 stationary phase, thermostated at 40 °C, and a mobile phase consisting of methanol:water:acetic acid 85:15:0.1 (v/v/v), delivered with 0.65 mL/min flow rate. Using these optimized parameters, a Rs = 3.21 ± 0.03 was achieved within seven minutes. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of different pharmaceutical preparations, such as film-coated tablets and gel, as well as fixed-dose combination tablets, containing both naproxen and esomeprazole. [ABSTRACT FROM AUTHOR]

To separate S-(-)-nicotine and R-(+)-nicotine in e-liquids, a reversed-phase HPLC-DAD method coupled with a chiral column was developed. The sensory differences between the two nicotine isomers were studied. The results showed that: 1) The optimized chromatography condition included an Agilent InfinityLab Poroshell Chiral-T column, with a mobile phase consisted of methanol and acetonitrile at the volume ratio 45: 55 (containing 0.25% acetic acid and 0.05% trimethylamine in methanol), and the flow rate of 1 mL/min under isocratic elution. 2) S-(-)-nicotine and R-(+)-nicotine presented good linear relationships, and the limits of detection (LODs) were both 0.008 mg/g. The intra- and inter-day RSDs of S-(-)-nicotine were 0.89% and 1.26%, and those of R-(+)-nicotine were 3.98% and 4.70%, respectively. The recoveries of S-(-)-nicotine and R-(+)-nicotine were in the range of 95.87%-104.22% and 102.43%-108.85% respectively. 3) The contents of S-(-)-nicotine and R-(+)-nicotine in 20 e-liquid samples available in Chinese markets were determined. S-(-)-nicotine was the main isomer with the contents ranging from 2.325 to 22.042 mg/g. The optical purities of S-( - )-nicotine was in the range of 96.74%-100%, and no racemic nicotine was found. 4) The strength, satisfaction and irritation of S-( - )-nicotine were the strongest; those of R-(+)-nicotine were the lowest; while those of (R, S)-nicotine were in between. [ABSTRACT FROM AUTHOR]

Anti‐mullerian hormone (AMH) is one of the least studied members of transforming growth factor beta superfamily showing pro‐apoptotic activity against cells positive for hormone type II receptor overexpressed by malignant cells in many cancer cases. Here, we propose an improved method for isolation of recombinant C‐terminal AMH fragment (C‐rAMH) to obtain homogeneous preparations of this protein with high biological activity. In contrast to our previously developed C‐rAMH purification technology based on reversed‐phase HPLC, the key stage of the new approach is hydrophobic interaction chromatography using Toyopearl Butyl‐650S resin performed under more benign conditions. This modification of the previously developed method allowed highly purified C‐rAMH to be obtained that is characterized by twice the specificity estimated as the ability to bind to the recombinant analog of AMH type II receptor and by significantly higher biological activity, that is, the ability to induce the death of target cells. Thus, we made the purification technology even more cost‐effective and suitable for the production of drug forms based on C‐rAMH. [ABSTRACT FROM AUTHOR]

A combination of Paracetamol and Tramadol is used in mild to severe pain management. In a private Hospital Semarang, this combination is included in fast-moving drugs that it is frequently compounded and prepared in advance. The study aims to determine Beyond Use Date (BUD) in compounding capsules combination between Paracetamol and Tramadol samples. Beyond Use Date is a time limit indicating that a medicine beyond the expiration date must not be used and determined based on the results of stability testing. Samples were stored for 14 days in a tightly closed container far from direct sunlight in room temperature without AC (280C) and without silica gel, room temperature with AC (250C) without silica gel, and room temperature with AC (250C) with silica gel. Furthermore, samples underwent physical and chemical stability testing. Physical stability testing was conducted using organoleptic testing by observing direct changes from the powder color in capsules, capsules form, and scent on the samples. Meanwhile, chemical stability testing was conducted by determining the content of active ingredient from the samples using reversed-phase HPLC method and C18 as the stationary phase, methanol and aquabidest (40:60) as the mobile phase, wavelength 271 nm, flow rate 0.6 mL/min and injection volume 10 μL. The result shows that samples were physically stable for being able to retain the original physical properties showed by consistent powder color and capsules form, and there was no available scent. However, the chemical stability testing method was unable to separate and quantify the content of Paracetamol, Tramadol, and formed degradation products. It can be concluded that Beyond Use Date based on organoleptic and chemical stability testing for 14 days of compounding capsules combination between Paracetamol and Tramadol could not be determined. Nevertheless, this study showed favorable storage conditions in a tightly closed container far from direct sunlight in Room Temperature with AC (250C) with Silica Gel.

A possibility of using an oil-in-water microemulsion of the composition 3% of sodium dodecyl sulfate, 8% of n-butanol, 1% of ethyl acetate, and 88% of water (by weight) as an extractant for the extraction and preconcentration of steroid hormones cortisol, cortisone, corticosterone, 11-deoxycortisol, and 11‑deoxycorticosterone from aqueous solutions and urine samples followed by their reversed-phase HPLC analysis with spectrophotometric detection is shown. In optimizing the extraction conditions, the nature of the oil, the time and temperature of extraction, and the time of the separation of the microemulsion were varied. Magnesium chloride was used to destroy the microemulsion. The concentration factors for steroid hormones increase with an increase in the hydrophobicity of the analytes. The limits of detection for steroids were 0.5–3 ng/mL, and concentration factors were 8–20. [ABSTRACT FROM AUTHOR]

A possibility of replacing acetonitrile for methanol in mobile phases containing an organic modifier, 10 vol. % of formic acid (pH regulator), and water in the separation of anthocyanins by reversed-phase HPLC on a C18 stationary phase (Symmetry®C18) is studied. It is found that in replacing acetonitrile for methanol, it is necessary to use two components of the mobile phase, containing only methanol and only formic acid, as on the joint presence of these substances, a prolonged retention drift is observed, presumably because of the acylation of methanol. It is found that the replacement of acetonitrile for methanol results in small changes in the selectivity of the separation of anthocyanins with identical substituents but different aglycones and with different carbohydrate substituents for one and the same aglycone. There are also no significant differences in the separation efficiency (by the number of theoretical plates) of anthocyanins, which makes it possible to reject expensive acetonitrile in favor of methanol. The developed procedure was applied to determine anthocyanins in cranberry fruits of various degrees of ripeness (by color). The specific features of the anthocyanin composition of cranberry fruits are determined and the need in controlling the composition of the sample solvent for excluding artifact peaks is shown. [ABSTRACT FROM AUTHOR]

Some organic compounds form hydrates in eluents under the conditions of reversed-phase high-performance liquid chromatography (RP HPLC). For some of them, variation of water to the organic solvent ratio in an eluent may influence the ratio of hydrated and non-hydrated forms of analytes, X + nH2O ⇄ X·nH2O, which complicates the relations of their chromatographic retention. To reveal the formation of such hydrates, the recurrent approximation of their retention parameters is recommended, tR(C + ΔC) = atR(C) + b (*), where ΔC = const is the concentration increment of an organic modifier in an eluent, and a and b are coefficients calculated by the least-squares method. If an analyte exists in a hydrated or non-hydrated form only, the correlation coefficients (R) of equation (*) exceed 0.999. If the reversible formation of hydrates takes place within the concentration range Cmin to Cmax, it leads to distortion of linear dependence (*) and to deviations of some data points from regression lines (R < 0.999). One of the structural factors responsible for the reversible formation of hydrates is the presence of polar sulfonamide group –SO2NRR' in a molecule. To confirm this, a series of N-substituted p-toluenesulfonamides were synthesized and characterized. However, the nonlinearity of recurrences (*) is observed only for acetonitrile-containing eluents. [ABSTRACT FROM AUTHOR]

The protein molecules experience various external stresses leading to denaturation of protein during the process of transforming original whey to the concentrated whey proteins or while the concentrated proteins are used in the protein-enriched food formulation. This study was designed for a comparative assessment of the denaturation of whey protein isolate (WPI) under an important thermal stress, isothermal heat treatment (IHT), and high hydrostatic pressure treatment (HPT). The type and extent of denaturation were determined using reversed-phase HPLC and FTIR spectroscopy. The HPLC results demonstrated that the isothermal heat treatment caused higher denaturation of protein due to IHT at 80oC for 600s (88.38%) than that of HPT (58.5%). However, the infra-red spectroscopic analyses suggested that the HPT caused severe destruction of the structural conformation of WPI. The state of protein has a great impact on food formation; hence, the findings of this study would alert the concentrate protein producers and protein-enriched food manufacturers to prepare more active functional foods. HIGHLIGHTS • Heat (IHT) and pressure (HPT) stresses caused 88% and 58% WPI to denature, respectively. • Reversed phase-HPLC determined the denatured protein through aggregation. • FTIR together with HPLC is required for better characterization of denatured protein.

A novel, validated, reversed-phase (RP), chiral high performance liquid chromatography (HPLC) method was developed for the enantiopurity control analysis of naproxen, a frequently used non-steroidal anti-inflammatory agent using polysaccharide-type chiral stationary phase (CSP). In the screening phase of method development, seven columns were tested in polar organic (PO) mode using mobile phases consisting of 0.1% acetic acid in methanol, ethanol, 2-propanol, and acetonitrile. Enantiorecognition was observed only in five cases. The best enantioseparation was observed on a Lux Amylose-1 column with 0.1% (v/v) acetic acid in ethanol with a resolution (Rs) of 1.24. The enantiomer elution order was unfavorable, as the distomer eluted after the eutomer. When the ethanolic mobile phase was supplemented with water, enantiomer elution order reversal was observed, indicating a difference in the enantiorecognition mechanism upon switching from PO to RP mode. Furthermore, by changing ethanol to methanol, not only lower backpressure, but also higher resolution was obtained. Subsequent method optimization was performed using a face-centered central composite design (FCCD) to achieve higher chiral resolution in a shorter analysis time. Optimized parameters offering baseline separation were as follows: Lux Amylose-1 stationary phase, thermostated at 40 °C, and a mobile phase consisting of methanol:water:acetic acid 85:15:0.1 (v/v/v), delivered with 0.65 mL/min flow rate. Using these optimized parameters, a Rs = 3.21 ± 0.03 was achieved within seven minutes. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of different pharmaceutical preparations, such as film-coated tablets and gel, as well as fixed-dose combination tablets, containing both naproxen and esomeprazole.

An HPLC method that separates four Non-Steroidal Anti-Inflammatory Drugs (Ketoprofen, Naproxen, Ibuprofen, and Flurbiprofen) and three of the four pairs of enantiomers in one run is reported. The NSAID samples were prepared with 1 mg/mL of Ketoprofen, Naproxen, Ibuprofen and Flurbiprofen, and 0.5 mg/mL thiourea as a t0 marker in a sample solvent consisting of 1: 1 acetonitrile and 0.2% formic acid. The separation of the enantiomers of the NSAIDs was investigated using a chiral column in two different lengths (5-cm, 10-cm) packed with Amylose tris(3,5-dimethylphenylcarbamate) coated on silica gel and using a tandem column that consists of a biphenyl column connected by a zero dead volume connector to a 5-cm chiral column packed with amylose tris(3,5-dimethylphenylcarbamate) coated on silica gel. Both isocratic and step-gradient methods were investigated, and the results of the different methods were compared to determine the benefits and drawbacks of each approach, with an emphasis on the resolution and analysis time. [ABSTRACT FROM AUTHOR]

Worldwide, 25% of the population suffers from metabolic syndrome (MetS). The treatment of patients with MetS regularly includes drugs prescribed simultaneously to treat several disorders that manifest at the same time, such as hypercholesterolemia, arterial hypertension, and diabetes. To the authors' best knowledge, there is no previous published analytical method for the simultaneous quantification of drugs used in the treatment of these diseases. In the present study, a rapid highperformance liquid chromatography with a diode-array detector HPLC-DAD methodology was developed for simultaneous quantification of carvedilol (CVD), telmisartan (TEL), bezafibrate (BZT), gliclazide (GZD), and glimepiride (GMP) in bulk and pharmaceutical form. The chromatographic separation of the five pharmaceuticals was achieved on a Hypersil GOLD C18 Selectivity (5 µm, 150 Ã--4.60 mm²) using a mobile phase of acetonitrile (50%) and 0.02 M KH2PO4, pH 3 (50%) at a flow rate of 1 mL/min and at 25 °C. The total separation time was 9 min. The analytical method was validated following the International Conference on Harmonization guidelines. A reproducible method was obtained with acceptable limits of detection (LOD) and quantification (LOQ) for CVD (0.012 and 0.035 µg mL-1), TEL (0.103 and 0.313 µg mL-1), BZT (0.025 and 0.076 µg mL-1), GZD (0.039 and 0.117 µg mL-1), and GMP (0.064 and 0.127 µg mL-1). The validated method allowed the determination of these drugs in commercial pharmaceutical products both individually and simultaneously. The present method was found to be suitable for simultaneous quantification of the five drugs that are most commonly used in the simultaneous treatment of the metabolic syndrome. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) was used to study the thermophysical properties of oils of amaranth, corn, flax, sunflower, rapeseed, milk thistle, camelina, and pumpkin seed, liquid at room temperature. The characteristic thermal effects of these oils (temperatures of the maxima of endothermic peaks and their areas in the DSC thermograms) were determined. Endothermic peaks of different intensities on the melting curves of liquid vegetable oils in the ranges from –40 to –15°C, from –25 to –8°C, from –19 to +6°C, and from –10 to +4 °C as identification factors are discussed. The coordinates of the maxima of these peaks on the abscissa axis (Ti) and their areas (Si) significantly correlate with the concentrations of basic fatty acids and triacylglycerols (Wi, %), determined by reversed-phase HPLC. We demonstrated that the authenticity of vegetable oils could be effectively controlled by DSC. [ABSTRACT FROM AUTHOR]

A method for the determination of the composition of carotenoids of tomato fruits of different colors is proposed using a combination of spectrophotometry and chromatography. An explanation of the elution order of mono-cis-isomers of lycopene under the conditions of reversed-phase chromatography on traditional "monomeric" reversed C18-phases is proposed for the first time. It was found that, for prolycopene, (7Z, 9Z, 7'Z, 9'Z)-lycopene, which is responsible for the orange color of fruits, there is an almost imperceptible transition in normal examination in the vibronic structure of the electronic absorption spectrum with the lowest energy, λmax(1) = 486.2 nm. The main carotenoids of tomato fruits of different colors were determined: trans-lycopene and its cis-isomers for fruits of red and pink colors, protolycopene and other carotenes preceding its biosynthesis for fruits of orange color, and the carotenoid composition of yellow tomatoes significantly differing from that of tomatoes of first two colors by a considerable accumulation of lutein. For the quantitative assessment of the concentration of carotenoids with different chromophores, a calculation system ensuring the determination of the contribution of each of the components of complex mixtures was proposed. [ABSTRACT FROM AUTHOR]

The work is devoted to study of seed oil composition of amaranth varieties: Kharkov, Lera, Andijan and Helios, acclimatized in Uzbekistan. We demonstrated the possibility of using reversed-phase HPLC using a refractometric detector, which allows simultaneous determination of squalene and triacylglycerides in plant seeds and determining the authenticity of amaranth oils. Established seed oiliness ranged from 6.39 to 7.81 % of the initial mass. Amaranth oil samples contained quite large amount of unsaturated fatty acids 72.72 – 73.28 %, 1.17 % of which is omega-3-alpha-linolenic acid. The squalene content in the seeds ranged from 0.35 % to 0.55 %. It was established that the squalene content in oils obtained by extraction is greater than the one obtained by cold pressing. In the triacylglyceride composition of the investigated cold-pressed and extracted oils, no significant differences were found.

The present work describes a validated reverse phase high performance liquid chromatographic method for simultaneous estimation of Irbesartan chlorthalidone and cilnidipine in tablet dosage form. The quantification was carried out using C18 column (250 x 4.6mm, 5 µm) and mobile phase comprised of Buffer, Acetonitrile and TEA in a proportion of 80:20:0.1 %v/v/v. The flow rate was 1.0 ml/min and the eluent was monitored at 222 nm. The selected chromatographic conditions were found to effectively separate Irbesartan Chlorthalidone and cilnidipine were 3.807 min, 4.667 min, and 6.887 min respectively. Linearity was found to be in the range of 30-90 µg/ml, 1.25-3.75 µg/ml and 1-3 µg/ml for Irbesartan Chlorthalidone and cilnidipine respectively. The percentage recoveries of all the drugs were found to be 99.27-99.81%, 99.57-99.99% and 99.22-99.44% for Irbesartan, chlorthalidone, and cilnidipine. The proposed method was found to be fast, accurate, precise, and reproducible and can be used for simultaneous estimation of these drugs in a tablet. [ABSTRACT FROM AUTHOR]

We have investigated the effect of deuteration of non‐exchangeable protons on protein global thermal stability, hydrophobicity, and local flexibility using well‐known thermostable model systems such as the villin headpiece subdomain (HP36) and the third immunoglobulin G‐binding domain of protein G (GB3). Reversed‐phase high‐performance liquid chromatography (RP‐HPLC) measurements as a function of temperature probe global thermal stability in the presence of acetonitrile, while differential scanning calorimetry determines thermal stability in solution. Both indicate small but measurable changes in the order of several degrees. RP‐HPLC also permitted quantification of the effect of deuteration of just three core phenylalanine side chains of HP36. NMR dynamics investigation has focused on methyl axes motions using cross‐correlated relaxation measurements. The analysis of order parameters provided a complex picture indicating that deuteration generally increases motional amplitudes of sub‐nanosecond motion in GB3 but decreases those in HP36. Combined with earlier dynamics measurements at Cα–Cβ sites and backbone sites of GB3, which probed slower time scales, the results point to the need to probe multiple atoms in the protein and variety of time scales to the discern the full complexity of the effects of deuteration on dynamics. [ABSTRACT FROM AUTHOR]

Patterns of the static sorption of anthocyanins on bentonite clay are determined. It is found that the approach used for static sorption is an alternative to dynamic solid phase purification on DIAPAK C18 concentrating cartridges. A way of determining the relative sorption capacity of anthocyanins characterized by different structures on bentonite clay using the Langmuir equation is proposed. It is shown that the sorption capacity falls as the structure of the glycoside radicals becomes more complicated (from pentoside to hexoside and then to di- and trisaccharides). The acylation of glycoside radicals by malonic acid has a weak effect on sorptive activity, while acylation by substituted cinnamic acids improves sorption. [ABSTRACT FROM AUTHOR]

The method of reversed-phase HPLC with diode-array and mass-spectrometric detection was explored to determine the qualitative composition of red cabbage anthocyanins. Mono- and diacylated derivatives of cyanidin-3,5-diglycosides with a complex structure of the substituent in position were found, as well as non-esterified compounds. The acylation acids were paracoumaric, ferulic and sinapic. Quantitative analysis was performed according to a simplified spectrophotometric method: absorbance measurement at pH 4.5 was excluded. The measurement showed that the level of anthocyanins accumulation is as high as 0.100 g of anthocyanins per 100 g of raw plant material (as cyanidin-3-glucoside chloride equivalent). Analysis of electronic spectra of the extract at different pH revealed the existence of some basic structures with absorbance maxima shifted bathochromically as compared to the spectrum of flavylium structure. The existence of one basic form at pH 4.5 forced us to exclude absorbance measurement at pH 4.5 during quantitative anthocyanin determination. Thus, the possibility of obtaining some differently colored encapsulated forms was proved. Because of relative instability of non-flavylium forms of anthocyanins the freeze drying technique was used to prepare six differently colored forms of 3% anthocyanins encapsulated in maltodextrin. The decrease of anthocyanins contents at drying did not exceed 30%, while no statistically proved loss of anthocyanins was found at storage in a refrigerator during more than six months.

The anthocyanin composition of five purple leaves cultivars of Ocimum basilicum L. was investigated by reversed-phase HPLC with mass-spectrometric detection by ESI mode with ion partial fragmentation as well as preparation of dried differently colored forms of anthocyanins encapsulated into maltodextrin matrix. Analysis of the mass spectra revealed that according to the chromatographic profile the set of basil cultivar anthocyanins under investigation may be divided into two groups with the common feature being a high level of acylation with (mainly) p-coumaric, ferulic and malonic acids of the same base: cyanidin-3-dihexoside-5-hexoside. The presence of acylation with substituted cinnamic acids permits us to obtain solutions not only with a red color (the property of the flavylium form) but also with blue shades of coloration due to quinonoid and negatively charged quinonoid forms. All forms except that of flavylium are not stable in solution but stable enough to prepare dried encapsulated forms by lyophilization. Although the loss of anthocyanins with drying is not negligible, the final product is characterized with high stability for storage in a refrigerator. [ABSTRACT FROM AUTHOR]

[Display omitted] In the course of reversed-phase HPLC analysis, increase in pressure at the column inlet can affect the retention of sorbates only when they penetrate into the grafted phase. Due to conformational changes in the alkyl groups of the loose grafted layer, the solvation of sorbates by these alkyl groups would increase, leading to a growth of the retention factors. In the case of the surface sorption of solutes, the effect is not observed. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) quantification in benthic marine sediments is typically performed by time-consuming and moderately accurate mechanical separation and microscopy detection. In this paper, we describe the results of our innovative Polymer Identification and Specific Analysis (PISA) of microplastic total mass, previously tested on either less complex sandy beach sediment or less demanding (because of the high MPs content) wastewater treatment plant sludges, applied to the analysis of benthic sediments from a sublittoral area north-west of Leghorn (Tuscany, Italy). Samples were collected from two shallow sites characterized by coarse debris in a mixed seabed of Posidonia oceanica, and by a very fine silty-organogenic sediment, respectively. After sieving at

The selectivity of the separation of isomeric chlorogenic acids often found in natural samples (3, 4, and 5-caffeoylquinic acids, 3CQA, 4CQA, and 5CQA, respectively) under the conditions of reversed-phase chromatography on stationary phases of different brands, Kromasil (C18, C8, and C4), Symmetry C18, Reprosil-Pur C18-AQ, Nucleosil RPC18, and Diasfer C18, is studied. The results obtained favor the retention mechanism with predominant surface adsorption. The change in the selectivity of separation of a pair of 5CQA and 4CQA correlates with a change in the activity of residual silanol groups. At their low activity, the order of elution 3CQA < 5CQA < 4CQA does not depend on the mode (isocratic or gradient), the type of organic modifier, and the addition of an acid (formic, orthophosphoric) to the mobile phase. With an increase in the activity of silanol groups, the separation of the pair of 5CQA and 4CQA deteriorates up to the inversion of retention times. A Kromasil 100-5C18 column (250 × 4.6 mm) was chosen for a reliable separation of three acids in plant samples (instant coffee, juice, and "Mate" tea). [ABSTRACT FROM AUTHOR]

Lipid nanocarriers incorporating glycerides, polyethylene glycol (PEG)-stearates and phospholipids have attracted great attention for in vivo diagnostic, in vivo imaging, activated or non-activated targeted drug delivery. For quality control purposes, the development of appropriate methods for the quantification of their lipid components is needed. In the present study, we developed an analytical method for lipid quantification in formulated nanoparticles. PEG-stearates and glycerides were analyzed in a single run by RP-UPLC-ELSD using a two-step gradient elution program, while the analysis of phospholipids was accomplished by HILIC-UPLC-ELSD after isolation using an SPE silica column. Using both isolated compounds and commercial lipid standards, calibration curves were produced using second-order polynomials to attain the quantitative evaluation of each lipid excipient. Relative standard deviation of all analytes was between 0.9% and 5.3% for intra-day precision and recovery ranged from 83.5% to 112.2%. The presented method was successfully implemented to study the manufacturing process and stability of the formulated lipid excipients during long-term storage and accelerated conditions. The formulation lipid yield was determined and found equal to 82.5%. [ABSTRACT FROM AUTHOR]

A sensitive, selective, rapid, precise, and economic stability indicating Reverse Phase High Performance Liquid Chromatographic (RP-HPLC) method were developed for the quantification of Brexpiprazole in bulk and pharmaceutical dosage form was performed on Shimadzu Model HPLC 3000 series, using a mixture methanol and water (90:10, v/v) with OPA as mobile phase with a flow rate of 0.9 mL/min. Detection was carried at 215nm. The retention time of Brexpiprazole was 5.099min. Linearity was observed over the concentration range of 10–50 μg/mL (R2 = 0.9989) with regression equation y = 71185x-482587.The Accuracy study was performed % recovery of Brexpiprazole. The % recovery was found to be 50%=100.13%,100%=99.58%,150%=99.84%.(NLT 98% and NMT 102%). The Relative standard deviation values for intraday precision and intraday precision were found to be less than 2% i.e. 0.25% and 0.40% respectively. Brexpiprazole was subjected to stress conditions (acidic, alkaline, oxidation and thermal degradation) and validated as per ICH guidelines. The validated method can be applied to perform long-term and accelerated stability studies of Brexpiprazole formulations. [ABSTRACT FROM AUTHOR]

A simple stability-indicating high-performance liquid chromatographic method was developed and validated for the determination of Osimertinib Mesylate in tablet dosage forms. Reversed-phase chromatography was performed on Shimadzu Model CBM-20A/20 Alite, using a mixture of 0.1% T.E.A and methanol (50:50, v/v) as mobile phase with a flow rate of 1.0 mL/min. Detection was carried at 211nm. Linearity was observed over the concentration range of 10-400 µg/mL (R2 = 0.9992) with regression equation y = 125927x + 192648 Osimertinib Mesylate was subjected to stress conditions (acidic, alkaline, oxidation and thermal degradation) and validated as per ICH guidelines. The validated method can be applied to perform long-term and accelerated stability studies of Osimertinib Mesylate formulations. [ABSTRACT FROM AUTHOR]

A simple stability-indicating high-performance liquid chromatographic method was developed and validated for the determination of Brexpiprazole in tablet dosage forms. Reversed-phase chromatography was performed on Shimadzu Model CBM-20A/20 Alite, using a mixture of 0.1% acetic acid and methanol (65:35, v/v) as mobile phase with a flow rate of 0.9 mL/min. Detection was carried at 214nm. Linearity was observed over the concentration range of 0.1-250 ìg/mL (R2 = 0.9999) with regression equation y = 39617.94x + 3300.8. Brexpiprazole was subjected to stress conditions (acidic, alkaline, oxidation and thermal degradation) and validated as per ICH guidelines. The validated method can be applied to perform long-term and accelerated stability studies of Brexpiprazole formulations. [ABSTRACT FROM AUTHOR]

Introduction: Camellia japonica L. (Theaceae) is an evergreen shrub, which is cultivated as a popular ornamental tree in Korea, China, and Japan and its seeds have been used as a source of cooking oil, in cosmetics and as a traditional medicine. Intensive phytochemical works have revealed that oleanane‐type saponins are the characteristic compounds of the seeds of C. japonica. Objective: The purpose of the present study is to isolate and determine oleanane‐type saponins from C. japonica using high‐performance countercurrent chromatography (HPCCC) coupled with reversed‐phase high‐performance liquid chromatography (RP‐HPLC) and spectroscopic evidences, respectively. Methodology: HPLC electrospray ionisation quadrupole time‐of‐flight mass spectrometry (ESI‐Q‐TOF‐MS) was applied to profile the saponin composition of an enriched saponin extract of C. japonica seeds. The enriched saponin extract was separated by HPCCC using a dichloromethane/methanol/isopropanol/water (9:6:1:4, v/v/v/v) system and RP‐HPLC. The structures of the isolates were determined utilising ESI‐Q‐TOF‐MS, one‐dimensional and two‐dimensional NMR and optical rotation. Results: HPCCC on enriched saponin extract of C. japonica yielded four saponin fractions in the order of the number of sugars attached to the triterpene aglycone, and preparative RP‐HPLC on each saponin fraction led to the isolation of nine novel saponins, namely camoreoside A–I, along with six known ones. Conclusions: This study indicates that combination of HPLC‐ESI‐Q‐TOF‐MS analysis and HPCCC coupled with RP‐HPLC are excellent tools for discovering saponins from natural sources. High‐performance liquid chromatography electrospray ionisation quadrupole time‐of‐flight mass spectrometry (HPLC‐ESI‐Q‐TOF‐MS) revealed that enriched saponin extract of Camellia japonica contained a variety of saponins with di‐, tri‐, tetra‐saccharides as oligo‐glycoside moieties. High‐performance countercurrent chromatography (HPCCC) coupled with reversed‐phase (RP) HPLC were successfully applied to isolate nine new saponins namely camoreoside A–I along with six known ones from enriched saponin extract of C. japonica seeds. The structures of the isolates were determined utilising ESI‐Q‐TOF‐MS, one‐dimensional and two‐dimensional NMR and optical rotation. [ABSTRACT FROM AUTHOR]

Abstract Sialic acids (Sia) are involved in various biological and pathological processes, and are often found attached to non-reducing ends of glycans through either α2,3- or α2,6-linkages. To quantitatively analyze glycan structures with these linkage isoforms by liquid chromatography-mass spectrometry (LC-MS), we established a linkage-specific two-step alkylamidation method for N -glycans. Using this method, carboxyl groups of α2,3- and α2,6-linked Sia are derivatized with two kinds of alkylamines with different mass values in a linkage-specific manner, allowing products to be easily distinguished. The reaction efficiencies for di-, tri-, and tetra-sialyl PA- N -glycans were >94%, with few by-products. Mixtures of 2-aminopyridine (PA)-tagged N -glycans from human α1-acid glycoprotein were subjected to the method, and products were analyzed by LC-MS and MS/MS, and simultaneously monitored with a fluorescence detector. The relative content of Siaα2-3Gal and Siaα2-6Gal was estimated from the integrated fluorescence intensity of each peak. Moreover, MS/MS data clearly indicated characteristic B-ion fragments of N -glycan branches, such as the sialyl Lex sequence, with Sia linkage-specific alkylamidation, suggesting that this method also provides useful information of branch sequences. We optimized the method with the aim of (1) enabling high-throughput analysis and (2) maximizing the analysis of glycans from various types of samples, including highly heterogeneous glycans. Graphical abstract Image 1 Highlights • Linkage-specific two-step alkylamidation for PA-tagged N -glycans was established. • Products were analyzed by LC-MS and MS/MS, and simultaneous fluorescence detection. • The method is applicable for heterogeneous glycans in complex biological samples. [ABSTRACT FROM AUTHOR]

Using reversed-phase HPLC, we developed a procedure for the qualitative and quantitative analytical control of the production of N-octadecyl-1,3-diaminopropane from stearic acid by the nitrile method. The optimum composition of the eluent is determined, which ensures the control of each stage of the process. The calibration dependences for the mixtures initial reagent–reaction product are obtained, suggesting a quantitative estimation of the conversion. The possibility of determining the presence of synthesis by products is shown. The analysis time for each stage does not exceed 20 min. [ABSTRACT FROM AUTHOR]

Worldwide, 25% of the population suffers from metabolic syndrome (MetS). The treatment of patients with MetS regularly includes drugs prescribed simultaneously to treat several disorders that manifest at the same time, such as hypercholesterolemia, arterial hypertension, and diabetes. To the authors’ best knowledge, there is no previous published analytical method for the simultaneous quantification of drugs used in the treatment of these diseases. In the present study, a rapid high-performance liquid chromatography with a diode-array detector HPLC-DAD methodology was developed for simultaneous quantification of carvedilol (CVD), telmisartan (TEL), bezafibrate (BZT), gliclazide (GZD), and glimepiride (GMP) in bulk and pharmaceutical form. The chromatographic separation of the five pharmaceuticals was achieved on a Hypersil GOLD C18 Selectivity (5 µm, 150 × 4.60 mm2) using a mobile phase of acetonitrile (50%) and 0.02 M KH2PO4, pH 3 (50%) at a flow rate of 1 mL/min and at 25 °C. The total separation time was 9 min. The analytical method was validated following the International Conference on Harmonization guidelines. A reproducible method was obtained with acceptable limits of detection (LOD) and quantification (LOQ) for CVD (0.012 and 0.035 μg mL−1), TEL (0.103 and 0.313 μg mL−1), BZT (0.025 and 0.076 μg mL−1), GZD (0.039 and 0.117 μg mL−1), and GMP (0.064 and 0.127 μg mL−1). The validated method allowed the determination of these drugs in commercial pharmaceutical products both individually and simultaneously. The present method was found to be suitable for simultaneous quantification of the five drugs that are most commonly used in the simultaneous treatment of the metabolic syndrome.

Alkenones are among the most widely used paleotemperature biomarkers. Traditionally, alkenones are analyzed using gas chromatography-flame ionization detector (GC-FID), or GC-chemical ionization-mass spectrometry (GC-CI-MS). However, these methods encounter considerable challenges for samples that exhibit matrix interference or low concentrations, with GC-FID requiring tedious sample preparations and GC-CI-MS suffering from nonlinear response and a narrow linear dynamic range. Here we demonstrate that reversed-phase high pressure liquid chromatography-mass spectrometry (HPLC-MS) methods provide excellent resolution, selectivity, linearity and sensitivity for alkenones in complex matrices. We systematically compared the advantages and limitations of three mass detectors (quadrupole, Orbitrap, and quadrupole-time of flight) and two ionization modes (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) for alkenone analyses. We demonstrate that ESI performs better than APCI as response factors of various unsaturated alkenones are similar. Among the three mass analyzers tested, orbitrap MS provided the lowest limit of detection (0.4, 3.8 and 8.6 pg injected masses for Orbitrap, qTOF and single quadrupole MS, respectively) and the widest linear dynamic range (600, 20 and 30 folds for Orbitrap, qTOF and single quadrupole MS, respectively). Single quadrupole MS operated in ESI mode provides accurate quantification of proxy measurements over a wide range of injection masses, and with its modest instrument cost, represents an ideal method for routine applications. Analysis of global core-top sediment samples confirmed the efficacy of HPLC-MS methods for the detection and quantification of paleotemperature proxies based on alkenones and their superiority over GC-based methods. The analytical method demonstrated in this study should also allow highly sensitive analyses of diverse aliphatic ketones in complex matrices. [Display omitted] • Reversed-phase HPLC methods developed to resolve alkenone critical pairs. • ESI is advantageous over APCI due to higher sensitivity and lower discrimination. • Orbitrap MS provides the highest sensitivity, linearity and selectivity. • HPLC-single quadrupole MS is sufficient for routine analysis. • Method to convert HPLC-MS measured pseudo proxy values to GC-FID compatible results developed and validated. [ABSTRACT FROM AUTHOR]

Spray-dried forms of anthocyanins were prepared in a maltodextrin matrix. The anthocyanins were extracted by maceration of elderberry fruits in 0.1 M HCl followed by extract filtration through a paper filter. The extract was partially purified by solid phase extraction in a column filled with styrene-divinylbenzene copolymer beads (Sepabeads SP859/L) or in syringe cartridges with C18 silica (BioChemMack ST, Moscow, RF) followed by re-extraction with aqueous HCl and alcohol mixtures. The procedure of reversed-phase HPLC determination of the extracted anthocyanin type is discussed in comparison to HILIC method in DIOL silica columns. The latter method was shown to be preferable to avoid systematic errors in the anthocyanin type determination. Solidphase extraction in syringe cartridges gave samples with very high anthocyanins concentration (up to 70 g of cyanidin-3-glucoside chloride equivalent). When using the copolymer sorbent, the concentration was somewhat lower: up to 27 g/l. After spray drying red powder samples with anthocyanins content more than 2% were prepared, although freeze drying gave only dark resin. The red color of the samples indicates the space separation of flavylium ions in the solid state by radicals of the maltodextrin background.

Cefixime is essential member of orally energetic third generation cephalosporin and has tremendous activity aligned with many pathogens. The virtual bioavailability of a newly industrial dispersible tablet as compared with a recognized identified formulation. A simple and available reversed-phase HPLC method with UV detection has been urbanized and validate for cefixime evaluate in human plasma using a C18 analytical column and a mobile phase of tetrabutylammonium hydroxide (pH 6.5)-acetonitrile (3:1 v/v). The detection wavelength was 280 nm. To method observed major linear response-concentration association all through the cefixime concentration range of 15-100 ng/ml, with the average accuracy within-run and between-run values of 97.29% and 99.27%. The average drug recovery from plasma was 98.2% throughout the linear concentration range. The limits of detection (LOD) and quantitation (LOQ) of the method were 5 and 15 ng/ml, respectively. The method is quick, easy, very steady and precise for the partition, assignment, evaluation of cefixime in human plasma.

Purpose: A simple and available reversed-phase high performance liquid chromatography (HPLC) method with UV detection has been developed and validated for mycophenolic acid (MPA) assay in human plasma. Methods: MPA was extracted from plasma with protein precipitation method by acetonitrile: percholeric acid: methanol (75:5:20 v/v/v). The drug separation was achieved using a C8 analytical column and a mobile phase of 0.1M triethylammonium phosphate (pH=5.4)-acetonitril (65:35, v/v), with a flow rate of 1.5 ml/min. The detection wavelength was 304 nm. Limit of detection (LOD) of the method was determined as the lowest MPA concentration producing a signal-to-noise (S/N) ratio of about 3. Limit of quantitation (LOQ) was determined as the lowest MPA concentration capable of being quantitated with enough accuracy and precision. Results: The method showed significant linear response-concentration relationship throughout the MPA concentration range of 0.2-10 µg/ml. A typical linear regression equation of the method was: y = 8.5523 x + 0.094, with x and y representing MPA concentration (in µg/ml) and peak height respectively, and the regression coefficient (r) of 0.9816. The average within-run and between-run variations of 7.81 and 4.78 percent. The average drug recovery from plasma was 95.24 percent throughout the linear concentration range. The limits of detection (LOD) and quantitation (LOQ) of the method were 0.05 and 0.2 µg/ml, respectively. The practical applicability of the method was proven throughout a bioequivalence study. Conclusion: The results showed the acceptable degree of linearity, sensitivity, precision, accuracy and recovery for the method. The method was used successfully for quantitation of MPA in plasma samples of healthy volunteers throughout a bioequivalence study.