Elution Research Articles

Analytical method development and validation for the simultaneous estimation of montelukast and Acebrophylline by RP- HPLC method

High performance liquid chromatography is at present one of the most sophisticated tool of the analysis. The estimation of Montelukast and Acebrophylline was done by RP-HPLC. The Phosphate buffer was pH 3.0 and the mobile phase was optimized with consists of Methanol: Phosphate buffer mixed in the ratio of 70:30 % v/ v. Inertsil C18 column C18 (4.6 x 150mm, 5mm) or equivalent chemically bonded to porous silica particles was used as stationary phase. The detection was carried out using UV detector at 260 nm. The solutions were chromatographed at a constant flow rate of 0.8 ml/min. the linearity range of Montelukast and Acebrophylline were found to be from 100-500 mg/ml of Montelukast and 1-5mg/ml of Acebrophylline . Linear regression coefficient was not more than 0.999.The values of % RSD are less than 2% indicating accuracy and precision of the method. The percentage recovery varies from 98-102% of Montelukast and acebrophylline. LOD and LOQ were found to be within limit. The results obtained on the validation parameters met ICH and USP requirements .it inferred the method found to be simple, accurate, precise and linear. The method was found to be having suitable application in routine laboratory analysis with high degree of accuracy and precision.

Pharmacokinetic and oral bioavailability study of schaftoside in rats.

A simple and sensitive LC-tandem mass spectrometry method was established and validated for the determination of schaftoside in rat plasma. After prepared by protein precipitation with acetonitrile, schaftoside and internal standard were separated on a Waters HSS T3 column using acetonitrile containing 0.1% formic acid and 0.1% formic acid in water as the mobile phase by gradient elution. The method showed excellent linearity over the range of 0.5-500 ng/mL with acceptable intra- and inter-day precision, accuracy, matrix effect, and recovery. The stability assay indicated that schaftoside was stable during the sample acquisition, preparation, and storage. The method was applied to a pharmacokinetic study of schaftoside in rats. The result suggested that after intravenous administration at a dose of 1 mg/kg, schaftoside was quickly eliminated from the plasma with an elimination half-life of 0.58 h. After oral administration at doses of 5, 10, and 20 mg/kg, schaftoside was quickly absorbed into the plasma and reached the peak concentration (Cmax) of 45.1-104.99 ng/mL at 0.67-1.17 h. The increase of exposure (area under the curve) was linear with the increase of dose. The oral bioavailability was 0.42%-0.71% in the range of 5-20 mg/kg.

Advancements in RP-HPLC Method Development and Validation: A Comprehensive Review

Reverse-phase high-performance liquid chromatography (RP-HPLC) has emerged as a cornerstone technique in analytical chemistry, offering high sensitivity, selectivity, and efficiency in separating and quantifying a wide range of compounds. This comprehensive review explores recent advancements in RP-HPLC method development and validation, focusing on key strategies, challenges, and emerging trends. The review encompasses a detailed examination of critical parameters such as column selection, mobile phase optimization, detection techniques, and validation protocols. Furthermore, it discusses innovative approaches and technologies that enhance the robustness, speed, and accuracy of RP-HPLC analyses. Through a thorough analysis of current literature and case studies, this review provides valuable insights for researchers and practitioners engaged in method development and validation in the field of chromatographyies.

Improving the Current European Pharmacopoeia Enantio-Selective HPLC Method for the Determination of Enantiomeric Purity in Atorvastatin Calcium Salt Drug Substance

Atorvastatin (ATV) is a well-established lipid-lowering agent. ATV has two stereogenic centers, and of the four possible stereoisomers, only the (3R,5R) form is used therapeutically. The European Pharmacopoeia (EP) monograph 2022 for ATV calcium salt describes a normal-phase high-performance liquid chromatography (HPLC) method for the determination of enantiomeric purity in both drug substance and working standard samples, based on a 150 mm × 4.6 mm Chiralpak AD-H column. The main problems with this method are the very long analysis time and the high solvent consumption. Here, an alternative chromatographic protocol was developed using the Chiralpak AD-3 column (250 mm × 4.6 mm) packed with 3 μm silica particles instead of the 5 μm silica particles of the Chiralpak AD-H chiral stationary phase and characterized by the same polysaccharide selector, amylose-tris(3,5-dimethylphenylcarbamate). Using a mobile phase consisting of a mixture of n-hexane-ethanol-formic acid 90:10:0.1 (v/v/v) as the mobile phase and setting the flow rate and column temperature to 1.0 mL min−1 and 35 °C, respectively, a simultaneous stereo-selective separation was achieved within 35 min without observing any overlap between the enantiomeric impurity peak and peaks related to other ATV impurities. Compared to HPLC EP conditions, the analysis time to elute all the potentially related substances was faster and significantly less mobile phase volume was required. The linearity of the method has been demonstrated in the range of 4.4 μg mL−1 to 1000 μg mL−1 (R2 > 0.999). At a concentration of 4.4 μg mL−1, which is 0.075% of the test solution (5.8 mg mL−1, as ATV free acid), the signal-to-noise ratio was found to be 20.

A rapid and highly sensitive HILIC-HPLC based analytical assay method for quantification of azacitidine and venetoclax in a single run

Venetoclax and Azacitidine combination has recently been approved by the USFDA to treat old people with acute myeloid leukemia. Pharmaceutical formulations of the combination of these two drugs are expected to be launched soon. Till date, an analytical method of any type has not been reported in literature for quantification of Venetoclax and Azacitidine in a single run. The current work set out to establish an HILIC-HPLC based analytical assay method for simultaneous quantification of Azacitidine and Venetoclax from the mixed sample. The method has been developed employing Poroshell HILIC column. Ammonium formate (10 mM, pH 5.0) and acetonitrile were used as a mobile phase in gradient programme. A variety of parameters, including linearity, accuracy, precision, specificity, robustness, and ruggedness were evaluated to validate the method. Azacitidine and Venetoclax were eluted at 8.8 min and 4.0 min, respectively. Method was linear over the range of 1-100 µg/mL. Recovery was found to be 98.29-99.28% and 101.84-101.95% for Azacitidine and Venetoclax, respectively. The method was reproducible with a relative standard deviation of less than two in precision studies. The developed method can suitably be employed for quantifying Venetoclax and Azacitidine in a single run from their mixed samples.

Development and validation of stability indicating ultra‐high‐performance liquid chromatographic method for assay and impurities of mexiletine hydrochloride and mexiletine hydrochloride capsules

AbstractMexiletine (MEX) is an antiarrhythmic drug used to treat acute and chronic ventricular arrhythmias. A simple isocratic, rapid, specific, stability‐indicating, and sensitive reverse‐phase ultra‐high‐performance liquid chromatography (UHPLC) method was developed and successfully validated to quantify the assay and impurities of MEX hydrochloride. The new UHPLC method showed the optimum separation of MEX and its seven impurities in 20 min by using sodium acetate buffer (0.14 mM) with 0.3% of glacial acetic acid (pH 4.8) and methanol in the ratio of 40:60 (v/v) as mobile phase. The method used an Acquity HSS T3 (100 × 3.0 mm, 1.8 µm) chromatographic column at a 0.2 mL/min flow rate. The injection volume is 2 µL, and 254 nm is the detection wavelength. Note that, 25°C is the column oven temperature. The method is linear over the concentration range of the quantification limit (0.03%) to 150% (0.3%) of the specification level (0.2%) for the impurities and 50%–150% for the assay method. The quality control lab of bulk drugs and finished dosage form successfully applied the new UHPLC method for quantification of assay and impurities of MEX hydrochloride.

DEVELOPMENT AND VALIDATION OF HPLC-METHOD FOR QUANTITATIVE DETERMINATION OF PROPOXUR IN COLLARS AND SPRAYS

Propoxur is a carbamate non-systemic insecticide, an acetylcholinesterase blocker of invertebrates, leading to their paralysis and death. Propoxur is used in insect acaricidal sprays and collars to kill fleas and ticks on pets. The aim of the work was to develop a method of identification and quantification of propoxur in spray for external use and collars with different matrices. The method was developed and validated by indicators of selectivity, linearity, suitability parameters of the chromatographic system and repeatability. Spray and collars with different polymer composition were used as a sample-object for the development of the technique. The standard sample and the test sample of the spray were dissolved in acetonitrile to a propoxur concentration of 50 μg/ml. The collar was dissolved in tetrahydrofuran and acetonitrile was added to precipitate the matrix. The samples were separated on a Dionex Ultimate 3000 chromatograph equipped with chromatographic column Acclaim C18 150×4.6, 5 μm. The mobile phase was a mixture of acetonitrile and water in a volume ratio of 80:20. Propoxur was detected at an absorption wavelength of 270 nm. Under the above conditions, it was possible to completely separate propoxur (retention time of the chromatographic peak – 2.2 min) and other components of the studied drugs. At the same time, the suitability parameters of the chromatographic system did not exceed the limits specified in the recommendations of the USA Food and Drug Association. For propoxur, the efficiency of the chromatographic system was 10,300–10,540 theoretical plates. The relative standard deviation (RSD) for the peak areas of the active substance was ± 0.37%, and the peak separation ratio (RS) of propoxur and other components of the drug was 3.1–5.7. The symmetry coefficient of the propoxur peak was 1.49. The calibration curve was linear in the recommended DFU 2.0 range (80–120% of the nominal concentration of the active substance). The coefficient of linearity (R2) for propoxur was 0.9985.

Emerging mycotoxin occurrence in chicken feed and eggs from Algeria.

Poultry farming has developed into one of Algeria's most productive industrial farming because of the growing demand for sources of protein among Algerian society. Laying hen feed consists mainly of cereals, which can be contaminated with molds and subsequently with their secondary metabolites known as mycotoxins. These later can pose a serious danger to the production and quality of eggs in the commercial layer industry. This work focuses on the detection of emerging mycotoxins, mainly enniatins (ENNs) and beauvericin (BEA), in poultry feed and eggs from different locations in Algeria. Two different QuEChERS-based extractions were established to extract ENNs and BEA from chicken feed and eggs. The determination of mycotoxin occurrence was achieved by a UHPLC-MS/MS method using 0.1% (v/v) formic acid in water and MeOH as mobile phase, an ESI interface operating in positive mode, and a triple quadrupole mass spectrometer operating in MRM for the detection. Matrix-matched calibration curves were carried out for both matrices, obtaining good linearity (R2 > 0.99). The method performance was assessed in terms of extraction recovery (from 87 to 107%), matrix effect (from - 47 to - 86%), precision (RSD < 15%), and limits of quantitation (≤ 1.1µg/kg for feed and ≤ 0.8µg/kg for eggs). The analysis of 10 chicken feed samples and 35 egg samples composed of a 10-egg pool each showed that ENN B1 was the most common mycotoxin (i.e., found in 9 feed samples) with contamination levels ranging from 3.6 to 41.5µg/kg, while BEA was detected only in one feed sample (12µg/kg). However, eggs were not found to be contaminated with any mycotoxin at the detection limit levels. Our findings indicate that the searched mycotoxins are present in traces in feed and absent in eggs. This can be explained by the application of a mycotoxin binder. However, this does not put a stop on the conduction of additional research and ultimately setting regulations to prevent the occurrence of emerging mycotoxins.

Sustainable cannabinoids purification through twin-column recycling chromatography and green solvents.

In the present study, twin-column recycling chromatography has been employed for the purification of a Cannabis extract by using a green solvent, ethanol, as the mobile phase. In particular, the complete removal of the psychoactive tetrahydrocannabinol (THC) from a Cannabis extract rich in cannabidiol (CBD) was achieved under continuous conditions. The performance of the method, in terms of compound purity, recovery, productivity and solvent consumption, was compared to that of traditional batch operations showing the potential of the twin-column recycling approach. The employment of a theoretical model to predict the band profiles of the two compounds during the recycling process has facilitated method development, thus further contributing to process sustainability by avoiding trial and error attempts or at least decreasing the number of steps significantly.

Bioanalytical Method Development and Validation and forced degradation of Sitagliptin and determination of Pharmacokinetic application study in Human Plasma by RP-HPLC method

In the present investigation, an attempt was made for the development, validation, forced degradation and pharmacokinetic application of sitagliptin in the human plasma spiking studies by UV - HPLC method. The experimentation was developed based on the extensive literature survey and ascertained by the statistical parameters of the sampling. A simplified, accurate method was created by the liquid chromatographic system from Shimadazu LC 20AD consisting of manual injection. The optimized chromatogram was obtained with acetonitrile in the isocratic mobile phase method at a 1.0 mL/min flow rate. A thermo C-8 column (4.6X250mm,5μm) was used as a stationary phase, and 265.0nm was selected as the detection wavelength with the aid of a UV-Vis detector. The proposed method was validated as per ICH guidelines. The technique was linear in the range of 10-50μg/mL with correlation coefficient R2 = 0.9746, respectively. Recovery studies postulated that % RSD 19.14, 3 &amp; 9.95 respectively. Injection repeatability values were found to be % RSD 17 &amp; 10.63 for intraday and interday, respectively. Stress degradation studies revealed that sitagliptin degrades more rapidly when subjected to 0.1 NaoH. Human plasma spiking studies reported 3.02 ng/mL at 3.02+/-60 min of C and T max, respectively. Keywords: Sitagliptin, Method development, HPLC, Validation, Stress degradation studies, Human plasma spiking studies

STABILITY BASED HPLC METHOD FOR CYCLOPHOSPHAMIDE RELATED SUBSTANCES IN FINISHED DRUG PRODUCTS: DEVELOPMENT AND VALIDATION

Objective: The current study aimed to develop a simple, sensitive, and precise high-performance liquid chromatographic (HPLC) method for estimating cyclophosphamide and its related substances, as well as to implement the developed method in a capsule product. Methods: Method development was performed using various solvent and buffer-solvent ratios at different flow rates for better resolution and to decrease the run time. The developed method was validated in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The developed method was implemented to estimate the amount of cyclophosphamide and its related substances. Results: Chromatographical conditions were optimised, and the best chromatographical conditions with adequate resolution for cyclophosphamide and its related substances were achieved using the enable X-Bridge C18 column, using a mobile phase combination of phosphate buffer pH 7.0, water, methanol, and acetonitrile at a flow rate of 0.5 ml/min. The detection was monitored at a wavelength of 200 nm. The developed method was validated for system suitability, specificity, limit of detection (LOD), limit of quantitation (LOQ), linearity, precision, accuracy and robustness. The results indicate that the method was sensitive and could detect and quantify lower levels of cyclophosphamide and its related substances. The linearity range was from LOQ to 150 %, and a correlation coefficient ranging from 0.9987 to 0.9999 indicates that at this concentration range, substances were highly linear. This was further supported by satisfactory forced degradation studies. Conclusion: The developed analytical method is simple, precise, and reproducible and thus can be used for the stability-indicating analysis of cyclophosphamide and its related substances in pharmaceutical formulations.

A Validated Chiral Chromatography Method for Enantiomeric Separation of Pomalidomide in Human Plasma.

In the present work, new chiral stationary phase high-performance liquid chromatography (CSP-HPLC) method was established and validated for the quantification of pomalidomide (PMD) enantiomers in human plasma. The chromatographic enantiomeric separation was achieved on a Daicel-CSP, Chiralpack IA 4.6 × 250mm, 5μm; because of its advantages of high degree of retention, high resolution capacity, better reproducibility, ability to produce lower back pressure and low degree of tailing. The mobile phase was maintained as methanol: glacial acetic acid (499.50ml:50μL). Ultraviolet wavelength for detection was 220nm. PMD enantiomer-I and enantiomer-II were separated at 8.83 and 15.34min, respectively. Limit of detection and limit of quantification for each enantiomer and the calibration curve of standard PMD was linear in range between 10-5,000ngmL-1. The method was validated according to The International Council for Harmonisation of Technical Requirements of Pharmaceuticals for Human Use (ICH(Q2R1)) specific guidelines. We found no interference peak with PMD chromatogram obtained. This is a simple, reliable and specific method for detection and quantification of enantiomer of PMD in human plasma sample.

COF-SiO2@Fe3O4 Composite for Magnetic Solid-Phase Extraction of Pyrethroid Pesticides in Vegetables

Pyrethroid pesticides (PYRs) have found widespread application in agriculture for the protection of fruit and vegetable crops. Nonetheless, excessive usage or improper application may allow the residues to exceed the safe limits and pose a threat to consumer safety. Thus, there is an urgent need to develop efficient technologies for the elimination or trace detection of PYRs from vegetables. Here, a simple and efficient magnetic solid-phase extraction (MSPE) strategy was developed for the simultaneous purification and enrichment of five PYRs in vegetables, employing the magnetic covalent organic framework nanomaterial COF-SiO2@Fe3O4 as an adsorbent. COF-SiO2@Fe3O4 was prepared by a straightforward solvothermal method, using Fe3O4 as a magnetic core and benzidine and 3,3,5,5-tetraaldehyde biphenyl as the two building units. COF-SiO2@Fe3O4 could effectively capture the targeted PYRs by virtue of its abundant π-electron system and hydroxyl groups. The impact of various experimental parameters on the extraction efficiency was investigated to optimize the MSPE conditions, including the adsorbent amount, extraction time, elution solvent type and elution time. Subsequently, method validation was conducted under the optimal conditions in conjunction with gas chromatography–mass spectrometry (GC-MS). Within the range of 5.00–100 μg·kg−1 (1.00–100 μg·kg−1 for bifenthrin and 2.5–100 μg·kg−1 for fenpropathrin), the five PYRs exhibited a strong linear relationship, with determination coefficients ranging from 0.9990 to 0.9997. The limits of detection (LODs) were 0.3–1.5 μg·kg−1, and the limits of quantification (LOQs) were 0.9–4.5 μg·kg−1. The recoveries were 80.2–116.7% with relative standard deviations (RSDs) below 7.0%. Finally, COF-SiO2@Fe3O4, NH2-SiO2@Fe3O4 and Fe3O4 were compared as MSPE adsorbents for PYRs. The results indicated that COF-SiO2@Fe3O4 was an efficient and rapid selective adsorbent for PYRs. This method holds promise for the determination of PYRs in real samples.

Development and Validation of a RP-HPLC Method for the Simultaneous Determination of Silver Sulfadiazine and Sodium Hyaluronate in the Presence of Methyl and Propyl Paraben in a Pharmaceutical Cream for Burns.

A direct and precise isocratic RP-HPLC method for simultaneous determination of silver sulfadiazine (SSD) and sodium hyaluronate (SH) in the presence of methyl (MP) and propyl parabens (PP) was developed and validated. Agilent chromatograph with X-Select C18 column (250 × 4.6mm2, 5μm) was used. Chromatographic separation was achieved using a mobile phase consisting of acetonitrile and 0.05M phosphate buffer (pH5.0 to which added triethyl amine 0.5ml/L), at a ratio 35: 65v/v. Elution was used at flow rate of 1.0mL/min at ambient temperature with UV detection at 205nm. The retention times for SH, SSD, MP and PP were 1.49, 3.3, 6.7 and 19.5min, respectively. The presented chromatographic method was fully validated in accordance with ICH requirements, it was valid over linearity ranges of (0.80-100.00μg/mL) and (3.20-100.00μg/mL) for SSD and SH, respectively. Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges and the sensitivity of the method, as the limits of detection and quantification for each active ingredient was also determined. The validated method was successfully applied for the quantification of SSD and SH in pharmaceutical cream formulation and the mean recovery %±SD were 100.93 ± 0.985 and 100.05 ± 0.668 for SSD and SH; respectively, indicating satisfactory accuracy of the method.

Chromatographic methods and approaches for bioequivalence study, drug screening and enantioseparation of indapamide

AbstractIndapamide (Indp) and certain other diuretics have been abused in sports, therefore, having sensitive methods for its detection and assay in biological fluids (whole blood, plasma, serum, and urine) is of significant importance. The racemic mixture of Indp is being used as an active pharmaceutical ingredient among other commonly prescribed diuretics. The regulatory authorities and pharmaceutical industries demand analytical methods for successful enantioseparation of such molecules. The paper presents a critical overview of the scientific issues of the application of contemporary techniques involving various chromatographic approaches (with liquid or supercritical fluid as mobile phases) and capillary electrophoresis and method development, for drug screening, assay, bioequivalence studies and enantioseparation of indapamide with their results. It also covers the historical developments that led to significant breakthroughs in research and concise evaluations of research in the area.Different types of chromatographic methods (HPLC, CEC, SFC etc) discussed herein provide an insight and a choice to select a method to (i) screen Indp for drug abuse, (ii) separate, isolate and quantify the enantiomers of Indp and (iii) investigate their pharmacokinetics as markedly different species and not as a total drug. The article evaluates the field's status with a broad base and practical oriented approach so that the underlying principles are easily understood to help chemists and non-specialists gain useful insights into the field outside their specialization and provide experts with summaries of key developments. To the best of authors' knowledge there has been no attempt to review such methods for analysis of Indp and this is the first report of its kind.

LC-MS Lipidomic Analysis of Macrophages

Currently, an increasing incidence of cardiovascular diseases is observed in the population. Factors contributing to their development are obesity and pro-inflammatory processes occurring in the adipose tissue. Macrophages, cells of the non-specific immune system, which can be divided into pro-inflammatory and anti-inflammatory, play a significant role in these processes. For a better understanding of these phenomena, it is necessary to analyze the lipidome of macrophages of the two mentioned groups. The presented work was focused on the optimization of selected parameters of the LC-MS method for the analysis of 71 lipids from 16 lipid classes. Best results were achieved with column Acquity UPLC BEH C18 (1.7 µm, 2.1 mm × 100 mm) operating at the flow rate of 300 μL min–1 and temperature of 55 °C. The optimal desolvation temperature was 350 °C and the gradient elution started at 0 % of solvent B in the mobile phase. Retention dependencies were characterized for individual lipid classes. They were successfully fitted with a linear model (R2 &gt; 0.99) and subsequently used to confirm the accuracy of lipid identification. The optimized LC-MS method was also used to analyze the real samples of macrophages isolated from the adipose tissue of kidney donors. Samples were provided by Institute for Clinical and Experimental Medicine. The principal component analysis gave insight into the division of macrophages according to their type. The volcano plot showed a significant increase in the concentration of five lipids in the case of pro-inflammatory macrophages.

Design of experiments and Derringer's desirability function in optimisation and validation of RP-HPLC method for the analysis of enrofloxacin and its impurities

AbstractUsing the Design of Experiments methodology (Response-Surface Methodology and Derringer's Desirability Function), a simple, fast and robust RP-HPLC method was developed for the analysis of enrofloxacin (EFC), its impurity A (fluoroquinolonic acid, FQ) and impurity B (ciprofloxacin, CPX). Gradient elution of samples was performed on a Zorbax Eclipse XDB C18 column (150 × 4.6 mm, 3.5 μm) with a mobile phase consisting of 32 mM phosphate buffer pH 3.5 – methanol (0 min-19.6% methanol; 15.5 min-19.6% methanol; 29.5 min-80% methanol; 30 min-19.6% methanol; 35 min-19.6% methanol), delivered at a flow rate of 1.5 mL min−1, wavelength of detection 278 nm (for EFX and CFX) and 265 nm for FQ. A good linear response was achieved in the range 15–35 μg mL−1 (EFX) and LOQ-150% for impurities (CFX and FQ). Other validation parameters were also tested: precision, accuracy, sensitivity and robustness. The developed method was shown to be simple, practical and suitable for the analysis of EFC and its impurities (CPX, FQ) in veterinary drugs.

Determination of pancratistatin in mouse blood by ultra-liquid chromatography-tandem quadrupole mass spectrometry and its application

AbstractIn this study, a UPLC-MS/MS method was developed for determination of pancratistatin in the mouse blood, and the pharmacokinetics of pancratistatin in mice after intravenous (5 mg kg−1) and intragastric (15 mg kg−1) administration was studied. HSS T3 column was used for separation with mobile phases of acetonitrile and 0.1% formic acid using gradient elution procedure. The blood sample was treated by protein precipitant with acetonitrile, midazolam was used as internal standard (IS). Multiple reaction monitoring mode (MRM) was used for quantitative analysis, m/z 326.2→83.8 for pancratistatin and m/z 326.2→291.4 for IS in electrospray (ESI) positive interface. It showed a good linear in the range of 10–4,000 ng mL−1 (r &gt; 0.998); the intra-day and inter-day precision was &lt;15%, and the accuracy was 93%–105%. The recovery was better than 82%, and the matrix effect was 94%–105%. The developed UPLC-MS/MS method was fast, selective, and suitable for the pharmacokinetics of pancratistatin in mice.

Analysis of scopolamine and its related substances by means of high-performance liquid chromatography

AbstractThe retention behaviour of scopolamine (hyoscine) and its related compounds (norhyoscine, atropine, homatropine, and noratropine) was investigated on the silica-based HPLC stationary phase. The retention of investigated tropane alkaloids was interpreted by using the Soczewiński-Wachtmeister equation. A high correlation between the retention parameter (log k) and lipophilicity (log P) (R = 0.9923) confirms the significant influence of hydrophobic interactions on the retention behaviour of the aforementioned compounds. It was found that by increasing the acetonitrile fraction, a decrease in retention of the more polar epoxide derivatives (scopolamine, norhyoscine) and an increase in retention of the more lipophilic derivatives (atropine, noratropine, homatropine) is obtained. The best separation of the tropane alkaloids was achieved by a simple procedure that involved a mobile phase composed of acetonitrile and 40 mM ammonium acetate/0.05% TEA, pH 6.5; 50:50 v/v. Selected conditions were assumed for the determination of scopolamine hydrochloride in the eye drops (Scopolamini hydrobromidum 0.25%). The method was validated and it was found as selective, sensitive, precise, accurate, and robust for the further qualitative analysis of the scopolamine-related compounds.

Resin screening and process optimization for erythritol mother liquor chromatographic separation

In order to improve the utilization value of the erythritol mother liquor, the separation and purification of the erythritol mother liquor was selected in this study. The selected chromatographic separation programme for erythritol crystallizing mother liquor is as follows: Firstly, erythritol is resolved from mannitol and arabitol with DTF-01Ca (Suqing Group) resin and then mannitol is resolved from arabitol with 99Ca/320 (Dowex) resin. At the same time, the chromatographic conditions of the DTF-01Ca (Suqing Group) and 99Ca/320 (Dowex) resins were optimized, resulting in an optimal separation temperature and mobile phase flow rate of 70 °C, 10 ml/min. On this basis, a single-column chromatographic model was used to calculate the TD model parameter ( N ) and the mass transfer coefficient ( k m ) of the separation of erythritol mother liquor by DTF-01Ca (Suqing Group) and 99Ca/320 (Dowex) resins. The adsorption isotherms, TD model parameter ( N ) and the mass transfer coefficient ( k m ) provides data references for the design and operation of the simulated moving beds (SMB) separation system for the industrial-scale separation of erythritol crystallizing mother liquor.