Cyanopropyl Column Research Articles

Simultaneous HPLC–UV analysis of telmisartan and hydrochlorothiazide in human plasma

A specific, sensitive and rapid method based on high performance liquid chromatography (HPLC) was developed for the simultaneous determination of telmisartan (TELM) and hydrochlorothiazide (HCT) in human plasma using indapamide as internal standard. The method utilizes proteins precipitation with acetonitrile as only sample preparation prior to RP-HPLC.The analytes were chromatographed on shim-pack cyanopropyl column in isocratic elution with methanol: 10mM ammonium acetate solution (pH 6.0) (35:65 v/v) as mobile phase at a flow rate of 1ml/min and the wavelength of detection was 270nm.The method was validated over the concentration range of 1–10μgml−1 for TELM and 0.31–3.12μgml−1 for HCT in human plasma.Inter- and intra-run precision of TELM and HCT were less than 3.60% and the accuracy was less than 1.868%. The linearity, recovery, matrix effect and stability were validated for TELM/HCT in human plasma.

Determination of polycyclic aromatic hydrocarbons (PAHs) from organic aerosols using hollow fiber micro – porous membrane liquid – liquid extraction (HF-MMLLE) followed by gas chromatography–mass spectrometry analysis

A method for determination of polycyclic aromatic hydrocarbons (PAHs) from aerosols was developed. Instead of conventionally used non-polar or slightly polar phenylmethylpolysiloxane column a highly polar, highly substituted, cyanopropyl column (VF-23 MS) was used for separation of PAHs. Based on hollow fiber micro-porous membrane liquid–liquid extraction (HF-MMLLE) a method was developed for sample clean up and pretreatment. An enrichment factor of 617–1022 was obtained with extraction efficiency 10.2–18.9% for different PAHs analyzed in this study. The optimized method was successfully applied to aerosol samples and limits of detection between 1.2 pg m −3 and 180 pg m −3 was obtained. Almost all PAHs were found in most of the aerosol samples.

Development, application and validation of RP-HPLC method for the simultaneous determination of butamirate citrate and its main degradation product in pharmaceutical dosage forms

A simple, rapid and sensitive reversed phase high performance liquid chromatographic (HPLC) method was developed and validated for the simultaneous determination of butamirate citrate (BT) and its hydrolysis product (α-ethylbenzeneacetic acid (EA)). The method was based on HPLC separation of BT from its hydrolysis product using a Shim-pack cyanopropyl column (250 mm × 4.6 mm i.d., 5 μm particle diameter) at ambient temperature with the mobile phase consisting of acetonitrile–25 mM potassium dihydrogen phosphate, pH 3.4 (40 : 60, v/v). Quantitation was achieved with UV detection at 210 nm based on peak area. The method was validated with respect to specificity, linearity, limit of detection, limit of quantitation, accuracy, precision and robustness. The method was successfully applied for the determination of BT and its hydrolysis product in syrup. The proposed method was used to investigate the kinetics of acidic and alkaline hydrolysis processes of BT at different temperatures and the apparent pseudo-first-order rate constant, half-life and activation energy were calculated. The pH–rate profile of hydrolysis of BT in Britton–Robinson buffer solutions within the pH range 1.4–12 was studied.

Simple and rapid HPLC method for simultaneous determination of atenolol and chlorthalidone in spiked human plasma

A simple, sensitive and rapid chromatographic method was developed and validated for the simultaneous quantification of atenolol and chlorthalidone in human plasma using hydrochlorothiazide as internal standard (IS). The method utilized proteins precipitation with acetonitril as the only sample preparation involved prior to reverse phase-HPLC. The analytes were chromatographed on Shim-pack cyanopropyl column with isocratic elution with 10 mM KH 2PO 4 (pH 6.0) – methanol (70:30, v/v) at ambient temperature with flow rate of 1 mL min −1 and UV detection at 225 nm. The chromatographic run time was less than 10 min for the mixture. The calibration curves were linear over the range of 0.1–10 μg mL −1. The method was validated in terms of accuracy, precision, absolute recovery, freeze–thaw stability, bench-top stability and re-injection reproducibility. The within- and between-day accuracy and precision were found to be within acceptable limits <15%. The analytes were stable after three freeze–thaw cycles (deviation <15%). The proposed method was specific for the simultaneous determination of atenolol and chlorthalidone in human plasma where there was no interference from endogenous biological substances.

Chromatographic behavior of a new hybrid type RP material containing silica bonded 1,3-alternate 25,27-bis-[cyanopropyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene

A novel 1,3-alternate 25,27-bis-[cyanopropyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene-bonded silica gel stationary phase (CalixPrCN) was prepared and its structure was confirmed by ATR-FTIR spectroscopy and elemental analysis. The CalixPrCN phase was characterized in terms of its surface coverage, hydrophobic selectivity, aromatic selectivity, shape selectivity, hydrogen bonding capacity, residue metal content, and silanol activity based on Tanaka, Lindner, and SMR 870 test protocols. The effect of the acetonitrile content on the retention and selectivity of the selected neutral, basic, and acidic solutes was studied. The neutral and acidic analytes exhibited classical RP behavior, in which retention time decreases with increasing acetonitrile content. In contrast, basic analytes showed an increase in retention at low and high percentages of acetonitrile, forming "U-shaped" retention profiles. The new calixarene phase was compared with previously reported 1,3-alternate 25,27-bis-[propyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene stationary phase and commercial cyanopropyl column. The results indicate that the CalixPrCN stationary phase behaves like RP packing; however, inclusion complex formation, dipole-dipole, and π-π interactions seem to be involved in the separation process. The selectivity of this phase was demonstrated in separation of polynuclear aromatic hydrocarbons, non-steroidal anti-inflammatory drugs, and sulfonamides as analytes.

Development and Application of an Analytical Method for the Determination of Partition Coefficients of Tributyltin in the Forth and Clyde Canal, Glasgow, Scotland

Abstract Tributyltin (TBT) was widely used in the past as a biocide for boats. This has led to widespread environmental contamination. Most analytical methods are based on high resolution techniques with complicated sample preparation. For this study, a simple application of an analytical method was developed using HPLC/UV. The developed method was studied to determine TBT, dibutyltin, and monobutyltin in sediment and water samples. The separation was performed in isocratic mode on a cyanopropyl column with a mobile phase of hexane containing 5 % tetrahydrofuran and 0.03 % acetic acid. This method was confirmed using standard GC-MS techniques and verified by statistical paired t-test method. Under the experimental conditions used, the limit of detection of TBT and DBT were 0.70 and 0.50 ppm, respectively. An optimized extraction method for butyltins in water and sediment samples was developed by using hexane containing 0.05 %–0.5 % tropolone, and 0.2 % sodium chloride in water at pH1.7. The quantitative extraction of butyltin compounds in a certified reference material (BCR-646) and naturally contaminated samples was achieved with recoveries ranging from 95 % to 108 % and precision of 0.02 %–1.00 % relative standard deviation. This developed method was used to determine the contamination level of butyltins in environmental samples collected from the Forth and Clyde canal, Scotland, United Kingdom. The values obtained exceeded the Environmental Quality Standard values. Partition coefficients are major parameters influencing the behavior of pollutants, therefore the methodology developed was used to determine experimentally the partition coefficients Koc, Kd, and Kow. The comparison between values obtained experimentally and computational default model values (EPI Suite V 3.20) showed disparity. In terms of bioaccumulation, the implications of this finding may lead to greater biomagnification in the food chain.

Development and Validation of an LC Method for Simultaneous Determination of Amiloride Hydrochloride and Hydrochlorothiazide in Human Urine

An HPLC method with photometric detection has been developed for determination of a binary mixture of amiloride hydrochloride and hydrochlorothiazide in human urine using chlorthalidone as the internal standard. Reversed-phase chromatography was performed at room temperature on a cyanopropyl column with the mobile phase consisting of a 10 mM KH2PO4 solution (pH 4.5)-methanol (70 + 30, v/v) at a flow rate of 1 ml/min. The detector was set at 214 nm. The total analysis time was 10 min. The method was validated in terms of accuracy, precision, absolute recovery, freeze-thaw stability, bench-top stability, and re-injection reproducibility. The procedure shows good accuracy, repeatability, and selectivity. Moreover, the method was applied directly to urine that had not undergone prior treatment. The intra- and interday coefficients of variation for all compounds were below 4%, and the method was highly accurate, with a relative error for all compounds that was below 8%. No interference from endogenous compounds in urine samples was found. The proposed method, which is rapid, simple, and does not require any separation steps, has been successfully applied to the assay of human urine containing amiloride hydrochloride and hydrochlorothiazide.

Development and validation of an HPLC-UV-visible method for sunitinib quantification in human plasma

Background Sunitinib malate is a novel oral multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activities. Only mass spectrometry detection is currently available to determine sunitinib in human plasma. The purpose of this study was to develop a simple and sensitive high-performance liquid chromatographic method with UV-Visible detection for quantification of sunitinib concentrations in human plasma. Methods After a liquid–liquid extraction with ethyl acetate, sunitinib and ranitidine (internal standard) are separated on cyanopropyl column using a simple binary mobile phase of ammonium acetate buffer (20 mM; pH 6.8):acetonitrile (55:45,v/v). Samples were eluted isocratically at a flow rate of 1 mL/min throughout the 10 min run. Dual wavelength mode was used, with ranitidine monitored at 255 nm, and sunitinib at 431 nm. Results The calibration was linear in the range 20–200 ng/mL. Inter- and intra-day coefficients of variation were less than 7%. This method is sensitive, accurate and selective. It has been successfully implemented to monitor trough sunitinib concentrations in plasma samples ( n = 39) from 14 unselected cancer patients treated with the recommended once daily dose of 50 mg or less. Conclusion This method can be used in routine clinical practice to monitor plasma sunitinib concentrations in cancer patients treated with once daily administration.

Development and Validation of a Reversed-Phase High-Performance Liquid Chromatographic Method for the Simultaneous Determination of Amiloride Hydrochloride, Atenolol, Hydrochlorothiazide, and Chlorthalidone in Their Combined Mixtures

A high-performance liquid chromatographic method was developed for the simultaneous determination of 2 ternary mixtures containing amiloride hydrochloride, atenolol, hydrochlorothiazide, and chlorthalidone used in hypertension therapy. The use of cyanopropyl column results in satisfactory separation of both mixtures. The mobile phase consisted of 10 mM KH2PO4 buffer (pH 4.5) and methanol in a ratio of (75 + 25% v/v), at a flow rate of 1 mL/min. UV detector was operated at 275 nm. Calibration graphs were linear in the concentration ranges of 2-10, 20-200, 10-100, and 5-50 microg/mL for amiloride hydrochloride, atenolol, hydrochlorothiazide, and chlorthalidone, respectively. Intraday and interday precision values (relative standard deviation) were <1.13 for mixture I (amiloride hydrochloride, atenolol, chlorthalidone), and <0.93 for mixture II (amiloride hydrochloride, atenolol, hydrochlorothiazide). The method was successfully applied for the determination of the 2 combinations in laboratory-prepared mixtures and commercial pharmaceutical formulation with high accuracy and precision. Statistical comparison of the results with those of the published methods showed excellent agreement and indicates no significant difference between them.

Development of a low-cost method of analysis for the qualitative and quantitative analysis of butyltins in environmental samples

Most analytical methods for butyltins are based on high resolution techniques with complicated sample preparation. For this study, a simple application of an analytical method was developed using High Performance Liquid Chromatography (HPLC) with UV detection. The developed method was studied to determine tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) in sediment and water samples. The separation was performed in isocratic mode on an ultra cyanopropyl column with a mobile phase of hexane containing 5% THF and 0.03% acetic acid. This method was confirmed using standard GC/MS techniques and verified by statistical paired t-test method. Under the experimental conditions used, the limit of detection (LOD) of TBT and DBT were 0.70 and 0.50 μg/mL, respectively. The optimised extraction method for butyltins in water and sediment samples involved using hexane containing 0.05–0.5% tropolone and 0.2% sodium chloride in water at pH 1.7. The quantitative extraction of butyltin compounds in a certified reference material (BCR-646) and naturally contaminated samples was achieved with recoveries ranging from 95 to 108% and at %RSD 0.02–1.00%. This HPLC method and optimum extraction conditions were used to determine the contamination level of butyltins in environmental samples collected from the Forth and Clyde canal, Scotland, UK. The values obtained severely exceeded the Environmental Quality Standard (EQS) values. Although high resolution methods are utilised extensively for this type of research, the developed method is cheaper in both terms of equipment and running costs, faster in analysis time and has comparable detection limits to the alternative methods. This is advantageous not just as a confirmatory technique but also to enable further research in this field.

Retention behavior of trans isomers of eicosapentaenoic and docosahexaenoic acid methyl esters on a polyethylene glycol stationary phase

AbstractA polyethylene glycol (PEG) stationary phase was evaluated for the separation of mono‐trans isomers of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) methyl esters. The resolution patterns were compared to patterns achieved with previously applied conditions on a cyanopropyl phase. There were no overlaps between all‐cis EPA/DHA and their mono‐trans isomers on the PEG phase. Because of overlap between 22:0 and 22:1 isomers, the PEG column is not a good choice for analyses of EPA trans isomers in crude fish oils. However, if the saturated and monounsaturated fatty acids are not present in significant amounts, PEG can be a better choice than cyanopropyl columns.

Development and Validation of LC Method for Simultaneous Determination of Two Binary Mixtures Containing Indapamide

A new sensitive, simple, rapid, and precise RP LC method with hydrochlorothiazide as internal standard has been developed for resolving two binary mixtures, perindopril with indapamide and captopril with indapamide, in pharmaceutical formulations. The drugs were separated at room temperature on a 250 mm × 4.6 mm, 5-μm particle, cyanopropyl column with 10 mm KH2PO4, pH 6.0-methanol 55:45 (v/v) as mobile phase at a flow rate of 1 mL min−1. Detection was at 210 nm. Factors affecting the separation process were studied and optimized. The linearity, accuracy, and precision of the method were good, and the method was successfully applied to the determination of the two binary combinations in synthetic mixtures and commercial pharmaceutical products.

Application of a Validated, Stability-Indicating LC Method to Stress Degradation Studies of Ramipril and Moexipril.HCl

A stability-indicating reversed-phase liquid chromatographic (RPLC) method has been established for analysis of ramipril (RAM) and moexipril hydrochloride (MOEX.HCl) in the presence of the degradation products generated in studies of forced decomposition. The drug substances were subjected to stress by hydrolysis (0.1 m NaOH and 0.1 m HCl), oxidation (30% H2O2), photolysis (254 nm), and thermal treatment (80 °C). The drugs were degraded under basic and acidic conditions and by thermal treatment but were stable under other stress conditions investigated. Successful separation of the drugs from the degradation products was achieved on a cyanopropyl column with 40:60 (v/v) aqueous 0.01 m ammonium acetate buffer (pH 6)–methanol as mobile phase at a flow rate of 1 mL min−1. Detection was by UV absorption at 210 nm. Response was a linear function of concentration over the range 5–50 μg mL−1 (r > 0.9995), with limits of detection and quantitation (LOD and LOQ) of 0.04 and 0.09 μg mL−1, respectively, for RAM and 0.014 and 0.32 μg mL−1, respectively, for moexipril. The method was validated for specificity, selectivity, solution stability, accuracy, and precision. Statistical analysis proved the method enabled reproducible and selective quantification of RAM and MOEX as the bulk drug and in pharmaceutical preparations. Because the method effectively separates the drugs from their degradation products, it can be used as stability-indicating.

Stability-Indicating Method for Determination of Oxyphenonium Bromide and Its Degradation Product by High-Performance Liquid Chromatography

A high-performance liquid chromatographic (HPLC) method was developed for determination of oxyphenonium bromide (OX) and its degradation product. The method was based on the HPLC separation of OX from its degradation product, using a cyanopropyl column at ambient temperature with mobile phase of acetonitrile-25 mM potassium dihydrogen phosphate, pH 3.4 (50 + 50, v/v). UV detection at 222 nm was used for quantitation based on peak area. The method was applied to the determination of OX and its degradation product in tablets. The proposed method was also used to investigate the kinetics of the acidic and alkaline degradation of OX at different temperatures, and the apparent pseudo first-order rate constant, half-life, and activation energy were calculated. The pH-rate profile of the degradation of OX in Britton-Robinson buffer solutions within the pH range 2-12 was studied.

Development and Validation of Chemometrics-Assisted Spectrophotometry and Liquid Chromatography Methods for the Simultaneous Determination of the Active Ingredients in Two Multicomponent Mixtures Containing Chlorpheniramine Maleate and Phenylpropanolamine Hydrochloride

Multivariate spectrophotometric calibration and liquid chromatography (LC) methods were used for the simultaneous determination of the active ingredients in 2 multicomponent mixtures containing chlorpheniramine maleate and phenylpropanolamine hydrochloride with ibuprofen and caffeine (mixture 1) or with propyphenazone (mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least squares (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in distilled water. A leave-1-out cross-validation procedure was used to find the optimum numbers of latent variables. Analytical parameters such as sensitivity, selectivity, analytical sensitivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC method depends on the use of a cyanopropyl column with the mobile phase acetonitrile-12 mM ammonium acetate, pH 5.0 (25 + 75, v/v), for mixture 1 or acetonitrile-10 mM potassium dihydrogen phosphate, pH 4.7 (45 + 55, v/v), for mixture 2; the UV detector was set at 212 nm. In spite of the presence of a high degree of spectral overlap of these components, they were rapidly and simultaneously determined with high accuracy and precision, with no interference from the matrix excipients. The proposed methods were successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations.

Highly Specific Quantification of Ergotamine in Urine, Blood, and Hair Samples by Liquid Chromatography-Tandem Mass Spectrometry

Ergotamine has been used for therapeutic purposes since the 1950s, usually to treat vascular headache. It is highly toxic and in large, repeated doses can produce all the symptoms of ergot poisoning. A selective and sensitive method, based on liquid chromatography-tandem mass spectrometry (LC-MS2), has been developed for quantifying ergotamine in biological fluids with use of a quick and easy sample preparation. Ergotamine and the internal standard, trideuterated lysergic acid diethylamide, were extracted from human urine, blood, and hair by means of liquid-liquid extraction at alkaline pH. Gradient elution on a cyanopropyl column was used for chromatographic separation. Positive ion electrospray ionization and tandem mass spectrometry determination by collision-induced dissociation were performed in an ion trap mass spectrometer. The method was validated and successfully applied to a case of iatrogenic ergotism resulting from the intake of ergotamine tartrate for treating headache. For the first time, ergotamine was identified and quantified in hair. The ergotamine concentrations measured were 320 pg/mL in blood, 100 pg/mL in urine, 24 pg/mg in proximal hair, and 15 pg/mg in distal hair.

Separation and determination of alkylglycosides by liquid chromatography with electrospray mass spectrometric detection

The separation of alkylpolyglycosides by liquid chromatography with electrospray mass spectrometric detection, using either an alkylamide or a cyanopropyl column, and acetonitrile/water mixtures as mobile phases, was developed. Using the alkylamide column and isocratic elution, the α- and β-epimers and ring isomers (pyranosides and furanosides) of the alkylmonoglycosides were resolved. The ring isomers were also resolved in a much shorter time using the cyanopropyl column with gradient elution. Using these columns, the isomers of the alkyldiglycosides and alkyltriglycosides were also partially resolved. The equilibration time was much shorter with the cyanopropyl column, which was selected to perform quantitation studies. The response factors increased more than an order of magnitude with the length of the alkyl chain, from the methyl to the decylmonoglycoside, and decrease largely for the dodecyl and tetradecylmonoglycoside. The limits of detection were of ca. 25 μM from the hexyl up to the dodecylmonoglycoside. The procedures were applied to the characterisation and determination of alkylmonoglycosides in toiletries.

Simultaneous determination of albendazole metabolites, praziquantel and its metabolite in plasma by high-performance liquid chromatography–electrospray mass spectrometry

The analysis of albendazole sulfoxide, albendazole sulfone, praziquantel and trans-4-hydroxypraziquantel in plasma was carried out by high-performance liquid chromatography–mass spectrometry ((LC–MS–MS). The plasma samples were prepared by liquid–liquid extraction using dichloromethane as extracting solvent. The partial HPLC resolution of drug and metabolites was obtained using a cyanopropyl column and a mobile phase consisting of methanol:water (3:7, v/v) plus 0.5% of acetic acid, at a flow rate of 1.0 mL/min. Multi reaction monitoring detection was performed by electrospray ionization in the positive ion mode, conferring additional selectivity to the method. Method validation showed relative standard deviation (precision) and relative errors (accuracy) lower than 15% for all analytes evaluated. The quantification limit was 5 ng/mL and the linear range was 5–2500 ng/mL for all analytes. The method was used for the determination of drug and metabolites in swine plasma samples and proved to be suitable for pharmacokinetic studies.

New Validated Methods for the Simultaneous Determination of Two Multicomponent Mixtures Containing Guaiphenesin in Syrup by HPLC and Chemometrics‐Assisted UV‐Spectroscopy

High pressure liquid chromatographic (HPLC) and spectrophotometric methods are developed for the determination of two multicomponent mixtures containing guaiphenesin, dextromethorphane hydrobromide, and sodium benzoate together with either phenylephrine hydrochloride, chlorpheniramine maleate, and butylparaben (mixture 1) or ephedrine hydrochloride and diphenhydramine hydrochloride (mixture 2). The HPLC method depended on using an ODS column with mobile phase consisting of acetonitrile −10 mM potassium dihydrogen phosphate, pH 2.7 (40∶60 v/v) containing 5 mM heptane sulfonic acid sodium salt (for mix 1) and a cyanopropyl column with mobile phase consisting of acetonitrile −12 mM ammonium acetate, pH 5 (40∶60 v/v) (for mix 2) and UV detection at 214 nm. The cyanopropyl column is much less hydrophobic, less sterically restricted to the penetration of bulky solute molecules into the stationary phase, and has weaker hydrogen‐bond acidity than the ODS column. So the cyanopropyl column is more suitable for separation of components of mix 2. The chemometric‐assisted spectrophotometric method with, principal component regression (PCR) and partial least squares (PLS‐1) was used. For the chemometric method a calibration set of the mixture consisting of each compound in each mixture was prepared in distilled water. The absorbance data in the UV spectra were measured in the spectral region (210–240 or 210–224 nm for mix 1 and mix 2, respectively, as this range provided the greatest amount of information about the two mixture components). The spectrophotometric method does not require a separation step. The proposed methods were successfully applied for the analysis of the two multicomponents combinations in laboratory‐prepared mixtures and in commercial syrups, and the results were compared with each other.

High performance liquid chromatographic determination of etofibrate and its hydrolysis products

High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile–10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min −1. The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton–Robinson buffer solutions within the pH range 2–10 were studied.