Improved and Rapid Liquid Chromatographic Determination of Indomethacin in Serum

Abstract

A rapid, specific and sensitive reversed-phase liquid chromatographic (LC) assay for the quantitative determination of indomethacin in serum without extraction was developed. Chromatographic separation using flunixin meglumine as the internal standard was achieved on octadecylsilane-coated particles with a mobile phase of 0.15 M acetate buffer pH 3.0 (50% v/v), acetonitrile (30% v/v) and methanol (20% v/v). The recovery of indomethacin from serum samples in the concentration range of 0.1-25 μg/ml was 95.5 ± 5.8% and as little as 100 ng/ml of indomethacin in serum samples can be quantitated by this procedure. A serum level versus time profile of dog with intravenously administered indomethacin demonstrated the applicability of the assay.     

A Simple and Rapid Reversed Phase High Performance Liquid Chromatographic Method for Quantification of Alprazolam and α-Hydroxyalprazolam in Plasma

Abstract

A simple and rapid reversed-phase liquid chromatographic method for the determination of alprazolam and a-hydroxyalprazolam in plasma is described. Flunictrazepam was used as internal standard. Plasma samples were buffered with sodium borate and extracted with dichloromethane /n-pentane 4:6 v/v for 60 sec on a vortex apparatus. Extraction solvent was evaporated to dryness and extraction residues were reconstituted in the mobile phase. Samples were chromatographed on a 5μ Lichrospher RP-18 column (25cm × 4mm i. d) using acetonitrile/water 40:60 v/v as the mobile phase. The column effluent was monitored at 230nm. The lower limit of detection was 1ng/ml for alprazolam and a-hydroxyalprazolam while the lower limit of quantification was 2ng/ml for both compounds. Peak height and plasma     

HPLC Determination of Valproic Acid in Human Serum Using Ultraviolet Detection

Abstract

A sensitive HPLC method with minimal sample preparation and good reproducibility for the determination of valproic acid in serum is described. Serum samples were precipitated using acetonitrile containing diazepam as the internal standard. Chromatography was performed on a Hewlett Packard model 1090 equipped with an octadecylsilane column and a Beckman model 163 variable wavelength detector. The drug and internal standard were eluted isocratically using a mobile phase consisting of 0.01M sodium phosphate monobasic solution, pH 2.3 and acetonitrile (63:37 v/v) followed by a gradient to flush the column before the next sample injection. The flow rate was 2.5 mL/min, the injection volume was 25 μL and the effluent was monitored at 210 nm. The serum standard curve was linear from 2.5-200.0 μg/mL with a correlation coefficient of 0.9994. Day-to-day precision for quality control samples (10.0, 25.0, 75.0 μg/mL serum) ranged from 5.6-9.6% CV. Possible interferences from other drugs which might be administered concurrently were studied. The method has been applied to the analysis of human serum samples.     

Effect of monomer molecular flow on electrode surface on the structure of poly(α-tetrathiophene) obtained by anodic polymerization

Different structures have been found for poly(α-tetrathiophene) [poly(α-4TF)] electrosynthesized on Pt by anodic oxidation of 1.0 mM monomer solutions in media such as 45:35:20 (v/v/v) acetonitrile/THF/DMF, 45:35:20 (v/v/v) acetonitrile/ethanol/DMF and 72:28 (v/v) acetonitrile/DMF containing 0.1 M LiClO₄; as well as 72:28 (v/v) acetonitrile/DMF with 0.1 M NaClO₃, under dynamic and static conditions at 25 °C. In all cases the polymer was generated by chronoamperometry at 1.000 V vs. Ag∣AgCl, corresponding to the first oxidation peak detected by cyclic voltammetry. Uniform, adherent, insoluble and black polymer films were obtained under these conditions. The resulting structures have been elucidated by combining the information of their IR spectrum, n_ox-value and doping level of the counterion. The degree of crosslinking of every polymer has been quantified and related to the molecular flow of monomer on the Pt electrode. A monomer concentration flow between 4 × 10⁻⁶ and 5 × 10⁻⁶ mmol cm⁻² s⁻¹ was determined as the limiting value below which the polymer grows with crosslinking. This value corresponds to the electropolymerization rate of α-4TF by Pt area unit at 25 °C.     

A Simple and Sensitive HPLC Method for Antipyrine in Plasma

Abstract

A rapid, simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of antipyrine in small volume (50 μl) of plasma samples. Aminopyrine was employed as the internal standard. The sample preparation is a direct plasma protein precipitation procedure so is less tedious and rapid. The assay employs a column packed with a C₁₈ reversed-phase material (5 μm Nucleosil) with an isocratic mixture of acetonitrile and water (25:75, v/v) as the mobile phase. The eluant was detected at 254 nm. The assay achieves the level of sensitivity (0.5 μg/ml) and accuracy required to obtain meaningful data about the single-dose pharmacokinetics of antipyrine in guinea pig and rat. The method gave high reproducibility with coefficients of variation less than 5%.     

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography. Part 2: The direct analysis of mixed standard solutions of triphenyltin halides/pseudohalide and of triphenyltin carboxylates containing functional group variations in the esteryl moiety

Simultaneous speciation of mixed standard solutions of triphenyltin halides (triphenyltin chloride, bromide, iodide) and pseudohalide (triphenyltin isothiocyanate) has been achieved with reversed‐phase high‐performance liquid chromatography on a Waters Spherisorb S5W ODS‐2 (octadecyl‐silica) column. An isocratic mixture of 95:5 (v/v) acetonitrile:water was used as the mobile phase at a flow rate of 1 ml min^?1. A series of selected triphenyltin carboxylates, Ph₃SnOCOZ, where Z = Me, Ph, CH:CHPh, CH:NOMe, CH₂SC₅H₄N and CH₂SC(S)NMe₂, was also similarly analysed using this system with two separate isocratic elutions using 100% acetonitrile and 96:4 (v/v) acetonitrile:water as the mobile phase. UV detection was done at 254 nm and the total run time for each analysis was less than 3 min. The detection limits for all the phenyltin(IV) compounds were in the range 0.01–0.03 ppm. Spiked water samples containing the triphenyltin carboxylates could also be simultaneously analysed by the above method without the need for any prior derivatization, following extraction with hexane. Pretreatment of the aqueous sample with NaCl/HCl and of the organic phase with hexamethylphosphoramide enabled recoveries of about 80% of the triphenyltins. Copyright © 2002 John Wiley & Sons, Ltd.     

Separation of chlorogenic acid and concentration of trace caffeic acid from natural products by pH‐zone‐refining countercurrent chromatography

Chlorogenic acid and caffeic acid were selected as test samples for separation by the pH‐zone‐refining countercurrent chromatography (CCC). The separation of these test samples was performed with a two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/water at a volume ratio of 4:1:5 v/v/v where trifluoroacetic acid (TFA; 8 mM) was added to the organic stationary phase as a retainer and NH₄OH (10 mM) to the aqueous mobile phase as an eluter. Chlorogenic acid was successfully separated from Flaveria bidentis (L.) Kuntze (F. bidentis) and Lonicerae Flos by pH‐zone‐refining CCC, a slightly polar two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/n‐butanol/water at a volume ratio of 4:1:1:5 v/v/v/v was selected where TFA (3 mM) was added to the organic stationary phase as a retainer and NH₄OH (3 mM) to the aqueous mobile phase as an eluter. A 16.2 mg amount of chlorogenic acid with the purity of 92% from 1.4 g of F. bidentis, and 134 mg of chlorogenic acid at the purity of 99% from 1.3 g of crude extract of Lonicerae Flos have been obtained. These results suggest that pH‐zone‐refining CCC is suitable for the isolation of the chlorogenic acid from the crude extracts of F. bidentis and Lonicerae Flos.     

High Performance Liquid Chromatographic Determination of Amiodarone in Plasma and Tissues

Abstract

A simple and rapid high-performance liquid chromatographic (HPLC) method for the determination of amiodarone (AD) in plasma and tissues was developed. The method involved deproteinization of plasma or homogenized tissue with acetonitrile containing an internal standard (N-Cetylpyridinium chloride) followed by reversed phase chromatography using μ bondapack C₁₈ column (10μm) with a mobile phase consisting of acetonitrile - methanol - sodium dihydrogen phosphate buffer (70:10:20%, v/v), the pH adjusted to 4.0 and pumped at flow rate of 1.0 ml/min. The column effluent was monitored at 242 nm. A linear relationship was obtained between peak height ratios (drug to internal standard) versus drug levels over the concentration range of 50–750 ng/ml. The detection limit of AD in plasma and tissues by this method was 20 ng/ml.     

Reliable Separation of Xylitol from Some Carbohydrates and Polyols by High Performance Liquid Chromatography

Abstract

An acceptable separation of xylitol from a mixture of sucrose, glucose, fructose, mannitol and sorbitol was carried out by High Performance Liquid Chromatography. A Sugar Pak I column at 80°C was used employing acetonitrile/water (25/75) (v/v) as the mobile phase.     

High Performance Liquid Chromatograph 1C Method for Determination of Mifobate in Rat Feed

Abstract

A high performance liquid Chromatographie (HPLC) method is described for the quantitative determination of Mifobate (SR-202) in rat feed. Mifobate is extracted in acetone and isolated from other extractants on a Waters Sep-pak® C₁₈ disposable pre-column. The extracted drug and internal standard are chromatographed on a μBondapak? C₁₈ reverse phase column with a mobile phase consisting of water and acetonitrile (55:45, v/v). The eluent is monitored at 225 nm.

The method provided a 101.56 ± 5.1% mean recovery of Mifobate from spiked feed samples ranging in the 22.24 to 433.04 mg/kg concentration range. Standard curves bracketing this concentration range had linear coefficients greater than 0.9998. The average relative standard deviation (%) for the entire concentration range was 4.2%. The critical steps and precision of the method were also evaluated.     

A rapid and simple HPLC method for the determination of curcumin in rat plasma: assay development,validation and application to a pharmacokinetic study of curcumin liposome

This paper describes a sensitive, specific and rapid high‐performance liquid chromatography (HPLC) method for the determination of curcumin in rat plasma. After a simple step of protein precipitation in 96‐well format using acetonitrile containing the internal standard (IS), emodin, plasma samples were analyzed by reverse‐phase HPLC. Curcumin and the IS emodin were separated on a Diamonsil C₁₈ analytical column (4.6 × 100 mm, 5 µm) using acetonitrile–5% acetic acid (75:25, v/v) as mobile phase at a flow rate of 1.0 mL/min. The method was sensitive with a lower limit of quantitation of 1 ng/mL, with good linearity (r² ≥ 0.999) over the linear range 1–500 ng/mL. All the validation data, such as accuracy and precision, were within the required limits. A run time of 3.0 min for each sample made high‐throughput bioanalysis possible. The assay method was successfully applied to the study of the pharmacokinetics of curcumin liposome in rats. Copyright © 2009 John Wiley & Sons, Ltd.     

高效液相色谱手性流动相添加剂法分离3种黄酮类化合物对映体

采用反相高效液相色谱法(RP-HPLC),以磺丁基醚-β-环糊精(SBE-β-CD)作为手性流动相添加剂,建立了二氢黄豆苷原(dihydrodaidzein)、雌马酚(equol)和山姜素(alpinetin)3种黄酮类化合物的手性拆分方法。考察了环糊精的种类和浓度、有机相的种类和比例、缓冲盐的种类和浓度以及pH对3种化合物手性拆分效果的影响。结果表明:采用Kromasil 100-5C₁₈(250 mm×4.6 mm, 5 μm)色谱柱,流动相为乙腈-10 mmol/L SBE-β-CD水溶液(含20 mmol/L KH₂PO₄, pH值到4.0)(体积比为20:80)的条件下,二氢黄豆苷原、雌马酚和山姜素的对映体都达到了基线分离,分离度分别为1.8, 1.9和1.4。该方法简便,分离效果好,对黄酮类化合物的拆分具有应用价值。     

Determination of Diketopiperazine in Soft Drinks by High Performance Liquid Chromatography

Abstract

Analytical method of diketopiperazine (5-Benzyl-3, 6-dioxo 2 piperazineacetic Acid: DKP), a major degradation product of aspartame (AMP), in soft drinks was developed by means of high performance liquid chromatography (HPLC). A sample was purified using Bond Elut SCX connected to Bond Elut C8 with 20% acetonitrile as the eluent. A Nucleosil 5-C₁₈ column was employed for the HPLC with 10 mM potassium dihydrogenphosphate and acetonitrile (85+15, v/v) adjusted pH to 4.0 as the mobile phase. The calibration curve was rectilinear in the range of 0.5 to 10.0 μg/ml for DKP. The average recoveries were 99.8% and 96.0% for DKP added to soft drinks at the level of 10 μ g/ml and 2.5 μ g/ml, respectively. The DKP was found in six commercial samples in the range of 9.5 to 26.0 μ g/ml.     

Simultaneous Determination of Fluvoxamine and Its Metabolites in Human Liver Microsomes by High‐Performance Liquid Chromatography with Solid‐Phase Extraction

Abstract

A simple and sensitive high‐performance liquid chromatography method was developed for the simultaneous quantitative determination of fluvoxamine and its two metabolites, fluvoxamino alcohol and fluvoxamino acid, in human liver microsomes. Chromatographic separation was achieved with a Grand‐pak C4‐5 column using a mobile phase at pH 2.5 of 0.5% KH₂PO₄‐acetonitrile (75:25, v/v). Analysis involved a solid‐phase extraction with an Oasis HLB cartridge, which gave high extraction recovery (>92.8%) with good selectivity. The lower limit of quantification of this assay was 78.6 nM for fluvoxamine and fluvoxamino acid, and 82.2 nM for fluvoxamino alcohol, respectively. The coefficient of variation of intra‐ and interday assays was less than 5.8% and accuracy was within 5.3% for all analytes (concentration range 78.6 nM–2.36 µM for fluvoxamine and fluvoxamino acid, and 82.2 nM–2.47 µM for fluvoxamino alcohol, respectively). This method is applicable for accurate and simultaneous determination of oxidative metabolites of fluvoxamine by human liver microsomes.     

Simultaneous Determination of Abacavir,Efavirenz and Valganciclovir in Human Serum Samples by Isocratic HPLC-DAD Detection

A rapid, sensitive, and specific reverse phase high performance liquid chromatography with diode array detection procedure for the simultaneous determination of abacavir, efavirenz and valganciclovir in spiked human serum is described. Separation was performed on a 5 μm Waters Spherisorb column (250 × 4.6 mm ID) with acetonitrile: methanol:KH₂PO₄ (at pH 5.00) (40:20:40 v/v/v) isocratic elution at a flow rate of 1.0 mL min⁻¹. Calibration curves were constructed in the range of 50–30,000 ng mL⁻¹ for abacavir and efavirenz, and 10–30,000 ngmL⁻¹ for valganciclovir in serum samples. The limit of detection and limit of quantification concentrations of the HPLC method were 3.80 and 12.68 ng mL⁻¹ for abacavir, 2.61 and 8.69 ng mL⁻¹ for efavirenz, 1.30 and 4.32 ng mL⁻¹ for valganciclovir. The method has been applied, without any interference from excipients or endogenous substances, for the simultaneous determination of these three compounds in human serum.

     

Simultaneous Determination of Norfloxacin and Tinidazole in Tablets by Reverse Phase High Performance Liquid Chromatography (RP - HPLC).

Abstract

A new simple, precise, rapid and selective HPLC-RP method has been developed for the simultaneous determination of Norfloxacin and Tinidazole in formulations, using 0.2 % Triethylamine (TEA) in water : Acetonitrile (80:20,v/v) and pH adjusted to 2.6 to 2.8 with Phosphoric acid, as a mobile phase, and C₁₈ SHODEX column (5 micron, 25 cm × 3.9 mm, ID) as stationary phase. Detection was carried out using a UV detector at 311 nm Linearity range and percentage recoveries for Norfloxacin and Tinidazole were 20 - 200 μg/mL and 30 - 300 μg/mL, 999.91 % and 99.94 % respectively.     

Determination of Tetracycline and Related Compounds by High-Performance Liquid Chromatography

Abstract

An isocratic high-performance liquid chromatography method for the determination of tetracycline and its related compounds is described. The method uses a reverse phase (C₁₈) column, a modified acetonitrile/water mobile phase, and banzoic acid as the internal standard. Elution of all compounds of interest is complete within seven minutes. Results are presented for thirteen commercial capsule formulations and are compared with results by microbiological assay and thin-layer chromatographic methods.     

Studies on the retention behaviour of some thiazolylazo derivatives in reversed phase liquid chromatography

The retention behaviour of thiazolylazo derivatives, 4-(2-thiazolylazo) resorcinol (TAR), 4-(2-thiazolylazo)-orcinol (TAO), 2-(2-thiazolylazo)-4-methylphenol (TAC) and 1-(2-thiazolylazo)-2-naphtol (TAN) was studied by reversed phase liquid chromatography. The optimum conditions for the separation of four thiazolylazo derivatives were examined with respect to column, flow rate, mobile phase composition and pH of mobile phase. These derivatives were separated simultaneously on Symmetry C₈ column using composition of acetonitrile/water (60/40, v/v) as mobile phase. The capacity factor (k′) has been decreased at higher pH than pK_a of solute which may due to the increasing concentration of the ionized species as increase the pH of mobile phase. The dependence of log k′ on the volume faction of water in the binary mobile phase and k′ on the liquid–liquid extraction distribution ratio (D_c) in acetonitrile–water (60/40, v/v)/n-octane extraction system for thiazolylazo derivatives were obtained good linear relationship. The results showed that the retention behaviour of these derivatives was mainly affected by the hydrophobic interaction between thiazolylazo as solute and mobile phase.     

An Improved Microanalytical Procedure for the Quantitation of Procainamide and N-Acetyl Procainamide in Serum by High-Performance Liquid Chromatography

Abstract

A high-performance liquid chromatographic method for analysis of procainamide (PA), and N-acetyl procainamide (NAPA) is presented. Sample preparation employs a simple base-acid double extraction procedure and analysis is carried out on a reverse phase chromatographic system using a μBondapak C₁₈ column and buffered aqueous acetonitrile as the mobile phase. The extraction procedure gives quantitative recovery of both PA and NAPA, and chromatographic results show that drug levels of as low as 0.3 mg per liter of serum can be conveniently analyzed without significant background interferences. The small volume (0.2 ml) of serum needed to perform an analysis makes this method suitable for pharmacokinetic studies in humans and animals as well as for clinical therapeutic drug monitoring studies.     

Analysis of Invertebrate Neuropeptides by RP-HPLC

Abstract

The application of reverse phase-high performance liquid chromatography to the analysis of four synthetic invertebrate neuropeptides is described. Proctolin (Arg-Try-Leu-Pro-Thr), locust adipokinetic hormone (p-Glu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH₂), crustacean erythrophore concentrating hormone (p-Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH₂) and mulluscan cardioexcitatory neuropeptide (Phe-Met-Arg-Phe-NH₂) were analyzed on several different reverse phase columns by means of gradient elution with 0.01M KH₂ PO₄, 0.1% H₃PO₄, 0.25N triethylammonium phosphate (TEAP), pH 2.20, or 0.1% trifluoroacetic acid (TFA) versus acetonitrile. Column effluents were monitored at both 254 and 195 nm except in the case of TFA where 254 and 210 nm were monitored. At the lower wavelength computerized background correction was sometimes necessary to correct excessive baseline drift during the course of the gradient run. Best results were obtained on the Supelcosil LC-18DB column with a concave gradient of 90° 40%B over 1 hr at 1.1 ml/min where B[dbnd]0.25N TEAP, pH 2.20, A[dbnd]acetonitrile. With this system less than 5 ng of peptide was detectable. The use of the volatile TFA buffer permitted recovery of peptides from the column effluent by lyophilization.