High-Performance Liquid Chromatographic Determination in Human Plasma of a Anticonvulsant Benzodiazepine: Clonazepam

Abstract

A rapid and specific high-pressure liquid chromatography method for determination of clonazepam in human plasma is described.

The analysis is linear for concentrations ranging from 5 to 100 ng. ml^-1 plasma for clonazepam.

The method is applicable to quantitation of clonazepam in human plasma of subjects receiving 0.05 at 0.20 mg.kg^-1 orally, with satisfactory accuracy and precision.     

Improved High-Pressure Liquid Chromatographic Assay of Serum 25-Hydroxycholecalciferol and 25-Hydroxyergocalciferol After Reverse-Phase Sep-Pak C18 Cartridge Preparation of Sample

Abstract

A simplified method is described for extracting and purifying 25-hydroxycholecalciferol and 25-hydroxyergocalciferol from serum for quantitation by high-pressure liquid chromatography. The method involves extracting and purifying these metabolites from serum (1–10 ml) with a reverse-phase octadecylsilane bonded silica cartridge (Sep-Pak C₁₈). This method is faster than a previously described method involving extraction with dichloromethane and purification by Sephadex LH-20 chromatography. The correlation between the two methods was excellent (r² = 0.96, p≤0.0001). The coefficient of variation for the new method is 4.3%. The new method allows measurement of 25-hydroxyergocalciferol from human serum since both 25-hydroxycholecalciferol and 25-hydroxyergocalciferol are extracted equally. This allows the use of [³H] 25-hydroxycholecalciferol to monitor the recovery of both the D₂ and the D₃ forms of the metabolite.     

Application of Electrochemical Detection for the Quantitation of 1, 4-Dihydroxy-5, 8-Bis-[2-(2-Hydroxyethyl) Aminoethylamino]-9,10-Anthracenedione Following Liquid Chromatography

Abstract

Electrochemical monitoring of 1, 4-dihydroxy-5, 8-bis-[2-(2-hydroxyethy1) aminoethy amino]-9, 10-anthracenedione was employed for the quantitation of this cancer chemotherapy drug following high performance liquid chromatography. Detection was performed by oxidation of the compound at a glassy carbon electrode at +0.80 V vs. SCE. A rapid and convenient sample treatment procedure was developed which is suitable for determination involving physiological samples. A detection limit of 2 ng injected was obtained for urine samples.     

Preparative High-Performance Liquid Chromatography Isolation of the True Proazulenes from Artemisia Arborescens L

Abstract

The use of the preparative medium-pressure liquid chromatography (prep-MPLC) and the preparative high-pressure liquid chromatography (prep-HPLC) techniques for the separation of the main true proazulenes from a purified extract of Artemisia arborescens L. are reported and discussed.     

Quantitation of P-Aminohippuric Acid and N-Acetyl-P-Aminohippuric Acid from Blood by HPLC

Abstract

P-aminohippuric acid, N-acetyl-p-aminohippuric acid, and p-aminobenzoic acid can be separated by a reverse-phase, isocratic high-pressure liquid chromatographic procedure in less than 4 minutes. The eluent is 10 mM sodium phosphate buffer, pH 3.5, containing 30% methanol. Detection is by absorbance at 270 nm; quantitation is accomplished by peak height. Linear response was obtained from 3 to 1600 nmoles of each compound in aqueous standards and in blood deproteinized with perchloric acid.     

Rapid Determination of Propranolol and 4-Hydroxypropranolol in Plasma by High Pressure Liquid Chromatography

Abstract

The resolving power of high pressure liquid chromatography has been combined with the sensitivity of fluorescence detection to develop a method for the determination of propranolol and 4-hydroxypropranolol in plasma. A single selective extraction step precedes chromatography on a high efficiency bonded phase column. The limits of quantitation are approximately 2 ng/ml of plasma for each drug. The analysis of a number of clinical samples has demonstrated the application of the method in pharmacokinetic studies, but the possible interference of other drugs and their metabolites is still under investigation.     

Validation of UV Spectrophotometric Method for Fexofenadine Hydrochloride in Pharmaceutical Formulations and Comparison with HPLC

Abstract

A simple, reproducible, accurate, and effective spectrophotometric method was developed and validated for the quantitation of the antihistamine fexofenadine in capsules and coated tablets. Ethanol was used as solvent and the absorbance at the wavelength of 220 nm was employed to the quantitation of the drug. The method validation was fulfilled through the evaluation of the analytical parameters of linearity, precision, accuracy, limits of detection, and quantitation and specificity. The method was linear (r=0.9999) at concentrations ranging from 8.0 to 20.0 µg ml^?1, precise (RSD intra‐day=0.29; 0.18; 0.39; RSD inter‐day=0.12 for capsules and RSD intra‐day=0.13; 0.16; 0.13; RSD inter‐day=0.13 for coated tablets), accurate (percentage recovery=99.97% for capsules and 100.51% for tablets), sensitive (limits of detection and quantitation of 0.10 and 0.29 µg ml^?1, respectively) and specific. The method was compared to a high performance liquid chromatography (HPLC) method, which was previously developed to the same drug. The results showed no significant difference between the methods in fexofenadine hydrochloride quantitation.     

Enzymatic Estimation and Quantitative High-Pressure Liquid Chromatography of Fructose,Glucose and Sucrose in Powders from Rose Petals

Abstract

There was no significant difference between mean mass fractions of fructose, glucose and sucrose measured enzymatically and by liquid chromatography. So the chromatographic method can be used on powders from rose petals as the peaks of the chromatograms are really caused by the sugars.

A method is described for clean-up of the rose extract before injecting it into the high-pressure liquid chromatograph.     

High Performance Liquid Chromatographic analysis of the Biological Response Modifier Synthetic Double-Stranded RNA (dsRNA,Ampligen)

Abstract

A high performance liquid chromatographic method was developed for analysis of the antitumor agent synthetic, double-stranded RNA (dsRNA, Ampligen) in plasma. In this procedure the agent was extracted from plasma by ion-exchange chromatography and then degraded to its primary components, inosine and cytidine, by treatment with nuclease and alkaline phosphatase. Inosine and cytidine derived from degradation of ampligen were quantified by reversed phase HPLC. Standard curves for quantitation of inosine derived from ampligen were generated by addition of various amounts of ampligen to plasma. Utilizing this method, extraction of drug from the plasma was approximately 70–80%. Standard curves were linear over the concentration range of 0.25 to 100 ug/ml plasma. There were no peaks from plasma which interfere with quantitation of inosine. The approximate lower limit of detection of drug by this method was 0.25 ug/ml plasma. Interassay and intra-assay mean variability of standards was 9.6 and 3.2% respectively. Analysis of plasma samples obtained from one patient after infusion of ampligen (640 mg/m²) show that this method is sensitive enough to monitor plasma for clinical pharmacology studies of ampligen.     

Quantitative Analysis of Adulterants in Illicit Heroin Samples via Reversed Phase HPLC

Abstract

Methodology is presented using reversed phase liquid chromatography for the simultaneous quantitation of phenobarbital, methaqualone, phenolphthalein, nicotinamide, and N-phenyl-2-naphthylamine in heroin samples. A Partisil 5 ODS-3 column was used with a gradient system using methanol and a sodium dodecylsulfate-phosphate buffer.     

Applications of a Technique for the HPLC Analysis of Liquid Carbon Dioxide Solutions

Abstract

A novel technique has been developed whereby substrate and solvent quantitation can be effected by means of reversed-phase high performance liquid chromatography. Carbon dioxide is detected by a differential refractometer.

Applications of this technique include the analysis of liquefied carbon dioxide-based aerosol mixtures, solubility measurements and liquid carbon dioxide extraction studies. Preliminary experiments suggest that this technique may also find application to the direct analysis of supercritical carbon dioxide extraction systems.     

Application of Electroanalytical Detectors in Chromatography

Abstract

Just as the gas chromatographic technique became one of the most frequently used analytical methods in the sixties, the development of high-pressure techniques has made liquid chromatography one of the most dynamically developing methods of today.     

Determination of thiamphenicol residues in chicken muscles by column liquid chromatography

A column liquid chromatographic (CLC) method for the determination of thiamphenicol residues in chicken muscles was developed. The drug is extracted from minced muscles with ethyl acetate and the extract is evaporated to dryness. The residue is dissolved in 10% sodium chloride solution and partitioned with n-hexane. Thiamphenicol is extracted with ethyl acetate and, after evaporation of the solvent, the residue is cleaned up by alumina column chromatography. CLC analysis is carried out on a Nucleosil C18 column with ultraviolet detection of thiamphenicol at 230 nm. The average recoveries of thiamphenicol added to muscles at 0.2 and 0.1 ppm were 92.8 and 90.0%, respectively. The detection limit was 5 ng for thiamphenicol standard, which corresponds to 0.05 ppm in muscles.     

Quantitation of Terfenadine,Pseudoephedrine Hydrochloride,and Ibuprofen in a Liquid Animal Dosing Formulation Using High Performance Liquid Chromatography

Abstract

Stability-indicating assay methods based on high performance liquid chromatography have been developed for the quantitation of terfenadine, pseudoephedrine hydrochloride, and ibuprofen when combined in an aqueous 0.5% w/v Tween 20 and 0.5% methylcellulose animal dosing formulation. Because of the diversity of this drug mixture two separate chromatographic systems were required for the assays. A reversed phase system using a 3-μm Spherisorb 0DS-2 column was used to assay for terfenadine and ibuprofen. An ion-exchange system using a 10-μm Partisil SCX column was used to assay for pseudoephedrine hydrochloride. The methods are accurate and precise with relative standard deviations over the concentration ranges of interest of 2% or less.     

High Pressure Liquid Chromatographic Separation of 6-Acetoxybenzo(A)pyrene from In Vitro Incubation of 6-Nitrobenzo(A)pyrene

Abstract

We carried out studies of the microsomal metabolism of 6-nitrobenzo(a)pyrene (NBaP) to understand why the compound is a marginal carcinogen. Microsomal incubation products were separated by reverse phase high-pressure liquid chromatography. A chromatographic peak with a retention time of 24.8 mins was isolated and examined by ultraviolet, mass and nuclear magnetic resonance spectra. The product was characterized as 6-acetoxy-benzo(a)pyrene. The source of the acetylating agent could be cytosolic.     

A Specific and Highly Sensitive Method for the Determination of Protriptyline in Body Fluids and Tissues

Abstract

Protriptyline, a tricyclic antidepressant, was converted to its heptafluorobutyramide using heptafluorobutyrylimidazole as the acylating agent. Conditions for the gas chromatography of the derivative and its quantitation by an electron capture detector were established. The smallest detectable amount of the protriptyline derivative was 0.05 nanogram. Isolation and purification procedures were devised which permit the determination of the drug in biological materials without interference from reagents, drug metabolites or naturally occurring substances. Protriptyline extracted from plasma, erythrocytes, urine and tissues was determined in concentrations as low as 10 nanograms/ml.     

Quantitative Determination of Acenocoumarin in Anticoagulated Patients

Abstract

A new procedure of pre-concentration on Tenax GC followed by high performance liquid chromatography analysis has been developed for the quantitative determination of acenocoumarin in human plasma. The recovery of acenocoumarin was greater than 90% over a concentration range of 0.10 to 1.00 μg/ml and the limit of quantitation by the assay was 10 ng/ml of plasma. This method allows quantitative determinations in patients under acenocoumarin therapy and can be used as a routine clinical monitoring.     

High Performance Liquid Chromatographic Method for Prostaglandin E2 Determination in Human Gastric Juice Without Derivatization

Abstract

A rapid and practical method for the separation and quantitation of PGE² in human gastric juice by high performance liquid chromatography is described. Separation on a reversed-phase column and UV detection allows quantities as little as 20 nanograms of PGE² to be detected. Specificity, sensitivity, high yield and reproducibility make this method particularly suitable for prostaglandin determination in human gastric juice.     

Determination of Methacholine Chloride by Ion-Pair High-Pressure Liquid Chromatography

Abstract

A method of analysis of methacholine chloride is presented, which is adaptable to other choline esters. The method uses ion-pair high-pressure liquid chromatography. Using 1-heptane sulfonic acid optically transparent at low UV wavelengths as the specific ion-pair, it was possible to assay for a specific choline ester using ultraviolet detection at 210 nm without interference by hydrolytic by-products. The method can be used to provide quality control and stability data on methacholine chloride in 0.9% sodium chloride solutions.     

Urinary Uric Acid Determination by Reversed-Phase High Pressure Liquid Chromatography

Abstract

Reversed-phase high pressure liquid chromatography with UV detection was proven to be a powerful method for the separation and quantitation of urinary uric acid. We have compared three different treatments for urine samples previous chromatographic injection: alkaline methanol extraction, ethylacetate extraction and centrifugation. It was also studied storage conditions for urine samples.

Our findings show that the method has high specificity and reproducibility for urinary uric acid. Samples are stables and require only centrifugation previous injection to the chromatograph.