Bioanalysis of Naproxen by High Performance Reversed Phase Liquid Chromatography with Photometric and Fluorimetric Detection

Abstract

Methods for the quantitative determination of NAPROXEN and its main metabolite in plasma and urine are described. The separation is based on reversed phase liquid chromatography with LiChrosorb RP 8 (5 μm) as the support and methanol/phosphate buffer pH 7 as mobile phase, in some cases with addition of tetrabutyl ammonium ion as ion-pairing agent to improve the chromatographic selectivity. With UV-detector and a simple filter fluorometer an extraction-evaporation procedure is used for both plasma and urine determinations, while the high selectivity and sensitivity of a sophisticated fluorescence detector permits the direct injection of diluted samples on to the column. Use of an internal standard improves the within-run precision (s_rel%), which for plasma determinations of NAPROXEN are - with UV-detection, 0.2 – 1.7% (range 10 – 40 μg/ml), with filter fluorometer, 2.4 – 5.9% (range 12 – 58 μg/ml), and with fluorescence detector, 0.8 – 4.1% (range 5 – 20 μg/ml).     

Simultaneous Determination of Diazepam,Oxazepam and Temazepam in Spiked Urine By Hplc

ABSTRACT|Oxazepam and temazepam are two minor metabolites of diazepam. These three benzodiazepines may be found in presence of each other in biological fluids.

Therefore, in this study an HPLC method was developed to separate and analyze them. Benzodiazepines have ability to form inclusion complexes with p-cyclodextrin (β-CyD). According to the degree of binding constant with β-CyD, these compounds can be separated by β-CyD bound to silica (cyclobond column) as the stationary phase using HPLC.

The development and validation of the HPLC procedure for the separation and determination of these compounds in mixtures were studied. The mobile-phase system consisted of phosphate buffer (pH 7): methanol [75:25], with flow rate 0.8 ml min^?1 and UV detection at 240 nm was used.

The calibration graphs were rectilinear from 0.1-2.5 μg/ml and coefficients of variation were <2% for the three compounds in bulk forms.

The method was used to analyse these bezodiazepines in spiked urine containing all three compounds in combination. Recoveries were 97-99.8%

The limit of detection and limit of quantitation were 0.05 μg/ml and 0.1 μg/ml, respectively.

The described method is selective, rapid, simple, reproducible and accurate.     

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.     

Thiothenoyltrifluoroacetone as the Extracting and Colorimetric Reagent for Bismuth

Abstract

Thiothenoyltrifluoracetone (STTA) was used for the simultaneous extraction and direct spectrophotometric determination of bismuth at microgram concentration. About 98.5 μg of bismuth was extracted as the orange-red colored complex with 10 ml of 0.001 M STTA in carbontetrachloride. The extraction was quantitative at pH 6. The system conformed to Beer's Law in the concentration range of 2.5 to 30 μg/ml of bismuth at 460 nm. The method is both sensitive and selective.

The molar absorptivity was 5.6 × 10³ and sensitivity was 0.037 μg/cm². The method is selective as it is possible to accomplish extraction and colorimetrically determination of bismuth in the presence of 1:50 of several ions. Only ions such as cadmium, tin, iron, titanium and nickel interfere seriously. The overall process of extraction and determination takes hardly 30 minutes. The method is reproducible.     

A Validated Ion-Pairing High Performance Liquid Chromatographic Method for the Determination of Enoxacin and its Metabolite Oxo-Enoxacin in Plasma and Urine

Abstract

A rapid, sensitive, and specific determination of enoxacin and its principal metabolite, oxo-enoxacin, in plasma and urine is described. the method, which employs the structurally related compound ciprof loxac in as internal standard, involves a protein precipitation step for plasma and solid-phase extraction for urine. Liquid chromatographic analysis is carried out on a C-18 bonded silica column; the mobile phase consists of 0.1 M citric-acid/acetonitrile employing ammonium perchlorate and tetrabutyl-ammonium hydroxide as ion-pairing agents. Quantitation is performed by UV-detection at 340 nm.

The analytical method was validated by examining the performance characteristics specificity, linearity, precision, accuracy, sensitivity, and recovery. Enoxacin calibration curves were linear between 0.02 and 3.2 μg/ml of plasma and from 0.5 to 125 μg/ml of urine. Limits of quantitation in plasma and urine were 0.01 and 0.5 μg/ml, respectively. For oxo-enoxacin, linear of calibration curves were obtained i n the range 0.05 to 1.6 μg/ml (plasma) and 1 to 50 μg/ml (urine); the respective quantitation limits were approximately 0.02 and 1 μg/ml.

The present assay procedure has been applied to monitoring plasma and urine concentrations in several pharmacokinetic studies in humans and different animal species.     

Detection and Spectrophotometric Determination of Uranyl Ion with Erichromcyanine R

Abstract

Colour reaction has been studied for the identification and the spectrophotometric determination of uranyl ion with Erichromcyanine R. The detection limit was 7 μg. Beers law is obeyed in the concentration range containing 13 μg to 125 μg/10 ml of uranium.     

A Fluorescence Quenching Method for the Determination of Iodide Ion with Salicylfluorone and Hydrogen Peroxide

Abstract

A highly sensitive and selective fluorescence quenching method has been developed for rapid determination of iodide ion with salicylfluorone (SAF) as fluorogenic reagent (λ_ex = 495 nm, λ_em = 520 nm) at pH 2.5-3.0. The calibration graph is linear over the range 0.05-300 μg/25 ml. The detection limit is 0.05 μ/25 ml iodide. Other halide ions do not interfere with the determination even when present in large excess. The method is rapid and was successfully applied for the determination of iodide ion in sodium chloride, table salt and low sodium salt.     

Assay of the Anti-Inflammatory Compound CGS 5391 B in Blood Plasma by Automated HPLC

Abstract

An automated HPLC method for the quantitative determination of the anti-inflammatory compound CGS 5391B in blood plasma was devised and tested. The method provides quantitation in the concentration range of 1 to 200 μg/ml of drug in plasma, with an average recovery of 96.6±6.0%.     

A High-Performance Liquid Chromatographic Method for the Determination of Doxefazepam in Human Plasma Using a Solid-Phase Extraction Column

Abstract

A procedure for the rapid, quantitative isolation of doxefazepam from plasma with Supelclean LC-18 cartridges is described together with a sensitive HPLC assay for the quantitative determination of the drug. The recovery of doxefazepam was greater than 80 % over an investigated range of 0.1–2.0 μg/ml of plasma. The column extraction of doxefazepam coupled with the versatility of HPLC make this procedure well suited for detailed pharmacokinetic studies and as well as routine plasma analysis of doxefazepam.     

Glc Determination of Valproic Acid in Plasma

Abstract

A one-step glc procedure was developed for the quantitative determination of valproic acid in plasma. After addition of internal standard (4-methyl valeric acid), plasma is buffered at pH 4.5 to avoid hydrolysis of valproic acid conjugate (s). Evaporation is avoided by extraction into a chloroform bead. The method is sufficiently sensitive to quantitate 0.8 μg of the drug in 0.2 ml of plasma. The procedure has been thoroughly tested for precision and reproducibility through the determination of over two thousand samples.     

A Stability-Indicating Liquid Chromatographic Method for the Analysis of Erythromycin in Stored Biological Fluids Using Amperometric Detection

Abstract

A simple, sensitive and reliable high-performance liquid chromatographic procedure has been developed for the determination of erythromycin in human serum and urine using amperometric detection. A solid-phase extraction procedure was used followed by chromatography on a reverse-phase column. The mean recovery of erythromycin from serum and urine was 80%. Calibration plots for erythromycin base in serum and urine were linear over the ranges 0.25–5.0 μg/ml and 1.25–25.0 μg/ml respectively, with a sensitivity limit of 0.1 μg/ml.

This method allows both erythromycin and its principle degradation product, anhydroerythromycin, to be determined during a period of sample storage at 4°C and ?15°C. The method is sufficiently sensitive and precise and is thus highly suited for use in both pharmacokinetic and stability studies.     

Kinetic Spectrophotometric Determination of Acetaldehyde

ABSTRACT

A method for determination of trace quantities of acetaldehyde based on its inhibition effect on the malachite green-sulfite reaction is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance at 613 nm by a fixed time method of 60 seconds. The method allows the determination of acetaldehyde in the range of 0.2-10 μg/ml. The limit of detection was 0.1 μg/ml and the relative standard deviation for ten determinations of 2 μg/ml acetaldehyde was 1.8%. The method is applied to the determination of acetaldehyde in chemical industrial waste water with satisfactory results.     

A Simple Electrochemical Method for the Quantitative Determination of Acetaminophen in Serum

Abstract

A simple electrochemical method for the determination of acetaminophen in serum is described. The eleotrode and associated electronics are simple, reliable, and inexpensive to build. The apparatus can be operated at a rate of 2–3 determinations per minute using only 10 μl serum per determination. The procedure includes extraction of acetaminophen in ethyl acetate and subsequent oxidative amperometric detection of the drug by a form of flow-injection analysis. The system parameters of buffer, pH, and redox potential have been optimized to permit measurement of less than 10 μg/ml of acetaminophen. The determination is linear over the range of 10–300 μg/ml with a C.V. of less than 3% for replicate analysis of the same sample.     

Spectrophotometric Assay of Certain Cephalosporins Based on Formation of Ethylene Blue

Abstract

The hydrolytic degradation of antibiotics is very often used as a preliminary step in the analytical procedures for their determination. Therefore, a procedure was developed for measuring small amounts of cefadroxil and cefotaxime in pure samples as well as in formulations.

The method depends on forming a vis-absorbing compound with N,N-diethyl-p-phenylenediamine sulphate (N,N-DPPD) (ethylene blue dye), after the hydrolysis of cefadroxil and cefotaxime in sodium hydroxide solution to give hydrogen sulphide. The method is selective for cephalosporins, since other β-lactam compounds such as penicillins do not give hydrogen sulphide under alkaline hydrolysis. Variables such as pH, temperature, reagent concentrations and stability of the colour produced have been evaluated to permit selection of the most advantageous technique. Beer's law obeyed over the concentration range 0.5–10 μg/ml and 0.5–7 μg/ml for cefadroxil and cefotaxime, respectively. The detection limit being 0.1 μg/ml and 0.05 μg/ml (defined as the amount of the drug that gave a signal of twice the background noise) for cefadroxil and cefotaxime, respectively. The method has been successfully applied to the analysis of some pharmaceutical formulations.

The results have been statistically compared with those obtained by the official method. The relative standard deviation (for 10 replicates) was 1.12 (9 μg/ml) and 0.49% (5 μg/ml) for cefadroxil and cefotaxime, respectively. Procedural details and data for the effect of operating parameters are presented.     

Sensitive Spectrophotometric Determination of Some Dibenzazepine Drugs with Diazotized P-Phenylenediamine Dihydrochloride

ABSTRACT

A simple, sensitive and selective spectrophotometric procedure was developed for the determination of imipramine hydrochloride, desipramine hydrochloride, clomipramine hydrochloride and trimipramine maleate belonging to dibenzazepine class of drugs. The method is based on the interaction of diazotized p-phenylenediamine dihydrochloride with the drug in sulphuric acid medium. The resulting chromophore was measured at 565 nm, and was stable for about 2.5 hr. The commonly encountered excipients and additives do not interfere with the determination. Dibenzazepine drugs can be determined in the range of 0.1-4.0 μg/ml, with a relative standard deviation of 1.92% for ten replicate measurement of 2.0 μg/ml dibenzazepine drugs. Results from the analysis of preformulations and commercial tablets by this procedure agree well with those of the official method.     

New Rapid Assay for Nafcillin by Spectrofluorimetry in Pharmaceutical Dosage

Abstract

A method for the spectrofluorimetric determination of nafcillin is proposed (λ_ex = 226 nm, λ_em = 366 nm), for concentrations between 0.10 and 1.0 μg mL^?1. The method was performed in ethanol/water medium (30% V/V), at apparent pH 6.0 provided by adding of phosphate buffer solution with pH = 6.20.

The obtained values of detection and determination limits are 0.016 and 0.054 μg mL^?1, respectively.

The method was successfully applied to assay a commercial injection containing nafcillin sodium monohydrate.     

Extractive Spectrophotometric Determination of Chlorprothixene Hydrochloride

ABSTRACT

A simple, rapid and accurate method for determination of chlorprothixene hydrochloride is presented. It is based on the liability of the chlorprothixene tertiary amine group nitrogen atom to form ion pair complexes with niobium (V) thiocyanate complex. The formed compound is insoluble in water but well soluble in some organic solvents. The reaction is followed spectrophotometrically by measuring the absorbance at λ= 362 nm. This property has been successfully used for the extractive spectrophotometric determination of chlorprothixene. Beer's law was obeyed in the range 9- 50 μg/ml of chlorprothixene hydrochloride. The method is suitable to the determination of analyte in commercial products. The results were compared with those obtained by the official procedure.     

Improved High-Performance Liquid Chromatographic (HPLC) Assay Method for Ceftizoxime

Abstract

We improved a high-performance liquid chromatographic method for the quantitative determination of ceftizoxime in human serum and urine using cefotaxime as internal standard. It employs a μ Bondapak Alkyl Phenyl column, elution with acetonitrile-phosphate buffer and measurement of UV absorption at 254 nm. Results obtained using the HPLC assay were compared to those obtained using a microbiological assay. The correlation coefficient was 0.987 (n:25). The method is rapid, accurate and reproducible with a sensitivity of 2.5 μg/ml of ceftizoxime. Cefotaxime and its major metabolite, the desacetylcefotaxime, can also be quantitated by this procedure.     

Use of an Aqueous Micellar Medium to Improve the Spectrophotometry Determination of Cyanide Ion with 5,5′-Dithiobis(2-Nitrobenzoic Acid)

Abstract

The spectrophotometric method for the determination of cyanide, which is based on the reaction of cyanide ion with 5,5′-dithiobis(2-nitrobenzoic acid) to displace the corresponding absorbing thiol anion, has been reinvestigated using an aqueous cetyltrimethylammonium bromide micellar reaction medium. The rate of the analytical reaction is increased considerably in the presence of the cationic surfactant. Thus, the time required for the spectrophotometric determination of cyanide ion in the 0.18 – 2.80 μg/ml range using this procedure is decreased from 25 minutes to 1 – 3 minutes.     

An Isocratic HPLC Method for the Determination of Cephalosporins in Plasma

Abstract

An isocratic reversed-phase liquid chromatographic method for the determination of eight cephalosporins in human plasma using UV detection at 254 nm is described. Plasma proteins were precipitated using acetonitrile prior to injection of a 10 μl aliquot onto an octadecylsilane column. The mobile phases consisted of 6–11% acetonitrile in sodium dihydrogen phosphate (0.01M). The minimum detectable limit for each drug was less than 1 γg/ml of plasma. Possible interference from other drugs which might be administered concurrently is discussed. The reproducibility and precision of the method for cephalosporin assay are shown from the analysis of plasma containing 5–500 γg/ml of plasma. The chromatographic behavior of the eight cephalosporins was examined by varying mobile phase conditions.