Determination of Chloramphenicol (CAP) in Food Products by Differential Pulse Polarography

ABSTRACT

The electrochemical determination of chloramphenicol (CAP) in food using mini- and micro- mercury drop electrodes and differential pulse polarography (DPP) has been elaborated. A phosphate buffer with pH 6.6 was used as the basic electrolyte. The analysis was based on a peak at the potential E_p = ?0.320 V which showed a clearly linear dependence of the peak current on the concentration of chloramphenicol in the sample under investigation. Prior to the determination of chloramphenicol in actual samples it was necessary to extract this antibiotic with organic solvents such as methanol, ethanol and ethyl acetate.

In order to separate CAP in its basic form, various modifications of sample preparation procedures were made for the analysis with the use of selected hydrolytic enzymes. The determined quantities of CAP in the samples of meat, milk, eggs and their products ranged in the ng/g d.w. range.

For purposes of comparison and verification of the electrochemical results of CAP determination, chloramphenicol was determined in the same samples, by the immunoenzymatic method ELISA.     

HPLC Determination of Chloramphenicol,Chloramphenicol Monosuccinate and Chloramphenicol Glucuronide in Biological Matrices

Abstract

An isocratic reversed-phase liquid chromatographic method for the determination of chloramphenicol 1- and 3-succinate and chloramphenicol in serum within 5 minutes following precipitation with perchloric acid is described. An ion-pair chromatographic method gives the additional option of co-determination of chloramphenicol 3-glucuronide in urine and serum. An extraction method for the determination of chloramphenicol in biological tissues is presented.     

Spectrophotometric Determination of Some Fluoroquinolone Derivatives in Dosage Forms and Biological Fluids Using Ion‐Pair Complex Formation

Abstract

A simple, rapid, sensitive, and reproducible procedure for assaying norfloxacin (NOR), ciprofloxacin (CIP), and ofloxacin (OFL) was investigated. The procedure is based on the reaction of selected drugs with Sudan II (I), Congo red (II), and Gentian violet (III) in universal buffer to give soluble ion‐pair complexes. The effects of various parameters have been studied. Beer's law plots were obeyed in the concentration ranges 0.5–11 µg ml^?1, whereas Ringbom optimum ranges were 0.7–9.5 µg ml^?1. The apparent molar absorptivity (6.4×10⁴ L mol^?1 cm^?1), Sandell sensitivity (4.99 ng cm^?2), detection (0.13 µg ml^?1), and quantification (0.44 µg ml^?1) limits were calculated. The relative standard deviation for ten determinations, for samples containing 4.0 µg ml^?1, was found to be 1.40%. The influence of commonly employed excipients in the determination of the studied drugs was examined. There was no interference from degradate product results from thermal and hydrolytic treatments. The results obtained by the proposed procedure were statistically validated. The developed procedure was successfully applied to the determination of the studied drugs in dosage forms and biological fluids.     

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.     

HPLC analysis of aspartame and saccharin in pharmaceutical and dietary formulations

Summary A reversed-phase HPLC method has been developed suitable for a reliable quality control of pharmaceutical and dietary formulations containing the synthetic sweeteners aspartame and saccharin. The proposed method is able to separate acesulfame, aspartame and saccharin, and their impurities such as 5-benzyl-3,6-dioxo-2-piperazineacetic acid (the major degradation product of aspartame) and 4-sulphamoylbenzoic acid,o- andp-toluenesulphonamides (the synthesis impurities of saccharin). A convenient solid-phase extraction (SPE) procedure using C-18 sorbent, was also developed for the determination of potential saccharin impurities.     

High-Performance Liquid Chromatographic Determination of Ceftazidime in Serum,Urine, CSF,and Peritoneal Dialysis Fluid

Abstract

A rapid, sensitive and specific high performance liquid chromatographic method is described for the determination of ceftazidime in serum, urine, CSF and peritoneal dialysis fluid. The procedure employs reversed-phase chromatography, using hydrochlorothiazide as an internal standard. The assay only requires 100 μl of sample with direct injection of diluted urine, CSF, peritoneal dialysis fluid or protein precipitated serum. Stability studies indicate good drug recovery if urine and serum are stored under proper conditions. The method is specific for ceftazidime in the presence of amikacin, gentamicin, kanamycin, tobramycin, methicillin, penicillin G, ampicillin, chloramphenicol and caffeine. The method has been successfully employed in the assay of over 700 samples obtained during human clinical trials.     

Determination of Lithium in Pharmaceutical preparations with 1-(2-Arsenophenylazo)-2-Hydroxy 3, 6-Naphthalendisulfonic Acid

Abstract

This paper reports the characteristics, in acetonic medium, of the lithium complex with 1-(2-arsenophenylazo)2-hydroxy 3,6-naphthalenedisulfonic acid (APHNDS).The analytical optimization is also reported. The coloured product was measured spectrophotometrically at 468 nm. The Beer's law was realized at 0.1–4.0 μg ml^?1. The method was used for the determination of lithium in pharmaceutical preparation. The reproducibility of the described method was efficient. The accuracy of the procedure was evaluated measuring the recovery, between 86.0–97.9 %.     

Observation of nicotinic acid in nicorandil samples and simultaneous determination of nicorandil and its three degradation products in raw drug and tablet form by high performance liquid chromatography

Nicotinic acid (NA) as a degradation product of nicorandil (NIC) was identified and quantified by HPLC-DAD and GC / MS. In the present paper a rapid, sensitive, precise and specific HPLC-DAD method was developed for the simultaneous determination of NIC, NA and two known degradation products, nitrate (NI) and de-nitrated nicorandil [N-(2-hydroxyethyl) nicotinamide] (HEN) in raw drug and tablet form. The present method was performed on an ODS C₁₈ column (150 × 4.6 mm, 5 μm) using detection at 204 nm and employing nicotinamide (NT) as internal standard. The procedure was validated by evaluating linearity, accuracy and recovery and applied to monitor the increased level of NI, HEN and NA as a function of NIC storage time at room temperature.     

Determination of Vitamin A in Presence of its Degradation Product by First - Derivative U.V.- Spectrophotometry

Abstract

A rapid spectrophotometric method for the determination of retinol palmitate (vitamin A) in the presence of its oxidative degradation product is presented. The method is based on the first-derivative measurement of the peak-trough amplitude at 288 – 336 nm. The mean percentage recovery for mixtures of vitamin A with their respective degradation product was 100(1.0). Graphs of log 0% versus time for vitamin A in 0.1 N hydrochloric acid/isopropanol was a straight line with a slope of ?0.0007 min^?1. The method has been succesfuly applied to monitor the vitamin stability.     

Utility of p-chloranilic Acid and 2,3 Dichloro-5,6-dicyano p-Benzoquinone (DDQ) for the Spectrophotometric Determination of Triamterene

Abstract

Two simple and sensitive spectrophotometric procedures are suggested for analysis of triamterene. The first procedure is based on the reaction of triamterene with p-chloranilic acid (p-CA) in methylene chloride to form a highly stable coloured product, exhibiting maximum absorbance at λ 530 nm. Beer's law is obeyed in the range of 40–220 μg.ml^?1 with a mean percentage accuracy of 99.98 ± 0.446. Limit of determination is 20 μg.ml^?1. In the second procedure, the drug is determined via charge transfer complex formation with 2,3 dichloro-5,6-dicyano p-benzoquinone (DDQ) using methylene chloride as a solvent. Here the reaction product has two well defined maxima at 460 nm and 530 nm where each has been utilized for quantitative determination. Beer's law is obeyed in concentration ranges of 25–125 μg.ml^?1 and 25–150 μg.ml^?1 with mean percentage accuracies of 99.92 ± 0.449 and 100.00 ± 0.511 for both maxima. 460 and 530 nm. respectively. Limit of determination is 12.5 μg.ml^?1 at both maxima. Optimum conditions for each procedure have been studied and the stoichiometry of both reactions was ascertained using Job's method of continuous variation. The validity of the suggested procedures was assessed by applying the standard addition technique using the drug capsules. Both procedures are statistically analyzed as compared with BP method for analysis of triamterene (non aqueous titration) revealing good accuracy and precision as indicated by t and F tests.     

Use of Alkaline Degradation for the Analysis of Dihydrotriazines via High Pressure Liquid Chromatography

Abstract

An HPLC method is described for the determination of 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3′,4′-dichlorobenzyloxy)-1,3,5-triazine hydrochloride (WR 38839). The procedure required the isomerization of the drug sample by alkaline treatment with sodium hydroxide, as the parent compound was retained by the column. The reaction product of the drug was analyzed by HPLC using a strong cation exchange resin as the stationary phase and glycine buffer, pH 10.4 as the mobile phase. The product was isolated and identified by TLC, UV, IR, mass spectroscopy and elemental analysis. The postulated mechanism indicates that this would be a general analytical method for dihydrotriazine compounds. This technique, developed for the assay of the dihydrotriazine in an aqueous system, was successfully applied to rat urine samples spiked with the drug.     

Spectrophotometric Determination of Etilefrine,Ritodrine, Isoxsuprine and Salbutamol by Nitration and Subsequent Meisenheimer Complex Formation

Abstract

A simple and sensitive colorimetric method has been developed for the determination of four phenolic drugs, namely, etilefrine hydrochloride, ritodrine hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate. The method is, mainly, based on the nitration of the drug molecule followed by the subsequent formation of meisenheimer complex with a nucleophilic reagent (acetone) in alkaline medium. The experimental conditions leading to optimum chromogen intensity and stability were carefully studied and incorporated in the general procedure. Under the proposed conditions, the method was applicable over the concentration range of 4.8–16 μg ml^?1 for the four drugs. The suggested method was further applied for the determination of the studied drugs in bulk and pharmaceutical dosage forms. The results of the analysis were found to agree statistically with those obtained with either the official or the referee methods. The procedure is characterized by its simplicity with accuracy and precision.     

A Bidimensional HPLC System for Direct Determination of Theophylline in Serum

Abstract

A bidimensional HPLC system combining steric gel exclusion and reverse phase ODS columns for determination of theophylline in serum is reported. Factors involved in the development of the method and its performance are discussed. This technique is a practical alternative for the determination of theophylline levels in serum without any clean up procedure before chromatography.     

Stability-Indicating Method For The Determination Of N-Desmethyldiazepam And Simultaneous Determination Of Its Degradation Products

Abstract

A simple, direct and sensitive spectrophotometric method for the determination of the intact N-desmethyldiazepam in the presence of its degradation products, 2-amino-5-chlorobenzophenone and glycine, is developed. The proposed procedure is based on direct measurement of the absorbance of its acidified methanolic solution at 361 nm. The procedure determines 8–56 mcg ml^?1 of N-desmethyldiazepam with an accuracy of 100.2 ± 0.51%. The proposed procedure retains its accuracy in presence of up to 80% of the different degradation products. The procedure is applied successfully for the determination of N-desmethyldiazepam in bulk powder, tablets and drops.

Simultaneous determination of the different degradation products in the presence of the parent drug is also described. Thus, 2-amino-5-chlorobenzophenone is determined by direct measurement of its methanolic solution at about 380 nm, with an accuracy of 100.4 ± 0.42%. Glycine is determined colorimetrically using ninhydrin reagent in presence of pyridine, with an accuracy of 99.5 ± 0.78%.     

Electrochemical Behavior of Dopamine at a Mercury Electrode in the Presence of Citrate: Analytical Applications

Abstract

Dopamine can be determined by voltammetric methods using a mercury electrode, previously oxidized at +0.30 V. The oxidation product formed is stabilized in the presence of citrate and undergoes reduction at ?0.31 V. This work describes the electrochemical behavior of dopamine at a mercury electrode in the presence of citrate and its application in the development of a square‐wave voltammetric method for the dopamine determination in pharmaceutical formulations. The method was in‐house validated for determination of dopamine in injectable formulations. The detectability of the method was 0.02 µg ml^?1.     

Determination of Identity in Paraffin-Embedded Tissues and Slides

Abstract

A procedure is presented for the determination of donor identity or commonality of origin among paraffinembedded tissues and slides. Samples are de-paraffinized with xylene and ethanol and subjected to Chelex^R extraction. The Polymarker forensic DNA typing kit is utilized for identity testing. Following multiplex amplification, PCR product is verified on an agarose gel and then the samples are geiotyped using reverse dot-blot hybridization. When this procedure was applied to paraffin-embedded samples involved in a legal action, all samples were successfully genotyped. The advantages of using this procedure are discussed.     

Spectrofluorimetric Determination of Antimony

Abstract

A spectrofluorimetric procedure for the determination of micromolar concentrations of antimony(III) was devised based on its reduction of cerium(IV) to produce fluorescent cerium(III). The method was optimized and the reaction was fast enough in hydrochloric acid media without the need for iodide or osmium(VIII) as catalysts. Linear calibration graphs were obtained in the range 1-10 10^?6M. The standard deviation for determining 5 × 10^?6M antimony(III)(10 times) was 1.43 × 10^?7M and the relative error was -3.4 %. The method was applied to the determination of antimony(III) in its mixture with antimony(V), total antimony was later determined after reduction with mercury metal in deoxygenated solutions. The affect several reducing agents on the determination of antimony-was also examined.     

Spectrophotometric Determination of Ampicillin with Some Nitro Compounds

Abstract

A spectrophotometric procedure for the determination of ampicillin (Amp.) in pure solutions and in its pharmaceutical preparations has been developed. This new method offers advantages of simplicity, rapidity and stability in comparison with the official BP (1980) method. The proposed method is based on the formation of a colour condensation product through the reaction of ampicillin and nitrobenzene derivatives in an alkaline aqueous-acetone medium 40% (v/v). Beer's law is obeyed in the range 0.5–28 μg ml^?1. The colours were produced within 20 min. after heating at 60±5°C and stable for at least 6 h. The method is relatively accurate (recovery 100±2%) and precise (RSD 1.9%) and can be used successfully for the preparation of capsules, syrup and ampoules.     

The Use of Derivative Spectrophotometry for the Determination of Acyclovir and Diloxanide Furoate in Presence of Impurity or Degradation Product

Abstract

Second (D₂) and third (D₃) derivatives spectrophotometry have been developed for the determination of acyclovir in the presence of guanine (its main impurity) and diloxanide furoate in the presence of diloxanide (its degradation product). The methods depend upon measuring D₂ and D₃ peak amplitudes at 269 and 262 nm for acyclovir and at 260 and 270 nm for diloxanide furoate in 0.1 N hydrochloric acid.

Accuracy of analysis with the proposed derivative spectrophotometric procedure is significantly greater than the classical methods.     

The Determination of Serne by the Use of Hantzsch Reaction

Abstract

A simple procedure for the determination of serine is described. The method involves the oxidation of serine to formaldehyde by periodate. The formaldehyde is then converted to 3,5-diacetyl - 1,4-dihydrolutidine by Hantzsch reaction in which acetyl acetone and ammonia are the reactants. The reaction product in low ranges (concentration of serine from 0.1 to 4 μg) is measured fluorometrically. In samples containing serine at concentrations higher than 4 μg colorimetric analysis is used. Recovery studies of serine added to washed mitochondrial preparations have been satisfactory. From the standpoint of sensitivity, simplicity and time required, this technique is an improvement over previously described procedures for serine determination.