Determination of Pentaerythritol Tetranitrate in Pharmaceuticals by High Performance Liquid Chromatography

Abstract

A high performance liquid chromatographic procedure for the analysis of pharmaceutical formulations containing pentaerythritol tetranitrate including the diluted bulk drug and finished products consisting of uncoated tablets and timed-release capsules and tablets was developed. The method employs a reversed-phase system with UV detection at 230 nm. Replicate analyses of 11 commercial formulations (5 diluted bulk drugs and 6 dosage forms gave precision values (CV) having a range of 0.17 to 1.80%. Recovery values obtained from these commercial preparations via fortification ranged from 98.8 to 102.0% while recoveries from 3 synthetic mixtures varied from 99.2 to 100.8%. The detector response for the analyte was observed to be linear over a 50-fold concentration range using nitroglycerin as the internal standard. The proposed HPLC method is specific, easy to perform and exhibits excellent accuracy and precision. Seven different brands of HPLC columns were evaluated for possible use with the method.     

Simultaneous Determination of Phenanthrene and Benzo(a)pyrene in Water Samples by Synchronous Fluorescence Spectroscopy

Abstract

A simple and sensitive method was developed to simultaneously determine phenanthrene and benzo(a)pyrene in water samples using synchronous fluorescence spectroscopy with a 56-nm Δλ. The method was used to simultaneously determine both compounds in samples of spiked surface water. Analytical recoveries were 96.9–101.1% for phenanthrene and 95.8–103.5% for benzo(a)pyrene. Analytical results were checked for precision with 15 measurements for each compound. Relative standard deviations were 1.9% for phenanthrene and 2.9% for benzo(a)pyrene, which shows that the proposed method is quite precise.     

Determination of Sodium Tolyltriazole and Sodium Mercaptobenzothiazole in Engine Coolants

Abstract

A high performance liquid chromatography method was developed to quantitatively determine the corrosion inhibitors sodium tolyltriazole and sodium mercaptobenzothiazole in fresh and used ethylene glycol-based engine coolant formulations. Aliquots of coolant, diluted with water and methanol, are analyzed directly. Approximately one-half hour is required to determine both inhibitors with relative standard deviations of about 4%.     

Immunosensor for the Measurement of Human Serum Albumin in Urine Based on the Spreeta Surface Plasmon Resonance Sensor

The application of SPR for measurement of the concentration of human serum albumin (HSA) in urine was studied using the compact integrated SPR sensing system Spreeta. HSA was immobilized via cystamine and glutaraldehyde onto the gold sensing area and a competitive assay for HSA was developed using a limited amount of the monoclonal antibody AL-01 in solution. Measurements were carried out in the flow-through mode and the interaction between immobilized HSA and antibody was observed in real time. To obtain reproducible results, different conditions of the measurement (method of immobilization of HSA, data evaluation, concentration of antibody, regeneration procedure) were tested. The calibration curve for clinically relevant concentrations of HSA in urine samples was constructed using 300-times diluted antibody in the form of ascites fluid. The measuring range was between 0.1 and 5 mg/l of HSA, the sensing surface was successfully regenerated and suitable for more than 20 assays. The developed method was tested on real samples of urine; to overcome the non-specific adsorption of urine components, the differential approach was adopted and the measured signal was corrected by subtraction of the response observed in the absence of the antibody.     

Bis-Thiourea Bearing Aryl and Amino Acids Side Chains and Their Antibacterial Activities

Abstract

A series of symmetrical 1,3-bis thiourea 1a–e and 1,4-bis thiourea derivatives 2a–e have been successfully synthesized from the reactions of amines with 3-acetylbenzoyl isothiocyanate and 4-acetylbenzoyl isothiocyanate, respectively. All the synthesized compounds were characterized by FT-IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The compounds were screened for their antibacterial activity by turbidimetric method using gram-negative bacteria (E. coli ATCC 8739) using turbidimetric method. The newly synthesized bis-thiourea derivatives bearing aryl side chains showed good antibacterial activity against E. coli. The effect of the molecular structure of the synthesized compounds on the antibacterial activity is discussed.     

Analysis of Fruit Juices by Inductively Coupled Plasma-Maas Spectroscopy: Determination of Iron,Tin and Lead by Direct Aspiration

Abstract

A method has been developed for the determination of iron, tin and lead in fruit juices using inductively coupled plasma mass spectroscopy. These metals can be determined by direct aspiration of the sample after suitable dilution with water. It is not necessary to treat the sample prior to analysis.     

Preparation and Characterization of Heparin‐Stabilized Gold Nanoparticles

A simple method for preparing gold nanoparticles in aqueous solution has been developed by using glycosaminoglycan‐heparin as reducing and stabilizing agent and HAuCl₄ as precursor. The obtained gold nanoparticles were characterized by UV‐vis spectroscopy, resonance light scattering spectroscopy (RLS), transmission electron microscopy (TEM) and electrophoresis technology. The influence of reactant concentration for the preparation of gold nanoparticles was investigated. The results indicated that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration of the heparin. Moreover, the gold nanoparticles obtained with relatively high concentration of heparin were very stable and had relative narrow size distribution.     

Simultaneous Quantitative Determination of Codeine Phosphate,Chlorpheniramine Maleate Phenylephrine Hydrochloride and Acetaminophen in Pharmaceutical Dosage Forms Using Thin Layer Chromatography Densitometry

Abstract

A simple and specific method for the analysis of codeine phosphate, chlorpheniramine maleate, phenylephrine hydrochloride and acetaminophen in pharmaceutical dosage forms was developed. The procedure consists of direct application of diluted liquid dosage forms and the solutions of solid dosage forms on silica gel plates. The mobile phase for development consisted of n-butanol-methanol-toluene-water and acetic acid. The separated components were measured quantitatively by densitometry. Linearity, reproducibility and percentage recovery of active ingredients from dosage forms were calculated.     

The Estimation of Serum Digoxin by Combined HPLC Separation and Radioimmunological Assay

Abstract

A specific method for the quantitation of digoxin in serum has been developed and applied to determination of drug concentrations in serum from digitalized patients. One ml of the supernatant from acetonitrile denatured serum, subsequently diluted with water, was chromatographed on a reversed phase HPLC column. The eluent corresponding to the retention time of digoxin was collected and analysed using a commercial radioimmunoassay kit. The recovery at 3ng/ml was 96.1 ± 3.0%. Endogenous substances, drugs and metabolites of digoxin do not interfere with the method. The mean value of the samples estimated by the present method was 84% of those determined by direct R.I.A.     

Determination of Aminacrine Hydro-Chloride in Drug Preparations by TLC with Fluorescence Densitometry

Abstract

A densitometric TLC method was developed for quantification of aminacrine hydrochloride in creams, jellies, and suppositories. Aminacrine was extracted into acidic ethanol, diluted to a known volume, and separated by high performance silica gel TLC. The fluorescence of aminacrine zones in samples and standards was compared by in situ scanning. Recoveries of aminacrine from authentic samples ranged from 95.4 to 103.4%.     

A new non-linear high sensitivity spectroscopy in the slow molecular motion regime

Abstract

The application of doubly modulated E.S.R. (DOMESR) to viscous samples is discussed. An experimental study on a model system is reported which points out, in contrast to E.S.R. spectroscopy the very high sensitivity of DOMESR to slow molecular motions. It is shown that a satisfactory phenomenological interpretation may be given in terms of a dressed atom formalism.     

HPIC Separation of Tautomsric Compounds of 4-Aminoisoxazolyl-1,2-Naphthoquinones

Abstract

A sensitive and efficient method for determining a mixture of 4-aminoisoxazolyl-1,2-naphthoquinones isomera was developed using high performance liquid chromatography. The assay is also stability indicating because precursors and isomerization products can be determined simultaneously. The results obtained are in agreement with those obtained by UV spectroscopy.     

Determination of Lead in Whole Blood and Urine Using Zeeman Effect Flameless Atomic Absorption Spectroscopy

Abstract

Lead is the most frequently quantitated toxic metal in biological matrices. We describe methodologies for lead determinations in whole blood and urine using Zeeman effect flameless atomic absorption spectroscopy. The whole blood determination requires a simple aqueous 1:10 dilution while the urine lead methodology utilizes a twofold dilution with 5% nitric acid. Within-run relative standard deviations (RSD) for the whole blood determination are approximately 4. 9%, while urine lead within-run PSD's are approximately 6.7%. Detection limits for both the whole blood lead determination and the urine lead determination are 3 ppb. Linearity for both assays is to 200 ppb in the diluted specimens.     

Production of Polyclonal Antibodies for the Detection of Dehydroabietic Acid in Pulp Mill Effluents

Abstract

An enzyme immunoassay for resin acids was developed using polyclonal antibodies raised in rabbits. Dehydroabietic acid (DHA) was chosen as a representative resin acid due to its common occurrence and relatively high concentration and toxicity in pulp effluents. Dehydroabietylamine was conjugated to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA), respectively. The former was used as the immunogen and the latter as the coating antigen. By indirect ELISA, using the biotin-streptavidin system, antiserum can be diluted to 1:30,000 when the coating antigen was used at a concentration of 25 ng/100μl/well. The 50% inhibition concentration (IC₅₀) and the detection limit were determined as 20.2 ppb and 1.9 ppb, respectively.     

Determination of Sulfanilamide and Sulfisoxazole in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for quantification of sulfanilamide and sulfisoxazole in creams, supppositories, and tablets. The sulfas were extracted into acidic ethanol, diluted to an appropriate volume, and separated by silica gel HPTLC. The fluorescence quenching of the sulfa zones in samples and standards was compared by in situ scanning. Recoveries of the drugs from authentic samples ranged from 96–105%. Recoveries from products with old expiration dates were low. Identity of the sulfa drugs in products was confirmed by application of fluorescamine and Bratton-Marshall detection reagents.     

Determination of Ochratoxin A in colored food products: Sample preparation and an immunoassay test method

A method is proposed for the purification of highly colored food products (red wine, red pepper) for the immunochemical test determination of Ochratoxin A (OTA) with visual detection. The method is based on passing an analyzed sample (wine diluted with a solution of polyethylene glycol and sodium hydrocarbonate or water-ethanol extract of pepper diluted with a solution of sodium hydrocarbonate) though an adsorbent layer. Criteria for selecting the adsorbent are considered, and silica gels with aminopropyl and trimethylaminepropyl groups are used as the optimal ones. A test system for the determination of OTA combines the indicated purification method with the immunoaffinity preconcentration and immunoenzyme detection. The developed approach has allowed the test determination of OTA in red wine and red pepper at levels of 2 μg/L and 10 μg/kg, respectively.     

Determination of Aluminium in Dialysis Fluids and Graphite-Tube Furnace Atomic Absorption Spectroscopy Using the l'Vov Platform

Abstract

A method was developed for aluminium determination in dialysis fluids by graphite-tube furnace atomic absorption spectroscopy utilizing the L'vov platform.

Results are reported for various kinds of dialysis fluids.

In all cases accuracy and precision of the analytical procedure were ascertained.     

Radioimmunoassay of Plasma Dehydroepiandrosterone Sulfate

Abstract

This report describes a radioimmunoassay method for the direct measurement of dehydroepiandrosterone sulfate (DHEA-S) in diluted plasma. Utilizing a specific DHEA-S antiserum which reacted completely with DHEA, we have measured DHEA-S accurately in small aliquots of diluted plasma. Due to the relatively high concentration of DHEA-S in plasma, the effect of DHEA and other steroids on the assay was negligible. The usable range of the standard curve was between 10 and 500 pg DHEA-S. The range of levels that could be measured per ml of plasma varied from 0.02 to 5.0 pg. The range of values obtained by this method for plasma DHEA-S compared favorably with the ronge of levels observed in adult men and women, using various other techniques.     

Viscosities and Excess Properties of Aqueous Solutions of Ethanolamines from 25 to 80°C

Viscosities of aqueous solutions of monoethanolamine and triethanolamine have been measured from 25 to 80°C over the entire range of concentrations. The excess Gibbs energies for viscous flow have been calculated for aqueous solutions of monoethanolamine, triethanolamine, and also for diethanolamine and methyldiethanolamine from our earlier work [J. Chem. Eng. Data 39, 290 (1994)]. The entropy of viscous flow was obtained by using the temperature dependence of the excess Gibbs energy for viscous flow. The structural effects on the viscosity, excess Gibbs energy, and entropy for viscous flow are discussed.     

Evidences for Chelating Complexes of Lithium with Phenylphosphinic and Phenylphosphonic Acids: A Spectroscopic and DFT Study

Abstract

Lithium complexes were prepared with phenylphosphinic and phenylphosphonic acids. The complexes were studied in the solid state using Fourier transform infrared spectroscopy spectroscopy and in solution (methanol) using ¹H, ¹³C, and ³¹P Nuclear magnetic resonance spectroscopy (NMR) spectroscopy; the most preferred structures of the complexes were determined by density functional theory (DFT) computational method. Although methanol has a strong solvation effect on lithium ions and ligands, which causes dissociation of the complexes, significant changes of the NMR spectra of the complexes (relative to those of the free ligands) were observed. The new spectroscopic results indicate the presence of the phenylphosphinic acid tautomer (I: C₆H₅PH(?O)OH) rather than that of phenyl-phosphorous acid (II: C₆H₅P(OH)₂) in deuterated methanol showing PH/PD exchange. On the other hand, tautomer I predominates in the complex with lithium without showing PH/PD exchange. The DFT calculations predict that tautomer I is the preferred structure in the case of free ligand and lithium complex. The absence of a PH/PD exchange in the complex is due to the formation of a chelating complex, rather than of a simple salt between lithium ion and the two oxygen atoms of I, which prevent tautomerization of I into II. DFT calculations support the formation of lithium chelating complexes. The lithium ion was found to affect the spectroscopic properties of phenylphosphinic acid more dramatically than those of phenylphosphonic acid.