Fluorescence Spectrometric Determination of Chloroquine in a Flowing Streah

Abstract

The effect of photolysis upon the fluorescence of chloroquine is studied and found to give only a marginal (～16%) increase in signal. On the other hand, a pH of 7–11 gives a constant maximum fluorescence signal which is ≈4X greater than at a pH of 3–5. Chloroquine in a flowing solution is passed through a flow cell in a fluorimeter. A detection limit of 0.25 ng/ml is obtained and linearity to greater than 60 ng/ml is obtained. Chloroquine added in vitro to human blood serum is determined with recoveries greater than 94%.     

Spectrophotometric Determination of Primaquine,Chloroquine, 8-Aminoquinoline and 4-Aminoquinalidine with Chloranil

Abstract

Primaquine, Chloroquine, 8-aminoquinoline and 4-aminoquinalidine form molecular complexes with chloranil at pH 9. The composition and stability of these complexes have been studied spectrophotometrically. The results indicate that all complexes were of 1:1 type. The method of complexation was used to determine a ppm amount of the intended compounds in solution spectrophotometrically.     

Modern Countercurrent Distribution

Abstract

Interest in liquid-liquid extraction continues to grow as evidenced by such divergent applications as industrial waste water treatment^1,2 cleanup for pesticide residue analysis³, and resolution of optical isomers.⁴ This activity results from increased understanding of the chemistry of solvent extraction which is leading to the design of specially selective systems^4,5as well as the development of improved extractors emanating from studies of mass transfer phenomena^6,7 in continuously flowing systems     

A Sensitive Colour Reaction for the Deterination of Primaquine in Pharmaceutical Preparations

Abstract

Primaquine reacts with diszo-p-nitroaniline in acid medium to give an orange yellow colour having and absorption maximum at 478 nm. On rendering the medium alkaline, a bathochromic ahift acompanied by hypochromic effect was revealed; the new maximum is located at 525 nm. The mean percentage recoveries for authentic samples amout to 100+, and 100.21+, 0.9 by the acid and alkaline procedures respectively, (p=0.05). Both methods could be applied to determine primaquine salts in pharmaceutical preparatins; the results obtained were in good agreement with those of the offictial method.     

The Use of Automated Headspace Gas Chromatography for Determination of 1,1,1-Trichloroethane in Rat Blood and Brain Tissue

Abstract

1,1,1-trichloroethane in blood and brain tissue from rats which had been artificially ventilated with solvent (8000 ppm) was analysed by automated headspace gas chromatography using a fused silica capillary column. A given concentration of 1,1,1-trichloroethane in the brain could be correlated with a corresponding concentration in the blood; both the uptake and release of the solvent were quicker in blood than in brain. No volatile metabolites of the solvent were found. Automated headspace gas chromatographic analysis is a rapid and sensitive technique for the quantitative registration of volatile organic solvents, e.g. of industrial importance, in body fluids and tissues.     

Quantitation of Chloroquine Phosphate And Primaquine Phosphate In Tablets Using High-performance Liquid Chromatography

Abstract

Reverse phase high-performance liquid chromatography methods for the quantitation of chloroquine phosphate and primaquine phosphate in tablets have been developed. The methods require one column and 2 mobile phases for complete analysis of both drugs when present in combination. The methods are accurate and precise with percent relative standard deviations based on 6 injections of 0.5 and 0.9 for chloroquine and primaquine, respectively. The results of single ingredient, chloroquine phosphate tablets are in excellent agreement with the USP-NF method which is nonspecific. Primaquine interfers with the USP-NF method and not with the developed HPLC method. Both drugs appear to be very stable to heat.     

Determination of Serum Chloramphenicol by High Performance Liquid Chromatography

Abstract

A simple single extraction procedure for the analysis of serum chloramphenicol levels by high performance liquid chromatography (HPLC) is described. Serum is mixed with buffer and extracted with ether, which is then evaporated. The residue is dissolved in the eluting solvent and analyzed on a reverse-phase column. The eluting solvent is methanol/distilled water (50/50, V/V) and the effluent is monitored at 280 nm. Serum samples as small as 50 μl can be used.     

OH−-induced β-elimination reactions with 1-(2-Xethyl)-4-nitrobenzene substrates in solvent mixture H2O/CH3CN and H2O/DMSO: Reactivity and mechanism

The behaviour of 1-(2-bromoethyl) 4-nitrobenzene (1), N,N,N-triethyl-2-(4-nitrophenyl)ethanaminium bromide (2) and N,N-diethyl-N-[2-(4-nitrophenyl)ethyl]octan-1-aminium bromide (3) in the OH⁻-induced elimination reactions with formation of 1-nitro-4-vinylbenzene in mixtures of DMSO/H₂O or CH₃CN/H₂O has been investigated. With all three substrates an increase in dipolar aprotic solvent content implies a limited increase of the second-order rate constant k _OH up to ≅605, and then an exponential increase is observed. The variation of activation parameters ΔH ^# and dGS ^#, measured in DMSO/H₂O mixtures, is parallel for 1 and 2. This similar behaviour of 1 and 2 with respect to variation in solvent composition is evidence that it is not possible to use this technique of solvent effect for the mechanistic diagnosis of elimination reactions.     

Nanoparticles based on gadolinium(iii) and europium(iii) complexes for biovisualization

Complexes Ln(TTA)₃ and [Ln(TTA)₃·1] (Ln = Eu, Gd; ТТА is thenoyltrifluoroacetyl-acetonate; 1 is 2-(5-chlorophenylene-2-hydroxy)-2-phenylethylene-bis(2-methoxy)phosphine oxide) in individual form, and as a part of a core of the polyelectrolyte stabilized colloids have been studied by Mössbauer spectroscopy and X-ray powder diffraction. The photophysical and colloidal characteristics of the solutions of polyelectrolyte nanoparticles were studied in water, artificial cerebrospinal fluid solution, solution of bovine serum albumin, and human blood serum. A stability of a luminescent response of the nanoparticles in solutions of bovine serum albumin and human blood serum at 37 °С for 2 hours has been revealed. This is a prerequisite for the potential application of studied nanoparticles for biovisualization.

     

Flow-Injection Determination of Glucose by a Photoinduced Chemiluminescent Reaction

Abstract

A flow-injection procedure for the photochemical determination of glucose has been developed. The method is based on the photo-oxidation of glucose sensitized by 9,10-anthraquinone-2.6-disulfonate (disodium salt). The hydrogen peroxide formed in the photochemical reaction was measured by means of the chemiluminescent reaction with luminol and hematin. A linear calibration graph was obtained over the range 2.0x10^?6-8.5 x 10^?5 mol L^?1. The method was applied to determining glucose in blood serum, urine and fruit juices.     

A Simplified Extraction for Mexiletine from Serum and Analysis by High Performance Liquid Chromatography

Abstract

The analysis of mexiletine by High Performance Liquid Chromatography (HPLC) requires organic extraction followed by evaporation of the organic solvent. Calibration curves must be prepared using standards in drug-free serum. This procedure has been simplified by using a back extraction of the mexiletine from serum. Calibration curves can then be more quickly prepared since good agreement can be obtained using standards in hydrochloric acid (HCl) instead of having to prepare standards in serum with the time-consuming necessity of having to extract these standards.     

The Formation of Rosocyanin in the Presence of Water

Abstract

The reaction between curcumin and boric acid to form the 2:1 complex rosocyanin has hitherto been considered to require an almost water-free solution. It has now been shown that rosocyanin may be formed even if large amounts of water are present, provided that a suitable organic solvent is added. The theoretical conditions for such a solvent have been investigated. Procedures are given where the reaction takes place in a homogeneous solution or possibly at the organic interface. For analytical purposes the rosocyanin formed could either be measured in a homogeneous solution or extracted into an upper or lower organicphase. Methylisobutylketone seems to be the most suitable solvent which possesses convenient analytical properties.     

Dielectric Studies of Binary Mixtures of some Amines—Aniline and Pyridine—in Nonpolar Solvents—Solute–Solvent Interactions

Abstract

Dielectric constant of binary mixtures of aniline and also pyridine in nonpolar liquids namely benzene, carbon tetrachloride, p-xylene and n-heptane have been measured at 455 kHz for four different temperatures. Eyring's interaction parameter G? based on the significant structure model is calculated in the mixtures using the experimentally determined value of dielectric constant.

The nature of the solvent is found to influence this parameter G? reflecting the non-specific solute-solvent interaction. The calculated value of G? is used for interpreting dipole interaction of solute molecules in the solvent environment.     

Quantitation of Meclizine Dihydrochloride in Serum by Reversed Phase Ion Pair High Performance Liquid Chromatography

Abstract

A specific and sensitive HPLC method has been developed for the assay of meclizine dihydrochloride in dog serum using an internal standard technique with a single step extraction. The extracts are injected into a reversed phase ion pair HPLC system using a solvent containing camphorsulfonate as paring anion. The detection limit is 5 ng/ml and the range of linearity is 5–250 ng/ml. The method has been used to quantitate meclizine dihydrochloride levels in bioavailability and pharmacokinetic studies in dogs.     

Solvent Donicity Influence in the Fluorescence Emission of the Lithium/1,4-Dihydroxyanthraquinone System. Improvement in the Quantification of Lithium.

Abstract

The fluorescence emission from the lithium/1,4-dihydroxyanthraquinone system shows a great enhancement in the presence of certain water-miscible solvents. This is justified from the donicity (nucleophilic properties) of the solvent that facilitates the solvation of the lithium cation in solution and the stabilization of an nondissociated ion-pair between the solvated lithium cation and the 1,4-dihydroxyanthraquinonate anion. A very sensitive analytical method was proposed for the spectrofluorimetric determination of lithium based on its reaction with 1,4-dihydroxyanthraquinone (quinizarin) in a dimethylsulfoxide medium (90%) and in presence of sodium hydroxide. The fluorescence is measured at an excitation wavelength of 602 nm and an emission wavelength of 670 nm and it is stable at 25°C at least 6 h. The calibration curve is linear over the concentration ranges of 2–40 μg/l of lithium in an aqueous matrix and 3–50 μg/l in a serum matrix; the RSD's in the determination of 20 μg/l of Li⁺ were 2.6% and 3.2%, respectively. The proposed procedure was satisfactorily applied to the determination of lithium in drugs, dietetic products and human serum.     

Hypnotic-Sedative Screen by High Performance Liquid Chromatography

Abstract

In this procedure some of the most commonly abused sedatives and hypnotics can be identified and quantitated using 100 ul of serum. Ethosuximide, primidone, methyprylon, phenobarbital, butabarbital, butalbital, glutethimide, mephobarbital, phenytoin, carbamazepine, secobarbital, phensuximide, pentobarbital, amobarbital, and methaqualone are extracted into a chloroform-ethanol solvent containing either 5-(p-methylphenyl)-5-phenyl-hydantoin or hexobarbital as an internal standard, evaporated to dryness, reconstituted with mobile phase and injected into a high performance liquid chromatograph in conjunction with a radial compression separation system. Peak heights are measured at 195 nm and 254 nm and sensitivity for all drugs is one μg/ml. Day to day precision obtained CV's ranging from 4.5 to 10.4%.     

Determination of Doxorubicin,Daunorubicin and some of their Metabolites in Mouse Plasma by High-Performance Reversed-Phase Liquid Chromatography with Amperometric Detection

Abstract

A selective and sensitive reversed-phase liquid chromatographic method with electrochemical detection for the analysis of doxorubicin, daunorubicin and some of their metabolites in plasma is reported. A mobile phase consisting of acetonitrile-phosphate buffer solution-tetrahydrofuran (25–71,5–3,5) flowing at 1 ml/min through a Lichrocart RP 18 column was employed. The influence of various parameters on the separation (solvent composition, pH, tetrahydrofuran content) has been examined. An extraction of anthracyclines from plasma was performed using chloroform-ethanol mixture (4: 1) with high extraction efficiency; reproducible results were attained by working with a 1 M phosphate buffer which ensured a real buffering of the plasma samples. The sensitivity of amperometric detection makes this method suitable for analyzing small amounts of the parent drugs and their metabolites. The precision was better than 4% in the range 0.2 to 5 μg/ml plasma.     

The Solvent-Like Nature of Silica Particles in Organic Solvents

Summary.   Kamlet-Taft’s α (hydrogen bond donor acidity) and π^* (dipolarity/polarizability) values of various silica batches measured in various solvents are presented. The α and π^* parameters for the various solid acids are analyzed by means of Fe(phen)₂(CN)₂ (cis-dicyano-bis-(1,10)-phenanthroline-iron(II), 1), Michler’s ketone (4,4′-bis-(dimethylamino)-benzophenone, 2), and two hydrophilic derivatives of 2, (4-(dimethylamino)-4′-(di-2-hydroxyethyl)-amino-benzophenone (3a) and 4,4′-bis-(di-(2-hydroxyethyl)-amino)-benzophenone (3b) as well as coumarin 153 (4) as solvatochromic surface polarity indicators. Apparent β (hydrogen bond acceptor basicity) parameters for bare silica have been evaluated by means of an aminobenzodifuranone dye (5) as solvatochromic probe. The chemical interpretation of the α and π^* parameters and the nature of the solvent/surface interaction which they reflect are discussed. It can be shown that an increase of the HBA (hydrogen bond accepting) capacity of the solvent significantly decreases the HBD (hydrogen bond donating) capacity of the surface environment, whereas the dipolarity/polarizability value of the silica/solvent interface is a composite of many effects. The classification of the polarity of silica particles in organic solvents compared to pure liquids is outlined. Theoretical E _T(30) values of the solid/solvent interfaces are calculated by applying linear solvation energy (LSE) relationships using the independently measured α and π^* values of the solid acids according to Received February 2, 2001. Accepted (revised) March 3, 2001     

Method for Gradient Elution in Micro-Flow Liquid Chromatography

This paper describes a new method for gradient elution at low flow rate. By adjusting the solvent composition flowing into a dynamic mixer, we can program the concentration of solvent, B, inside a dynamic mixer to form a time-resolved solvent gradient delivered to the column. The input gradient is related to the output gradient by the equation, B_in = B_out + τ × dB_out/dt, in which τ is the gradient response time constant at specified flow rate, and B_in and B_out are input and output concentration of solvent B, respectively.     

Optimisation of a Gas Stripping Concentration Technique for Trace Organic Water Pollutants

Abstract

The application of gas stripping for the concentration prior to analysis of organic water pollutants at the parts per million and parts per billion level has been studied. Solutes are stripped from solution by a stream of inert gas and subsequently adsorbed onto active carbon from which surface they are taken up in a solvent for analysis.

The method is shown to be applicable to the analysis of a wide range of compounds including pesticides and polychlorinated biphenyls. The effect of gas flowrate, the time of stripping, adsorbent particle size, and desorbing solvent on the percentage recovery of a range of organic compounds has been measured.

Problems of contamination of aqueous solutions by absorption of atmospheric vapours prior to analysis are considered, and the analysis of a typical water sample is demonstrated.