Fluorescence enhancement of coumarin-6-sulfonyl chloride amino acid derivatives in cyclodextrin media.

Coumarin-6-sulfonyl (6-CS) amino acid derivatives form inclusion complexes with a- and /-cyclodextrins (CD) in aqueous solution. The stoichiometry of the inclusion complex and the equilibrium constant were investigated. Using a fluorescence technique and alanine-beta-CD as a model, a 1:2 guest-host complex was established, and K = 4.7 x 10(5) mol(-2) l(2) was obtained. Fluorescence enhancement was observed for all derivatives studied, with glycine exhibiting a greater enhancement, and tyrosine showing the least. The stability of the inclusion complex was found to depend on the respective sizes of the guest-host complex and their interaction.

The determination of carbonyl compounds in air using a robotic sampling preparation system integrated to a gas chromatograph with a nitrogen-phosphorus detector.

A totally automated solid phase extraction gas chromatography procedure was developed for the sampling and analysis of carbonyl compounds in air. In this system, two PrepStation modules were used, one for the preparation and elution of 2,4-dinitrophenylhydrazine silica cartridges, and the other for air sampling. The sample collected by the sampling module was eluted to an autosampler vial in the PrepStation module and then transferred to the gas chromatograph for analysis via a robotic arm. The sampling module was modified to enable air sampling via an external pump. A typical run by this technique required 142 min, 100 min for air sampling and 42 min for the other operations, including a GC analysis time of 25 min. Recoveries of at least 85% were obtained for all compounds studied. The detection limits for formaldehyde, acetaldehyde and acetone were 2.2, 2.7 and 2.2 ppbv, respectively. All operations, including the conditioning of the cartridges, were performed without any intervention from the analyst.

Ion-association method for the spectrophotometric determination of the antitussive drug noscapine.

A simple, sensitive and fairly rapid method for the determination of noscapine is described, based on the measurement of the absorbance of the organic soluble ion-association complex formed between the noscapine monocation and a bulky counter anion. Methyl Orange, Bromothymol Blue and Bromocresol Green (BCG) were examined as counter ions. The effect of few solvents, the counter-ion concentration and pH on the extraction were also investigated. The most suitable system was based on BCG (pH 3.0) with chloroform as the extraction solvent. The use of the other counter ions, in conjunction with their respective solvents, was found to be less sensitive. The BCG system exhibits negligible or no interference when used for the determination of 38 ppm of noscapine in the presence of several drug excipients, thus lending itself as a possible procedure for the determination of this alkaloid in pharmaceutical preparations.

Sequential optimization of a flow injection spectrophotometric method for the assay of chlorpromazine in pharmaceutical preparations.

A new simple flow injection spectrophotometric method for the assay of chlorpromazine using cerium(IV) in sulfuric acid media was developed. The oxidized form of the drug was monitored at the maximum absorbance of 526 nm. The optimum conditions were 0.035M sulfuric acid, 3.80 x 10(-3)M cerium(IV), flow rate 4.85 ml/min, coil length 45 cm and sample size 110 mm(3). Optimization was carried out by the modified simplex method. Response surface methodology was employed to investigate the ruggedness of the method. A sampling frequency of 120 hr(-1) was attained. Relative standard deviations for standard sample were usually less than 0.75. The method was applied to the determination of chlorpromazine in proprietary drugs and results were statistically compared with the official British Pharmacopoeia (BP) method.

Flow injection colorimetric method for the assay of vitamin C in drug formulations using tris,1-10-phenanthroline-iron(III) complex as an oxidant in sulfuric acid media.

A simple, fast and accurate colorimetric flow injection (FI) method suitable for the assay of vitamin C in drug formulations was proposed. In the method, vitamin C was injected into a flowing stream of iron(III) and then mixed with 1,10-phenanthroline in 0.05M sulphuric acid media. The mixture was allowed to react in a 45-cm long coil and the resulting solution of tris, 1-10-phenanthroline-iron(II) complex was monitored at 510 nm. The method was adopted by fully investigating the kinetics of the reaction and proposing a suitable mechanism. A throughput of 100 samples per hour was achieved with a relative standard deviation of 0.88% for vitamin C concentration range of 100-400 ppm.

Flow injection method for the assay of the anti-arrhythmic procainamide HCl in drug formulations utilizing statistical optimization techniques.

A flow injection spectrophotometric method for the determination of procainamide HCl was explored. The method was based on the oxidation of procainamide HCl with cerium(IV) in sulphuric acid media and subsequent monitoring of the absorbance of the oxidized form of the drug at 480 nm. A sample rate of 250 samples per hour was attained. The procedure was optimized by the Factorial Design at two upper and lower levels of the five parameters sample loop size, flow rate, coil length, sulphuric acid and cerium(IV) concentrations. The latter three indicated high interactions and revealed significance to peak height value therefore optimized by the Super Modified Simplex programme. The optimized FI system with a linear calibration range of 100-600 ppm was found to be adequate and suitable for determination of procainamide HCl in proprietary drugs. A high degree of accuracy of the results was demonstrated by a statistical comparison with those obtained by the British Pharmacopoeia method of the same batch of drugs.