Microextraction of 17-β-Estradiol from Medicinal Preparations for the Subsequent Determination by HPLC-UV

Journal of Analytical Chemistry - A method is proposed for the chromatographic determination of 17-β-estradiol in medicinal preparations with the microextraction of the analyte from a sample...     

Flow-Injection Determination of Benzylpenicillin Novocaine Salt in Penicillin Preparations with Spectrophotometric Detection

Working conditions were found for determining the novocaine salt of benzylpenicillin antibiotic as its 4,6-dinitrobenzofuroxan derivative by flow-injection analysis with spectrophotometric detection ( = 510 nm). The best results were obtained for flows of methanol (ethanol) and water with a volume ratio of 30 : 70. The calibration range of the pharmaceutical is 0.28–10 g/mL with a throughput capacity of 30 samples/h. The limit of detection (3, n= 4) is 0.14 g/mL. Amino acids and components of penicillin-containing pharmaceuticals did not interfere with the determination. Procedures for determining benzylpenicillin novocaine salt in medicinal formulations containing benzylpenicillin N,N"-dibenzylethylenediamine, potassium, and sodium salts and some other     

Flow-Injection Analysis of Pharmaceuticals

The current state and outlooks of the development of the flow-injection analysis of medicinal substances in pharmaceuticals and biological fluids are considered. The role of chemical, photochemical and enzymatic reactions of derivatization in the flow-injection determination of pharmaceuticals is outlined. The role of detection methods in improving the selectivity and sensitivity of the flow-injection analysis of pharmaceuticals and expanding its possibilities in pharmaceutical analysis is considered     

Test Films for the Determination of Aromatic Amines and Hydrazines in Aqueous Solutions

Conditions of the test determination of toxic aniline (I), N,N-dimethylaniline (II), N,N-diethylaniline (III), 2,2,4-trimethyl-1,2-dihydroquinoline (IV), 1,1-dimethylhydrazine (V), and phenylhydrazine (VI) as their 4,6-dinitrobenzofuroxan (I) and 5,7-dinitrobenzofurazan (II, III, IV, V, VI) derivatives in aqueous solutions were found. Visual and spectrophotometric measurement of the signal was used. The reagents were immobilized in nitrocellulose films. Optimal results of visual determination of color development in test films were obtained with reagents immobilized in nitrocellulose at their concentration of 5 mass % and pH of the test solution in the range 6.0–7.5. The spectrophotometric measurement of the signal of test films was performed at wavelengths of 500–560 nm for I, V, and VI and 610–620 nm for II, III, and IV. The detection limit for spectrophotometric measurement was 0.01, 0.18, 0.13, 0.15, 0.16, and 0.04 mg/L for I, II, III, IV, V, and VI, respectively. The analytical range of the toxicants was 0.05–6.0 mg/L. Test determination is possible in the presence of alkylamines, ammonia, phenols, carboxylic acids, and inorganic salts.     

Flow-Injection Determination of Toxic Aromatic Amines in Medicinal Preparations

Working conditions were found for the flow-injection determination with spectrophotometric detection (510 nm) of the toxic aromatic amines p-aminophenol (I) and o-phenylenediamine (II) as 4,6-dinitrobenzofuroxan derivatives in mixtures on the basis of Paracetamol and Dibazol medicines. The optimal results were obtained with the use of flows of an ethanol (methanol)–buffer solution at pH 6.68. The analytical range of the toxicants is 0.03–0.98 g/mL. The detection limit is 0.025 g/mL for I and 0.01 g/mL for II. Compounds I and IIwere determined in medicinal forms (pellets, syrup, and suppositories) and in reaction mixtures in the synthesis of Paracetamol and Dibazol.     

Sorption–Chromatographic Determination of Aniline, 4-Chloroaniline, and 2,5-Dichloroaniline in Air

Conditions were found for the chemisorption preconcentration of aniline, 4-chloroaniline, and 2,5-dichloroaniline from air using tubes packed with silica gel with immobilized 4-chloro-5,7-dinitrobenzofurazan and for the subsequent HPLC determination with diode-array detection. The maximum analyte recoveries (98, 90, and 75% for aniline, 4-chloroaniline, and 2,5-dichloroaniline, respectively) were achieved at a 2-cm thickness of the adsorbent layer (silica gel with a grain size of 0.1–0.3 mm impregnated with 3 wt % 4-chloro-5,7-dinitrobenzofurazan), an aspiration rate of 0.6–0.8 L/min, and an aspirated air volume of 10 L. Taking into account a tenfold preconcentration of analytes after the desorption, the detection limit for aniline is equal to 0.0007 mg/m³.     

Selective determination of 4-aminobenzoic and 4-aminosalicylic acid derivatives in mixtures by flow-injection analysis

The working conditions were found for the determination of medicinal substances anesthesin (benzocaine,I), novocaine (II), novocainamide (procainamide,III), and sodium 4-aminosalicylate (IV) as their 4,6-dinitrobenzofuroxan derivatives by flow-injection analysis with spectrophotometric detection (λ 510 nm). The best conditions were attained using a mixture of ethanol (methanol) and a buffer solution of pH 6.68 (30: 70 vol %). The analytical range for the analytes was 0.08-5.0 μg/mL. The detection limits (3σ,n = 4) were 0.04 (I), 0.05 (II), 0.07 (III), and 0.03 (IV) μg/mL. Procedures for determining 4-aminobenzoic and 4-aminosalicylic acid derivatives in pharmaceuticals containing ephedrine, atropine, dimedrol, and inorganic salts and in biological fluids (protein hydrolyzate, blood plasma, and whole blood) were developed.     

Test Method for the Determination of Toxic Irritants in Air

It is shown that 10-chloro-9,10-dihydrophenarsazine and dibenz[b, f][1,4]oxazepine can be determined with the use of indicator tubes containing 4-chloro-5,7-dinitrobenzofurazan and its N-oxide immobilized on silica gel. The conditions for the determination of these substances in air are determined. The following effects are studied: the nature, particle size, and layer thickness of the support; the nature and concentration of the analytical reagent in the chemisorption layer; the rate and time of air aspiration through the indicator tube; and various components of the sample matrix. The limit of visual detection of the toxic substances is 0.05 mg/m³.     

Flow-injection determination of indole derivatives in pharmaceutical mixtures

The reactions of tryptamine derivatives with 4-chloro-5,7-dinitrobenzofurazan were studied. The composition of the products of analytical reactions was found from the data of elemental analysis, and their structures were confirmed by ¹H NMR spectra. The working conditions were selected for the flow-injection determination of 22 indole derivatives in pharmaceutical mixtures as 5,7-dinitrobenzofurazans with spectrophotometric detection at 490 nm. Optimum results were obtained using acetonitrile-buffer solution (pH 6.8) flows. The analytical range for biologically active substances was between 0.04 and 0.61 μg/mL. The throughput was 25–35 sample/h. The detection limit was 0.01 μg/mL. Serotonin, mexamine, melatonine, sumatryptan, and indolylacetic acid derivatives were determined in pharmaceuticals and in reaction mixtures from the synthesis of biologically active substances.     

Determination of Amine-Containing Drugs in Micellar Matrices by Spectrophotometry Using Box–Behnken Plans

Journal of Analytical Chemistry - The results of using the “response surface” methodology and the Box–Behnken design in the spectrophotometric determination of medicinal...