Spectrophotometric estimation of ketotifen fumarate in pharmaceutical formulations

Four simple and sensitive spectrophotometric methods (A–D) for the determination of Ketotifen fumarate in bulk samples and pharmaceutical formulations are described. They are based on the formation of coloured species by the coupling of the diazotised sulphanilamide with the drug (method A, _max 520 nm) or by oxidizing it with excessN-bromo-succinimide and determining the consumed NBS with decrease in colour intensity of celestine blue (method B: _max 540 nm) or by the reduction of Folin-Ciocalteau reagent (method C: _max 720 nm) or by the formation of a chloroform-soluble, coloured ionassociation complex between the drug and Azocarmine G at pH 1.5 (method D: _max 540 nm). Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 1–10, 2–12, 4–28 and 2.5–25 g/ml for methods A–D, respectively. The validity of the proposed methods was tested by analysing pharmaceutical formulations containing KTF: the relative standard deviations were within ±1.0%. Recoveries were 98.9–100.2%.     

Spectrophotometric methods for the determination of labetalol hydrochloride in pure and dosage forms

Simple and sensitive Spectrophotometric methods for the determination of labetalol hydrochloride are described. The first two are based on the oxidative coupling reaction of labetalol hydrochloride withp-N,N-dimethyl-phenylenediamine dihydrochloride (method A, _max 685 nm) and 3-methyl-2-benzothiazolinone hydrazone hydrochloride (method B, _max 545 nm) in the presence of sodium hypochlorite and eerie ammonium sulphate as oxidants, respectively. The third depends on the formation of an ion-association complex of labetalol hydrochloride with suprachen violet 3B at pH 1.3, which is extracted into chloroform (method C, _max 565 nm). The methods obey Beer's law and the precision and accuracy of the methods were checked against the B.P. reference method and the relative standard deviations were in the range 0.35–0.52%. These methods are applied to the determination of labetalol in dosage forms.     

Four spectrophotometric methods for determination of nitrofurazone in pharmaceutical formulations

Four simple and sensitive visible spectrophotometric methods (A-D) for the determination of nitrofurazone in bulk samples and pharmaceutical formulations are described. They are based on the formation of colored species by treating either its reduction product with 3-methylbenzothiazolin-2-one hydrazone in the presence of ferric chloride (method A: _max 600 nm) or its hydrolysis product with thiobarbituric acid (method B: _max 520 nm, 440 nm) or barbituric acid (method C: _max 400 nm) or by oxidizing it with excess N-bromosuccinimide and determining the consumed NBS using metol-isonicotinic acid hydrazide (method D: _max 620 nm).     

Assay of cisapride in pharmaceutical formulations by visible spectrophotometry

Three spectrophotometric methods (A-C) for the assay of cisapride (CPD) in pure and dosage forms are described. Method A is based on the oxidative coupling reaction of CPD with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ferric chloride to form a coloured species (_max; 565 nm.) Method B is based on the oxidation of CPD with Fe (III) and subsequent chelation of Fe(II) to form a coloured complex with 1,10-phenanthroline (_max: 520 nm). Method C is based on the formation of a coloured charge-transfer complex between CPD and chloranilic acid (_max; 555 nm). Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 2.0–32.0, 0.4–6.4 and 25.0–450.0 g/ml for methods A,B and C, respectively. The validity of the proposed methods was tested by analysing pharmaceutical dosage forms containing CPD and the relative standard deviations were within 1.0%     

Spectrophotometric Methods for the Determination of Nelfinavir Mesylate

Three visual spectrophotometric methods are described for the assaying of nelfinavir mesylate (NEL) in either bulk form or dosage forms. Methods A-C are based on the oxidation of NEL with an excess of oxidant (N-bromosuccinimide (NBS) in methods A&B or chloramine-T (CAT) in method C) in acidic medium. The unreacted oxidant is then estimated colorimetrically using an oxidisable dye (Celistine blue (CB) in method A or Gallocyanine (GC) in method C) or p-N-methyl aminophenol sulphate (PMAP)-sulphanilamide (SA) reagent (in method B). These methods obey Beer's law and give reproducible results. Recoveries range from 99.3–100.5%.     

Determination of cefadroxil by three simple spectrophotometric methods using oxidative coupling reactions

Three simple and sensitive visible spectrophotometric methods for the assay of cefadroxil have been developed. MethodA (_max 410 nm) is based on the reaction of cefadroxil with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the presence of eeric ammonium sulphate. MethodB (_max, 510 nm) involves the reaction with 4-aminophenazone in the presence of potassium hexacyanoferrate(III). MethodC (_max, 620 nm) involves reaction with 2, 6-dichloroquinone-4-chlorimide (Gibb's reagent). All variables have been optimised and the reaction mechanisms presented. Regression analysis of the Beer's plots showed good correlation in the concentration ranges 1.0–6.0, 2.0–24.0 and 1.0–6.0 g/ml for methodsA, B andC, respectively. No interferences were observed from excipients and the validity of the methods was tested by analysing pharmaceutical dosage forms. Recoveries were 98.0–100.3%. The concentration measurements were reproducible within a relative standard deviation of 1.0%.     

Spectrophotometric procedures for the determination of roxithromycin in pharmaceutical formulations

Four simple and sensitive visible spectrophotometric procedures for the assay of roxithromycin (RXT) have been developed. Procedures A and B are based on the formation of ion-pairs of roxithromycin with the dyes supracen violet 3B and tropaeolin 000, which are extracted into chloroform and have absorption maxima at 590 nm (SV 3B) and 490 nm (TP 000). Procedures C and D are based on condensation between the hydrolysis product of RXT in the presence of 3.6M hydrochloric acid in acetic acid medium and vanillin orp-dimethylaminobenzaldehyde (PDAB) to form coloured products with _max at 500 nm. Regression analysis of the Beer's plot showed good correlation in the concentration ranges 5–60 (A), 5–40 (B) and 5–50 (C & D) g/ml. No interference was observed from excipients and the validity of the procedures was tested by analysing pharmaceutical formulations. Recoveries were 99.0–102.0%. The concentration measurements are reproducible within a relative standard deviation of 1.0%.     

A clustering-based discretization for supervised learning

We address the problem of discretization of continuous variables for machine learning classification algorithms. Existing procedures do not use interdependence between the variables towards this goal. Our proposed method uses clustering to exploit such interdependence. Numerical results show that this improves the classification performance in almost all cases. Even if an existing algorithm can successfully operate with continuous variables, better performance is obtained if the variables are first discretized. An additional advantage of discretization is that it reduces the overall computation time.     

Active and Recyclable Gold Metal Nanoparticles Catalyst Supported on Nitrogen-Doped Mesoporous Carbon for Chemoselective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol

Several supported gold metal catalysts with different Au nanoparticles sizes were prepared and evaluated for the chemoselective hydrogenation of cinnamaldehyde (CA) to cinnamyl alcohol (CAL). To investigate the structure-activity relationship, stability of catalyst, heterogeneity and recyclability, the structural characteristics of materials and Au catalysts (fresh and spent catalysts) were studied by employing variety of physico-chemical techniques. The interrelationship among Au nanoparticles size (nm) with turnover frequency (h⁻¹) of Au catalysts has also been explored. Among the various Au catalysts tested, nitrogen-doped mesoporous carbon (NMC) supported Au catalyst having homogeneously dispersed (78.8%) Au nanoparticles (1.6 nm) synthesized by sol-immobilization method (Au-NMC-SI) demonstrated improved catalytic activity affording 78% CAL selectivity and 94.2% CA conversion without using any promoter. Moreover, Au-NMC-SI catalyst exhibited good recyclability and stability. The catalyst synthesis approach described in this investigation opens up a novel strategy for the design of highly efficient metal nano-catalysts supported on NMC materials.