Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas

Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes.

Determinação condutométrica de captopril em formulações farmacêuticas utilizando sulfato de cobre(II) como titulante

A simple and rapid conductometric method for captopril determination using copper(II) sulphate solution as titrant was developed. The method was based on the chemical reaction between captopril and Cu(II) ions yielding a precipitate. The conductance of the solution was monitored as a function of the added volume of titrant. The method was applied with success for captopril determination in three pharmaceutical formulations. The relative standard deviation for six successive measurements was smaller than 0.5%. Recovery values from three samples, ranging from 97.7 to 103%, were obtained.

Determinação espectrofotométrica de citrato de sildenafil em formulações farmacêuticas

This paper describes a simple and rapid spectrophotometric method for quantitative determination of sildenafil citrate based on its reaction with p-chloranil accelerated by hydrogen peroxide, producing a stable purple compound (λmax= 535 nm). In the absence of peroxide this reaction is very slow. The experimental conditions were optimized by using response surface methodologies. Beer's law is obeyed in a concentration range of 8.52 x 10-5 - 1.70 x 10-3 mol L-1 (r = 0.999). The detection limit was 1.96 x 10-5 mol L-1. The method was successfully applied for the determination of sildenafil citrate in medicines with good accuracy and precision.

Determinação espectroscópica multivariada de glucosamina e condroitina em formulações farmacêuticas

The objective of this study was to develop and validate an analytical method for quantification of glucosamine and chondroitin in pharmaceutical formulations. Multivariate calibration combined with infrared spectrophotometry allowed this analysis. 25 mixtures of glucosamine-6-sulphate and chondroitin-6-sulphate were used for calibration. Average errors found with this model during external validation were 1.37% for glucosamine sulphate and 1.30% for chondroitin sulphate. This method presented satisfactory results for assessed variables, what indicating that it is suitable for simultaneous quantification of glucosamine and chondroitin.

Aplicação e avanços da espectroscopia de luminescência em análises farmacêuticas

This paper provides a review on the latest advances and applications of the luminescence spectroscopy for the development of pharmaceuticals analyses methods, basically based on the photo- and chemiluminescence. The different forms of the drugs determination on pharmaceuticals through the fluorescence and chemiluminescence are discussed. The analyses include the drugs native fluorescence (liquid and solid-phases); the fluorescence from the oxidizing or reducing forms of the drug; the fluorescence from the chemical derivatization and their photochemistry and hydrolysis reactions. The quenching of luminescence and chemiluminescence generation for the pharmaceutical quantification are also shown. Finally, the trends and future perspectives of the luminescence spectroscopy in the field of the pharmaceutical research are discussed.

Determinação condutométrica de cloridrato de metformina em formulações farmacêuticas empregando nitrato de prata como titulante

A simple, precise, rapid and low-cost conductometric titration method for the determination of metformin hydrochloride (MET) in pharmaceuticals using silver nitrate as titrant is proposed. The method was based on the chemical reaction between the chloride of metformin hydrochloride molecule and Ag(I) ions, yielding the precipitate AgCl(s). The method was applied for MET determination in three pharmaceuticals and the obtained results with proposed method were in close agreement with those results obtained using an official method of the British Pharmacopoeia, at a 95% confidence level.

Determinação turbidimétrica em fluxo de cloridrato de fluoxetina em formulações farmacêuticas

A simple, accurate and precise flow-injection turbidimetric procedure for the determination of fluoxetine hydrochloride in pharmaceutical formulations is reported. The procedure is based on the precipitation of chloride of fluoxetine hydrochloride with silver nitrate solution and the yielded insoluble AgCl(s) was monitored at 420 nm. The analytical curve was linear in the fluoxetine hydrochloride concentration range 3.0 x 10-5 - 5.0 x 10-4 mol L-1 with a detection limit of 10 µmol L-1 and, a sample throughout of 60 h-1.

Desenvolvimento de um método reflectométrico ambientalmente mais amigável para a determinação de metoclopramida em formulações farmacêuticas

A simple and more environmentally friendly method by combined spot test-diffuse reflectance spectroscopy for determining metoclopramide in pharmaceutical formulations is described. The method is based on the reaction between metoclopramide and p-dimethylaminocinnamaldehyde, in the presence of HCl, producing a colored compound (λmáx = 580 nm) on the filter paper. The linear range was from 5.65 x 10-4-6.21x10-3 mol L-1 (r = 0.999). The limit of detection was 1.27 x 10-4 mol L-1. The proposed reflectometric method was applied successfully to the determination of metoclopramide in pharmaceuticals and it was favorably compared with the Brazilian or British Pharmacopoeia methods at 95% confidence level.

Determinação de olanzapina em formulações farmacêuticas por espectrofotometria: desenvolvimento e validação

Spectrophotometric methods of zero order, first and second derived order had been developed for olanzapine determination in tablets using ethanol and isopropanol as solvent. The two solvents revealed to be adequate. For the three methods the calibration curve coefficient of correlation had been greater than 0.9998 with limit of detection varying from 0.068 to 0.190 mg L-1, in ethanol, and 0.026 to 0.205 mg L-1, in isopropanol. The inter-day precision was inferior to 1.1 and 1.9 mg L-1 for ethanol and isopropanol, respectively. The average recoveries varied from 98 to 101%, in ethanol and 99 to 103% in isopropanol.

Determinação espectrofotométrica de cefalexina em formulações farmacêuticas explorando a sua reação de transferência de carga com a quinalizarina

This work proposes a new simple and fast spectrophotometric method for cephalexin determination in pharmaceutical formulations. The method is based on the charge transfer reaction between cephalexin and quinalizarin in dimethylsulfoxide medium. Several analytical parameters related to the system were optimized and the reaction was characterized in terms of stoichiometry. Also, association constant and apparent molar absorptivity of the product were determined. The method presented a limit of detection of 0.46 mg L-1 and a quantification limit of 1.5 mg L-1. It was successfully applied in the determination of cephalexin in two samples of commercial pharmaceutical formulations.

Análise térmica aplicada à caracterização da sinvastatina em formulações farmacêuticas

Thermogravimetry (TG) and differential scanning calorimetry (DSC) are used in pharmaceutical studies for drugs characterization, purity, formulations compatibility, polymorphism identification, stability evaluation, and thermal decomposition of drugs and pharmaceutical formulations. Simvastatin showed fusion at 138.5 ºC and thermal stability up to 248 ºC. Simvastatin was incompatible with preservative excipient butylhydroxyanisole (BHA) performing a process of crystal amorphization. The drug showed morphological polymorphism, where it has the same unit cell but with different crystal habits according to the recrystallization solvent.

Determinação de heparina fracionada em preparações farmacêuticas utilizando turbidimetria

A turbidimetric method has been used for quantification of fractionated heparin (FH) in pharmaceutical dosage. The UV detection at two wavelengths (290 and 500 nm) showed a significant increase in sensitivity of the method, specificity, and linearity to range 5.0-50.0 µg mL-1 and 50.0-200.0 µg mL-1, respectively (r < 0.99). At both wavelengths, the method was precise (inter-assay CV < 5.0%, and intra-assay CV < 3.0%), accurate (maximum deviation of ± 12%), and robust to the parameters evaluated. Turbidimetry proved to be easy, inexpensive and relatively fast. The results obtained attest to the reliability of the method.

Análise térmica aplicada a fármacos e formulações farmacêuticas na indústria farmacêutica

Several matters of the pharmaceutical demonstrate the great importance of thermal analysis application, especially TG and DSC for the pharmaceutical industry future, namely: characterization of the drugs with the thermal events definition, in studies of drug purity, in the polymorphs identification, in compatibility studies of solid dosage pharmaceutical formulations, in drugs and pharmaceutical formulations thermal stability, and in determination of shelf life for isothermal degradation kinetics by extrapolation using the Arrhenius equation. Thus, the test results obtained from thermal analysis are directly related to the quality of a pharmaceutical product, whether the stability or bioavailability of the pharmaceutical product.

Determinação simultânea de olanzapina e cloridrato de fluoxetina em formulações farmacêuticas por espectrofotometria derivativa

Simple, sensitive and accurate spectrophotometric derivative methods were developed for the simultaneous determination of olanzapine and fluoxetine hydrochloride in pharmaceutical formulations by derivative spectrophotometry. On all orders of derivative studied, the linear response range was 10 to 60 mg L-1, with limit of quantitation (LoQ) ranging from 0.73 to 1.49 mg L-1 for fluoxetine hydrochloride and from 0.18 to 0.96 mg L-1 for olanzapine. The best orders for derivative analyses showed recoveries ranging from 99 to 103% and from 98 to 100%, and inter-day accuracy < 2.1% and < 2.8%, for fluoxetine hydrochloride and olanzapine, respectively.

Avaliação de métodos de extração para a determinação de cromo e níquel em formulações farmacêuticas e em matérias-primas usadas na fabricação de medicamentos à base de cefalexina e ciprofloxacino

This paper reports the evaluation of extraction strategies for the treatment of medicine samples to determine chromium and nickel by GFAAS. Different approaches for extraction were evaluated and the most efficient involved magnetic stirring. The metals were quantitatively extracted by stirring 0.20 g samples with 25 mL of 2.0 mol L-1 HCl solution for 60 min. The developed method was successfully applied for the determination of Cr and Ni in tablets containing antibiotics and raw materials, with cephalexin and ciprofloxacin as active ingredients.