Katia Christina Leandro

Selective Determination of Rutin by Fluorescence Attenuation of the CdS-2-mercaptopropionic Acid Nanocrystal Probe

In this work, an analytical method for the determination of rutin was developed based on the CdS-2-mercatopropioinic acid (Cd-2MPA) luminescence attenuation. The optimized experimental parameters were: (1) the Tris-HCl buffer concentration (0.05 mol L−1); (2) the pH of the system (7.4); (3) the amount of organic solvents (30% of methanol and acetonitrile) and the time required to stabilize the signal (30 min). The luminescence (387/498 nm) signal presented a linear range up to 4 × 10−5 mol L−1 of rutin (Y = 3 × 104X + 0.99; r = 0.997). The limit of detection (based on xb − 3 sb of the signal attenuation curve) was 1.2 × 10−6 mol L−1. It was observed that the attenuation of signal was caused by two effects: the contribution from the inner filter effect and a static luminescence quenching component. Luminescence lifetimes of CdS-2MPA in the presence and in the absence of rutin were the same, indicating the static nature of the quenching caused by rutin. No interferences were observed from the flavonoids hesperidin and hesperetin when these were present in concentrations as high as 10 times the one of rutin. In samples containing the flavonoid quercetin, thin layer chromatography (TLC) was used in order to previously separate the analyte since an inner filter effect from quercetin was expected. The TLC/CdS-2MPA attenuation approach enabled recoveries for rutin of approximately 99%. In pharmaceutical formulations and in simulated saliva samples recoveries were between 100 and 104%.

Development and validation of an electroanalytical methodology for determination of isoniazid and rifampicin content in pharmaceutical formulations

Tuberculosis remains a major public health problem, especially in developing countries. Brazil presents the largest number of cases in Latin America and is among the 22 countries considered priorities by the World Health Organization (WHO). The Rio de Janeiro state has the largest number of cases registered in the country. The treatment of patients, commonly, makes use of the drugs isoniazid and rifampicin for six months. This study aimed to develop and validate an electroanalytical methodology, using the technique of differential pulse voltammetry for the determination of these drugs in the associated form, in order to evaluate the quality of medicines distributed in the state of Rio de Janeiro. The potential reduction for the isoniazid and rifampicin were -1.10 and -0.90 V. The developed and validated electroanalytical method presented a linear range of 0.25 to 1.25 mg/L to isoniazid, limits of detection and quantification of 0.05 and 0.14 mg/L, and recovery of 98.2 ± 0.4%; a tracking linear of 0.40 to 2.00 mg/L for rifampicin, with limits of detection and quantification of 0.07 and 0.19 mg/L and recovery of 95.8 ± 0.6%. Six lots of medicines from two pharmaceutical companies were analyzed. Only one of the samples showed unsatisfactory levels of rifampicin.

Determination of Zidovudine in Pharmaceuticals by Differential Pulse Voltammetry

The zidovudine (AZT) has been extensively used in the treatment of HIV patients due to its antiretroviral activity. The quality control of this substance in drugs is of outstanding importance to public health because of its undesirable effects and short therapeutic interval. For the determination of AZT in pharmaceuticals, an alternative analytical methodology using voltammetry was developed. The reduction of AZT at a hanging mercury drop electrode (HMDE) is at −0.96 V at pH 8.0. The influence of electroanalytical parameters, such as scan rate (20 mV/s), amplitude (50 mV), nature of the support electrolyte (phosphate buffer), and pH (8.0) on the voltammetric signal, was optimized. Under these optimized conditions, the AZT peak current varied linearly with its concentration from 0.25 to 1.25 mg/L (1 to 5 μM). Detection and determination limits of 0.0025 and 0.025 mg/L, respectively, and recovery of 99.88% with a relative standard deviation of 0.95% were obtained. The results obtained using this methodology in analyzing drugs containing AZT were compared favorably with those obtained by technique liquid chromatography as recommended by The United States Pharmacopoeia.

Development of a new analytical method for determination of acetylsalicylic and salicylic acids in tablets by reversed phase liquid chromatography

Acetylsalicylic acid (AAS) is a drug utilized as analgesic, anti-inflammatory, and antipyretic medication, available worldwide and commonly used in Brazil. Salicylic acid (AS) is a precursor in AAS synthesis and is also produced during its degradation. The official United States Pharmacopoeia (USP) suggests the determination of these drugs by high performance liquid chromatography (HPLC), with ultraviolet detection, but this method has neither a high sensitivity (SAAS=0.12 mAbs/(μg/mL) and SAS=0.48 mAbs/(μg/mL)) nor resolution (Rs=1.61). The purpose of this study was to develop a new more adequate, accurate method by liquid phase chromatography than the current official methodology, and to use this new method in the determination of the tenors of acetylsalicylic, as of salicylic acids in tablets. The parameters of the chromatographic system for both the AAS and AS were satisfactory. Selectivity was verified by absorption spectra comparison in the ultraviolet (UV) range, during and after substance retention time. The linear range for AAS was 0.21 to 0.39 mg/mL, and that for AS was 6.3 to 11.7 μg/mL. The correlation coefficients (r) of the analytical curves of AAS and AS were 0.9995 and 0.9988, respectively; and the detection and quantification limits for the AS were 0.23 and 0.69 μg/mL. The sensitivity (SAAS=1.88 mAbs/(μg/mL) and SAS=1.84 mAbs/(μg/mL)) and the resolution (Rs =5.06) show the improvement obtained using this method over that described by the USP.

Voltammetric determination of sibutramine in beverages and in pharmaceutical formulations

A simple and sensitive method has been proposed for the determination of sibutramine-HCl in energy drinks, green tea and pharmaceutical formulations using differential pulse voltammetry performed on a hanging mercury drop electrode. In the chosen experimental condition (Mcllvaine pH 4.0 buffer, 50 mV pulse amplitude and 40 mV s-1 scan velocity), sibutramine-HCl presented a reversible behavior and a peak maximum at -80 mV. Detection limit was 0.4 mg L-1 and the working linear range extended up to 33.3 mg L-1 (r = 0.99). Analysis of real and fortified samples enabled recoveries between 91 and 102%. The electroanalytical method was compared with a HPLC method which indicated it accuracy.

Estudo da presença da toxina microcistina na água de reservatório de Mundaú (Garanhuns-PE) pelas metodologias ELISA e CLAE

Cyanobacteria are responsible for the production of cyanotoxins, and once accumulated, it might cause serious harm to the human and animals health. Microcystins are the most common type of cyanotoxins and they cause liver tumor. The Mundau reservoir, located in the municipality of Garanhuns-PE, was the selected site for presenting historical blooms of microcystins-producing cyanobacteria. This study analyzed the occurrence of microcystins in raw water samples from the Mundau reservoir by using Enzyme Linked Immunosorbent Assay (ELISA) and High Performance Liquid Chromatography (HPLC) methodologies. During the consecutive fifteen months, water samples were collected in duplicate at the intake point of this water source, and they were analyzed by both ELISA and HPLC techniques. The presence of microcystins was detected in 100 % of analyzed samples, confirming the relevance of performing the microcystins monitoring in public water supplies. And as well as the Mundau river, various water sources of Pernambuco show cyanobacterial blooms, which might be toxic. The techniques used in this study were implemented in the Central Laboratory of Public Health of Pernambuco (LACEN-PE), and they showed to be a relevant tools as a complementary methodology to the cyanobacteria counting assay for providing preventive subsidies to the health surveillance.

Perfil de queixas técnicas relacionadas a seringas hipodérmicas de uso único comercializadas no Brasil após certificação compulsória

Metrological certification is an important Sanitary Surveillance tool. The objective of this study was to evaluate the profile of notifications of technical complaints of hypodermic syringes performed in Notivisa/Anvisa (Sistema Nacional de Notificacoes de Eventos Adversos e Queixas Tecnicas/Agencia Nacional de Vigilância Sanitaria) between 2012 and 2015. The notifications were analyzed individually and classified according to the reasons reported. 4181 notifications were evaluated and the most prevalent complaints were: ‘broken product in the sealed package’ (22%) and ‘dirt/stains inside the product/packaging’ (15.8%). There were no significant changes in the profile of the complaints after compulsory certification, which, although indispensable, is not capable of replacing post-marketing monitoring.

Otimização e validação da metodologia para a determinação de 5-hidroximetilfurfural em soluções anticoagulantes e preservadoras de bolsas de sangue por cromatografia líquida de alta eficiência

Anticoagulant and preserving solutions are designed to maintain the viability of blood and blood components. Plastic bags used for human blood storage are classified as Class III product for health. The RDC No. 35 of June 12, 2014 is the legislation that describes the quality control of blood units in Brazil. According to the resolution of the physical and chemical tests to be performed on anticoagulants solutions is the determination of 5-hydroxymethylfurfural content (5-HMF), a highly toxic pollutant formed by thermal decomposition of glucose present in the solutions, which may lead the patient even to death, justifying the need for their control. This work aimed to optimize and validate the methodology for determining the 5-HMF as recommended by ANVISA and the Inmetro. The parameters analyzed in the analytical validation were: specificity, linearity, detection limit, quantification limit, accuracy, precision and robustness. The results showed that the method is very effective for determining the 5-hydroxymethylfurfural which culminated in their integration into technical regulations published in June 2014.