Validação em laboratório de método analítico para determinação do teor de adipato e ftalato de di-(2-etil-hexila) utilizados como plastificantes em filmes flexíveis de PVC

The validation of analytical methods was carried out for di-(ethylhexyl) phthalate (DEHP) and adipate (DEHA) the determination of in PVC films. The level of DEHP and DEHA in samples was determined by leaving the film in contact with n-heptane during 48 hours and analysis in a gas chromatograph (GC) equipped with a flame ionization detector and fused silica column with 5% phenylmethyl silicone in the dimensions 30 m x 0.53 mm x 2.65 mm. The results for detection and the quantification limits were smaller than the restriction limits. The recovery rates of DEHP and DEHA were, respectively, 69.10 and 75.30 %.

Reconhecimento de padrões por métodos não supervisionados: explorando procedimentos quimiométricos para tratamento de dados analíticos

An activity for introducing hierarchical cluster analysis (HCA) and principal component analysis (PCA) during the Instrumental Analytical Chemistry course is presented. The posed problem involves the discrimination of mineral water samples according to their geographical origin. Thirty-seven samples of 9 different brands were considered and the results from the determination of Na, K, Mg, Ca, Sr and Ba were taken into account. Non-supervised methods for pattern recognition were explored to construct a dendrogram, score and loading plots. The devised activity can be adopted for introducing Chemometrics devoted to data handling, stressing its importance in the context of modern Analytical Chemistry.

Otimização e validação da técnica de extração líquido-líquido com partição em baixa temperatura (ELL-PBT) para piretróides em água e análise por CG

The liquid-liquid extraction with the low temperature partition technique was developed for the analysis of four pyrethroids in water by CG. Using a factorial design the extraction technique was optimised evaluating the effect of the variables ionic strength, contact time and proportion between sample and solvent volumes. The validation parameters sensitivity, precision, accuracy and detection and quantification limits were evaluated. The LOD and LOQ of the method varied from 1.1 to 3.2 µg L-1 and 2.7 to 9.5 µg L-1, respectively.

Desenvolvimento e validação de metodologia analítica para determinação de itraconazol em produtos farmacêuticos por CLAE

Itraconazole is a synthetic antifungal drug administered orally with a broad spectrum of activity against mycotic infections. The present work consists of the development and validation of analytical methodology for evaluation of itraconazole in pharmaceutical products by high performance liquid chromatography. The separation was made using the reversed-phase column LC-18, acetonitrile/diethylamine 0.05% v/v, 60:40 v/v, pH 8.0 as mobile phase, methanol as solvent and detection and quantification at 254 nm. The results here obtained show that the analytical methodology is accurate, reproducible, robust and linear over the concentration range 8.0-12.0 µg/mL of itraconazole. The method was applied to pharmaceutical capsules containg itraconazole pellets and showed to be efficient, yielding good results.

Validação de metodologia analítica por cromatografia líquida para doseamento e estudo da estabilidade de pantoprazol sódico

Pantoprazole is a proton pump inhibitor used in the treatment of digestive ulcers, gastro-esophageal reflux disease and in the eradication of Helicobacter pylori. In this work, an analytical method was developed and validated for the quantification of sodium pantoprazole by HPLC. The method was specific, linear, precise and exact. In order to verify the stability of pantoprazole during dissolution assays, pantoprazole solution in phosphate buffer pH 7.4 was kept at room temperature and protected from light for 22 days. Pantoprazole presented less than 5% of degradation in 6 hours and the half live of the degradation was 124 h.

Validação de método por cromatografia líquida de alta eficiência para determinação da lamivudina e zidovudina em comprimidos

An HPLC method was validated to assay lamivudine and zidovudine combined in tablets. The chromatographic separation was carried out using methanol and acetate buffer pH 6.5 (50:50 v/v) and a RP-18 column, as mobile and stationary phase, respectively. The UV detection was at 270 nm. The method was linear in the range of 24 - 36 µg/mL (lamivudine) and 48 - 72 µg/mL (zidovudine). The recovery (accuracy) ranged from 101.35% to 103.04% and the precision (repeatability and intermediate precision) was less than 2%. The method can be also applied to the quantification of these drugs in the dissolution test of tablets containing both drugs.

Validação de metodologia analítica para o doseamento simultâneo de mebendazol e tiabendazol por cromatografia líquida de alta eficiência

The aim of this work was to develop and validate an analytical methodology for simultaneous determination of mebendazole and thiabendazole, two benzimidazoles used as anthelmintics. The method was based on high performance liquid chromatography, using a C18 column, a mobile phase composed of KH2PO4 0.05 mol L-1 and methanol 40:60 (v/v) and UV detection at 312 nm. The results showed that the method presented linearity from 60.0 to 140.0 µg mL-1 for mebendazole and from 99.6 to 232.4 g µL-1 for thiabendazole and it was considered selective, accurate, precise and robust according to the specific resolution from ANVISA, the Brazilian regulatory agency.

O enfoque da metrologia química em análises toxicológicas na atividade turfística: validação de método analítico para determinação de cafeína em matrizes biológicas

This paper proposes an alternate method to detect forbidden doping substances present in biological matrices of horseracing. The method was fully validated for caffeine, identified as the most frequent forbidden substance in the analysis conducted by the Antidoping Laboratory of the Brazilian Jockey Club, which adopts a zero threshold limit according to national and international horseracing practices. The metrological reliability of the method applied to toxicological analysis in biological matrices is discussed. Although the analytical method proposed for detection of a zero threshold level of the doping substance is qualitative, it was validated for the determination of the limiting value (also known as quantification limit value) introducing a criterion that prevents the issuing of incorrect results ("false-positives" and "false-negatives").

Desenvolvimento e validação de metodologia de análise de misturas biodiesel: diesel utilizando cromatografia gasosa-espectrometria de massas

The aim of this work was to develop and validate a method of analysis of biodiesel:diesel blends using HRGC-MS in SIM mode. The proposed method is applicable to biodiesel from linoleic oils, such as soybean oil. The following results were obtained: linearity over the methyl linoleate concentration range of 250-2500 mg L-1 (R² > 0.999); limits of detection and quantification of 2 and 5 mg L-1, respectively; recovery from 82 to 96% of biodiesel in diesel and repeatability < 2% (RSD). Comparison between two operators showed that it is not necessary the same operator to do the analysis.

Desenvolvimento e validação de método de análise de glifosato em grãos de soja

The main objective of this work is to develop an efficient procedure to determine glyphosate in soybean grains. The cleanup of the aqueous extracts was done in two steps, beginning with liquid-liquid partitioning and then solid-phase extraction with anion exchange resin. After derivatization with a mixture of trifluoroacetic anhydride (TFAA) and trifluoroethanol (TFE), quantification was done by gas chromatography coupled to mass spectrometry. The mean recovery and RSD of the spiked samples were, respectively, 80.5% and 3.1% at level 0.200 mg kg-1, 93.3% and 18.7% at level 0.500 mg kg-1 and 92% and 3.5% at level 1.000 mg kg-1. The method was linear in the working range (correlation coefficient = 0.9965).

Planilha de validação: uma nova ferramenta para estimar figuras de mérito na validação de métodos analíticos univariados

This work presents the VALIDATION SPREADSHEET, a public domain tool that can be used to evaluate the figures of merit for univariate analytical methods. A real example of BTEX determination in environmental samples is included to illustrate its use. The spreadsheet has been developed for Excel® and Open Office®, and is available on the internet at http//lqta.iqm.unicamp.br.

Validação de métodos cromatográficos por clae para análise das vitaminas B1, B2, B6 e niacina naturalmente presentes em farinha de cereais

Complex B vitamins are present in some cereal foods and the ingestion of enriched products contributes to the recommended dietary intake of these micronutrients. To adapt the label of some products, it is necessary to develop and validate the analytical methods. These methods must be reliable and with enough sensitivity to analyze complex B vitamins naturally present in food at low concentration. The purpose of this work is to evaluate, with validated methods, the content of vitamins B1, B2, B6 and niacin in five cereal flours used in food industry (oat, rice, barley, corn and wheat).

Desenvolvimento e validação de método analítico para determinação simultânea de lamivudina, zidovudina e nevirapina em comprimidos dose-fixa combinada por cromatografia líquida de alta eficiência

An analytical method has been developed and validated for the quantitation of lamivudine, zidovudine and nevirapine in the fixed-dose combination film-coated tablet by high performance liquid chromatography, in accordance with RE No. 899/2003, National Sanitary Surveillance Agency. It was based on an isocratic elution system with a potassium phosphate buffer pH 3.0: acetonitrile (60:40 v/v) mobile phase, C18, 250 x 46 mm column, 10µm particle size, λ 270 nm. The statistically evaluated results have shown that the method is specific, precise, accurate, and robust, ensuring the analytical safety of 3TC, AZT and NVP determination, which emerges as a new therapeutic alternative for antiretroviral treatment.

Validação de métodos cromatográficos para a determinação de resíduos de medicamentos veterinários em alimentos

Different agencies that supply validation guidelines worldwide establish almost the same parameters to be evaluated in the validation process of bioanalytical methods. However, they recommend different procedures, as well as establish different acceptance criteria. The present review delineates and discusses the stages involved in the validation procedures of bioanalytical methods designed for determining veterinary residues in food, explaining the main differences in the guidelines established for this purpose by the main regulatory agencies in the world.

Contaminantes voláteis provenientes de embalagens plásticas: desenvolvimento e validação de métodos analíticos

Plastic packaging materials intended for use in food packaging is an area of great interest from the scientific and economic point of view due to the irreversible internationalization and globalization process of food products. Nevertheless, a debate related to food safety aspects has emerged within the scientific community. Therefore, the development of analytical methods that allow identifying and quantifying chemical substances of toxicological potential in the packaging is considered essential. This article focuses on the main analytical methods, including validation parameters, as well as extraction and quantification techniques for determination of volatile organic compounds from food packaging materials.