Carotenoids profile and total polyphenols in fruits of Pereskia aculeata Miller

Pereskia aculeata Mill. (Ora-pro-nóbis) is a native cactaceae from tropical America, whose leaves have high protein content. In Brazil it is found in all territorial extension between the states of Bahia and Rio Grande do Sul. Most studies have focused on chemical characterization of the leaves of this specie. The objective was to assess the carotenoids profile and the total polyphenols present in the fruits of P. aculeate. Carotenoids were determined by HPLC-PAD (high performance liquid chromatography - photodiode array detector), total polyphenols were determined by Folin-Ciocalteu and vanillin methods. Trans-β-carotene was the main carotenoid, followed by α-carotene, lutein and other minor carotenoids. It was found 64.9 ± 1.1 mg.100g-1 of gallic acid equivalent, 14.8 ± 0.2 mg.100g-1 of catechin equivalent. Carotenoid identification of P. aculeate fruits are presented here by the first time and indicate that these fruits can be researched as source of bioactive substances, especially antioxidant and provitamin A carotenoids.

Influência do material do alambique na composição química das aguardentes de cana-de-açúcar

This paper describes variations in the profile of the main volatile organic compounds present in Brazilian sugar cane spirits distilled in copper and stainless steel distillers. The main organic compounds: aldehydes, ketones, carboxylic acids, alcohols and esters, were determined through High Performance Liquid Chromatography (HPLC) and High Resolution Gas Cromatography (HRGC). The spirits produced in copper distillers exhibit higher contents of aldehydes with respect to the ones produced in stainless steel. The inverse is true with respect to the higher alcohol and ester contents. No significant variation has been observed for the carboxylic acids.

Drosophila melanogaster Meigen: 3. sensibilidade ao carbofuran e biomonitoramento de seus resíduos em repolho

The susceptibility of Drosophila melanogaster to carbofuran and the use of this organism in biomonitoring residues of the insecticide in cabbage was evaluated. Under the conditions of the bioassay, residues-film bioassay in Petri dish, carbofuran degraded depending on the temperature and time of exposure. Bioassays conducted with D. melanogaster showed that its toxicity increases with temperature (20 to 35 °C). LC50 values, calculated as a function of temperature, ranged from 3.6 to 10.5 mg/g body weight (bw) for males and from 2.9 to 8.7 mg/g bw for females. The formulated product Furadan® G was applied on cabbage (Brassica oleracea, var. capitata) and the residues of carbofuran were determined by bioassay. The determination limit of the bioassay was 0.1 mg/kg and the method presented reproducibility with coefficient variation of 17 %. The validation of the bioassay by high performance liquid chromatography confirms the viability of the bioassay with D. melanogaster in monitoring the residues of carbofuran in cabbage.

Determinação de alfa-Tocoferol em alho irradiado utilizando cromatografia líquida de alta eficiência (CLAE)

The effects of 60Co ionizing radiations in doses of 0, 75, 100, 150, 200 and 250Gy on garlic, upon the alpha-tocopherol concentration were studied. The alpha-tocopherol contents were established by high performance liquid chromatography (HPLC), after direct hexane extraction from the garlic samples. The alpha-tocopherol was determined through normal-phase column, and mobile phase was composed by hexane: iso-propyl alcohol (99:01 v/v), with 2mL/min flow rate and fluorescence detector. It is statistically shown that an irradiation dose of up to 150 Gy does not affect the garlic alpha-tocopherol content.

Cassava and corn starch in maltodextrin production

Maltodextrin was produced from cassava and corn starch by enzymatic hydrolysis with alpha-amylase. The cassava starch hydrolysis rate was higher than that of corn starches in maltodextrin production with shorter dextrose equivalent (DE). DE values do not show directly the nature of the obtained oligosaccharides. Maltodextrin produced from cassava and corn starch was analysed by high performance liquid chromatography (HPLC), and the analysis showed that maltodextrin production differs according to the source of the starch. This is important in defining the application of the maltodextrin, according to its desired function.

Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência

A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.

Fases estacionárias monolíticas para separações cromatográficas

Monolithic stationary phases represent a new generation of chromatographic separation media. These phases consist of a continuous separation bed prepared by in situ polymerization or consolidation inside the column tubing. In recent years, their simple preparation procedure, unique properties and excellent performance have attracted quite remarkable attention in liquid chromatography and capillary electrochromatography. This review summarizes the preparation, characterization and applications of monolithic stationary phases. The analytical potential of these columns is demonstrated with separations involving various families of compounds in different separation modes.

Determinação de lamivudina, estavudina e nevirapina, em comprimidos, por cromatografia líquida de alta eficiência

A high performance liquid chromatography method was developed to quantify lamivudine, stavudine and nevirapine combined in tablets. The separation was carried out in less than 10 min using a phosphate buffer of pH 3.0 and acetonitrile (75:25, v/v) as mobile phase, a LiChrospher ODS column and UV detection at 266 nm. The method was linear over the range of 15-135 µg/mL (lamivudine), 4-36 µg/mL (stavudine) and 20-180 µg/mL (nevirapine). The accuracy ranged from 98.56 to 102.04% and intra-day and inter-day precision was less than 1% for the three drugs. The method showed robustness, remaining unaffected by deliberate variations in relevant parameters.

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.

Comparison of GC and HPLC for quantification of organic acids in two jaboticaba (Myrciaria) fruit varieties

Gas chromatography (GC) with trimethylsilyl derivative formation was compared to high-performance liquid chromatography (HPLC) for quantification of organic acids (OAs) in two jaboticaba (Myrciaria) fruit (pulp and pericarp) varieties (Sabará and Açu Paulista). Succinic and citric acids were the major OAs found in all the samples analyzed. Besides being much more tedious, the results obtained with GC were significantly lower than HPLC (p<0.05) when the data (acids, variety, two parts and flowering days) were considered together. The presence of both acids was confirmed by gas chromatography-mass spectrometry (GC-MS).

Determinação da espessura da camada polimérica de fases estacionárias imobilizadas para cromatografia líquida de alta eficiência por termogravimetria

This paper presents a simple and practical thermogravimetric method for determining the layer thickness of immobilized polymer stationary phases used in reversed-phase high-performance liquid chromatography. In this method, the weight loss of different polysiloxanes immobilized onto chromatographic supports, determined over the temperature range 150-650 ºC, demonstrated excellent agreement with the sum of carbon and hydrogen content obtained by elemental analysis. The results presented here suggest that the thermogravimetric procedure is an accurate and precise method to determine the polymeric material content on polymer-coated stationary phases.

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 metodologia analítica por cromatografia líquida de alta eficiência para quantificação de bupivacaína (S75-R25) em nanoesferas de poli(lactídeo-co-glicolídeo)

Bupivacaine (S75-R25, NovaBupi®) is an amide type local anesthetic widely used. The present work consists of the development and validation of analytical methodology for evaluation of NovaBupi® content in the poly-lactide-co-glycolide nanospheres (PLGA-NS) by high performance liquid chromatography. The separation was made using the reversed-phase column LC-18, acetonitrile/phosphate buffer 85:15 v/v as mobile phase and detection at 220 nm. The results obtained show that the analytical methodology is accurate, reproducible, robust and linear over the concentration range 10-220.0 g/mL of NovaBupi®. The method was applied to determine the encapsulation efficiency and evaluate the release profile of NovaBupi®, showing good results.

Desenvolvimento e validação de um método analítico rápido por cromatografia líquida de alta eficiência para determinação de nimesulida em estudos de liberação in vitro

A high performance liquid chromatography (HPLC) method has been developed for a rapid determination of nimesulide in dissolution studies. Nimesulide was analyzed using 5 µm Lichrospher® RP-18 column (125 x 4 mm i.d.) and mobile phase acetonitrile: phosphate buffer pH=6.0 (55:45) at a flow-rate of 1.0 mL min-1. Detection was carried out at 300 nm at 25 ºC. The method was applied to analysis of nimesulide in in vitro release studies and showed a rapid and efficient analytical alternative for evaluation of dissolution profile of nimesulide.

O estado da arte da cromatografia líquida de ultra eficiência

Ultra Performance Liquid Chromatography (UPLC) retains the same principles as High Performance Liquid Chromatography (HPLC), but uses 1-2.1 mm i.d. columns with sub-2 µm particles. It is considered the newest advance in analytical separation science. The use of these small particles with mobile phases at high linear velocities increases resolution and detectability and decreases analysis time. Thus, the analyses are faster, the solvent volume is smaller, the efficiency is higher and the detectability is 2-3 times higher when compared with HPLC analysis.