Docosahexaenoic acid (DHA) is an n-3 polyunsaturated fatty acid that is highly enriched in the brain, and the oxidation products of DHA are present or increased during neurodegenerative disease progression. The characterization of the oxidation products of DHA is critical to understanding the roles that these products play in the development of such diseases. In this study, we developed a sensitive and specific analytical tool for the detection and quantification of twelve major DHA hydroperoxide (HpDoHE) and hydroxide (HDoHE) isomers (isomers at positions 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19 and 20) in biological systems. In this study, HpDoHE were synthesized by photooxidation, and the corresponding hydroxides were obtained by reduction with NaBH4. The isolated isomers were characterized by LC-MS/MS, and unique and specific fragment ions were chosen to construct a selected reaction monitoring (SRM) method for the targeted quantitative analysis of each HpDoHE and HDoHE isomer. The detection limits for the LC-MS/MS-SRM assay were 1−670 pg for HpDoHE and 0.5−8.5 pg for HDoHE injected onto a column. Using this method, it was possible to detect the basal levels of HDoHE isomers in both rat plasma and brain samples. Therefore, the developed LC-MS/MS-SRM can be used as an important tool to identify and quantify the hydro(pero)xy derivatives of DHA in biological system and may be helpful for the oxidative lipidomic studies.

This work aimed to propose two analytical methods for the quantitative and qualitative analysis of major anthocyanins and non-anthocyanin phenolic compounds in jussara () extracts, using ultra performance liquid chromatography-mass spectrometry. These methods were evaluated for selectivity, precision, linearity, detection and quantification limits. The complete separation of 5 anthocyanins and 22 non-anthocyanins polyphenols was achieved in 4.5 and 7 min, respectively. Limits of detection ranged from 0.55 to 9.24 µg/L, with relative standard deviation for concentration up to 7.0%. In jussara extract, 13 of the 27 analytes were characterized. The dominant compound was cyanidin-3-O-rutinoside, representing about 73% of the total phenolic compounds content (approximately 23 mg/g of extract in dry weight). Other phenolic compounds found in the extract were: cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, quercetin, rutin, myricetin, kaempferol, kaempferol-3-O-rutinoside, luteolin, apigenin, catechin, ellagic acid and 4,5-dicaffeoylquinic acid.

Recebido em 26/3/12; aceito em 17/7/12; publicado na web em 7/12/12 A sensitive, accurate and simple method using HPLC-MS/MS was developed and validated for levodopa quantitation in human plasma. Analysis was achieved on a pursuit ® C18 analytical column (5 µm; 150 x 4.6 mm i.d.) using a mobile phase (methanol and water , 90:10, v/v) containing formic acid 0.5% v/v, after extracting the samples using a simple protein plasma precipitation with perchloric acid. The developed method was validated in accordance with ANVISA guidelines and was successfully applied to a bioequivalence study in 60 healthy volunteers demonstrating the feasibility and reliability of the proposed method.

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A técnica de cromatografia líquida acoplada a um espectrômetro de massas com ionização "electrospray" (LC-ESI-MS/MS) foi usada para a determinação simultânea de resíduos de dez sulfonamidas (SAs: sulfacetamida, sulfatiazol, sulfamerazina, sulfametazina, sulfametoxipiridazina, sulfametazol, sulfacloropiridazina, sulfametoxazol, sulfadimetoxina e sulfaquinoxalina) em ovos. As amostras foram preparadas por precipitação das proteínas com acetonitrila seguida por extração em fase sólida. Após remoção do solvente e reconstituição, os extratos finais foram injetados no LC-ESI-MS/MS no modo positivo para todas as sulfonamidas. O método validado resultou em recuperação entre 87 e 116% com desvios padrão relativo entre 8,5 e 27,2%, CCa entre 101,0 e 122,1 ng g -1 e CCb entre 114,5 e 138,8 ng g -1 . O método analítico, no qual foram utilizadas amostras fortificadas, foi validado baseado na Decisão da Comissão 2002/657/CE.Liquid chromatography-electrospray ionization -tandem mass spectrometry (LC-ESI-MS/MS) was used to simultaneous determination of ten sulfonamide (SAs) residues (sulfacetamide, sulfathiazole, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfamethizole, sulfachloropyridazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline) in eggs. Samples were extracted with acetonitrile and the supernatants were cleaned up by solid phase extraction. After solvent evaporation and reconstitution, aliquots of the final extracts were injected into a LC-ESI-MS/MS in positive mode for all sulfonamides. The validated method resulted in recoveries ranging between 87 and 116% with relative standard deviations between 8.5 and 27.2%, CCa between 101.0 and 122.1 ng g -1 , and CCb between 114.5 and 138.8 ng g -1 . The analytical method, using fortified samples, was validated based on the Commission Decision 2002/657/EC.