Novos sorventes baseados em Poli(Metiloctilsiloxano) sobre sílica para uso em extração em fase sólida.

This paper presents an easy and practical procedure to obtain silica-based C-8 type sorbents for use in solid-phase extraction. The materials are prepared by depositing poly(methyloctylsiloxane), PMOS, on the silica support. Two different treatments for immobilization were used: thermal treatment or gamma irradiation. Suitable recoveries were obtained after pre-concentration of dilute solutions, at the ng/L level, of a mixture of pesticides, indicating the good performance of the materials

Development of solid-phase extraction for triazines: application to a biological sample.

A sensitive extraction method for the triazines simazine, atrazine, and ametryn was developed and applied to a biological sample (urine). After protein precipitation with acetonitrile, a further purification using solid-phase extraction (SPE) was carried out. The samples were then analysed by high performance liquid chromatography (HPLC) usina a C18 column and an acetonitrile-water (40:60, v/v) mobile phase. The pH of the mobile phase was adjusted to 9.0 with NH4OH, the flow-rate was 0.5 mL/min and UV detection was at 220 nm. Recovery values were satisfactory and the method developed can be used for monitoring urine samples of workers exposed to simazine, atrazine, and ametryn, in forensic, veterinay, and environmental toxicologies

Determination of pesticides in water by liquid chromatography-(Electrospray Ionization)-mass spectrometry (LC-ESI-MS).

A method for determination of a selected group of pesticides in water (tap and ground water) was developed using liquid chromatography-(electrospray ionization)-mass spectrometry (LC-ESI-MS). The pesticides dimethoate, carbaryl, simazine, atrazine, ametryne, tebuthiuron, diuron and linuron were isolated using liquid-liquid extraction with dichloromethane and analyzed on a reversed phase column, C-18, with gradient elution at flow rate of 1 mL. min-1. Recoveries ranged from 89% to 112% (R.S.D. <_10%) for tap water and from 76% to 98% (R.S.D <_ 6%) for ground water. The enrichment procedure, followed by use of the selected ion monitoring (SIM) mode gave quantification limits low enough to reach the international legislation level of 0.1 µg.L-1, with a 500-fold preconcentration. The method developed is practical, efficient and reliable for the determination of the selected group of pesticides in the water samples. Um método para a determinação de um grupo selecionado de resíduos de pesticidas em água (de torneira e subterrânea) foi desenvolvido usando cromatografia líquida-ionização electrospray-espectrometria de massas (LC-ESI-MS). Os pesticidas dimetoato, carbaril, simazina, atrazina, ametrina, tebutiuron, diuron e linuron foram isolados usando extração líquido-líquido com diclorometano e analisados em uma coluna de fase reversa, C-18, com eluição gradiente a uma vazão de 1 mL/min. Foram obtidas recuperações de 89 a 112% (RSD <_10%) para água de torneira e 76 a 98% (RSD <_ 6%) para água subterrânea. O procedimento de enriquecimento, seguido pelo uso do monitoramento seletivo de íons (SIM) forneceu limites de quantificação baixos o suficiente para atingir a legislação internacional (Comunidade Européia) que é de 0,1 µg/L. O método desenvolvido é prático, eficiente e confiável para a determinação do grupo selecionado dos pesticidas em amostras de água

Application of new high-performance liquid chromatography and solid-phase extraction materials to the analysis of pesticides in human urine.

A method for the simultaneous determination of diuron and linuron pesticides in human urine was developed, using both solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) phases made in our own laboratory. These materials were prepared by sorption of polysiloxanes onto a silica surface, followed by immobilization. The HPLC columns were prepared from poly(methyloctylsiloxane), PMOS, immobilized onto silica with microwave radiation while the SPE cartridges where made with poly(methyloctadecylsiloxane), immobilized thermally. Method validation was performed for diuron and linuron for three fortification levels. The recoveries obtained were 85?103%, the inter- and intra-assay precisions were less than 1.6 and 1.8%, respectively. The limits of quantitation and detection for diuron were 2.4 and 8.0 ?g/l and for linuron were 5.0 and 12 ?g/l, respectively

Métodos para a determinação de multiresíduos de agrotóxicos em produtos agrícolas.

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Systematics of Palicoureeae (Rubiaceae): recent advances in Brazilian groups

Palicoureeae (Rubiaceae) has its centre of diversity in the neotropics and comprises about 1500 species. Two genera with great diversity considering the Brazilian Flora are Palicourea Aubl. and Rudgea Salisb. with ca 170 and 70 species, respectively. These numbers are still underestimated, especially because several species of Psychotria L. subgenus Heteropsychotria Steyerm. need to be transferred to Palicourea, and there are several undescribed species of Rudgea. Some of our recent studies focused on resolving some taxonomic gaps and phylogenetic questions with these genera. Considering Palicourea, phylogenetic analyses are being conducted with sections Codonocalyx, Solenocalyx, and Suteria, which include 15 species of Atlantic Forest. The monophyly of sections is being tested using molecular markers. Considering Rudgea, we are investigating its diversity in the Northeast region of Brazil, trying to answer how many species occur in the region and how climatic changes may affect its distribution. Besides, the domatia of Rudgea are also being investigated, since these structures have an important taxonomic value, but its description is not very clear in the literature. These studies are being conducted with field work, especially in eastern Brazil, exsiccatae analyses, mostly from Brazilian herbaria, and from images of digital herbaria. The phylogenetic analyses used rps16, psbA-trnH, trnL-F, and ITS markers, and were conducted using maximum likelihood and Bayesian inference. Regarding the phylogenetic inference of Palicourea, the preliminary results showed that Codonocalyx, Solenocalyx, and Suteria do not have molecular support to be sustained as monophyletic taxa. Regarding the diversity of Rudgea, there are at least 22 (~31% of the total) species in Northeast Brazil, with 18 occurring in the state of Bahia. However, there are 12 uncertain taxa still being analysed. Finally, a new proposal to classify the domatia of Rudgea is being carried out, to accommodate variation and intermediate types of domatia. Acknowledgments: CAPES, FAPES, and FAPESP