Sistema limpo em linha para extração em fase sólida de contaminantes emergentes em águas naturais

A solid-phase in-line extraction system for water samples containing low levels of emerging contaminants is described. The system was specially developed for large volume samples (up to 4 L) using commercial solid-phase extraction (SPE) cartridges. Four sets containing PTFE-made connectors, brass adapters and ball valves were used to fit SPE cartridges and sample bottles to a 4-port manifold attached to a 20 L carboy. A lab-made vacuum device was connected to the manifold cap. The apparatus is robust and less expensive than the typical available system. Its also provides less experimental handling, avoiding cross contamination and sample losses.

Caracterização de contaminantes presentes em sistemas de tratamento de esgotos, por cromatografia líquida acoplada à espectrometria de massas tandem em alta resolução

This work shows results on the characterization, by liquid chromatography coupled to high resolution tandem mass spectrometry (LC-IT-TOF-MS) with electrospray ionization, of organic compounds present in raw and treated effluents from a combined sewage treatment systems (upflow anaerobic sludge blanket-trickling filter). The sewage samples were prepared by C18 solid phase extraction and the spectra obtained from the various extracts were submitted to principal component analysis to evaluate their pattern and identify the major deprotonated species. Some target compounds were submitted to semiquantitative analysis, using phenolphtalein as internal standard. The results showed the anaerobic step had little impact on the removal of anionic surfactants (LAS), fatty acids, and some contaminantes such as bisphenol A and bezafibrate, whereas the aerobic post-treatment was very efficient in removing these organics.

MSPD procedure combined with GC-MS for the determination of procymidone, bifenthrin, malathion and pirimicarb in honey

A method based on matrix solid-phase dispersion and gas chromatography-mass spectrometry to determine procymidone, malathion, bifenthrin and pirimicarb in honey is described. The best results were obtained using 1.0 g of honey, 1.0 g of silica-gel as dispersant sorbent and acetonitrile as eluting solvent. The method was validated by fortified honey samples at three concentration levels (0.2, 0.5 to 1.0 mg kg-1). Average recoveries (n=7) ranged from 54 to 84%, with relative standard deviations between 3.7 and 8.5%. Detection and quantification limits attained by the developed method ranged from 0.02 to 0.08 mg kg-1 and 0.07 to 0.25 mg kg-1 for the honey, respectively.

Alternativas verdes para o preparo de amostra e determinação de poluentes fenólicos em água

The restricted availability of water sources suitable for consumption and high costs for obtaining potable water has caused an increase of the conscience concerning the use. Thus, there is a high demand for "environmentally safe methods" which are according to the principles of Green Chemistry. Moreover, these methods should be able to provide reliable results for the analysis of water quality for various pollutants, such as phenol. In this work, greener alternatives for sample preparation for phenol determination in aqueous matrices are presented, which include: liquid phase microextraction, solid phase microextraction, flow analysis, cloud point extraction and aqueous two-phase systems.

Desenvolvimento de metodologia para determinação de piretroides em manteiga

The objective of this study was to evaluate the use of the matrix solid-phase dispersion technique associated with purification at low temperature for the determination of pyrethroids in butter. Evaluated parameters included: sample/adsorbent ratio, type of adsorbent and extractor solvent. The optimized method was validated based on predetermined requirements. The detection limits of the pyrethroids cypermethrin and deltamethrin were 0.082 and 0.11 μg g-1, and quantification limit were 0.28 and 0.32 μg g-1, respectively, with extraction percentages near 90% and coefficients of variation less than of 10%..

Determinação seletiva de tributilestanho na presença de Sn(IV) em amostras ambientais usando HG-ICP OES e Saccharomyces cerevisiae como material sorvente

A method for selective determination of tributyltin in the presence of Sn(IV) by combining hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP OES) and solid phase extraction (SPE) using baker's yeast is proposed. The procedure is based on selective retention of TBT by the yeast at pH = 6. Detection limit of 1.9 µg L-1 and quantification limit of 6.3 µg L-1 were obtained. TBT and San(IV) were determined in the range of 0-25 µg L-1 and the proposed approach was applied to analyze river water, sea water and biological extracts, with recoveries of 114, 101 and 86%, respectively.

Determinação de hormônios estrógenos em água potável usando CLAE-DAD

An analytical procedure for determination of estriol, 17β-estradiol, estrone and 17α-ethinylestradiol in drinking water is presented. The method employs solid phase extraction (SPE) and sample dechlorination as cleanup procedures, followed by HPLC-DAD analysis. Validation was carried out using RE No. 899/2003 guidelines established by the Agência Nacional de Vigilância Sanitária (National Agency of Sanitary Surveillance, Brazil), with some adaptations. The statistically evaluated results have shown that the method is selective, precise (0,06% to 19,40% CV) and accurate (91,52% to 109,41% average recoveries). The developed method was applied to the analysis of these contaminants in drinking water from São Luís, MA.

Uso de perfis cromatográficos de voláteis de cafés arábicas torrados para a diferenciação das amostras segundo o sabor, o aroma e a qualidade global da bebida

In this work, the volatile chromatographic profiles of roasted Arabica coffees, previously analyzed for their sensorial attributes, were explored by principal component analysis. The volatile extraction technique used was the solid phase microextraction. The correlation optimized warping algorithm was used to align the gas chromatographic profiles. Fifty four compounds were found to be related to the sensorial attributes investigated. The volatiles pyrrole, 1-methyl-pyrrole, cyclopentanone, dihydro-2-methyl-3-furanone, furfural, 2-ethyl-5-methyl-pyrazine, 2-etenyl-n-methyl-pyrazine, 5-methyl-2-propionyl-furan compounds were important for the differentiation of coffee beverage according to the flavour, cleanliness and overall quality. Two figures of merit, sensitivity and specificity (or selectivity), were used to interpret the sensory attributes studied.

Aplicação de métodos quimiométricos na caracterização de charutos utilizando extração por dispersão da matriz em fase sólida e análise por cromatografia gasosa acoplada à espectrometria de massas

In this work, the organic compounds of cigar samples from different brands were analyzed. The compound extraction was made using the matrix solid-phase dispersion (MSPD) technique, followed by gas chromatography and identification by mass spectrometry (GC-MS) and standards, when available. Thirty eight organic compounds were found in seven different brands. Finally, with the objective of characterizing and discriminating the cigar samples, multivariate statistical analyses were applied to data, e.g.; principal component analysis (PCA) and hierarchical cluster analysis (HCA). With such analyses, it was possible to discriminate three main groups of three quality levels.

Desenvolvimento de métodos de análise por CLAE-UV para os antimicrobianos tetraciclina, sulfametoxazol e trimetoprima utilizando materiais à base de sílica como sistemas de pré-concentração

This paper evaluates the adsorption capacity of zirconocene-based silica materials in the pre-concentration of antimicrobians (tetracycline, sulfamethoxazole and trimethoprim) in aqueous medium. These materials were prepared by grafting the zirconocene onto silicas pre-treated at different temperatures. The retention capacity of these materials was evaluated by off line SPE and HPLC-UV and the proposed methodology was validated in ultrapure, tap and river water. The recovery for tetracycline was 72% (in the solid phase A) and, for sulfamethoxazole and trimethoprim was 68 and 95% in the commercial C18, respectively. The target antimicrobians were not detected in the Arroio Dilúvio (Porto Alegre - RS).

Determination of aluminum in food samples after preconcentration as aluminon complex on microcrystalline naphthalene by spectrophotometry

A sensitive preconcentration procedure for spectrophotometeric determination of aluminum was developed. Aluminum as aluminon complex is adsorbed on microcrystalline naphthalene. The naphthalene containing the complex is dissolved in 3 mL of acetone and its absorbance is measured at 544 nm. The effect of various factors on the preconcentration of aluminum was investigated. The calibration graph was linear in the range of 1-60 mg L-1. The limit of detection was 0.52 mg L-1 and relative standard deviation for the determination of 5 mg L-1 was 2.65%. The proposed solid phase extraction procedure was applied to determination of aluminum in food samples.

Discriminação entre estádios de maturação e tipos de processamento de pós-colheita de cafés arábica por microextração em fase sólida e análise de componentes principais

A fruit chemical composition reflects its maturation stage. For coffee, it is also the reflex of the post-harvesting processing type, dry, semi-wet and wet. The object of this work was to verify if headspace solid phase microextraction coupled to gas chromatography (HS-SPME-GC) could be used to discriminate between samples harvested in different maturation stages and treated by different processes. With application of principal component analysis to the area of 117 compounds extracted by SPME, using divinylbenzene/Carboxen/polydimethylsiloxane fiber, it was possible to discriminate, in the roasted and ground coffee, the maturity stage and processing type used .

Análise de pesticidas organoclorados em água usando a microextração em fase sólida por headspace com cromatografia gasosa e espectrometria de massas

A method based on headspace - solid phase microextraction coupled with gas chromatography - mass spectrometry was validated for the quantitative determination of 18 organochlorine pesticides in water. For the extraction conditioning some parameters as the best type of coating fiber, time and temperature of extraction, pH and ionic strength were evaluated. The method HS-SPME/GC-MS/MS showed linear coefficient above 0.9948. The repeatability of the measurements were lower than 7.6%. Relative recoveries were between 88 and 110%. Limits of detection from 0.5 x 10-3 to 1.0 mg L-1 were obtained. A total of 31 samples were analyzed and 16 presented from 1 to 5 pesticides.

Principais técnicas de preparo de amostra para a determinação de resíduos de agrotóxicos em água por cromatografia líquida com detecção por arranjo de diodos e por espectrometria de massas

The determination of pesticide residues in water samples by Liquid Chromatography require sample preparation for extraction and enrichment of the analytes with the minimization of interferences to achieve adequate detection limits. The Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Dispersive Liquid-Liquid Microextraction (DLLME) techniques have been widely used for extraction of pesticides in water. In this review, the principles of these sample preparation techniques associated with the analysis by Liquid Chromatography with Diode Array Detection (LC-DAD) or Mass Spectrometry (LC-MS) are described and an overview of several applications were presented and discussed.

Determinação de bifenilos policlorados em milho através de extração em fase sólida seguida de cromatografia a gás acoplada à espectrometria de massas

This paper describes an analytical method for analyzing polychlorinated biphenyls in corn samples using solid phase extraction (SPE) followed by determination by GC-MS. All calibration curves proved linear (r> 0.99). Recoveries ranged between 74.1 and 110.6% with relative standard deviation lower than 20% for all compounds. The limits of quantitation for the method were between 0.025 and 0.1 ng g-1. Of the 51 samples analyzed, PCB 180 showed the highest frequency, being detected in more than 39%, followed by PCB 138, detected in more than 33% of samples.