the extraction-separation of lanthanum and europium ions with bis(2-ethylhexyl) phosphoric acid (dehpa) in cyclohexane was improved by adding 12-crown-4 (12c4) to the aqueous phase as a masking agent. in the presence of this crown ether the extraction curve of lanthanum ions versus ph shifts to the higher ph region, while the curve is not influenced for the europium ions. consequently the separ...

Recebido para publicação em 8/10/2008 Aceito para publicação em 8/7/2009 (003881) 1 Departamento de Engenharia de Alimentos, Universidade Regional Integrada do Alto Uruguai e das Missões – URI, CEP 99700-000, Erechim RS, Brasil, E-mail: [email protected] 2 Departamento de Física e Quimica, Universidade de Caxias do Sul – UCS 3 Departamento de Engenharia Química, Universidade Federal de Santa ...

this paper deals with the extraction of l-theanine containing aliquat 336 as a carrier and cyclohexane as solvent across bulk liquid membrane. the optimum operation condition are as follows: extraction time of 150 min, initial concentration of theanine in the feed phase is 1.8 g/l, the carrier concentration is 0.5 m, the ion of the receiving phase is 0.2 m nacl of na2hpo4-nah2po4 buffer solutio...

This work examines a newly developed dynamic air sampling technique, known as HighSurface Area Solid Phase Micro Extraction (HSA-SPME), in sampling and analysis of chemical warfare agent surrogate and degradation compounds. The polymer coating of this device has 10 times the surface area of commercially available SPME fibers, and at high sample flow rates (4 L·min) provided increased extraction...

In this study, a method for the determination of organic micro-pollutants, i.e. personal care products such as synthetic musk fragrances, household bactericides, organophosphate flame retardants and plasticizers, as well as phthalates in sludge, has been developed. This method is based on lyophilisation and accelerated solvent extraction followed by clean-up steps, i.e. solid phase extraction a...

We present a microfluidic device for specific extraction and thermally activated release of analytes using nucleic acid aptamers. The device primarily consists of a microchamber that is packed with aptamer-functionalized microbeads as a stationary phase, and integrated with a micro heater and temperature sensor. We demonstrate the device operation by performing the extraction of a metabolic ana...

This study proposes a novel device called micro polymeric magnetized bar adsorptive extraction (µ-PMBAE), as an and enrichment technique for trace analysis in aqueous samples. These micro-bar absorbent devices were prepared using easily accessible low-cost materials, incorporating different sorbent materials into polymer introducing small piece of neodymium magnet. Several stability tests appli...

A new fast screening method has been developed for the analysis of organochlorine pesticides in water that takes less than 10 min to perform and has detection limits of the order of 10 ng l21. Pesticide extraction was achieved by solid-phase microextraction and the separation was performed using a micro-bore (0.1 mm) capillary column. A laboratory-built cryotrap system was used to focus the ana...

A new, sensitive and fast dispersive liquid-liquid microextraction (DLLME) coupled with micro-solid phase extraction (μ-SPE) was developed for determination of zearalenone (ZEN) in wheat samples. The DLLME was performed using acetonitrile/water (80:20 v/v) as the disperser solvent and 1-octanol as the extracting solvent.  The acetonitrile/water (80:20 v/v) solvent was also used to extract ZEN f...