Environmental analysis of organic compounds in water using solid phase micro extraction

Abstract

SummarySolid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph.The fiber is contained in a syringe to facilitate handling.Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples.The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross-shaped stirrer bar.Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from -40 to -15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water samples.

Aplicação de SPME (Solid Phase Micro-Extraction) na análise de águas potáveis de três localidades do estado de São Paulo

“…Entre os estudos relatados na literatura encontram-se os de análises dos THM a níveis de pg.L -1 , que são comparáveis a detecções obtidas com técnicas convencionais 1 . Devido às características da técnica de SPME, extração sem solvente 2 , transferência direta, imediata e simplificada dos analitos para o cromatógrafo gasoso 2 e simplicidade de uso, tanto para amostragem no "headspace", quanto diretamente na matriz aquosa (desde que não exista suspensão de materiais que possam contaminar ou danificar a fibra) 3,4,5 , no nosso grupo de pesquisa estamos investindo esforços para sua implementação.…”

Extraction and analysis of polycyclic aromatic hydrocarbons (PAHs) by solid phase micro-extraction/supercritical fluid chromatography (SPME/SFC)

“…The adsorbant is a fiber glued into a stainless steel plunger, inserted into a holder. When a vial is traited, the plunger is pulled back, drawing the fiber into the needle of the holder.The fiber is either outside the needle during the adsorption or the desorption steps, or inside the needle when the needle is introduced or drawn out the vial piercing the septum or from the split/splitless injector.The fiber can be placed into the gazeous phase above the samples, which corresponds to the head space SPME extraction [6-9], or into the liquid sample, which corresponds to direct SPME [3][4][5]. These two SPME methods are complementary one from another, the first one concentrating the volatile componds (the BTEX for instance), and the second one the less volatile (chloro-phenols, pesticides).…”

“…SPME is also based on the use of an adsorbant to concentrate compounds contained in liquid or solid samples. The sample is put into a hermetical closed vial [3][4][5][6][7], whose volume goes from 10 to 30 mL. Generally, a gazeous phase stays above a known volume of sample.…”

“…The fiber can be placed into the gazeous phase above the samples, which corresponds to the head space SPME extraction [6-9], or into the liquid sample, which corresponds to direct SPME [3][4][5]. These two SPME methods are complementary one from another, the first one concentrating the volatile componds (the BTEX for instance), and the second one the less volatile (chloro-phenols, pesticides).…”

Padronização e validação do método extração sortiva em barra de agitação e cromatografia líquida de alta eficiência (SBSE/HPLC) para a determinação de antidepressivos em amostras de plasma

“…45 Para compostos muito apolares ocorrerá a distribuição dos analitos entre a fase aquosa, a fase extratora da fibra de SPME, a parede de vidro do frasco de extração, e a superfície do politetrafluoroetileno da barra magnética usada para agitar as amostras. Conseqüentemente, a sensibilidade analítica é aumentada de 50 a 250 vezes.…”