In this short review article, we discuss the significant progresses, which have been made in bacterial entrapment techniques over the past decade. Recently, the biocompatibility of conducting polymers as well as the straightforwardness in their preparation has focused more attention on this technique. The key feature of the technique is that bacteria-doped films can be prepared by a single-step electrochemical polymerization, due to the negative surface charges carried by bacteria. We have also included the results of a literature survey on bacterial imprinted polymers, which possess cavities complementary to the imprinted bacteria. Sensory devices using these polymer films will provide a new technology for FIA detectors.
Sequential injection system (SI system) was used for the pretreatment of a carbon electrode in an anodic stripping voltammetry (ASV) for the determination of arsenic (III). In this research, a screen-printed carbon electrode (SPCE) was used; SPCE was prepared in our laboratory by us. In ASV, SPCE was chosen as a working electrode because SPCE is less expensive, easy to use for a flow cell and suitable for thin-film modification method. ASV parameters were optimized with a handy-type potentiostat. The proposed method is one of alternatives for the determination of arsenic (III), which is fast, accurate and precise method with less expensive automated system.
Many spectrophotometric methods by FIA have been reported in the literature, which are based on the reaction of fluoride with lanthanum alizarin. In those methods, acetone was added to the reagent solution to enhance sensitivity. But, it is preferable to avoid the addition of acetone in the system with a peristaltic pump. In this study, the chemical factors and FIA variables influencing color development were examined using an alfusone reagent solution without acetone and a compact manifold, which consists of an all-in-one peristaltic pump, injector, thermostat and photometric detector. The absorbance was measured at 620 nm. The constant and maximum absorbance was obtained at a flow rate of 0.51 mL/min and a reaction temperature of 60°C, when alfusone solution (6 g/L) containing fluoride (0.6 mg/L) was used as the reagent solution. Under optimum conditions, with 400μL sample injection the calibration graph was linear from 0.008 to 0.8 mg/L of fluoride. The relative standard deviation was ca.4 % ( ｎ = 5) at the 0.008 mg/L level.
An open-tubular capillary chromatography is developed based on tube radial distribution of the ternary mixed carrier solvents of water-hydrophilic/hydrophobic organic under laminar flow conditions. This is called “tube radial distribution chromatography” (TRDC). Fluidic behavior of the polymer compounds, FluoSpheres (1.0 m diameter), was examined by the TRDC system. The ternary mixture of water-acetonitrile-ethyl acetate, 15:3:2 (water-rich) or 3:8:4 (organic solvent-rich) volume ratio, as a carrier solution was fed into the fused-silica capillary tube under laminar flow conditions. The peak of the FluoSpheres appeared with the apex at the maximum linear velocity and the slope of the non-Gaussian peak did not last longer than the elution time at the average linear velocity with the water-rich carrier solution. With the organic solvent-rich carrier solution FluoSpheres was eluted at near the average linear velocity.
A successive determination of cationic and nonionic surfactants using sequential injection lab-at-valve (SI-LAV) micro solvent extraction has been developed. The method is based on ion association formation between cationic and/or K+-nonionic surfactant with tetrabromophenolphthalein ethyl ester (TBPE•H). The blue associate is extracted quickly into 1,2-dichloroethane (DCE) in an extraction coil which is set in a SI-LAV manifold. The segments are dispensed to a pipette tip (like a miniature separation funnel) fitted onto a port of a multi-position valve. This leads to the separation of the aqueous and organic phases. Absorbance of the DCE phase (the bottom part in the pipette tip) can be measured at 610 nm via optic fibers. Without the addition of KCl, absorbance of cationic surfactant can be obtained, while with adding KCl, absorbance of nonionic surfactants can be obtained. The proposed method provides an automated, novel, simple and economical strategy for simultaneous determination of cationic and nonionic surfactants without a membrane separator.