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 ...

This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating ...

The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a micro...

The paper proposes a simple and sensitive approach for the preconcentration and determination of graphene oxide (GO) in environmental samples by using fluorescent graphene quantum dots (GQDs). The method is based on the preconcentration of GO on a cellulose membrane and their subsequent elution prior to fluorescence analysis of the quenching effect produced on the GQD solution due to the hydrop...

We report on the systematic investigation of electropreconcentration phenomena in hybrid micro/nanofluidic devices. The competition between the electroosmotic dragging force and the highly nonlinear electrophoretic forces induced by the polarization effect is responsible for four preconcentration regimes within such structures that can arise at both cathodic and anodic sides of the nanochannel....

Solid-phase extraction (SPE) is an effective tool for the preconcentration of trace elements and their separation from various sample constituents. Octadecyl and other alkyl-bonded silica gels are most widely used for these purposes. The fundamentals of the SPE of inorganic ions are reviewed and compared with those of related techniques (liquid-liquid extraction and reversed-phase liquid chroma...

in this research, nanoporous silica (sba-15) was physically functionalized using2-(2-nitrobenzylideneamino) guanidine compound. this functionalized sba-15 was utilized as a new sorbentfor separation and preconcentration of some lanthanide ions. inductively coupled plasma optical emissionspectrometry (icp-oes) was used as a detection technique. the preconcentration factor of the method is 100and...

Preconcentration of Cd in water has been carried out using Dowex 50WX2-200 resin as a solid phase extractor. The extraction process was with sonicator. Elution which adsorbed by the released again 1M HNO3, then measured Flame-Atomic Absorption Spectrophotometer. In this study, effects pH, sample solutian sonication time, elution time and eluent volume were studied. results optimization preconce...

In the last years, a growing number of fields such as air quality monitoring, breath analysis or explosives and chemical warfare agents detection requiring fast, on-site, sensitive has led to development portable gas chromatography systems. most cases, these systems integrate miniaturized preconcentrator, which provides significant enhancement sensitivity enabling quantification analytes presen...

In this paper we present a radial sample preconcentration strategy enabled by axisymmetric concentration polarization in a microfluidic chamber on a uniform nanoporous film. Sample analytes are focused into the centre, creating a concentrated plug that is injected vertically into the microfluidic analysis layer. No balancing pressure driven flows or tangential fields are required, and the proce...