A multi-residue method to determine fi ve groups of 85 pesticides chlorinated, carbamate, phosphorous, pyrethroid and others in vegetables, fruits and green tea has been developed using stir bar sorptive extraction (SBSE) coupled to thermal desorption and retention time locked (RTL) GC-MS. Pre-extraction with methanol and dilution with water prior to SBSE (60 min) were performed. Dilution of me...

Steady, Darcian, 1-D, 1-phase evaporation through a vertically inhomogeneous soil from a horizontal water table is simulated as an optimal control problem, i.e. the hydraulic properties of the porous medium (relative permeability of moisture and capillary water retention curve) are considered as control functions. The Richards nonlinear ordinary differential equation is integrated twice as a bo...

For decades it has been known that the olfactory sensory epithelium can act like a chromatograph, separating odorants based on their air-mucus sorptive properties (Mozell and Jagodowicz, 1973). It has been hypothesized that animals could take advantage of this property, modulating sniffing behavior to manipulate airflow and thereby directing odorant molecules to the portions of the olfactory ep...

Two extraction techniques that avoid solvent consumption and cut down the sample preparation to a minimum Solid Phase MicroExtraction (SPME) and Stir Bar Sorptive Extraction (SBSE) – were compared on the basis of their reproducibility and sensitivity for 16 US EPA PAH compounds. Theoretical calculations indicated nearly quantitative recovery of all compounds under consideration except naphthale...

This paper describes the initial investigation of PCB concentrations in four geographical regions (three on the Pacific and one in the Caribbean) of coastal Costa Rica: Bahia Culebra, Golfo Dulce, Golfo de Nicoya, and Limón. Overall total concentrations of PCB were low in all areas except around the port of Golfito (Golfo Dulce). Overall average concentration is 2.80 ng/g dw, with a standard de...

In the context of prevalence of high concentrations of arsenic in tubewell water, a wide range technologies has been tried for the removal of arsenic from drinking water. The most common technologies utilized the conventional processes of oxidation, co-precipitation and adsorption onto coagulated flocs, adsorption onto sorptive media, ion exchange and membrane techniques for arsenic removal. Th...