M icrow ave assisting the addition reaction of Wang resin bound secondary a mine 1 and isocyanatew as carried out for the first time. The reaction time coursew as determ ined by analyzing FT IR spect raob tained using the improved KB rpellet method by grinding down the resin beads priorto recording. The resu It s show ed that the react ion assisted by m icrow ave was accomp lished only in 12min, while the reaction without microw ave was completed in 210min.

of 0.01-50% v/v HCl, its sorption onto the surface of the PTFE fiber in the microcolumn, elution with 3% m/v KBH4 in 0.5% m/v KOH, hydride generation with 15% v/v HCl solution and determination with atomic fluorescence spectrometry. The alkaline KBH4 solution was employed not only as an efficient eluent but also as the reductant to produce selenide anion for subsequent hydride generation. With a consumption of 12.4ml of sample solution, a detection limit (3δ) of 4ng l-1 was achieved at a sample throughput of 26 samples h-1. The retention efficiency was 67%, being five times that obtained with a PTFE knotted reactor (KR). The linear ranges of the diagrams of signal intensity against sample loading flow rate, and sample loading time, were much wider than those achieved with a KR, offering more potential for obtaining high sensitivity by increasing sample loading rates and/or sample loading time. The precision for 11 replicate measurements of 0.5µg l-1 Se (IV) was 1.5% (RSD). The recoveries of Se (IV) from natural water samples varied from 96 to 108%. The concentration of Se (IV) in a certified reference material (NASS-5, sea-water) determined by the present method with a simple aqueous standard curve calibration was in good agreement with the certified value. The developed method was also successfully applied to the detection of Se (IV) in local river water, lake water and sea-water samples.

In this work, acrylic acid grafted PTFE fibers were prepared as a new packing material for flow injection (FI) on-line microcolumn preconcentration coupled with flame atomic absorption spectrometry (FAAS) for determination of trace lead and cadmium in environmental and biological samples. Effective preconcentration of trace cadmium and lead was achieved in a pH range of 3.5-6.5 on a microcolumn packed with the developed new packing material. The retained lead and cadmium were efficiently eluted, respectively, with 1.0mol/l HNO3 and 0.5mol/l HCl for on-line FAAS determination. The developed sorbent exhibited fairly fast kinetics for the adsorption of Pb (II) and Cd (II), permitting the use of high sample flow rates up to at least 10.8ml/min for the FI on-line microcolumn preconcentration system without loss of the retention efficiency. With a preconcentration time of 45 s at a sample loading flow rate of 10ml/min, the enhancement factor was found to be 49 for Pb and 73 for Cd at a sample throughput of 55h−1. The detection limits (3σ) was 0.26 and 0.10μg/l for Pb and Cd, respectively. The precision (RSD) for 11 replicate measurements was 1.9% at the 25μg/l Pb level, and 0.9% at the 10μg/l Cd level. The developed method was successfully applied to the determination of trace Pb and Cd in a variety of environmental and biological samples.

A general method for the solid phase synthesis of hydro-uracils and thiouracils is described. Resino ester 2 reacts with various primary amines to give secondary amines 3, which are converted to the resino ureas (thioureas) 4 by treatment with isocyanates (isothiocyanates). Prepa-ration of the hydro-uracils and thiouracils 5 is achieved by acidic cyclization-cleavage from the resin. The synthesis is designed to be amenable for structure based library approach to photosys-tem II D1 protein inhibitors.

The polytetrafluoroethylene fiber grafted acrylic acid was used as a cation exchanger. The exchange capacity of the cation fiber is 3.06mmol/g. The maximum Cu2+ adsorption capacity is 107.48mg/g. It could be desorbed completely by 1mol/L HCl.