George M. Murray

Polymer based lanthanide luminescent sensors for the detection of nerve agents

Several devices are being constructed to measure and detect the nerve nagents Sarin and Soman. The devices function by selectively binding the nphosphonate hydrolysis products to a luminescent functionality-imprinted ncopolymer. The copolymers possess a securely bound luminescent lanthanide nion, such as Eu n 3 n n + n, in a coordination complex that nhas been templated for the chemical functionality resulting from the nhydrolysis of Sarin and Soman but has had a weakly bound anion substituted nby mass action. The instrumental support for the device is being designed nto monitor the change that occurs in the luminescence spectrum of the nlanthanide when the analyte is coordinated. The ligand field shifted nluminescence of the lanthanide is excited by a compact laser and monitored nvia optical fiber by either a filter photometer or a nmonochromator. Miniaturization will be applied to each of the lab bench ncomponents to produce a field portable device that will potentially be ncomparable in size to a pH meter. Initial results using an Ar ion laser nexcitation source providing 0.3 mW at 465.7 nm yield a limit of detection nof 125 ppt. The chemical and spectroscopic selectivity of this device are nbeing combined to reduce the likelihood of false positive analyses.

Imprinted polymer sensors for contamination detection

Molecular imprinting is a useful technique for making a chemically selective binding site. The method involves building a synthetic polymeric scaffold of molecular complements containing the target molecule with subsequent removal of the target to leave a cavity with a structural memory of the target. Molecularly imprinted polymers can be employed as selective adsorbents of specific molecules or molecular functional groups. The imprinted polymers can be fashioned into membranes that can be used to form ion selective electrodes for an imprinted ion. By incorporating molecules or metal ions with useful optical properties in the binding sites of imprinted polymers, spectroscopic sensors for the imprinted molecule may be made. A variety of metal ion selective electrodes and a Pb2+ ion optrode based on imprinted polymers have been fabricated and tested.1-4 Additionally, a sensor for the hydrolysis product of the nerve agent Soman has been developed using a luminescent lanthanide ion, Eu(III), as optical transducer.5 Our research continues to explore other means to employ electrochemical and optical transduction.