Integrated plastic microftuidic devices with ESI-MS for drug screening andresidue analysis

For this work, two different plastic microfluidic devices are designed and fabricated for applications in throughput residue analysis of food contamin ants and drug screening of small-molecule libraries. Microfluidic networks on copolyester and poly(dimethylsiloxane) substrates are fabricated by sili con template imprinting and capillary molding techniques. The first device is developed to perform affinity capture, concentration, and direct identif ication of targeted compounds using electrospray ionization mass spectromet ry. Poly(vinylidene fluoride) membranes sandwiched between the imprinted co polyester microchannels in an integrated platform preside continuous affini ty dialysis and concentration of a reaction mix-lure containing aflatoxin B -1 antibody and aflatoxins. The second microfluidic device is composed of m icrochannels on the poly(dimethylsiloxane) substrates, The device is design ed to perform miniaturized ultrafiltration of affinity complexes of phenoba rbital antibody and barbiturates, including the sequential loading, washing , and dissociation steps, These microfabricated devices not only significan tly reduce dead volume and sample consumption but also increase the detecti on sensitivity by at least 1 - 2 orders of magnitude over those reported pr eviously. Improvements in detection sensitivity are attributed to analyte p reconcentration during the affinity purification step, limited analyte dilu tion in the microdialysis junction, minimal sample loss, and the amenabilit y of ESI-MS to nanoscale sample floss rates.