Pilot Projects

Title: Improved Analytic Methods for Arsenic Speciation and beta-carboline

Investigator: Wei Zheng, PhD

Description: The purpose of the pilot is to improve the analytical methods for arsenic speciation, beta-carboline quantitation, and homocysteine detection.  For the arsenic speciation study, the investigators will fine-tune the methodology by (1) exploring the precision and accuracy of the method, (2) by conducting a stability study to see if the storage of samples affects analytical outcomes, and (3) by measuring real samples to verify the practical applications of this method for the long-term arsenic research. For the beta-carboline study, improved sensitivity will be developed.  Currently, the method requires at least 12 ml of human blood. Two approaches will be taken, decrease the volumes in the extraction procedure and minimize sample loss during the evaporation process.  Rat blood will be used to determine if these approaches will improve this method.  The investigators also plan to develop an HPLC method to determine homocysteine, a thiol-containing amino acid derived from the metabolism of methionine. A labile sulfhydryl group in the structure renders the molecule susceptible to oxidation by formation of the disulfide homocystine, the mixed disulfide homocysteine-cysteine, or conjugates with other proteins.  Thus, stabilization of the sulfhydryl group during the assay is key for reliable estimation of homocysteine in biological matrices.  The thiol-labeling reagent monobromobimane (mBBr) was previously used to determine the dithiol chelating compound dimercaptosuccinic acid in urine.  Based on this experience, mBBr derivatization will be tested for its ability to covalently bind to thiol groups and thus prohibit further autooxidation of sulfhydryl groups.