COMPARISON OF SPUTTER-INITIATED RESONANCE IONIZATION SPECTROSCOPY AND LASER ATOMIZATION RESONANCE IONIZATION SPECTROSCOPY TO LOCALIZE TIN-LABELED DEOXYRIBOSE NUCLEIC-ACID

Resonance ionization spectroscopy (RIS) is becoming recognized as an emerging field with wide applications. RIS is an analytical technique providing extreme element sensitivity and selectivity by detecting ionization produced from lasers tuned to excited states of the analyte. Using either sputter-initiated RIS (SIRIS) or laser atomization RIS (LARIS), it is possible to localize and quantify with micrometer spatial resolution ultratrace concentrations of a selected element at or near the surface of solid samples. The sensitivity and selectivity of the RIS process is especially valuable for trace element analysis in biological media, where the complexity of the matrix is frequently a serious source of interference. We have compared both the SIRIS and LARIS technique to determine their characteristics to localize and quantify Sn-labeled deoxyribose nucleic acid (DNA). We will present (a) data showing differences between SIRIS and LARIS response as a function of atomization parameter, substrate and analyte, and (b) the detection and resolution (spatial and isotopic) of subattomole quantities of Sn-labeled DNA bands. Both techniques have the potential of making a strong contribution to DNA sequencing.