Coupling Single-Drop Microextraction with SERS: A Demonstration Using p-MBA on Gold Nanohole Array Substrate.

Single-drop microextraction (SDME) was coupled with surface-enhanced Raman scattering (SERS) to provide sample extraction and pre-concentration for detection of analyte at low concentrations. A gold nanohole array substrate (AuNHAS), fabricated by interference lithography, was used as SERS substrate and para-mercaptobenzoic acid (p-MBA) was tested as a probe molecule, in the concentration range 10-10 mol L. With this approach, a limit of 10 mol L was clearly detected.

Measurement of cation binding to immobilized vanillin by isothermal calorimetry.

Isothermal calorimetry was used to determine enthalpy changes for interaction of divalent cobalt, nickel, copper, and zinc chlorides with silica gel functionalized with vanillin, Sil-Van. The thermal effect, Q(int), and the corresponding amount of cation that interacts, n(int), were obtained in the same experiment. Langmuir expressions for adsorption isotherms were applied to determine the maximum adsorption capacity to form a monolayer, N(mon), and the energy of interaction for a saturated monolayer per gram of Sil-Van, Q(mon).