Nanoliter titration based on piezoelectric drop-on-demand technology and laser-induced fluorescence detection

An automated technique for fast acid-base titration of 9-nL sample volumes has been developed, based on the use of piezoelectrically driven pipets and laser-induced waveguide fluorescence detection. As an example, a standard titration of a H2SO4 solution with NaOH was examined by utilizing fluorescein as an: indicator. The technique had reproducibility in quantitative determination on the order of 1%. The technique allows hundreds of individually executed unattended titrations to be performed in a few hours on an area less than 3 cm(2). The lowest amount of acid titrated was similar to 670 fmol.