title: Experimental setup for the determination of analytes contained in ultrasonically levitated drops.
abstract: An automated technique for the determination of analytes in an ultrasonically levitated sample of 2 to 5 microL volume has been developed. Contactless dosing of reagents or solvents into an ultrasonically levitated drop was realized via piezoelectric micropumps. Drop size was continually controlled with a programmed CCD camera. A diode array spectrometer designed for the use with optical fibers was used for absorption and fluorescence measurements. Determinations via direct absorption measurements following the method of standard addition and acid-base titrations with an absorption indicator and a fluorescent indicator were carried out. The mean consumption of sodium hydroxide added via a piezoelectric micropump in five successive titrations with 18 nmol of sulfuric acid inside a levitated drop (indicator bromothymol blue) had a relative standard deviation of 0.7% and differed only by 0.2% from the expected value.
authors.affiliation: Institut für Physikalische und Chemische Analytik, GKSS-Forschungszentrum Geesthacht GmbH, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Rohling
authors.forename: C
authors.initials: C
authors.lastname: Weitkamp
authors.forename: B
authors.initials: B
authors.lastname: Neidhart