K. SereenonchaiP. SaetearN. AmornthammarongK. UraisinP. WilairatS. MotomizuD. NacaprichaMahidol UniversityNOAA Atlantic Oceanographic and Meteorological LaboratoryOkayama University2018-08-242018-08-242007-07-30Analytica Chimica Acta. Vol.597, No.1 (2007), 157-162000326702-s2.0-34447503853https://repository.li.mahidol.ac.th/handle/20.500.14594/24159A new apparatus, called 'membraneless vaporization' (MBL-VP) unit was designed and developed for direct analysis of solid samples. Solid analyte was converted into a gaseous form which then reacts with an indicator reagent. Change in absorbance was used to quantitate the analyte. Stirring with a magnetic bar was employed to facilitate the evaporation of the gas. Unlike the pervaporation technique, hydrophobic membrane was not required for this MBL-VP technique. Application of the membraneless technique for direct determination of calcium carbonate in calcium supplements, has shown to be very precise (R.S.D. = 2.5% for 0.16 mmol CO32-), with detection limit of 0.5 mg CaCO3. Results by this method agreed well with flame atomic absorption spectrometric method. Sample throughput was 20 samples h-1. © 2007 Elsevier B.V. All rights reserved.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyChemistryEnvironmental ScienceArticleSCOPUS10.1016/j.aca.2007.06.036