1 23 Microchimica Acta An International Journal on Micro and Trace Chemistry ISSN 0026-3672 Volume 172 Combined 1-2 Microchim Acta (2010) 172:225-232 DOI 10.1007/ s00604-010-0459-1 Towards a monolithically integrated microsystem based on the green tape ceramics technology for spectrophotometric measurements. Determination of chromium (VI) in water