(19)

(11)

EP 1 115 660 A1

(12)

(43) Date of publication: 18.07.2001 Bulletin 2001/29 (21) Application number: 99949126.9 (22) Date of filing: 22.09.1999

(51) International Patent Classification (IPC)7: C01G 41/00, G01N 27/12 (86) International application number: PCT/GB9903/160 (87) International publication number: WO 0017/106 (30.03.2000 Gazette 2000/13)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 23.09.1998 GB 9820745 (71) Applicant: CAPTEUR SENSORS & ANALYSERS LTD. Didcot, OX11 7HP (GB)	(72) Inventor: WILLIAMS, David, Edward Abingdon OX14 2EE (GB) (74) Representative: Colgan, Stephen James et al CARPMAELS & RANSFORD43 Bloomsbury Square London WC1A 2RA London WC1A 2RA (GB)