(19)

(11)

EP 0 525 091 A1

(12)

(43) Date of publication: 03.02.1993 Bulletin 1993/05 (21) Application number: 91908712.0 (22) Date of filing: 01.04.1991

(51) International Patent Classification (IPC):  G01N 33/ 68( . ) (86) International application number: PCT/US1991/002163 (87) International publication number: WO 1991/015765 (17.10.1991 Gazette 1991/24)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 30.03.1990 US 19900502258 (71) Applicants: SWANK, Roy L. Portland, OR 97225 (US) GARVIN, Roy A. Brookings, OR 97415 (US)	(72) Inventors: SWANK, Roy L. Portland, OR 97225 (US) GARVIN, Roy A. Brookings, OR 97415 (US) (74) Representative: Glawe, Delfs, Moll & Partner  Patentanwälte Postfach 26 01 62 D-80058 München D-80058 München (DE)