Flow injection chemiluminescence determination of ornithine and sequential determination of ornithine and lysine by using immobilized lysine oxidase

The flow injection chemiluminescence (CL) determination of ornithine and the sequential determination of lysine and ornithine by using immobilized lysine oxidase are described. Hydrogen peroxide produced in the enzyme-catalysed reaction is determined by luminol CL. The calibration graph obtained by injecting ornithine solutions into the carrier stream (phosphate buffer, pH 8.0), is linear over the range 1.0x10(-6)-2.4x10(-5) M. The detection limit (3 sigma) for ornithine is 4x10(-7) M. The sample throughput is 60 h(-1). Sequential determination of lysine and ornithine is based on chemiluminescence measurements on a lysine/ornithine mixture at both pH 6.0 (lysine response only) and 8.0 (lysine and ornithine). Lysine and ornithine can be determined in the range 1.2x10(-7)-6x10(-5) M. Relative errors are in the range 3-6%. The interference effects of some amino acids and metal ions are investigated. (C) 1999 Elsevier Science B.V. All rights reserved.