Flow Injection Determination of Lactate Using Immobilized Lactate Dehydrogenase Enzyme with Tris(2,2′-Bipyridyl)Ruthenium(III) Chemiluminescence Detection

ABSTRACT

A flow-injection procedure is reported for the determination of L-lactate based on its enhancement on tris(2,2′-bipyridyl)ruthenium(III) chemiluminescence in the presence of reduced nicotinamide adenine dinucleotide produced using immobilized lactate dehydrogenase. The calibration graph was linear between 4 and 50 × 10⁻⁷ mol L⁻¹ (r² = 0.9998) with relative standard deviation from 1.6 to 3.0% (n = 4). The limit of detection was 1 × 10⁻⁷ mol L⁻¹ with a sample throughput of 60 per hour. The effect of common organic compounds and metal ions was studied. The immobilized lactate dehydrogenase exhibited good operational activity at 37°C for one week and storage stability at 4°C over a period of 10 weeks. The method was applied to blood serum, and the results were in good agreement with those obtained by a conventional spectrophotometric method with no significant difference at the 95% confidence level.

KEYWORDS:

• Chemiluminescence
• flow injection analysis
• immobilized lactate dehydrogenase
• lactate
• reduced nicotinamide adenine dinucleotide
• Tris(2,2′-bipyridyl)ruthenium(III)

Acknowledgment

The authors are grateful to the Department of Chemistry, University of Balochistan, Quetta for providing laboratory facilities