Flow-injection method for the determination of serine using immobilized enzyme

A flow-injection method for the determination of serine using a mini-column containing immobilized serine dehydratase isolated and purified from rat liver is described. Ammonia produced from the enzymatic reaction is coupled with hypochlorite and phenol in an alkaline medium yields a blue product due to the indophenol anion formation, which is the basis of a spectrophotometric detection at 640 nm. The limit of detection (2×blank noise) is 0.01 mM with a sample throughput of 25 h−1. Calibration graph is linear in the range 0.2–1.0 mM, with relative standard deviation 0.6–1.0%.