Flow injection determination of neostigmine and galanthamine by immobilised acetylcholinesterase inhibition Original Research Article

Neostigmine (1×10−7–1×10−6 M) and galanthamine (5×10−7–6×10−6 M) are determined by measuring their inhibition of acetylcholinesterase immobilised on controlled pore glass. The determination is carried out by a flow injection procedure with spectrophotometric detection. The 3σ limits of detection were 0.5×10−7 M neostigmine and 5×10−7 M galanthamine. The relative standard deviations were 1.3% for five determinations of 5×10−7 M neostigmine and 2.0% for six determinations of 2×10−6 M galanthamine. Several reagents for achieving on-line reactivation of inhibited enzyme were studied. As a result, 2×10−3 M NaF was recommended for reactivation after neostigmine inhibition, and 2×10−4 M substrate solution for reactivation after galanthamine inhibition. The efficiency of the reactivation process was interpreted in terms of the inhibitory mechanisms relating to the above drugs.