Adsorptive voltammetry and hydrolysis kinetics of loprazolam mesilate.
Loprazolam is determined by square-wave adsorptive stripping voltammetry in 0.04M ammonium chloride at pH 4.0, with an accumulation potential of -0.25 V vs. Ag/AgCl/KCl(s), at which the nitro group is reduced to a hydroxylamine group, with adsorption of the product. Cathodic stripping results in reduction of the azomethine bond of the adsorbed product. With a deposition time of 120 sec the detection limit is 2.5 x 10(-10)M. The relative standard deviation is 1.7% for 5 x 10(-8)M loprazolam (60 sec deposition). Reversible hydrolysis of the azomethine group occurs in sulfuric or hydrochloric acid. The reaction is initially first-order, followed by an apparent second-order reaction. First-order rate constants and half-lives are reported for 0.1-1M sulfuric acid and 0.02M hydrochloric acid media and compared with the values for nitrazepam hydrolysis.
Arcos
J
J
Institut de Pharmcie, CP 205/6, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles, Belgium.
Vire
J C
JC
El Jammal
A
A
Patriarche
G J
GJ
Christian
G D
GD