Analysis of tricyclic antidepressants using electrogenerated chemiluminescence

A novel method has been investigated for the selective and sensitive determination of a range of tricyclic antidepressants including amitriptyline, doxepin, nortriptyline, promazine, chlorpromazine, imipramine, clomipramine, desipramine, protriptyline and trimipramine using electrogenerated chemiluminescence (ECL). The ECL mechanism is based on the reaction between tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)] and the tertiary amino groups on the antidepressants. After selecting the best operating parameters calibration curves were obtained over three orders of magnitude for amitriptyline, doxepin, nortriptyline, promazine and chlorpromazine. Linear calibrations were used to obtain limits of detection in the range 0.09-0.24 microgram ml-1 with relative standard deviations below 4% for five replicate samples. Rapid depression in the signal was observed with repeat analysis of imipramine, clomipramine, protriptyline, desipramine and trimipramine due to electrode fouling by the oxidation product of the reaction. Use of a lower concentration of the compound was found to alleviate the problem. Finally the concentration of doxepin was determined in a pharmaceutical preparation.