Chemiluminescence detection of piperazine designer drugs and related compounds using tris(2,2'-bipyridine)ruthenium(III).

We present an exploration of the chemiluminescence from reactions of benzylpiperazines and phenylpiperazines with tris(2,2'-bipyridine)ruthenium(III). The selectivity of the reagent towards these compounds was found to be highly dependent upon the pH of the solution, and the relative emission intensity was strongly influenced by electron donating or withdrawing substituents on the phenyl or benzyl ring. In spite of previous investigations showing poor responses for aromatic-substituted amines (compared to their aliphatic amine counterparts), intense emissions were observed with phenylpiperazines under acidic conditions, particularly those with halogen or trifluoromethyl substituents on the aromatic ring. Buffered alkaline conditions provided much broader selectivity for the detection of both phenylpiperazine and benzylpiperazine compounds, which we have applied to a rapid HPLC procedure for the determination of piperazines of forensic interest in 'party pill' samples.

Chemiluminescence detection of amino acids and related compounds using acidic potassium permanganate, manganese(IV) or tris(2,2'-bipyridine)ruthenium(III).

We have explored the chemiluminescence response of amino acids and related compounds (including the tripeptide glutathione, and disulfides: cystine, homocystine and glutathione disulfide) with several new adaptations of the permanganate and tris(2,2'-bipyridine)ruthenium(III) ([Ru(bipy)(3)](3+)) reagents and a recently developed colloidal manganese(IV) system. The selectivity of the permanganate reagent can be directed towards tyrosine or thiol compounds like cysteine, homocysteine and glutathione by manipulating reaction conditions (providing limits of detection of 4 nM tyrosine and 5 nM glutathione). Colloidal Mn(IV) produced measureable responses with all analytes, but was most suitable for tryptophan, tyrosine, thiols and disulfides, including α-lipoic acid and dihydrolipoic acid, for which the limits of detection were 30 nM and 20 nM, respectively. A stabilised form of [Ru(bipy)(3)](3+), prepared by oxidising [Ru(bipy)(3)](ClO(4))(2) in acetonitrile, exhibited similar selectivity to that of the conventional aqueous reagent. The [Ru(bipy)(3)](3+) reagent was effective for the detection of secondary amino acids such as proline and hydroxyproline, as well as the disulfide, homocystine.