Determination of phenothiazines in pharmaceutical formulations and human urine using capillary electrophoresis with chemiluminescence detection

Abstract

A CE instrument coupled with chemiluminescence (CL) detection was designed for the determination of promethazine hydrochloride (PTH) and promazine hydrochloride (PMH) in real samples. An important enhancement of the CL emission of luminol with potassium ferricyanide was observed in the presence of these phenothiazines; so this system was selected for their detection after CE separation. Parameters affecting the electrophoretic separation were optimized in a univariate way, while those affecting CL detection were optimized by means of a multivariate approach based on the use of experimental designs. Chemometrics was also employed for the study of the robustness of the factors influencing the postcolumn CL detection. The method allows the separation of the phenothiazines in less than 4 min, achieving LODs of 80 ng/mL for PMH and 334 ng/mL for PTH, using sample injection by gravity. Electrokinetic injection was used to obtain lower LODs for the determination of the compounds in biological samples. The applicability of the CE-CL method was illustrated in the determination of PTH in pharmaceutical formulations and in the analysis of PMH in human urine, using a previous SPE procedure, achieving an LOD of 1 ng/mL and recoveries higher than 85%.

Determination of catecholamines by CE with direct chemiluminescence detection

“…The LOQ has adopted the lowest analyte concentration yielding a signal ten times greater than the noise. LOD and LOQ were evaluated according to [15,38,39].…”

“…In recent years, CE has been proven to be one of the most powerful techniques for the analysis of biological matrices [11][12][13][14][15], pharmaceutical preparations [16,17], and metal ions [18,19], due to its high efficiency and resolution. Several detection techniques in CE, including LIF [20][21][22], UV [23,24], MS [25], EC [26][27][28], and fluorescence [29], have been developed to determine catecholamines.…”

Advances and analytical applications in chemiluminescence coupled to capillary electrophoresis

“…In all these cases, the setup was quite similar: luminol was dissolved in the running buffer and the CL reagents consisted of an alkaline solution of K 3 [Fe(CN) 6 ]. Phenothiazines have also been determined using the direct CL approach, allowing the separation of promethazine hydrochloride and promazine hydrochloride in less than 4 min [96]. The method was characterized by using two different injection modes: injection by gravity to determine promethazine as an impurity in thiazinamium methyl-sulfate ampoules and electrokinetic injection to determine promazine in human urine after solid-phase extraction.…”

Determination of Epinephrine by Flow Injection Analysis Coupled Ag(III) Complex‐Luminol Chemiluminescence Detection

“…The luminol-based chemiluminescence method has been widely used in the quantitative determination of many metal, organic, and inorganic compounds at very low concentrations. [4][5][6][7] Luminol is oxidized by strong oxidants such as H 2 O 2 , potassium hexacyanoferrate(III), BrO -or metal complex to produce chemiluminescence, leading to its use in a variety of analytical methods. Despite a huge number of studies, the mechanism of the reactions leading to enhancement or inhibition of luminol CL is still not fully understood.…”