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

Highly sensitive spectrofluorimetric procedure for the assay of phenothiazine derivatives in the presence of their sulfoxide oxidized product

A validated straightforward and sensitive spectrofluorimetric procedure was developed to assay trifluoperazine hydrochloride, promethazine hydrochloride, and perazine maleate. The procedure was dependent on oxidation of the investigated phenothiazines using a known excess of ammonium cerium sulfate as oxidizing agent and overseeing the fluorescence intensity of the resultant Ce³⁺ ion as the product of this reaction at λ_cx = 254 nm. and λ_em = 355 nm. Various parameters controlling the reaction were investigated and optimized. Linear calibration graphs were found in the general concentration range 5-30 ng/ml with a general correlation coefficient range 0.9994-0.9995. Limits of detection were 0.97, 0.70 and 0.56 ng/ml, whereas limits of quantification were 3.24, 2.12 and 1.89 ng/ml for trifluoperazine hydrochloride, promethazine hydrochloride and perazine maleate, respectively. The procedure was implemented successfully for analyses of the cited drugs in their trade dosage preparations such as tablets and syrups. The effect of possible interference from common excipients and their sulfoxide oxidized product was studied and the procedure showed good recovery of the drugs under study in their available dosage preparations. The possible effect of structure variation of the studied drugs on the experimental conditions and sensitivity observed with each one was also discussed.

Highly sensitive analysis of four hemeproteins by dynamically-coated capillary electrophoresis with chemiluminescence detector using an off-column coaxial flow interface

Dynamic coating of the surface in capillary electrophoresis with chemiluminescence detection (CE-CL) using an off-column coaxial flow interface for the determination of four hemeproteins was developed. This method is based on the luminol-hydrogen peroxide reaction catalyzed by metalloproteins in alkaline medium. The experimental setup of the CE-CL system with the proposed off-column coaxial interface was evaluated by separation and detection of dopamine and catechol based on inhibition of the luminol-potassium ferricyanide reaction. Highly efficient separation of the two model compounds with symmetrical peak shape and satisfactory reproducibility was achieved by using this interface. In addition, in order to obtain a good resolution for hemeproteins, polyvinylpyrrolidone (PVP) combined with sodium dodecyl sulfate (SDS) were introduced as dynamic modifiers to reduce the unwanted adsorption of non-specific protein. Several parameters affecting the CE separation and CL detection were investigated in detail. Under the optimized conditions, a mixture of the four hemeproteins (horseradish peroxidase (HRP), catalase (Cat), myoglobin (Mb) and cytochrome C (Cyt C)) could be well separated within 20 min. The linear ranges of the four proteins were 5.7 × 10(-8) to 1.1 × 10(-6) mol L(-1) for HRP, 4.0 × 10(-8) to 2.0 × 10(-6) mol L(-1) for Cat, 1.1 × 10(-10) to 5.6 × 10(-8) mol L(-1) for Mb, and 3.8 × 10(-7) to 7.7 × 10(-6) mol L(-1) for Cyt C. The limits of detection (LODs) (S/N = 3) for HRP, Cat, Mb and Cyt C were 2.2 × 10(-8) mol L(-1) (104.5 amol), 1.6 × 10(-8) mol L(-1) (74 amol), 5.6 × 10(-11) mol L(-1) (0.26 amol), and 1.95 × 10(-7) mol L(-1) (0.89 fmol), respectively. The proposed method has been successfully applied to the analysis of low-level Mb in a spiked human urine sample and the recoveries were above 97%. Our primary result demonstrated that the proposed CE-CL method has great potential for Mb determination in clinical diagnosis.

Promazine and chlorpromazine for prolonged spinal anesthesia in rats

Though promazine and chlorpromazine elicited cutaneous anesthesia, no study of spinal anesthesia with chlorpromazine and promazine has been reported. This study was to examine whether chlorpromazine and promazine produce spinal anesthesia. Using a rat model via intrathecal injection, we tested spinal blockades of motor function and nociception by promazine, chlorpromazine or bupivacaine, and so were dose-response studies and durations. We demonstrated that chlorpromazine and promazine elicited dose-dependent spinal blockades in motor function and nociception. On the 50% effective dose (ED(50)) basis, the rank of potency of these drugs was bupivacaine>promazine>chlorpromazine (P<0.05 for the differences). On an equipotent basis (25% effective dose [ED(25)], ED(50), and ED(75)), the block duration caused by chlorpromazine or promazine was longer than that caused by the long-lasting local anesthetic bupivacaine (P<0.01 for the differences). Chlorpromazine and promazine, as well as bupivacaine, showed longer duration of sensory block than that of motor block. Our data reported that intrathecal promazine and chlorpromazine with a more sensory-selective action over motor blockade had less potent and longer-lasting spinal blockades when compared with bupivacaine.

Sensitive and selective capillary electrophoretic analysis of proteins by zirconia nanoparticle-enhanced copper (II)-catalyzed luminol-hydrogen peroxide chemiluminescence

We report herein a sensitive, selective, convenient CE determination of heme proteins in complex matrices by a sodium-dodecyl-sulfate-assisted, zirconia nanoparticle-enhanced copper (II)-catalyzed luminol-hydrogen peroxide chemiluminescence (CCLHPCL). Introducing a segment of sodium dodecyl sulfate to the capillary after sample injection not only rendered selective detection by quenching the luminescence signals from the non-heme proteins but also owning to the suppressed protein adsorption, led to significant improvement in separation efficiency and detection sensitivity. The signals were further improved by addition of ZrO(2) nanoparticles to the chemiluminescence solution. Compared with the conventional CCLHPCL, the detection limits (S/N=3) were improved by 10.2-22.0 folds, with 7.8×10(-9), 3.3×10(-9) and 1.5×10(-9) M for three model proteins, viz, myoglobin, hemoglobin and cytochrome C, respectively. Because the method did not require sophisticated pretreatment, it was convenient to analyze heme proteins in complex matrices, as demonstrated, hemoglobin in human blood and spiked human urine samples.

Determination of trace amounts of dopamine by flow-injection analysis coupled with luminol-Ag(III) complex chemiluminescence detection

A novel flow injection analysis-direct chemiluminescence (FI-CL) method has been developed for determination of trace amounts of dopamine (DA) based on the enhancing effect of DA on the CL reaction of luminol with an Ag(III) complex in alkaline solution. Under optimum conditions, CL intensities are proportional to the concentration of DA in the range of 1.0 × 10(-10) to 4.0 × 10(-8)  mol L(-1). The detection limit is 3.0 × 10(-11)  mol L(-1) for DA (3s), with a relative standard deviation (n = 13) of 2.3% for 1.0 × 10(-8)  mol L(-1) DA. This method has also been applied for the determination of DA in commercial pharmaceutical injection samples. On the basis of the CL spectra and the results of the free-radical trapping experiment of this work, a reaction mechanism for this CL reaction is proposed and discussed.

Determination of cortisol in human blood sera by a new Ag(III) complex-luminol chemiluminescent system

A new chemiluminescence (CL) system based on the reaction of Ag(III) complex with luminol is, for the first time, reported in this work. Incorporated with a flow injection analyses (FIA), the new CL system has been applied for the determination of free cortisol in human sera. The system is based on the CL reaction of luminol with Ag(III) in alkaline solutions, while cortisol can dramatically enhance CL intensities. Under optimum conditions, CL intensities are proportional to concentration of cortisol in the range of 0.05-7.5 nM. The limit of detection is 2.0x10(-11) M (3sigma), with a relative standard deviation (n=11) of 1.9% for 3.5x10(-9) M cortisol. Eight human blood serum samples were all handled by solid-phase extraction (SPE) clean-up and enrichment before detection. This detection system is highly sensitive and convenient and may find wide applications. Based on the chemiluminescent spectra, a possible reaction mechanism is also suggested.

On-line coupling of solid-phase extraction, derivatization reaction and spectrophotometry by sequential injection analysis: Application to trifluoperazine assay in human urine

INTRODUCTION

This study deals with a new methodology of on-line solid-phase extraction (SPE), derivatization reaction and spectrophotometric measurement utilizing sequential injection analysis (SIA) technique. The method was applied for the assay of trifluoperazine in human urine.

METHODS

An SPE procedure was automated to perform sample clean-up, extraction and preconcentration into a homemade microcolumn connected to a SIA manifold. Unlike previous SIA methods, a simple SIA manifold included one syringe pump and one multi-position valve was constructed. This offered simplicity and rapidity to the proposed method (sampling frequency 11 sample h(-1)). Spectrophotometric measurement was based on a fast oxidation of trifluoperazine by Ce(IV) in sulfuric acidic media resulting in a spectrophotometrically detectable chromophore measured at wavelength 500 nm. The SPE procedure was optimized by the univariate method while the derivatization reaction and spectrophotometric measurement were optimized by multivariate methods.

RESULTS

The method was linear in a range of 70-200 ng ml(-1) and accurate with a recovery of 92.7%. Relative standard deviation of repeatability (n=10 in a day) and intermediate precision (n=5 over a week) did not exceed 4.3% indicating satisfactory precision. The limits of detection and quantification were 18.2 and 55.2 ng ml(-1), respectively. The sensitivity of the method was improved by the preconcentration, the use of extended pathlength in the detection device and the optimization of absorbance measurement. The method is selective in the presence of chlordiazepoxide, which is sometimes taken in combination with trifluoperazine.

DISCUSSION

The method is suitable for the application of overdose and therapeutic drug monitoring in human urine.

Determination of riboflavin in urine and beverages by capillary electrophoresis with in-column optical fiber laser-induced fluorescence detection

A simple, rapid and sensitive method was developed for routine analysis of riboflavin in beverage, green tea and urine by capillary electrophoresis with in-column optical fiber laser-induced fluorescence detection (LIF). The difference between the present detector in the study and others is that an optical fiber was adopted in the former, which can guide the excitation light into the capillary right at the detection window. The linearity of the method (r(2)=0.998) was good over the concentration range from 0.05 to 20 microM for riboflavin. The limit of detection (LOD) was determined using linear regression analysis and was found to be 3.0 nM. The percent recoveries of riboflavin in beverage, green tea and urine samples were 95.3+/-2.9, 105.5+/-3.9 and 94.3+/-1.7, respectively. These results of quantitative analysis of riboflavin in beverage and green tea samples is in agreement with that of obtained by the AOAC of fluorometric method. In the analysis of urine samples, all electropherograms of urine samples and corresponding concentrations of riboflavin in the period of 13 h after orally administrating the ingestion of vitamin B(2) tablets were illustrated.

Determination of catecholamines by CE with direct chemiluminescence detection

A rapid and sensitive method to detect three catecholamines, isoprenaline, epinephrine, and dopamine, by CE coupled with direct luminol-potassium periodate chemiluminescence (CL) detection is described. The conditions for CE separation and CL reaction were systematically optimized. Under the optimum conditions, the baseline separation of three catecholamines was achieved within 6.5 min. The LODs obtained in standard solution were 5.3 x 10(-8 )mol/L for isoprenaline, 4.7 x 10(-8 )mol/L for epinephrine, and 1.5 x 10(-7 )mol/L for dopamine. The RSD of the migration time and peak area were less than 1.8 and 3.6% (n = 5), respectively. The present method was applied to the determination of the dopamine in urine samples of cigarette smokers and nonsmokers. The results obtained indicate that there is a close relationship between the content of dopamine in human urine and the amount of cigarettes smoked daily; the level of dopamine in smokers is higher than in nonsmokers.

Ultrasensitive assay of clindamycin in medicine and bio-fluids with chemiluminescence detection

A simple chemiluminescence (CL) method using flow injection has been developed for the determination of clindamycin, based on the inhibitory effect of clindamycin on the CL generated from the luminol-K(3)Fe(CN)(6) system in alkaline medium. It was found that the decrement of CL intensity was linear with the logarithm of clindamycin concentration over the range 0.7-1000 ng/mL. The detection limit was 0.2 ng/mL with a relative standard deviation (RSD) of <5.0% (n = 7). At a flow rate of 3.0 mL/min, a complete analytical process could be performed within 0.5 min, including sampling and washing. The proposed procedure was applied successfully to the determination of clindamycin in pharmaceutical preparations and human urine without pretreatment.