Ultrasensitive Assay of Gatifloxacin at Picogram Level Based on its Enhancing Effect on the Myoglobin‐Luminol Chemiluminescence Reaction

Study on the chemiluminescence behavior of bovine serum albumin with luminol and its analytical application

In this paper, the luminescence behavior of bovine serum albumin (BSA) and luminol was first studied by flow injection chemiluminescence (CL). It was found that the hyperchromic effect of luminol in the presence of BSA led to the acceleration of the electrons transferring rate of excited 3-aminophthalate, which greatly enhanced the CL intensity of luminol/dissolved oxygen reaction. The increments of CL intensity were proportional to the concentrations of BSA with a linear range from 0.01 to 7 nmol L(-1). It was also found that azithromycin could inhibit the CL intensity of luminol/BSA reaction. The decrements of CL intensity were logarithm over the concentrations of azithromycin ranging from 0.1 to 700 ng mL(-1). At a flow rate of 2.0 mL min(-1), a complete analytical process, which included sampling and washing, could be performed within 30s with relative standard deviations of less than 3.1%. This proposed method was successfully applied in assaying azithromycin in pharmaceutical and human serum samples with recoveries from 91.0 to 104.3%. The possible luminescence mechanism of luminol/BSA/azithromycin reaction was discussed in detail by CL, UV and fluorescence methods.

Ultrasensitive study of gatifloxacin based on its enhancing effect on the cerium (IV)-sodium hyposulfite chemiluminescence reaction in a micellar medium

A sensitive and rapid flow-injection chemiluminescence (CL) method has been developed for the determination of gatifloxacin in pharmaceutical preparations and biological samples. The method is based on the enhancing effect of gatifloxacin on CL emission generated by the interaction of Ce (IV) in sulphuric acid and sodium hyposulphite (Na(2)S(2)O(4)) sensitized by sodium dodecyl benzene sulfonate (SDBS). Strong CL emission was observed when gatifloxacin was injected into the Ce (IV) in sulphuric acid and Na(2)S(2)O(4) solution incorporated with SDBS in a flow-cell. Several experimental parameters affecting the CL reaction were investigated and optimized systematically. Under the optimum conditions, it was found that the CL intensity is proportional to the concentration of gatifloxacin in the range of 1.12 × 10(-11)-4.40 × 10(-9) g mL(-1) with a co-relation coefficient of 0.9994. The limit of detection was found to be 4.87 × 10(-12) g mL(-1) and the relative standard deviation (RSD, n=7) was 1.8% for 4 × 10(-8) g mL(-1) of GFLX. The proposed method offers higher sensitivity, wide linear range and better stability without requiring sophisticated instrumentation. Thus, the proposed method has been successfully applied to the determination of gatifloxacin in pharmaceuticals, serum and human urine.

Subpicogram determination of melamine in milk products using a luminol-myoglobin chemiluminescence system

A sensitive chemiluminescence method based on a luminol-myoglobin system is proposed for the determination of melamine in milk products. It was found that the mixed solutions of melamine and myoglobin could react to form a complex on line, which could greatly inhibit the chemiluminescence intensity generated from the reaction between luminol and myoglobin. The decrease in chemiluminescence intensity was proportional to the concentration of melamine, giving a calibration graph linear over the concentration from 10 pg mL(-1) to 50 ng mL(-1) (R(2) = 0.9988) with a detection limit of 3 pg mL(-1) (3sigma). At a flow rate of 2.0 mL min(-1), one analysis cycle, including sampling and washing, could be accomplished in 20 s with a relative standard deviation of <4.0%. The proposed method was applied successfully to the determination of melamine in milk products, and the recovery was from 93.4 to 106.5%. The possible mechanism of luminol-myoglobin-melamine reaction is given.

Methods for the analysis of fluoroquinolones in biological fluids

Methods for the analysis of ten selected fluoroquinolone antibiotics in biological fluids are reviewed. Approaches for sample preparation, detection methods, limits of detection and quantitation, and recovery information are provided for both single analyte and multi-analyte fluoroquinolone methods.

Flow-injection chemiluminescence determination of enrofloxacin using the Ru(phen)3(2+)-Ce(IV) system and central composite design for the optimization of chemical variables

The main purpose of this study was to develop an inexpensive, simple, rapid and sensitive chemiluminescence (CL) method for the determination of enrofloxacin (ENRO) using a flow-injection system. This method is based on rapid reduction of Ru(phen)(3)(3+), which is produced in the reaction between Ru(phen)(3)(2+) and acidic Ce(IV) by ENRO, producing strong CL. A central composite design (CCD) was used for optimization of the chemical variables. Regression analysis of the data from the CCD demonstrated that a second-order polynomial model is an adequate description of the surface over the factor limits studied. Optimization using CCD gave approximately four-fold better results than the single-factor-at-a-time method. Under optimal experimental conditions, the CL response was proportional to the concentration of ENRO over a wide range (0.008-3.6 microg/mL) with a correlation coefficient of 0.9986 and a detection limit of 0.003 microg/mL (3sigma). The relative standard deviation for 11 repeated determinations of 0.14 microg/mL ENRO was 4.2%. This method was successfully applied to the analysis of commercial formulations, spiked plasma and spiked poultry tissue. Sample analyses showed good recovery percentages for drugs and spiked plasma (95.1-103.9%). Recovery percentages for spiked poultry tissue were in the range 77.6-87.3%. The minimum sampling rate was 100 samples/h.