Flow-injection chemiluminescence determination of chlortetracycline using on-line electrogenerated [Cu(HIO(6))(2)](5-) as the oxidant

A novel chemiluminescence (CL) flow system for the determination of chlortetracycline is described. It is based on the direct CL reaction of chlortetracycline and [Cu(HIO₆)₂]⁵⁻ in KOH medium. The unstable [Cu(HIO₆)₂]⁵⁻ was on-line electrogenerated by constant-current electrolysis. The CL intensity was linear with chlortetracycline concentration in the range of 0.1–100 μg ml⁻¹. The determination limit was 5.3×10⁻⁸ g ml⁻¹. The whole process could be completed in 1 min. The proposed method is suitable for automatic and continuous analysis, and has been applied satisfactorily to analysis of chlortetracycline in biological fluid.     

火焰原子吸收光谱法测定盐酸金霉素中钙,镁,铁

本文报道了火焰原子吸收光谱法测定盐酸金霉素中钙，镁，铁，测定钙，镁时，使用镧释放剂，消除共存元素的干扰，本法简便，快速，准确度和精密度均令人满意。     

High performance liquid chromatography of chlortetracycline and related substances on poly(styrenedivinylbenzene)copolymer

Summary An isocratic high performance liquid chromatographic method has been developed for assay and purity control of chlortetracycline, which is separated from all related compounds. The stationary phase is poly(styrene-divinylbenzene)copolymer (PSDVB), which is heated at 60°C. The mobile phase is 2-methyl-2-propanol-1.0 M perchloric acid (5.0 ml)-water (up to 100 ml). The amount of alcohol modifier varies between 2.5 and 6.5% m/v depending upon the brand and porosity of PSDVB used. The flow rate is 1.0 ml/min and UV detection is at 254 nm. The total analysis time does not exceed 40 min. Although the method has been shown to be applicable with several brands of 100 Å PSDVB e.g. PLRP-S, PRP-1, RoGeL and TSK-Gel, the best separations were obtained on the wide pore material PLRP-S 100 Å.     

火焰原子吸收光谱法测定盐酸金霉素中的锌、铁和镁

研究了火焰原子吸收光谱法测定盐酸金霉素中Zn、Fe、Mg的方法.方法的检出限Zn:0.006、Fe:0.03、Mg:0.003 mg/L,回收率98%-104%,RSD小于1.45%.结果表明,该方法准确、快速、结果令人满意.     

A flow injection method for the analysis of tetracycline antibiotics in pharmaceutical formulations using electrochemical detection at anodized boron-doped diamond thin film electrode

A method using flow injection (FI) with amperometric detection at anodized boron-doped diamond (BDD) thin films has been developed and applied for the determination of tetracycline antibiotics (tetracycline, chlortetracycline, oxytetracycline and doxycycline). The electrochemical oxidation of the tetracycline antibiotics was studied at various carbon electrodes including glassy carbon (GC), as-deposited BDD and anodized BDD electrodes using cyclic voltammetry. The anodized BDD electrode exhibited well-defined irreversible cyclic voltammograms for the oxidation of tetracycline antibiotics with the highest current signals compared to the as-deposited BDD and glassy carbon electrodes. Low detection limit of 10 nM (signal-to-noise RATIO = 3) was achieved for each drug when using flow injection analysis with amperometric detection at anodized BDD electrodes. Linear calibrations were obtained from 0.1 to 50 mM for tetracycline and 0.5–50 mM for chlortetracycline, oxytetracycline and doxycycline. The proposed method has been successfully applied to determine the tetracycline antibiotics in some drug formulations. The results obtained in percent found (99.50–103.01%) were comparable to dose labeled.     

Flow injection spectrophotometric determination of europium using chlortetracycline

A flow injection (FI) spectrophotometric determination of europium (III) is described, based on the complexation between europium (III), and chlortetracycline (CTC) in a Tris-buffer pH 8.0 medium. The resulting yellow-coloured complex is measured at its absorption maximum of 400 nm after 100 μl of sample or standard solution containing europium (III) are injected into the merged streams of CTC and Tris-buffer solutions. Optimum conditions for determining μg amounts of europium (III) are achieved by univariate method. Various types of reactors are also investigated. It is shown that the use of a single bead string reactor gives rise to the enhancement of peak height. A linear calibration curve over the range of 0.10-0.60 μg ml⁻¹ europium (III) is established with the regression equation (n=6) Y=34.93X+0.01 and the correlation coefficient of 0.9994 is obtained. A detection limit (3σ) of 0.01 μg ml⁻¹ of europium (III) and the relative standard deviation (R.S.D.) of 4.32% for determining 1.0 μg ml⁻¹ of europium (III) (n=7) are obtained. The recommended method has been applied to the quantitation of europium (III) in spiked water and stream sediment samples with average recoveries of 99.9 and 97.5%, respectively. The sampling rate is found to be 85 h⁻¹.     

New sensing materials of molecularly-imprinted polymers for the selective recognition of Chlortetracycline

As a result of the stressful conditions in aquaculture facilities there is a high risk of bacterial infections among cultured fish. Chlortetracycline (CTC) is one of the antimicrobials used to solve this problem. It is a broad spectrum antibacterial active against a wide range of Gram-positive and Gram-negative bacteria. Numerous analytical methods for screening, identifying, and quantifying CTC in animal products have been developed over the years. An alternative and advantageous method should rely on expeditious and efficient procedures providing highly specific and sensitive measurements in food samples. Ion-selective electrodes (ISEs) could meet these criteria. The only ISE reported in literature for this purpose used traditional electro-active materials. A selectivity enhancement could however be achieved after improving the analyte recognition by molecularly imprinted polymers (MIPs).Several MIP particles were synthesized and used as electro-active materials. ISEs based in methacrylic acid monomers showed the best analytical performance according to slope (62.5 and 68.6 mV/decade) and detection limit (4.1 × 10⁻⁵ and 5.5 × 10⁻⁵ mol L⁻¹). The electrodes displayed good selectivity. The ISEs are not affected by pH changes ranging from 2.5 to 13. The sensors were successfully applied to the analysis of serum, urine and fish samples.     

Peak height determination in analysis of chlortetracycline in animal feeds

Summary In an HPLC method for the analysis of chlortetracacline (CTC) in animal feed, a problem arose with the presence of peaks which did not return to baseline before the occurrence of a subsequent peak. Two methods were used to determine the peak height. In the first method, a perpendicular was dropped from the maximum of the second peak. A linear function was then fitted to the descending slope on the first peak. The point of intersection was taken as the baseline point. In the second approach, a polynomial fit was used instead. Results show excellent agreement with analysis obtained by established methodology. This approach provides a practical method for determination of chlortetracycline in animal feeds allowing up to six samples to be analyzed within 8 hours.     

Flow injection analysis of doxycycline or chlortetracycline in pharmaceutical formulations with pulsed amperometric detection

A flow injection with pulsed amperometric detection for determination of doxycycline or chlortetracycline in pharmaceutical formulations is described. Doxycycline or chlortetracycline were studied at a gold rotating disk electrode with cyclic voltammetry as a function of pH of supporting electrolyte solution. The optimized PAD waveform parameters were obtained with a flow injection system. The optimized pulsed conditions of doxycycline were 1150 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 220 ms (150 ms delay time and 70 ms integration time), 1500 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized pulsed conditions of chlortetracycline were 1050 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 300 ms (200 ms delay time and 100 ms integration time), 1300 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized PAD waveform was applied to the determination of doxycycline hydrochloride and chlortetracycline hydrochloride standard solution and in pharmaceutical formulations. The linear dynamic ranges of doxycycline hydrochloride and chlortetracycline hydrochloride were 1 μM–0.1 mM. The sensitivity of this method was found to be 23 μA/mM for doxycycline hydrochloride and 33.76 μA/mM for chlortetracycline hydrochloride. The detection limit for both compounds is 1 μM. The doxycycline hydrochloride and chlortetracycline hydrochloride content in commercially available tablet dosage forms by the proposed method was comparable to those specified by the manufacturer.     

A Study of Fluorescence System of Eu-Chlorotetracycline-Benzoylacetone-CTMAB Multibasic Complex

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