Occurrence and risk assessment of four typical fluoroquinolone antibiotics in raw and treated sewage and in receiving waters in Hangzhou, China.

A sensitive liquid chromatography-fluorescence detection method, combined with one-step solid-phase extraction, was established for detecting the residual levels of the four typical fluoroquinolone antibiotics (ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in influent, effluent, and surface waters from Hangzhou, China. For the various environmental water matrices, the overall recoveries were from 76.8 to 122%, and no obvious interferences of matrix effect were observed. The limit of quantitation of this method was estimated to be 17 ng/L for ciprofloxacin and norfloxacin, 20 ng/L for ofloxacin, and 27 ng/L for enrofloxacin. All of the four typical fluoroquinolone antibiotics were found in the wastewaters and surface waters. The residual contents of the four typical fluoroquinolone antibiotics in influent, effluent, and surface water samples are 108-1405, 54-429, and 7.0-51.6 ng/L, respectively. The removal rates of the selected fluoroquinolone antibiotics were 69.5 (ofloxacin), 61.3 (norfloxacin), and 50% (enrofloxacin), indicating that activated sludge treatment is effective except for ciprofloxacin and necessary to remove these fluoroquinolone antibiotics in municipal sewage. The risk to the aquatic environment was estimated by a ratio of measured environmental concentration and predicted no-effect concentration. At the concentrations, these fluoroquinolone antibiotics were found in influent, effluent, and surface waters, and they should not pose a risk for the aquatic environment.

Synchronous fluorescence measurement of enrofloxacin in the pharmaceutical formulation and its residue in milks based on the yttrium (III)-perturbed luminescence.

A simple, rapid and sensitive synchronous fluorescence method is put forward for the determination of enrofloxacin (ENRO) in the pharmaceutical formulation and its residue in milk based on the yttrium (III)-perturbed luminescence. When Y(3+) is added into the ENRO solution, the fluorescence of ENRO is significantly enhanced. The synchronous fluorescence technology is employed in the method to determine trace amount of ENRO residue in milks. The synchronous fluorescence intensity of the system is measured in a 1-cm quartz cell with excitation wavelength of 328 nm, Δλ=80 nm. A good linear relationship between the fluorescence intensity and the ENRO concentration is obtained in the range of 1.0 × 10(-9) to 2.0 × 10(-6)mol L(-1) (r(2)=0.9992). The limit of detection (LOD) of this method attains as low as 3.0 × 10(-10) mol L(-1) (S/N=3). The selectivity of this method is also very good. Common metal ions, rare-earth ions and some pharmaceuticals, which are usually used together with ENRO, do not interfere with the determination of ENRO under the actual conditions. The proposed method can be applied to determine ENRO residue in milks, and limit of quantification (LOQ) determined in the spiked milk is estimated to be 2.8 × 10(-8) mol L(-1) (10 µg L(-1)). Moreover, this method can be used as a rapid screening for judging whether the ENRO residues in milks exceed Minimal Risk Levels (MRLs) or not. In addition, the mechanism of the fluorescence enhancement is also discussed in detail.

[Fluorescence characteristic of enro floxacin sensitized by rare earth ion and its analytical application].

The fluorescence characteristic of enrofloxacin-yttrium (III) (ENRX-Y3+) was investigated in the present paper. Experimental results indicated that Y3+ ion could greatly increase the fluorescence intensity of the system. From this, a simple and sensitive method of determining the ENRX was set up. The fluorescence intensity of the system was measured with a 1 cm quartz cell at the excitation wavelengths of 274 nm and the emission wavelengths of 424 nm. The optimal conditions were obtained as follows: pH = 5.5-6.2, 0.1 mol x L(-1) hexamethylenamine (HMA) buffer, the concentration of yttrium(III) was 1.0 x 10(-4) mol x L(-1). Under the optimal conditions, the fluorescence intensity of the system showed a good linear relationship with the concentration of ENRX in the range of 1.0 x 10(-9) - 5.0 x 10(-6) mol x L(-1), its correlation coefficient was 0.9981, and the detection limit (S/N=3) was 2.3 x 10(-10) mol x L(-1). Interferences of common metal ions and other pharmaceuticals usually used for the compatibility of medicines with the fluorescence intensity of the system were studied, and the results showed that most metal ions except Tb3+, Cu2+ and AP+ and the compatible medicines used together with ENRX did not interfere with its determination. The recovery tests in the compatible medicines were also performed, and the results showed that all the recoveries were in the range of 98.0%-107.0%, and RSDs were in the range of 0.9%-4.5%. The presented method was used to determine the ENRX in actual pharmaceutical samples which were used in the treatment for animals as compared with the reported method of terbium (III) luminescence probe, and the results were satisfactory. In addition, the luminescence mechanism of the ENRX-Y3+ system was also discussed.