| Nonylphenol (NP) and short chains nonylphenol polyoxyethylene (NPnEO, n≈2), which are the main microbial degradation products of nonylphenol polyoxyethylene (NPnEO, n=1-20), are the typical environmental hormones. NPnEO is one kind of the most important nonionic surfactant, and is widely used in chemical industry. The wasted NPnEO will be discharged into the sewage treatment plant or natural waters along with the wasted water. Under the degradation of activated sludge or microorganism, NPnEO will be degraded progressively into NPnEO (n≈2) and NP, which are more stable and toxic than the matrix. Besides, because of their strong bioaccumulation, they can be enriched in environment and food cycle. Recent years, as the harm from environment hormones to animals and human beings increasing significantly, the detection and innocuous degradation of environment hormones in environment has become a hot research area.In this study, a dispersive liquid-liquid microextraction-high performance liquid chromatography (DLLME-HPLC) was established for the simultaneous determination of NP and NPnEO (n≈2) in water simple after the exploration of HPLC and DLLME condition separately. The HPLC analysis was carried out using a Hypersil APS-2 NH2 column. The detection wavelength is 277 nm. A mixture of hexane (A), isopropanol (B) and dichloromethane (C) was used as mobile phase at a flow-rate of 1.0 mL/min. A gradient elution style was used:A:B:C= 92:7:1 for the first 5 min, then changed into 24:75:1 linearly in 3 min, remained this for 3 min, and from the 11 to 13 min changed to 92:7:1. The injection volume is 10 μL, column temperature is 35℃. In the DLLME,8 mL water simple was used. The water simple was kept in the pH of 6-7, and added 0.5 g NaCl. The extraction system is consist of 80 μL carbon tetrachloride as extractant and 0.6 mL methanol as dispersing agent. The extraction take 3 min in ultrasound. In the optimal conditions, six components were detected in 18 min, working curves of each compound obtained with the linear correlation coefficients ranged from 0.9991 to 0.9999, and the linear ranges were 103. The detecting limits of 0.09-2.1 ng/mL (S/N=3) were obtained with the relative standard deviations under 5%. The average recoveries of 89%～117% obtained by spiking in samples.With the help of the DLLME-HPLC detection method, the NP degradation property of pseudomonas putida and citrobacter freundi was explored. The optimum condition of NP degradation was confirmed. The bacterial culture temperature was 30℃, pH was 6～7, the initial concentration of NP was 5μg/mL, the dosing quantity of strains is 2%, and cometabolic substrate is 0.1 g peptone. In this condition, the NP degradation rate of the two bacterial achieve 49%, which was supposed to high efficient degradation. This study also came to a conclusion that the mixed bacterial can get a higher NP degradation rate which was supposed to be synergistic effect.The results show that the DLLME-HPLC detection method which is convenient to operate with high sensitivity and enrichment factor, good accuracy, low analysis cost and friendly to environment can absolutely meet the requirements of simultaneous analysis and determination of NP and NPnEO (n≈2) in water simple, and has been successfully used in the research of micro-biological degradation of NP. In the established culture condition, the two bacterial can degrade NP efficiently, and act out a synergistic effect when mixed. This study paved the way to the following research. |
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