Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry

An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0 mL/min, and dicyandiamide was eluted with 20 mL of a methanol/acetonitrile mixture (V/V = 2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography–ultraviolet spectroscopy (HPLC–UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC^®-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50 mm × 2.1 mm, 3.5 μm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R² > 0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n = 3) were below 6.1% with a detection limit of 5.0 ng/mL for stream water samples.     

Impact of dicyandiamide on emissions of nitrous oxide, nitric oxide and ammonia from agricultural field in the North China Plain

Nitrous oxide(N_2O), nitric oxide(NO) and ammonia(NH_3) emissions from an agricultural field in the North China Plain were compared for three treatments during a whole maize growing period from 26 June to 11 October, 2012. Compared with the control treatment(without fertilization, designated as CK), remarkable pulse emissions of N_2O, NO and NH_3 were observed from the normal fertilization treatment(designated as NP) just after fertilization, whereas only N_2O and NH_3 pulse emissions were evident from the nitrification inhibitor treatment(designated as ND). The reduction proportions of N_2O and NO emissions from the ND treatment compared to those from the NP treatment during the whole maize growing period were 31% and 100%, respectively. A measurable increase of NH_3 emission from the ND treatment was found with a cumulative NH_3 emission of 3.8 ± 1.2 kg N/ha,which was 1.4 times greater than that from the NP treatment(2.7 ± 0.7 kg N/ha).     

多菌灵生产废水中污染成分的分析研究

应用色谱、质谱、红外和紫外等分析技术，对多菌灵废水进行成分分析和研究。结果表明，多菌灵废水中除已知污染物甲醇、邻苯二胺、硫氰化物和氰化物外，发现了双氰胺及苯并二氢咪酮－２的存在，并对二者的形成机理进行了探讨。     

双氰胺—甲醛絮凝剂对活性污泥的脱水性能研究

研究了有机合成阳离子高分子絮凝剂双氰胺－甲醛絮凝剂在污泥处理中的应用。从絮凝反的理论及其机理上分析了它的絮凝作用，从原理上解释并经实验证明了它在污泥脱水处理中所具有的优越性。