HPLC METHOD IMPROVEMENT FOR 4-NONYLPHENOL DETERMINATION IN ANAEROBIC REACTORS: DECREASING SOLVENT CONSUMPTION AND WASTE GENERATION

The aim of this study was to develop a chromatographic method for 4-NP determination in anaerobic batch reactors using low amount of organic solvents and also evaluate 4-NP degradation in the presence of different co-substrates. Chromatographic parameters was improved for stationary phase (C-8 column), mobile phase (acetonitrile/water solution 90:10, v:v), column temperature (40 ºC), eluent flow (0.8 mL min-1), injection volume (100 µL) and wavelengths in fluorescence detector (FLD) (λex=225 nm and λem=305 nm). Solid phase extraction (SPE) was performed for sample purification with smaller amount of solvents (methanol - 2 mL and ethanol - 1 mL) than previously reported. Reduction in reagent consumption was about 5.5 times for HPLC and about 19 times for SPE, according to previously reported. Method was validated according to the linearity (0.9951), selectivity and limits of detection and quantification were 15.7 µg L-1 and 55.6 µg L-1, respectively. The 4-NP removal in anaerobic batch reactors was higher than 50% (4-NP initial concentration of 398 µg L-1). Fumarate was a better co-substrate to favor methanogenesis in the presence of 4-NP, which provided higher organic matter removal, higher methane production speed and shorter start-up time for methane production.

本研究旨在开发一种可使用少量有机溶剂的色谱分析方法，用于厌氧分批反应器中4-硝基苯酚（4-NP）的定量检测，并评估不同共底物存在下4-NP的降解特性。研究对色谱相关参数进行了优化，包括固定相（C-8色谱柱）、流动相（乙腈/水溶液体积比90:10，v:v）、柱温（40℃）、洗脱流速（0.8 mL·min⁻¹）、进样体积（100 μL）以及荧光检测器（FLD）的检测参数：激发波长λex=225 nm，发射波长λem=305 nm。采用固相萃取（SPE）对样品进行纯化，所用有机溶剂用量（甲醇2 mL、乙醇1 mL）低于已有文献报道。相较于此前报道的方法，本方法的试剂消耗大幅降低：高效液相色谱（HPLC）试剂用量减少约5.5倍，固相萃取（SPE）试剂用量减少约19倍。本方法按照线性相关性（相关系数0.9951）、选择性进行验证，检出限和定量限分别为15.7 μg·L⁻¹和55.6 μg·L⁻¹。在初始4-NP浓度为398 μg·L⁻¹的条件下，厌氧分批反应器中4-NP的去除率高于50%。富马酸盐是4-NP存在下利于产甲烷作用的更优共底物，可实现更高的有机物去除率、更快的甲烷生成速率以及更短的甲烷生成启动时间。