High performance liquid chromatography coupled with ultra-violet, diode array detection (HPLC-UV-DAD), was used to study the degradation reactions of ultraviolet (UV) filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB). Degradation by-products were detected and identified by means of liquid chromatography coupled with diode array detection and mass spectrometry (LC-DAD-MS). Environmentally-relevant characteristics, such as water pH, chlorine levels, water temperature and dissolved organic matter (DOM) concentration, were modulated and studied in order to determine their influence on the degradation reactions.

Results show that DHHB degrades quite rapidly in typical drinking water disinfection conditions, displaying a kinetic rate constant of k_obs = 0.0060 ± 0.0002 s⁻¹ and a half-life period of merely t_1/2 = 116 ± 4 s. As far as the non-volatile disinfection by-products (DBPs) are concerned, only the mono and dichlorinated forms of DHHB were detected in the degradation reactions. Regarding influential variables on DHHB degradation, the presence or absence of DOM in solution did not alter the trends that were found (degradation of DHHB is more significant at lower pH values and higher levels of active chlorine in solution). Chlorinated DBPs have also been found to predominate under higher pH values and lower levels of chlorine, whereas they were found to be unstable and further degradable, quite likely into smaller and more volatile compounds, when in lower pH and higher chlorine concentrations. As for the photo-degradation studies, DHHB was found to be extremely photo-stable, with only about 15% degradation rate detected during artificial irradiation periods of 6 h.

高效液相色谱结合紫外二极管阵列检测（HPLC-UV-DAD），用于研究紫外滤光片2- [4-（二乙基氨基）-2-羟基苯甲酰基]苯甲酸己酯的降解反应（DHHB）。通过液相色谱与二极管阵列检测和质谱联用（LC-DAD-MS）检测和鉴定降解副产物。对与环境相关的特性（例如水的pH值，氯含量，水温和溶解的有机物（DOM）浓度）进行了调节和研究，以确定它们对降解反应的影响。

结果表明，DHHB在典型的饮用水消毒条件下降解速度非常快，其动力学速率常数为k _obs  = 0.0060±0.0002 s ^-1，半衰期仅为t _1/2 = 116±4 s。就非挥发性消毒副产物（DBP）而言，在降解反应中仅检测到DHHB的单氯和二氯形式。关于DHHB降解的影响变量，溶液中是否存在DOM并不会改变所发现的趋势（在较低的pH值和较高的活性氯水平下，DHHB的降解更为显着）。人们还发现，在较高的pH值和较低的氯含量下，氯化DBP占主导地位，而在较低的pH和较高的氯浓度下，它们却不稳定且可进一步降解，很可能变成更小和更具挥发性的化合物。至于光降解研究，发现DHHB具有极高的光稳定性，