The Determination Of Quaternary Ammonium Compounds By Gas Chromatography And Liquid Chromatography-mass Spectrometry And Their Distribution Characteristic In Urban Sewage Treatment Plant

Quaternary ammonium compounds(QACs) are one of the major cationic surfactants which are widely applied in household, industrial, agriculture and medical applications as wood preservatives, biocides, fungicides, disinfectants and detergents. QACs are ubiquitous in sewage, industrial wastewater, sludge, surface water and surficial sediments all over the world, posing a threat to biological treatment system and environmental system. Nowadays,environmental pollution of the QACs gradually aroused the concern of the environmental workers. Therefore, to establish a rapid, stable and reliable method to analyze QACs in environmental samples on environment monitoring of QACs is of great significance.Firstly, this study discusses using the TMSH derivative agent to determine hexadecyltrimethyl ammonium chloride(ATMAC-C16) by using GC-MS analysis method.Starting from the optimized derivatization conditions and GC-MS analysis conditions, the influence of the derivative agent amount on the detection of ATMAC-C16 derivative product is studied. However, due to the GC-MS method need to derive QACs first, which is complex,this experiment finally chose liquid chromatography coupled with mass spectrometry(LC-MS)combined with positive ions electrospray ionization(ESI+) method to detect quaternary ammonium salt. The LC-MS instrument approach for the analysis of quaternary ammonium salt is preliminary established. First of all, we selected C18 chromatographic column, and the mobile phase is methanol/water(7:3) solution containing 0.1% formic acid, and then the experiment optimize the gradient elution procedures of LC. The optimal gradient elution conditions start with 30% of the mobile phase A and 70%B; gradually increased to 100%B when 0 to 4 min; 100% B when 4 to 6 min; and decreased to 30%A and 70%B when 6 to 7min; kept to 30%A and 70%B when 7 to 8 min. The detection limit of these four quaternary ammonium salt, i.e. hexadecyltrimethyl ammonium chloride(ATMAC-C16), octadecyl benzyldimethyl ammonium chloride(BAC-C18), didodecyldimethyl ammonium bromide(DADMAC C12:C12), dioctadecyldimethyl ammonium bromide(DADMAC C18:C18) can reach 5ng/m L; The established linear equations of four quaternary ammonium salt are y=2494.9956+49182.4711 x, y=4525.7995+50788.1729 x, y=760.6959+35908.5828 x,y=2711.0139+14566.4124 x, respectively; All correlation coefficients are greater than 0.99;Relative standard deviation(RSD) is less than 10%, proving the precision of the method is very well.This article also applied the LC-MS method to the analysis of the influent and effluent sewage as well as sludge samples in each processing unit method in Changsha kaifu sewage treatment plant, by using soxhlet extraction and solid phase extraction to extract, enrich and purify quaternary ammonium salts. The results show that the influent contains ATMAC-C16,BAC-C18, DADMAC C12:C12, DADMAC C18:C18 these four kinds of quaternaryammonium salt. DADMAC C12:C12 has the highest content, which was 17.3093 ng/mL;followed by BAC-C18 and DADMAC C18:C18, which were 15.5366 ng/mL and 7.0409ng/m L, respectively; ATMAC-C16 has the lowest content, which was 5.2801 ng/m L. While the effluent sample detected only ATMAC-C16, with the content of 1.0418 ng/mL, and the other three kinds of quaternary ammonium salt could not be quantified due to lower than the detection limit. Thus we can conclude that the removal rates of four kinds of quaternary ammonium salt in the sewage treatment plant are greater than 80%. The test results of every processing unit sludge samples in the sewage treatment plant show that all the sludge samples contain the four kinds of quaternary ammonium salt, but cannot be quantified due to lower than the detection limit.