Huij-Feng S, Takamori M, Hata N, Kasahara I, Taguchi S
Toyama University, Faculty of Science, Gofuku, Japan.
J AOAC Int. 2001 Nov-Dec;84(6):1781-5.
Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB- ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 microM benzyldimethyl-tetradecylammonium ion, a standard material, were > or =93 and < or =5%, with a detection limit of 0.02 microM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.
采用2种膜滤器，通过分光光度法对城市河流水体和沉积物中的阳离子表面活性剂（CS+）进行提取和测定。水样中的CS+大多以与共存阴离子表面活性剂（AS）形成离子缔合物的形式存在，用聚四氟乙烯（PTFE）膜滤器收集，并用甲醇洗脱。依次向甲醇溶液中加入溴酚蓝（BPB）、盐酸和水，混合溶液通过混合纤维素酯膜滤器过滤。通过反离子交换形成的CS+-BPB-离子缔合物被收集在滤器上，并与混合纤维素酯膜滤器一起溶解于N，N-二甲基甲酰胺（DMF）中。加入2滴三乙醇胺后，测定DMF溶液的吸光度。沉积物样品中的CS+通过超声辐射用甲醇提取；然后将甲醇溶液通过PTFE膜滤器并蒸发至干。CS+重新溶解于少量甲醇中。对于水样，标准物质0.30 μM苄基二甲基十四烷基铵离子的回收率和相对标准偏差分别≥93%和≤5%，检测限为0.02 μM。沉积物中CS+的浓度远高于水样中的浓度，表明CS+吸附在沉积物表面。
