基于AgI2-缔合微粒共振散射效应测定阳离子表面活性剂

在pH 3.5 NaAc-HCl介质中,Ag 与过量的I-形成可溶性AgOI2-;当十六烷基三甲基溴化铵(CT-MAB)与AgI2-共存时形成粒径为700 nm的(CTMA-AgI2)n缔合微粒,在360 nm处产生一个共振散射峰,在470 m处产生一同步散射峰.CTMAB浓度cCTMAB在2.0～50.0×10-7mol·L-1范围内与散射光强度I360nm呈线性关系,回归方程为I360nm=2.03×107 cCTMAB 0.48,相关系数r为0.998 5,检出限为8.0×10-8mol·L-1.据此建立了一个测定阳离子表面活性剂含量的共振散射光谱法,用于水样分析,结果满意.共振散射光谱和激光散射研究表明,CTMAB 与AgI2-可通过静电力形成疏水性的CTMA-AgI2缔合物分子,该缔合物分子自动聚集形成稳定的(CTMA-AgI2)n缔合微粒.由于该缔合微粒仅在360 nm处产生共振散射效应,故体系呈乳白色.

A new Spectral Method for the Determination of Cationic Surfactant Based on the Resonance Scattering Effect of AgI2- Association Particles

In pH 3.5 NaAc-HCl medium, there is a maximum resonance scattering (RS) peak at 360 nm and a synchronous scattering peak at 470 nm for the association particle system of (CTMAB-AgI2)n in white color, with a diameter of 700 nm. The CTMAB concentration cCTMAB in the range of 2.0-50.0 x 10(-7) 4 mol x L(-1) is linear to the I360 nm value. Its regression equation is I360 nm = 2.03 x 10(7) cCTMB + 0.48, and regression coefficient is 0.9985. The detection limit is 8.0 x 10(-8) mol x L(-1). A new RS method has been proposed for the determination of cationic surfactant in samples with satisfactory results. The laser scattering and RS spectra show that CTMAB+ and AgI2- combine to CTMA-AgI2- association molecule by means of attractive forces. The association molecules automatically aggregate to (CTMA-AgI2)n association particles, so that the particles exhibit a resonance scattering peak at 360 nm, and the system is in white color.