Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167, Islamic Republic of Iran.
Department of Science, Farhangian University, Tehran, P.O. Box 19396-14464, Islamic Republic of Iran.
Spectrochim Acta A Mol Biomol Spectrosc. 2018 Mar 5;192:122-127. doi: 10.1016/j.saa.2017.11.007. Epub 2017 Nov 10.
Cocamidopropyl betaine (CAPB) is a zwitterionic surfactant that is synthesized using coconut oil and usually supplied in form of an aqueous solution with 25-37% w/w. In this study, a novel method based on UV-visible spectroscopy is developed for an accurate determination of CAPB synthesized from coconut oil. Eriochrome Black T (EBT) as a specific color indicator was added to CAPB and a red shift and color change were observed. This shift leads in increasing wavelength selectivity of the method. The change in the color intensity depends on the concentration of CAPB. By measuring the absorbance of a solution containing CAPB, its concentration was measured. After optimizing all the effective parameters, CAPB was detected in commercial real samples. Using the proposed approach, limit of quantification (LOQ) and relative standard deviation (RSD) were obtained about 4.30×10M and 4.8% respectively. None of unreacted materials or by-products, which were produced in the synthesis of CAPB, showed any interference in the determination of CAPB. This shows that the proposed method is specific and accurate, and can potentially be used for quantitative determination of CAPB in commercial samples with satisfactory results.
椰油酰胺丙基甜菜碱（CAPB）是一种两性离子表面活性剂，由椰子油合成，通常以 25-37％w/w 的水溶液形式供应。在这项研究中，开发了一种基于紫外可见光谱的新方法，用于准确测定从椰子油合成的 CAPB。将特定的显色指示剂铬黑 T（EBT）添加到 CAPB 中，观察到红移和颜色变化。这种位移导致方法的波长选择性增加。颜色强度的变化取决于 CAPB 的浓度。通过测量含有 CAPB 的溶液的吸光度，可以测量其浓度。在优化所有有效参数后，在商业实际样品中检测到 CAPB。使用所提出的方法，检测限（LOQ）和相对标准偏差（RSD）分别约为 4.30×10^-5 M 和 4.8％。在 CAPB 的合成中未反应的材料或副产物均未显示出对 CAPB 测定的任何干扰。这表明该方法具有特异性和准确性，并且可以潜在地用于商业样品中 CAPB 的定量测定，结果令人满意。
