Colorimetric determination of phenols using polydiacetylene vesicles with alpha-cyclodextrin

Abstract

The preliminary determination of phenolic compounds using polydiacetylene (PCDA) with ∝ -cyclodextrin (∝ -CD) was developed. PCDA is known as remarkable unique color changeable material upon environmental stimuli and chemicals stimulants. It is easily to observe by naked eyes. The PPCDA vesicles solution with an optimal absorbance in the range of 0.4-0.5 was photopolymerized to form an intense blue solution by using 10,12-pentacosadiynoic acid. The color transition from blue-to-red can be induced by inclusion complex of ∝ -CD at the concentration higher than 3 mM. The inhibition of the color change was investigated using 9 phenolic compounds i.e. o-nitrophenol, m-nitrophenol, p-nitrophenol, p-bromophenol, p-chlorophenol, p-methylphenol, p-hydroquinone, 2,4-dinitrophenol, and phenol. The concentrations of phenolic compounds played a critical role to inhibit the color change which observed in the presence of 3 mM of p-nitrophenol and p-bromophenol and 5 mM of p-chlorophenol and m-nitrophenol. Meanwhile, the effect of other phenolic compounds was not observed. This inhibition ability was due to the competition between phenolic compounds and PPCDA vesicles. The phenolic compounds have greater ability stability than that of PPCDA vesicles to form inclusion complex with ∝-CD. The validation data for the determination of m-nitrophenol showed the linear range of 1.0-2.0 mM, 0.5-1.75 mM of p-nitrophenol and p-bromophenol, and 0.75-2.0 mM of p-bromophenol. This method exhibited a good accuracy for p-nitrophenol and p-chlorophenol. The precision of p-nitrophenol and p-chlorophenol which calculated as relative standard deviation (%RSD) is less than 2.0% (n=10).