A neoteric dual-channel spectral sensor for wide-range pH detection based on variables in UV–vis peak and intensity. Issue 43 (26th October 2021)

• Record Type: Journal Article
• Authors: Hu, Lei; Zhang, Mengxin; Dong, Junwei; Dong, Ran; Yu, Caili; Gong, Shijie; Yan, Zhengquan
• Is Part Of: Analytical methods. Volume 13:Issue 43(2021)
• Page Start: 5224
• Page End: 5230
• Publication Date: 2021-10-26
• Subjects: Chemistry, Analytic -- Periodicals; Analytical biochemistry -- Periodicals; Chemical laboratories -- Standards -- Periodicals; 543.1905
• DOI: 10.1039/d1ay01141c
• Languages: English
• ISSNs: 1759-9660

Abstract

Abstract : A water-soluble 2′, 4′, 6′-trihydroxy phenylazo luminol dye (THPL ) was developed for pH detection from 3.0 to 10.0 by the dual-channel spectral absorption intensity (Abs) or peak ( λ max ) changes in aqueous solution. Abstract : A water-soluble 2′, 4′, 6′-trihydroxy phenylazo luminol dye (THPL ) with a D–π–A conjugated structure was developed for the first time for the dual-channel spectral sensing of a wide-range of pH values in aqueous solutions, using phloroglucinol as the electron-donating group, heterocycle amide luminol as the electron-accepting one and –NN– as the π-conjugated bridge. Its UV–vis absorption spectrum, especially its spectral response to pH, was investigated in detail. The results confirmed that the proposed THPL exhibited superior UV–vis spectral properties, a strong molar absorption coefficient ( ε max = 3.35 × 10 4 L mol −1 cm −1 ) and a small half-band width of ca . 126 nm. In particular, either the absorption intensity (Abs) or peak ( λ max ) changed linearly with pH values from 3.0 to 10.0 under the optimized conditions. Notably, THPL expressed an exclusive dual-channel spectral response to pH, i.e ., Abs (a.u.) = 0.1316 + 0.0278 pH ( R 2 = 0.9921), λ max = 441.5 − 6.64 pH ( R 2 = 0.9968, pH = 3.0–6.0) and λ max = 359.6 + 7.38 pH ( R 2 = 0.9879, pH = 6.0–10.0). Under the optimized conditions, THPL was applied to detect pH values in some aqueous and fruit juice samples with satisfactory results. The reversible recognition mechanism was deduced by UV–vis titration, 1 H NMR titration and theoretical calculation.