Sensors and Actuators B 109 (2005) 291–299 An ion-based chromogenic detecting method for phosphate-containing derivatives in physiological condition Caixia Yin, Fangjun Huo, Pin Yang ∗ Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Wucheng Road 36, Taiyuan 030006, China Received 8 September 2004; received in revised form 18 November 2004; accepted 29 December 2004 Available online 26 February 2005 Abstract The detection for phosphate-containing and ATP in water is a challenging task. Here, we report a simple and sensitive method for detecting both HPO 4 2- and ATP in aqueous solution. The new ensemble is prepared by mixing ytterbium chloride and pyrocatechol violet in a 2:1 molar ratio in aqueous solution of 10 mM 2-[4-(2-hydroxyethyl)-1-piperazinyl] ethanesulfonic acid (HEPES) buffer at pH 7.0. Upon the addition of YbCl 3 , the maximum absorption peak gradually shifted from 444 nm (yellow) to 623 nm (blue). With the addition of HPO 4 2- or ATP solution into the system, the ensemble resulted in a change back of color from blue to yellow and caused a variation in UV–vis absorption spectra. The ensemble exhibits excellent selectivity for HPO 4 2- and ATP over other common anions including Cl - , SO 4 2- , CH 3 COO - , HClO 4 - and HCO 3 - . © 2005 Elsevier B.V. All rights reserved. Keywords: Pyrocatechol violet; Ytterbium chloride; HEPES buffer; Phosphate ions; Adenosine triphosphate (ATP); UV–vis spectra 1. Introduction Phosphorus is one of the most important elements in lives. Together with heterocyclic bases and deoxyribose, phos- phates make up the nucleotides, which in turn make up the genes, the hereditary elements of lives. More straight saying, nucleotide acting as frame unit of nucleic acid and partic- ipating in life activity processes of all cells is a very im- portant biochemical substance in metabolizing. People have developed many technologies of detecting nucleotide such as spectrum analysis [1], mass spectrometry [2], chromatog- raphy [3] and electrophoretic method [4] in recent years. In addition, phosphate and its derivatives, particular adenosine triphosphates (ATP), play pivotal roles in energy utility and signal transduction in various biological processes. In vivo, the phosphate groups may form metallic complexes via co- ordination by taking O atoms as electron donors; this is es- ∗ Corresponding author. Tel.: +86 351 701 1022; fax: +86 351 701 1022. E-mail address: yangpin@sxu.edu.cn (P. Yang). pecially true when the metal ions are hard Lewis acids, such as Mg 2+ or Ca 2+ ions [5]. Numerous sensors for anions, in- cluding HPO 4 2- have been devised [6], but most of them use organic solvents as the detection medium because these sen- sors rely on hydrogen-bonding and electrostatic interactions for the recognition of analytes [7,8]. These interactions are, however, hindered drastically in a highly polar medium such as water because of the competing solvation effect [9]. The detection for phosphate anions, and more important for ATP in water is, hence, a challenging task. Among those anion sen- sors [6] in aqueous media, significant progress has been made in the detection of oxy-anions (such as HCO 3 - ,H 2 PO 4 - ) with lanthanide-containing receptors (especially Eu(III) and Tb(III)) by spectrometry and NMR methods [10,11]. During the investigation on biological effects of dinuclear lanthanide complexes stemmed from a phenol-based ligand, Hb- bimp [12], (2,6-bis(bisbenzimdazolylmethyl)aminomethyl)- 4-methyl-phenol), we found that this system is an efficient sensor for HPO 4 2- and ATP. It is prepared by mixing Hb- bimp, YbCl 3 , pyrocatechol violet (PV) in a 1:2:1 molar ratio 0925-4005/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2004.12.097