Lead 2 perchlorate trihydrate

2,4-dihydroxybenzoic acid (≥99.9%), hexamethylenetetramine (≥99.9%), Pluronic P123 (≥99.0%), sodium oleate (≥99.0%), potassium sulfate (≥99.0%), cesium sulfate (≥99.0%), perchloric acid (70%), lead (II) perchlorate trihydrate (98%), potassium hydroxide (≥85%), sulfuric acid (95.0-98.0%), and nickel (II) acetylacetonate (≥99.9%) were purchased from Sigma-Aldrich. The hydrophobic porous polytetrafluoroethylene (PTFE) substrates with 0.45 μm pore size were purchased from Beijing Zhongxingweiye Instrument Co., Ltd. Deionized water (18.2 MΩ) from an OmniaPure UltraPure Water System (Stakpure GmbH) was used for all the experiments. The Cu (99.999%) target was obtained from Kurt J. Lesker Company. Carbon dioxide (99.9%), nitrogen (99.99%), and oxygen gas (99.99%) were obtained from Air Liquide Singapore Pte. Ltd. Nafion 117 proton exchange membrane, Fumasep FAA-3-PK-130 anion exchange membrane and Ti screen mesh were purchased from Fuel Cell Store. The electrochemical flow cell and Ag/AgCl (3 M KCl) reference electrodes were purchased from Tianjin Aida Hengsheng Technology Development Co. The standard calibration gas mixtures for calibrating the gas chromatography system were obtained from Air Liquide Singapore Pte. Ltd. All the chemicals used in this work were of analytical grade and used without further purification.

All reagents used for device fabrication and sensing were utilized without further pre-treatment. ARS, a commercially available river sample with trace elements in river water (Elevated Level, NMIJ CRM 7202-c, Supplementary Table S1), and iron(III) nitrate enneahydrate (Fe³⁺) were obtained from FUJIFILM Wako Pure Chemical Co., Ltd. The target metal ions including cobalt(II) perchlorate hexahydrate (Co²⁺), calcium perchlorate tetrahydrate (Ca²⁺), lead(II) perchlorate trihydrate (Pb²⁺), cadmium perchlorate hydrate (Cd²⁺), nickel(II) perchlorate hexahydrate (Ni²⁺), copper(II) perchlorate hexahydrate (Cu²⁺), magnesium perchlorate hexahydrate (Mg²⁺), aluminum perchlorate non-ahydrate (Al³⁺), mercury(II) perchlorate hydrate (Hg²⁺), and zinc perchlorate hexahydrate (Zn²⁺) were purchased from Sigma-Aldrich. The building blocks of the chemosensors purchased from Tokyo Chemical Industry Co., Ltd. were 3-NPBA, BPR, PR, and PV. A buffer material purchased from DOJINDO was 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). All aqueous solutions were prepared using Milli-Q water (18.2 Ω cm).