Simple, Rapid and Sensitive Detection of Phenylarsine Oxide in Drinking Water Using Quartz Crystal Microbalance: A Novel Surface Functionalization Technique

Abstract

A simple, inexpensive, rapid and label-free detection of phenylarsine oxide (PAO) in the field is a significant and unmet need because of its fatally acute and chronic effects on human health. A chemically easy and applicable surface modification procedure can fill this deficiency. In order to determine the cheaper, simpler and rapid surface functionalization technique, gold surface of quartz crystal microbalance (QCM) sensor was modified with ethanol-dependent (3-mercaptopropyl)trimethoxysilane (MPS) coating at pH=4.5 first, and then seconder ethanol-dependent linker layers, which contain (3-mercaptopropyl)trimethoxysilane (MPS), dimercaprol (BAL) or 2-mercaptoethanol (ME), were tested at pH=9.0, respectively. QCM measurements were performed to analyze the stability of each layer in deionized water (DIW) and drinking water for both negative control and arsenic detection performance. Among those examined procedures, the procedure with acidic MPS + basic ME resulted in the best stability in aqueous mediums with a frequency change nearly zero and sensitivity with a frequency shift of 180 (+/- 22) Hz for a concentration of 100 ng/mL PAO in DIW. By using the optimum surface functionalization method, the minimum PAO with a concentration of 1 ng/mL in drinking water was measured as a frequency of 33 (+/- 9) Hz. Besides, this surface modification technique can be applied to the more readily available and cheaper sensor platforms, such as impedimetric electrochemical sensors