Hexamethyldisilazane Modified Paper as an Ultra-sensitive Platform for Visual Detection of Hg2+, Co2+, Zn2+ and the Application to Semi-quantitative Determination of Hg2+ in Wastewater

Abstract

The present article reports the application of hexamethylsilazane (HMDS) modified filter paper for ultrasensitive detection of Hg 2+ , Co 2+ and Zn 2+ . By chemical vapor deposition of HMDS, a highly hydrophilic filter paper was fabricated to a low wetting (hydrophobic) substrate. The water contact angle (θ) of modified paper was ~128 , whereas scanning electron and atomic force microscopy confirmed the surface modification. Using chromogenic reagents, a one-step assay for aforementioned ions was demonstrated onto pristine as well as hydrophobic paper. The assay was completed in less than 10 min and the end-result was in form of a color change that could be easily read by the naked eye. The limit of detection on modified paper was 0.5 ppb, which was 5-order of magnitude superior to that observed on pristine paper. The proposed method was successfully applied for semi-quantitative determination of Hg 2+ ions in real wastewater samples.

A Highly Structured 1,10-Phenanthroline Arrayed Hydrophobic Sulfone Membrane Platform for the Rapid Determination and Speciation of Fe2+/Fe3+ Ions in Water

“…This may further assist in enhancing the color density of the metal-ligand complex, thus improving the assay sensitivity. 14 …”

“…The spot intensity was quantified by flatbed scanning and scoring the pixel gray volume (PGV) as explained before. 13,14 Robustness (pH, temperature and volume of analyte). The influence of the pH on the performance of the Fe 2+ assay was investigated by preparing a Fe 2+ (10 μg mL -1 ) solution in a Britton-Robinson (B-R) buffer ranging from pH 2.0 -9.0.…”

“…A similar strategy concerning the analyte concentration on the substrate surface was successfully demonstrated for the ultrasensitive detection of Ni 2+ , 13 Hg 2+ , 14 and Zn 2+ 10 ions in water. According to them, the low-wetting substrate prevents the dissipation of aqueous metal ion droplets, thus enriching the reagent spot and enhancing the signal intensity as well as the assay sensitivity.…”

“…13,14,20 Hence, a study was performed to understand the influence of the pH on the color intensity of (Fe-phenanthroline) complex. A Fe 2+ (10 μg mL -1 ) solution was prepared in B-R buffer 13,21 ranging from pH 2.0 -9.0 and further tested by our developed method.…”

Microfluidic Paper-based Analytical Device for the Determination of Hexavalent Chromium by Photolithographic Fabrication Using a Photomask Printed with 3D Printer

“…[12][13][14][15][16] To date, μPADs have been used as elegant analytical tools for a variety of applications, including medical diagnosis, [17][18][19][20][21] food testing, 22 and environmental monitoring. [23][24][25][26][27][28][29] A lot of detection methods have been used for μPADs. The most common detection method for μPADs is colorimetry because analysis is relatively simple.…”