Development of nanomaterials-fabricated paper-based sensors for the analysis of environmental and biological samples: A Review

Background: Currently, the environmental and biological samples such as water, soil, vegetables, etc. are highly contaminated with metal ions, anions and pesticides. For analysis of these toxic substances from the environmental and biological samples, sophisticated and expensive instruments are being used. The present work deals with the developmentof a simple, faster, sensitive and economicalmethod forthe analysis of toxic substances present in the different samples. Methods: The general methods for synthesis and characterization of metallic (Ag, Au, Cu and graphene) nanoparticles and conductive polymer for its the development of conductive nano-ink, and fabrication of paper substrate by direct deposition and laser, wax, or inkjet printing techniques is reported. Results: Paper-based sensors fabricated with different nanomaterials used as colorimetric, electrochemical and fluorescence-based chemical sensors for the quantitative determinationof pesticides, toxic metal ions in various biological and clinical samples have been comprehensively discussed in this review. Conclusion: The low-cost, rapid, eco-friendly, flexible, portable, paper-based sensors using nanoparticles (NPs) is on-demand for on-site detection of differentchemical constituents present in various environmental, biological and clinical samples.

Automated Solid Phase Extraction of Cd(II), Co(II), Cu(II) and Pb(II) Coupled with Flame Atomic Absorption Spectrometry Utilizing a New Sol-Gel Functionalized Silica Sorbent

In this study a simple and sensitive on-line sorbent extraction platform coupled with flame atomic absorption spectrometry for trace metals determination was developed. The system utilized for the first time a novel sol-gel thiocyanatopropyl functionalized silica as adsorbent for metal’s separation and preconcentration. The main factors affecting the performance of the on-line system were investigated and optimized. The effect of potential interfering species that occur naturally in environmental and biological samples, as well as some toxic elements, was evaluated. Under optimum conditions the enhancement factors ranged between 73 and 152 for the target analytes. The LODs of the proposed methods were 0.15 μg L−1 for Cd(II), 0.5 μg L−1 for Co(II), 0.5 μg L−1 for Cu(II) and 1.9 μg L−1 for Pb(II) for 120 s preconcentration time. The relative standard deviation values for all elements were less than 3.8%, indicating good method precision. Moreover, the sol-gel thiocyanatopropyl functionalized silica-packed microcolumns exhibited limited flow resistance and excellent packing reproducibility. Finally, the proposed method was utilized for the analysis of environmental and biological samples.

Electrochemical and Optical Methods for the Quantification of Lead and Other Heavy Metal Ions in Liquid Samples

Minerals and elementary compounds of heavy metals are part of the ecosystem. Because of their high density and property to accumulate in stable forms, they are considered to be highly toxic to animals, plants and humans. Continuous mining activities and industrial effluents are the major sources which are adding toxic heavy metal ions into ecosystem and biota. Hence it is of utmost importance to quantify the levels of heavy metal ions in environmental and biological samples. On the other hand, it is equally important to remove the heavy metal ions and their compounds from the environmental and biological samples. That facilitates the environmental samples to be fit for using, consumption. In this regard, promising quantification methods such as electrochemical, spectrophotometric, naked eye sensing, test strips for spot analysis of heavy metal ions are considered for discussion. The main objective of this chapter is to give the overview of the most practiced quantification approaches available in the literature. Please note that reader cannot find the pin to pin publications regarding the same and that is not the aim of this book chapter.