Non-equilibrium potentiometric sensors integrated with metal modified paper-based microfluidic solution sampling substrates for determination of heavy metals in complex environmental samples

Ion-selective membrane modified microfluidic paper-based solution sampling substrates for potentiometric heavy metal detection

“…A linear response could be obtained in the range of 10 −5.0 to 10 −2.17 M Pb(NO 3 ) 2 with a lower detection limit of 10 −5 M Pb 2+ . The potentiometric response obtained with metal modified paper substrates 26 was found to be dependent on the thickness and type of the metal used, and the optimum response was obtained with paper substrates coated with gold of 38 nm thickness on both sides. It showed a linear response of 31.3 ± 1.4 mV dec −1 in the range of 10 −5.0 to 10 −2.2 M Pb(NO 3 ) 2 .…”

“…24 For Pb 2+ -ISEs, using filter paper treated with 10 −3 M Pb(NO 3 ) 2 and then drying prior to solution sampling resulted in a Nernstian response in the range of 10 −5.0 to 10 −2.17 M Pb(NO 3 ) 2 . Acidification of paper substrates 25 and sputtering both sides of paper substrates with metal 26 were also found to be effective for Pb 2+ ion detection. In the case of paper acidification, 25 the optimum potentiometric response was obtained when Pb 2+ -ISEs were coupled with paper substrates (containing the sample solution) at a pH range of 3 to 4.…”

“…These include the modification of paper with inorganic salts, 24 acid treatment, 25 or creating a physical barrier on the paper substrates (sputtered metal). 26 These techniques either deplete the active sites on the paper substrates or prevent the heavy metal ions from reaching active sites.…”

Microtoxicology by microfluidic instrumentation: a review

“…For the lower microlitre and nanolitre range, millifluidic and microfluidic techniques are required. Following methods have been used for miniaturized cultivation and screenings in recent years: (1) scaling of microtiter plates to the nanoliter range ("micro arrays"), 23,24 (2) chip-based micro cultivation systems, 25,26 (3) microfluid disc devices, 27,28 (4) micro-segmented flow in micro capillaries 29,30 and (5) paper-based microfluidics [31][32][33] (Fig. 1).…”

Low-cost microfluidics: Towards affordable environmental monitoring and assessment

“…In addition, other low-cost materials have also been reported. For example, sponge was used for thedetection of heavy metal ions in environmental samples (Ding and Lisak, 2019), leveraging the strength of sponge structure and the coupling with other materials for better mechanical properties (Hu et al, 2022;Silva et al, 2022). A few examples of the applications of low-cost porous materials are shown in Figure 3.…”