Subnanomolar detection limit application of ion-selective electrodes with three-dimensionally ordered macroporous (3DOM) carbon solid contacts

Abstract

Solid-contact ion-selective electrodes (SC-ISEs) can exhibit very low detection limits and, in contrast to conventional ISEs, do not require an optimization of the inner filling solution. This work shows that subnanomolar detection limits can also be achieved with SC-ISEs with three-dimensionally ordered macroporous (3DOM) carbon contacts, which have been shown recently to exhibit excellent long-term stabilities and good resistance to the interferences from oxygen and light. The detection limit of 3DOM carbon-contacted electrodes with plasticized poly(vinyl chloride) as membrane matrix can be improved with a high polymer content of the sensing membrane, a large ratio of ionophore and ionic sites, and conditioning with a low concentration of analyte ions. This permits detection limits as low as 1.6×10−7 M for K+ and 4.0×10−11 M for Ag+.

Highly Selective Amide-tethered 4-aminoquinoline-β-lactam Based Electrochemical Sensors for Zn (II) ion Recognition

“…No significant potential perturbation has been observed with these metal ions as their obtained slopes are far from Nernstian behavior. It is well known that different conditioning solution and the starting solution strongly affect the detection limits of SC-ISEs [45,46]. To investigate these effects, the calibration curves of the CGE-1 were noted by testing the conditioning protocols such as: 1 day in 10 À3 M Zn (NO 3 ) 2 followed by 2 days in 10 À5 M Zn (NO 3 ) 2 (protocol 1), 1 day in 10 À3 M Zn (NO 3 ) 2 followed by 2 days in 10 À8 M Zn (NO 3 ) 2 (protocol 2), 1 day in 10 À6 M Zn (NO 3 ) 2 followed by 2 days in 10 À8 M Zn (NO 3 ) 2 (protocol 3) and the best lower detection limit (8.26 Â 10 À8 M) is achieved by employing protocol 2 as shown in curve B of Fig.…”

Opportunities and challenges of using ion-selective electrodes in environmental monitoring and wearable sensors

“…Ordered macroporous carbon solid contact on the other hand allowed the preparation of ISEs for the monitoring of potassium and silver with LOD of 1.6 × 10 -7 M and 4.0 × 10 -11 M respectively [88]. Considering that potassium is an important electrolyte in sweat and that silver concentration above 0.17 μg L -1 are considered toxic to fish these results could be significant for wearable and environmental applications, respectively [88].…”

“…Considering that potassium is an important electrolyte in sweat and that silver concentration above 0.17 μg L -1 are considered toxic to fish these results could be significant for wearable and environmental applications, respectively [88]. Finally, very recently potentiometric strip cells were produced on screen printed substrates and applied to test potassium in saliva samples [89] although diluted with buffer (to equalize ionic strength and pH).…”

Applications of nanomaterials in potentiometric sensors

“…Also, there is no clear evidence for an aqueous layer forming between the polymeric sensing membrane and the underlying contact, due to the hydrophobic surface of 3DOM carbon. The applications of the 3DOM carbon-based solid-contact ISEs were further investigated [20] and the LODs of 1.6 Â 10 À7 M and 4.0 Â 10 À11 M were obtained for K + and Ag + ions, respectively.…”