Ultra-low concentrations of detection for fluoride and trivalent chromium ions by multiple biomimetic nanochannels in a PET membrane

The development of a detection method for fluoride and chromium (III) ions using a PET membrane with multiple biomimetic nanochannels is descibed. An asymmetric chemical etching technique was used to create conical nanochannels with a PET (polyethylene terephthalate) nuclear track membrane. SEM images showed that the pore diameter of the tip and base sides of the nanochannel were similar to 40 nm and similar to 180 nm, respectively. The compounds (4-aminophenyl) boronic acid (APBA) and 5-amino-2-nitrobenzoic acid (ANBA), with a specific recognition for F- and Cr3+ respectively, were modified by a conventional method with EDC and NHS. The current-voltage (I-V) curves of the modified PET membranes in response to the target ions at different con-centrations were measured with a picoammeter. Excellent linear relationships between the current value of the I-V curve at -2 V and the concentration of Cr3+ and F- were established to obtain standard detection curves for Cr3+ and F- . From these relationships unknown concentrations of Cr3+ and F- can be quantitatively detected, and the results showed that the detection limits of Cr3+ and F- were as low as 4.10 nM and 0.46 nM, respectively. The performance of the novel method was compared to conventional ICP-MS analysis by the determination of Cr3+ in tap water and samples of the Jing Mi diversion canal, and good agreement was found between the two methods. The accuracy and reliability of the method has demonstrated its potential applicability to a wide range of other ionic contaminants.

Automated summary

The development of a PET membrane with multiple biomimetic nanochannels for the detection of fluoride and chromium (III) ions is described. The membrane was created using an asymmetric chemical etching technique and was modified with specific recognition compounds for F- and Cr3+. The method showed excellent linear relationships between current values and ion concentrations, with low detection limits of 4.10 nM for Cr3+ and 0.46 nM for F-. The accuracy and reliability of the method were compared to conventional ICP-MS analysis and showed good agreement, demonstrating its potential application for detecting a wide range of ionic contaminants.