Single particle inductively coupled plasma mass spectrometry (spICP-MS) is widely employed for nanomaterials (NMs) characterization in environmental samples [1]. Though liquids can be directly analyzed using this technique, a filtration step is usually required to remove suspended solids to analyze wastewater samples. To this end, polyethersulfone filters have been recommended since they do not retain NMs present in this type of sample thus allowing accurate and precise determinations [2-3]. Another type of filter is not recommended for such applications since they retain NMs, particularly Nylon which capture them quantitatively.

Our research group has recently demonstrated that non-labile metallic NPs are efficiently released from

soils and microquartz filters unaltered using a microwave-assisted extraction (MAE) treatment with basic extractants (i.e., NaOH or NH4OH) [4-6]. So, a priori, such a strategy could be readapted for Nylon filters thus enabling to use of them to extract and preconcentrate NMs from wastewater samples. To achieve this goal, the retention capabilities of Nylon filters were initially tested for nanoparticles of varying chemical compositions (e.g., ZrO2, TiO2, Pt, and AuNPs), sizes (20-150 nm), and capping agents (citrate, polyethylene glycol, branched polyethyleneimine, and lipoic acid). Next, MAE experimental conditions were optimized by means Design of Experiments (Extractant concentration, MW time) and applied to the analysis of a wastewater sample. Our results show that Nylon filters allow complete NMs extraction from wastewater samples irrespective of analyte characteristics. All the NMs tested can be quantitatively released from the filters by means a MW-assisted extraction treatment with diluted NaOH using an appropriate temperature program in less than 10 minutes (Figure 1). This strategy is particularly advantageous to decrease matrix effects by wastewater concomitants as well as to improve particle number detection limits.

References

[1] D. Mozhayeva; Journal of Analytical Atomic Spectrometry, 2020, 35, 1740-1783.

[2] I. Jreije; Talanta, 2022, 238, 123060.

[3] L. Hong; Analytical Sciences, 2023, 39, 1349-1359.

[4] D. Torregrosa; Talanta, 2023, 252, 123818.

[5] C. Gómez-Pertusa; Talanta, 2024, 272, 125742.

[6] C. Gómez-Pertusa; Journal of Analytical Atomic Spectrometry, 2024, 39, 1736-1740.