Easy-to-make peptide-decorated C18 microspin columns combined with MALDI-MS enabling high-throughput enrichment and detection of arsenic (III) ions

Abstract

In this study, a user-friendly, cost-effective, and high-throughput method was developed for the selective enrichment and accurate quantification of arsenic (III) ions using peptide-decorated C18 microspin columns, integrated with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. The manufacturing process of the peptide-decorated C18 microspin columns originated from C18 StageTips packing with 3 μm C18 beads, followed by decoration with the peptide YYYCYCYYCR, which contained the arsenic (III) ion-binding motif CXCXXC, where X represents any amino acid. The microspin columns were applied to selectively capture arsenic (III) ions in environmental water by forming arsenic (III)-peptide complexes. After elution and drying, the high m/z ions from these complexes were directly desorbed and ionized with MALDI-MS by the addition of the α-CHCA matrix solution, effectively reducing interference from matrix-related ions and small molecules in the low m/z range. The developed method demonstrated a linear range from 10 μg/L to 1500 μg/L, with a limit of detection of 0.7 μg/L. Remarkably, this method enabled rapid quantification of arsenic (III) ions in environmental water, averaging under one minute per sample, using only a small volume of 50 μL. The reported method for detecting arsenic (III) ions in environmental water offers a practical approach and holds promise for analyzing other emerging toxic elements in the future.