Rapid analysis of metal ions and organic compounds in strong acidic solutions by nano-ESI mass spectrometry

Rapid analysis of metal ions and organic compounds in strong acidic solutions is of sustainable interest in multiple disciplines. However, complicated and time-consuming pretreatments are always required for MS analysis of the compounds in strong acidic solutions. Otherwise, it will result in a weak signal and cause serious damage to the mass spectrometer. Herein, a simple method inherited from nano-ESI MS was developed for rapid analysis of strong acidic solutions. Nanoliter (nL) strong acidic solution was first loaded in the nano-ESI emitter, followed by evaporation to remove the H+ and leave the analytes on the wall of the nano-ESI emitter. The evaporation process can be completed within 1 min because of the extremely tiny volume (≤ 1 nL) of the loaded solution. Then, the dried analytes on the wall of the nano-ESI emitter were redissolved by loading a new solvent, followed by nano-ESI MS analysis. By using this method, metal ions and organic compounds in the strong acidic solution can be detected with low sample consumption (1 nL), high speed (< 2 min/sample), high sensitivity (limit of detection = 0.2 μg/L), and high accuracy (> 90%). Proof-of-concept applications of the present method have been successfully achieved for the analysis of gastric juice (pH of the sample = 1), monitoring reaction catalyzed by strong acid (pH of the system = 0), and micro-area analysis of ores (pH of the extraction solvent = 0), showing great application potential in multiple fields. A simple method inherited from nano-ESI MS has been developed for rapid analysis of metal ions and organic compounds in strong acidic solution (pH = 0) with low sample consumption (≤1 nL), high speed (≤ 2 min/sample), high sensitivity (LOD = 0.2 μg/L), and high accuracy (> 90%). [Display omitted]