Development and application of on-site multielement simultaneous rapid determination system using microdroplets and a handheld X-ray fluorescence spectrometer

Abstract We developed an on-site system for the rapid simultaneous determination of multiple elements that integrates microdroplet technology with a handheld X-ray fluorescence spectrometer. This system combines the concentration of heavy metals in microdroplets through homogeneous liquid–liquid extraction with the widespread application of handheld X-ray fluorescence spectrometry. The focus of our research was the analysis of heavy metals, specifically lead. Under optimal conditions, we achieved a high extraction percentage of 93.3%, and a high volume ratio of 120 times was achieved (from 23.9 to 0.200 mL). Building on these optimal conditions, we explored a mixed solution of copper and lead to facilitate the simultaneous rapid determination of multiple elements. By exposing a 200-μL microdroplet to a focused X-ray beam (9.0 mm in diameter), we confirmed a good proportional relationship for copper and lead concentrations ranging from 0.0837 to 0.126 mg/L. The determination limit (10 σ) was 0.040 mg/L for copper and 0.030 mg/L for lead. This system enables the stable evaluation of heavy metals at low concentrations (ppb level) with a straightforward operation.