One-step effervescence tablet-assisted switchable hydrophilic solvent microextraction combined with micro spectrophotometry for the determination of copper in Salvia yunnanensis and environmental samples

Abstract

In this work, an efficient one-step effervescence tablet-assisted switchable hydrophilic solvent microextraction (ETA-SHS-ME) method was developed and firstly combined with micro ultraviolet-visible (micro UV-Vis) spectrophotometry for the determination of trace copper (Cu) in natural medicine Salvia yunnanensis and environmental samples (water and soil). The extraction was rapidly accomplished in one step by transferring the effervescence tablet into the aqueous sample, the proton donor agent (malonic acid) contained in the tablet reacted simultaneously with the organic phase source (sodium nonanoate) and the effervescent agent (sodium bicarbonate, NaHCO3) to produce the extractant nonanoic acid and CO2. The in situ generated CO2 promoted the dispersion of nonanoic acid in the aqueous sample and improved the extraction efficiency of the analytical method. Under the optimal conditions, the limit of detection (LOD) and the limit of quantification (LOQ) were 0.01 and 0.04 μg/L, respectively, and the enhancement factor (EF) was 76.3. The developed method was successfully applied to the analysis of trace Cu in natural medicine and environmental samples. The one-step extraction method coupled with portable spectrophotometer has a good prospect for application in field analysis.