An alternative analytical strategy based on QuEChERS and dissolvable layered double hydroxide dispersive micro-solid phase extraction for trace determination of sulfonylurea herbicides in wolfberry by LC-MS/MS.

In this work, a combination of QuEChERS and dispersive micro-solid phase extraction (D-μ-SPE) based on dissolvable layered double hydroxide (LDH) has been established for preconcentration and enrichment of sulfonylurea herbicides (SUHs) in wolfberry samples. The QuEChERS was used for extraction and purification of SUHs, followed by D-μ-SPE for further enrichment of targeted analytes to obtain superior extraction performance. Dissolvable LDH nanosheets were used as absorbents, thus eliminating the elution step needed in traditional D-μ-SPE. The main influence experimental variables including pH of sample solution, amount of LDH, vortex time and volume of acidic solution were optimized in detail. Under the optimized conditions, the proposed method shows high precision (RSDs < 12.7%), low limits of detection (0.01-0.5 ng/g) and limits of quantitation (0.1-2.0 ng/g), acceptable recovery (80.1%-97.1%), thus making it a good alternative analytical strategy for the determination of SUHs residues at the low nanogram per gram range with desirable sensitivity.