Combined application of dispersive liquid–liquid microextraction based on the solidification of floating organic droplets and charged aerosol detection for the simple and sensitive quantification of macrolide antibiotics in human urine

•A new method for the determination of 5 macrolide antibiotics was developed.•First use of CAD for detection of chromophore-lacking macrolides is reported.•First application of DLLME-SFO to extract macrolides in human urine is reported.•SFO technique allowed interfering precipitate-free extraction of analytes in urine.•This method is more sensitive, rapid, and greener than earlier methods.

A novel analytical method combining dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) and liquid chromatography with charged aerosol detection (LC-CAD) was established. For the first time, CAD was applied for the detection of macrolide antibiotics lacking chromophores. Parameters influencing the microextraction efficiency were systematically investigated, and the optimized microextraction conditions yielded high enrichment factors in the range of 60–106. The combined application of DLLME-SFO and LC-CAD provided the sensitivity of the method, expressed as the limit of detection (LOD), as low as 10 to 40 ng mL−1 and intra-day and inter-day precisions below 8.7% and 12.6%, respectively. The measured absolute recovery values were approximately 100%, indicating that the extraction efficiency was very high. Direct comparisons of the liquid–liquid extraction and organic solvent precipitation methods demonstrated that the proposed method was more sensitive, specific, rapid, and environmentally friendly for the determination of five macrolide antibiotics in human urine. The results suggest that the combined use of DLLME-SFO and LC-CAD may be applicable to the analysis of various compounds with poor to no chromophores in complex matrices.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide