Dispersive liquid-liquid microextraction for rapid and inexpensive determination of tetramethylpyrazine in vinegar

The concentration of tetramethylpyrazine (TMP) in vinegar is an active indicator of vinegar quality. Dispersive liquid–liquid microextraction (DLLME) was first applied to vinegar as a clean-up pre-treatment for the rapid (5 min) determination of TMP by high-pressure liquid chromatography with ultraviolet detection (HPLC-UV), and may serve as an alternative to solid-phase extraction (SPE) or solid-phase microextraction (SPME). High sensitivity of HPLC for TMP determination was obtained using the DLLME pretreatment, with a limit of detection (LOD) of 0.001 mg L−1 and limit of quantification (LOQ) of 0.005 mg L−1. The developed method exhibited excellent linearity in the concentration range of 0.050–80.000 mg L−1, with a correlation coefficient R2 > 0.999. Furthermore, the percentage recovery of TMP in vinegar using the developed method was within the range 97.97–105.24%. Therefore, DLLME coupled with HPLC-UV is a sensitive and promising method for vinegar clean-up and TMP assay.