Multiple headspace solid-phase micro-extraction for the total content determination of tetramethylpyrazine in various vinegar samples by GC-FID†
The total tetramethylpyrazine (TMP) content in vinegar samples could be detected by multiple HS-SPME coupled with GC-FID (MHS-SPME-GC-FID) as a routine method. Unlike the traditional HS-SPME method, only one working curve built with different levels of standard aqueous solutions in the MHS-SPME-GC-FID method was able to calibrate the total TMP level from different matrixes (calibration standards ranging from 0.05 to 5.00 μg mL−1, R2 = 0.9986). In addition, the developed method was sensitive to the determination of TMP in vinegars (the limit of detection of 1 μg L−1, the limit of quantification of 5 μg L−1). In addition, the excellent recovery at 0.10 μg mL−1, 1.00 μg mL−1 and 5.00 μg mL−1 of TMP (ranging from 81.01% to 113.5%) and good reproducibility of the method (inter-day RSD 7.79%, intra-day RSD 3.94%) confirmed that the developed method was accurate and stable for the analysis of vinegar samples. Moreover, the detection results in real samples were consistent with the results from the traditional HS-SPME-GC-FID corrected by external standard method. In conclusion, the uniqueness of the working curve and the absence of matrix effect in MHS-SPME-GC-FID method were useful for rapidly obtaining comparable data from liquid samples with different matrix.