Combination of single-point standard addition calibration and natural internal standardization for quantification of terpenes in Pisco samples

Combination of single-point standard addition calibration and natural internal standardization was investigated as a practical strategy for the quantification of terpenes in Pisco samples using HS-SPME-GC-MS. All GC-MS data were acquired under simultaneous Full Scan and SIM modes using two quantification strategies identified as "reference strategy" and "simplified strategy". Linearity was first confirmed for linalool oxide, linalool and alpha-terpineol in a non-aromatic Pisco sample. The simplified strategy consisted of standard multicomponent addition of these same three terpenes to aromatic Pisco samples evaluating functionality of naturally present esters acting as candidate internal standards. The reference strategy consisted in the individual addition of every terpene standard to samples, using other naturally present terpenes as internal standards. Uncertainty budgets were presented for both calibration strategies. Relative combined standard uncertainties were between 6.6% and 10% for the reference strategy and between 1.9% and 33% for the simplified strategy using isoamyl acetate as natural internal standard and obtaining zeta-score values smaller than 2. Combination of single-point standard addition and use of a natural internal standard for HS-SPME-GC-MS measurements appears to be a potentially useful and reliable approach for measurements of terpenes in Pisco, and possibly in other measurements fields still in development.