calibrant in extraction phase

https://doi.org/10.1351/goldbook.10167

Internal standard that is incorporated in the extraction phase for calibration.

Source:
PAC, 2016, 88, 517. 'Glossary of terms used in extraction (IUPAC Recommendations 2016)' on page 521 (https://doi.org/10.1515/pac-2015-0903)