Extra experiments were performed to obtain the recovery of
typical illicit additives added into the viscous cosmetic samples. As
calculated by following the equation Recovery (%) = 100(Amount
found−Amount added)/Amount added, the recovery for the oxybenzone (added 5 ppb) in the highly viscous cream was 87.2%.
The averaged recovery of most compounds (5 measurements for
each sample) added to relatively high concentration levels such
as 50–200 ppb were in the range of 90–110%. The relative narrow
range of the recovery for measuring various concentration levels of
the additives confirms that the GIND-EESI-MS has the capability to
fast detect trace illicit additives in actual samples of high viscosities