Quality Management 12 4/2017 eFOOD-Lab international
Table 1: System parameters UHPLC-MS/MS
Table 2: Quantification limits in honey
Figure 3: Calibration curve of Fipronil in egg ranging from
0.0005 mg/kg to 0.05 mg/kg
Figure 4: Stability of peak areas in real honey samples
Use of these compounds has recently become controversial because
they are believed to be a cause of Colony Collapse Disorder (CCD),
a particular form of bee mortality in honey bees. Since honey bee
pollination is essential for agriculture, extensive studies have been
conducted to evaluate the impact of neonicotinoids on bee health.
In order to better understand the effect of these compounds on bees
and the contamination of pollen and honey, a highly sensitive assay method
was necessary. For this purpose, a UHPLC-MS/MS analysis has been
developed, as was already done for the analysis of chicken eggs.
Sample preparation was performed using the QuEChERS method
(Quick, Easy, Cheap, Effective, Rugged and Safe) with an additional
dispersive Solid Phase Extraction step (dSPE) 3.
Honey sample analyses
Calibration curves were prepared in acetonitrile in order to obtain
final concentrations ranging from 2.5 pg/ml (2.5 fg on the column) to
5 ng/ml. These concentrations correspond to 5 ppt or 10 ppb.
Nine honey samples purchased at the local supermarket or used as
raw material in cosmetics (orange honey) were assayed as unknowns.
All honeys tested showed neonicotinoid concentrations far below the
maximum allowable residue limit. But even these low concentrations
could be quantified thanks to the very high sensitivity reached.
A thyme honey sample with no detectable target compounds
was spiked at 50 ng/kg with all substances prior to extraction. The
resulting extract was then consecutively injected 150 times into the
system. The results shown in Figure 4 show excellent signal stability
even at these low concentrations. This demonstrates that excellent
sensitivity can be maintained over a long series of real sample analysis
thanks to the ion source ruggedness.
A method has been developed for the most sensitive analyses of Fipronil
and neonicotinoids, which can be used for different foods such as eggs
and honey. Sample preparation was simple and provided excellent recovery
tedious sample preparation steps. The high sensitivity obtained enabled
assay in real samples at very low insecticide concentrations, far below the
regulated residue limit. The quantification limits are shown in Table 2.
1 Gesundheitliche Bewertung der in Belgien nachgewiesenen Einzeldaten
rates. The injection mode used (POISe mode) avoided the need for
von Fipronilgehalten in Lebensmitteln tierischen Ursprungs,
statement no. 016/2017 of the BfR of July 30th, 2017
2 Application news SCA_210_038, Sensitive method for the determination
of Fipronil in egg using UHPLC-MS/MS LCMS-8060
3 Shimadzu News 2017/1, Pesticides: killers of bee colonies, P. 2-5