Neonicotinoids are a relatively new class of insecticides chemically similar to nicotine. Their mode of action works by irreversibly binding to nicotinic acetylcholine receptors, resulting in insect paralysis and death. Recently they have come under scrutiny over their ecological impact, especially their role in honey bee colony collapse disorder. Neonicotinoid residues accumulate in pollen and nectar and pose a risk to honey bees. Due to their potential negative impact, the European Union recently restricted the use of three neonicotinoids for a period of 2 years.
This application note outlines a simple, fast and cost-effective method for the determination of 7 neonicotinoid pesticides in honey. Honey is dissolved in water and extracted via the QuEChERS technique followed by dSPE clean up. Analysis is performed by uHPLC/MS-MS using a Selectra® DA uHPLC column. Results provided excellent sensitivity, selectivity and reproducibility.
Procedure:
10 g of honey (processed or raw) was dissolved in 10mL DI water and extracted into 10mL acetonitrile using a QuEChERS shake out and partitioning technique. The QuEChERS pouch (p/n ECQUEU7-MP, UCT, LLC) contained 4 g MgSO4, 1 g NaCl, 0.5 g sodium citrate dibasic sesquihydrate and 1 g sodium citrate tribasic dehydrate. After extraction, 1 mL of the supernatant was cleaned up using a dSPE procedure (2 mL dSPE tube, p/n CUMPSC18CT, UCT, LLC, containing 150 mg MgSO4, 50 mg PSA and 50 mg endcapped C18).
Analysis:
Sample analysis was carried out on a Dionex™ Ultimate™ 3000 uHPLC system coupled with a TSQ mass spectrometer (Thermo Scientific, Waltham, MA) run in ESI+ mode. The analytical column was a Selectra DA, 50 x 2.1 mm, 1.8 µm (p/n SLDA50ID21-18UM, UCT, LLC Bristol, PA). A gradient mobile phase at 300 µL/min was used with acidified (0.1% formic acid) water and methanol.
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