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JA0027 QuEChERS-Based Method for the Multiresidue Analysis of Pesticides in Beeswax by LC-MS/MS and GC×GC-TOF
来源:Journal Of Agricultural and Food Chemistry | 作者:Silvina Niell | 发布时间: 2142天前 | 3393 次浏览 | 分享到:
The validation of an analytical procedure for the determination of pesticide residues in beeswax, an interesting matrix for environmental pollution monitoring, is presented. Using the QuEChERS template, the impacts of wax particle size, sample amount, and cleanup procedure (water addition, dispersive solid phase extraction, freeze-out, and combinations thereof) on extraction yield and coextractive load were studied. Sample preparation through liquid-liquid partitioning between acetonitrile and melted wax (∼80 °C), followed by freeze-out and primary-secondary amine dispersive cleanup, was performed on incurred and pesticide-free samples for 51 residues. Determinations were made through LC-MS/MS and GC×GC-TOF, and the whole procedure was validated. Matrix effects were evaluated, with recoveries between 70 and 120% and RSDs below 20% in almost all cases. LC-MS/MS LOQs ranged from 0.01 to 0.1 mg/kg for most pesticides, but for GC-amenable pesticides, GC×GC-TOF sensitivity was lower (0.1-0.2 mg/kg). This methodology can be applied for routine analysis of pesticide residues in beeswax.
1 Introduction

Beeswax is a pharmaceutical and cosmetic commodity listed in the U.S. and EU Pharmacopeias. It is also widely used as a food additive (E 901), for example, for the coating of fresh fruits, dried fruits, sweets, and cheeses, as well as a component of different polishing waxes. Beeswax is a very complex mixture of lipophilic compounds. Mono-, di-, and triesters of long-chain aliphatic alcohols with fatty acids or hydroxy-fatty acids constitute the largest fraction representing ca. 65% of the total weight. Free fatty acids, mostly C26 and C30, and longchain hydrocarbons represent ca. 12% each. Other components of beeswax are free hydroxy acids, free aliphatic alcohols, and carotenoids. In ancient times it was believed that beeswax was collected from flowers or made from pollen; it was not until 1744 that H. C. Hornbostel discovered that it is synthesized by four pairs of wax-secreting epidermal glands on the ventral side of worker bees’ abdomens. Bees use wax mainly for building the honeycombs; they remove, reshape, mold, and use it over and over again. The combs are literally the nursery, walls, storage pantry, home, pharmacy, and dance floor for the colony.1 Pesticides can enter the hive either directly or indirectly.2,3 Various acaricides, such as coumaphos, amitraz, and fluvalinate, are applied in beekeeping for Varroa mite control, but other environmental contaminants also find their way into the hive when bees fly around searching for nectar and pollen. For this reason honey bees and bee products have been used as bioindicators of environmental pollution in several countries.4-9 An emerging problem for apiculture is caused by the fact that beeswax is widely recycled when establishing a new hive, thus leading to a progressive accumulation of pesticides in it. In several studies conducted in different countries, residues of numerous pesticides have been found in beeswax.3,10-16 There are only a few methods described in the literature for the analysis of pesticide residues in beeswax. The most reported methodology is the single-residue one.