Development of a method for determination of pesticide residues in honey using liquid chromatography tandem mass spectrometry

Abstract: Honey is a product that may contain pesticide residues due to contamination from bees pollinating various plants as well as elimination of vermin inside the hive. Different methods are needed for analysis of pesticides, since the term includes a wide range of different substances. National Food Administration lacks a validated method for determination and quantification of pesticides in honey using liquid chromatography tandem mass spectrometry, LC-MS/MS. The technique is especially important in analysis of polar and non-volatile pesticides, where gas chromatography is not functioning optimally. After investigating what pesticides could be found in honey produced in Sweden, a number of four pesticides suitable for analysis with LC-MS/MS was compiled; boscalid, impidacloprid, tau-fluvalinate and thiacloprid. A validated multi method for pesticide analysis in fruit and vegetables using LC-MS/MS was utilized as reference method, as a new method was developed. Some of the alterations in the new method included addition of water, changed order of addition of salts, centrifuge settings and shakings of samples. Performing validation experiments at three levels; 0.01 μg/g, 0.02 μg/g and 0.1 μg/g, yielded recovery in the range from 69.4% to 91.8% with relative standard deviation <19%. These figures met, with one exception, the requirements for validation of new methods at National Food Administration and also held linear correlation coefficients higher than 0.97. Three labels of honey, with different origins, were used in the experiments. One of the honey labels formed emulsion during extraction. Absence of a separate ethyl acetate phase caused difficulties when creating a suitable extract for determination and quantification by LC-MS/MS. A special extraction procedure was developed for that specific honey label enabling extraction. As successful extraction procedures were developed and recovery tests yielded satisfying results, the aim to develop an analysis method for determination of pesticide residues in honey using liquid chromatography tandem mass spectrometry was fulfilled.