Pesticide residues in fresh and processed edible mushrooms from Czech markets.

The occurrence of pesticide residues, their metabolites and degradation products in 49 edible mushrooms (fresh, dried, canned and frozen) was investigated. Using QuEChERS extraction, followed by liquid and gas chromatography coupled with tandem mass spectrometry, the samples collected from Czech markets were tested for 427 analytes. A total of 21 pesticide residues, their metabolites and pesticide synergists were found in quantifiable concentrations. The most frequently detected pesticide residues included prochloraz and its metabolites, metrafenone and carbendazim. Two mushroom samples were found to be in violation of the maximum residue level. In addition, the fate of 13 pesticides during the processing of fresh mushrooms was investigated. The processing factors calculated from the data ranged from 6.0 to 12.3 for drying and from 0.3 to 1.3 for deep-freezing. The results showed that most of the pesticide residues tested were stable under the conditions of mushroom processing.