## 5 Results and Discussion
As noted, the lower sample weight makes it harder to achieve a LOQ of 10 mg/g. The study also emphasized that extending the training time to 15 min allowed for a better recovery result in the tested samples [16]. [PERSON] and [PERSON], while analyzing samples of species, found that the main analyte, marker of fumigation was 2-chloroethanol, while ethylene oxide, due to its high reactivity and volatility, is practically undetectable in these types of products. The researchers also performed a derivatization reaction using 2 mL of 0.02 N H\({}_{2}\)SO\({}_{4}\) and 200 mL of a saturated NaCl solution; the extraction solvent was ethyl acetate. The validation experiment was performed in three repetitions with the recoveries of 65.5% for pepper with 100-200 mg/kg and 70.6% for pepper with 400-500 mg/kg. By comparison, our method is based on similar physicochemical assumptions, in which, under the conditions of acid hydrolysis with the addition of water, it leads to the formation of the free acid 2-chloroethanol. [PERSON] et al. used sulfuric acid, while our procedure and experiments have shown that the best choice is to use HCl. Work on optimizing the method has ensured that the recovery that was obtained in our study oscillated within the range of 85.6-103.6% [17]. Treating the sample with sodium chloride in the presence of sulfuric acid before solvent extraction results in a rapid conversion of ethylene oxide to 2-chloroethanol, which was implemented in the study by [PERSON] et al. The recovery obtained for a concentration of 0.05 mg/kg was 62.5%, and for a concentration of 1.10 mg/kg was almost 98.9%. The LOQ was set at 50 ug/kg [18]. The validation experiment conducted by us did not confirm an increased efficiency of obtaining better recovery at higher concentration levels. However, the critical aspect of achieving a high level of recovery at low concentrations in food samples is through the strict observance of conditions of analysis, such as temperature. A different analytical approach was presented by [PERSON] et al. The sample extraction method was a modification of the QuEChERS extraction method (EN 15662) with minor changes. Recovery was in the range of 87-104% at the tested levels (0.02, 0.04, and 0.1 mg/kg 2-chloroethanol) [19; 20]. Similar parameters for the QuEChERS procedure, performed in accordance with the description of the EU reference laboratory for single residue methods (EURL SRM 2020), allow for achieving similar levels of recovery [10]. Based on the GC-MS/MS SCAN mode of operation, retention times were determined for the following compounds: ethylene oxide--2.646 min, 2-chloroethanols--4.862 min, 2-chloroethanols D4--4.870 min; optimization allowed for the selection of the appropriate MRM transitions that were used during the validation assay methods. The relevant MRM transitions are presented in Table 1. The obtained chromatogram in Figure 7 shows that the integration of the ethylene oxide peak in the food matrix is hindered due to peak tailing caused by the low retention time and high solvent influence. The chromatogram of 2-chloroethanol retains the shape of the Gauss curve, which is desirable in the chromatographic determination, and therefore the method described in the text is based on the reaction of derivatization of ethylene oxide to 2-chloroethanol as the most accurate way to determine the full definition of ethylene oxide in accordance with directive 868/2015. The analyses carried out confirmed the compliance with the SANTE/11312/2021 document as to the requirements for the use of mass spectrometry. The retention times of the registered compounds corresponded to retention times with a tolerance of \(\pm\)0.1 min. Enrichment with an analyte, which is isotopically modified and suspected to be present in the sample, will also help to increase the confidence of the identification.