## 1 Introduction  
Pesticides are used to improve crop productivity and isolate agricultural products from various pests, including insects and fungi. Crop production and farm household income may decrease if they are not used [1, 2]. They are used before planting seeds of crops or after germination. In addition, they are sprayed when diseases or pests spread. In addition, they are used before agricultural product shipment [3, 4, 5]. Currently, pesticides include herbicides, insecticides, fungicides, and other ingredients to enhance pesticide activity. Depending on the cultivation pattern and primary crops in each country, the types of pesticides in use may be different, as well as the amounts of them used in the fields [6; 7]. In this respect, it has been reported that some countries, including Korea, use more pesticides than other countries to protect crops [8; 9].  
However, the use of these pesticides creates an indispensable situation that impacts the agricultural ecosystem; environmental destruction has been reported numerous times, and is recognized as a major cause of various human diseases [10]. Therefore, efforts to produce crops by limiting their use are of interest [11]. For example, the positive list system (PLS) collectively applies the level of 0.01 ppm for the maximum residue limit (MRL) to pesticides for which MRL is unset, and PLS has recently been passed in Korea [12]. Used pesticides evoke adverse effects on the ecosystem after spraying; they disrupt the terrestrial and aquatic ecosystems, and many of the endocrine-disrupting chemicals are from pesticides [13].  
Therefore, it is inevitable to receive attention from the public regarding how high amounts of pesticides remain in cultivated crops, as well as agricultural soils and waterways, and monitoring of residual pesticides in agricultural products and environments contributes to the efficient safety management of pesticides [14; 15]. However, in addition to this efficient management, it is necessary to maintain the agricultural environment safely when crops are not grown, because many pesticides remain in agricultural water and soil after cultivation, and the dynamics of these environments are not understood in some cases. For example, the kinetics and toxicity of the original pesticides and their metabolites are often not studied in detail [16].  
Various kinds of pesticides may remain in agricultural soils for a long period, and studies have shown that they can be transferred to crops through roots when crops are growing [17; 18]. The risk of migration of residual pesticides from the agricultural soil to crops can be prevented or predicted by monitoring residual pesticides in the agricultural soil.  
Recently, monitoring of pesticide residues known as multiresidue pesticide analysis has been developed to analyze multiple pesticides simultaneously using GC-MS/MS and LC-MS/MS [19; 20]. With this multiresidue pesticides analysis, the QuEChERS extraction method with the dSPE clean-up method also was introduced [19], and the analytical time should be shortened, with a reduction in the analysis cost. In this study, we developed a multiresidue pesticide analytical method using GC-MS/MS and LC-MS/MS with QuEChERS extraction and dSPE clean-up. We used the developed multiresidue analysis for monitoring 40 agricultural soils near the industrial areas in Pohang and Ulsan cities in Southern Korea. We analyzed 342 pesticides, including a pesticide banned by the Korean government due to its isomers and metabolites such as alpha-endosulfan, beta-endosulfan, and endosulfan sulfate. These chemicals are registered as persistent organic pollutants (POPs), and they also have been prohibited in Korean agriculture.