Pesticides play a crucial role in improving agricultural productivity by protecting crops from pests and diseases. However, improper application of these chemical agents poses significant risks to human health and the environment. Soil, a fundamental resource in agriculture, can adsorb and retain pesticides. Once bound to soil particles, these compounds may undergo rapid degradation or be released gradually into the environment and groundwater systems. Persistent pesticides are particularly concerning due to their prolonged environmental presence, which can lead to detrimental effects on living organisms through bioaccumulation and ecological disruption. Similarly, the presence of heavy metals in soil presents substantial ecological and health risks. The main challenge in analyzing pesticide residues or heavy metals lies in the complexity of developing methods that ensure high sensitivity, accuracy, and precision while overcoming interference from diverse sample components.
Once a suitable analytical method is established and its accuracy and precision are verified, it is applied to real samples to evaluate their contamination by pesticides or heavy metals. The literature shows limited data on soil and fruit contamination by pesticides and heavy metals in the Aseer region, especially in Wadi Bin Hashbal. This demonstrates the necessity of research to evaluate soil and fruit quality in this important agricultural area. This study validates the QuEChERS method for detecting pesticide residues in four fruit samples obtained from local supermarkets in the Aseer region, Saudi Arabia, and two soil samples collected from Wadi Bin Hashbal and the Suda area in the same region, using gas chromatography-mass spectrometry (GC-MS). Calibration of pesticide standards yielded correlation coefficients ranging from 0.9997 to 0.9916, ensuring reliable quantitative analysis. Recovery rates for the studied pesticides in lemon samples ranged from 76.4% to 100.5%, while soil samples from Wadi Bin Hashbal exhibited recoveries between 70.5% and 90.3%. The relative standard deviation (RSD%) for lemon samples ranged from 2.19% to 10.69%, whereas for soil samples from Wadi Bin Hashbal, the RSD% ranged from 3.63% to 11.32%. The analysis revealed that all tested samples were free of pesticide residues, except for diazinon in the soil sample from Suda, piperophos in both the soil-Suda and apple samples, and permethrin-2 in the tangerine sample. The concentrations of these detected pesticides fell within the range of the limit of quantification (LOQ) and the limit of detection (LOD). Specifically, the LOD values for the analyzed pesticides were ≤ 0.112 μg/g (propyzamide), while LOQ values were ≤ 0.204 μg/g (propyzamide). Additionally, the concentrations of heavy metals in soil samples from Wadi Bin Hashbal, irrigated with treated and untreated water, were measured across different seasons using inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that some heavy metal concentrations exceeded permissible limits set by the Kingdom of Saudi Arabia, with the lowest concentrations observed during the spring season.