Crop models use mathematical equations to simulate the physical and chemical processes that generally control the uptake, translocation, and sorption of xenobiotics in all part of plants. Each compartment is anatomically characterized and described by a series of mathematical equations. Sample preparation, such as liquid extraction methods and solid-phase-based methods are presented. Analysis of xenobiotics are generally carried out by gas chromatography (GC) or liquid chromatography (LC) coupled to different detectors, especially to mass spectrometers (MSs) and hyphenated techniques that have become extremely developed in recent years. As an example the wheat plant, as a model to describe xenobiotic uptake by roots and sorption of xenobiotic in grain, is applied.