Still, the procedure is quite complex with limited sample throughput and generates a significant amount of waste. Direct injection of diluted juice or wine samples onto an LC column could be possible, but on the cost of sensitivity and assay robustness. Column-switching is primarily used in bioanalysis for direct injection of plasma and urine and is also suitable for the analysis of food liquids. The key parameter to optimize is the proper retention of the analytes onto the trapping column and the removal of matrix compounds. Several cartridges were evaluated under various trapping conditions to determine the most suitable parameters for pesticide retention. Seven pesticides were selected for this purpose: acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam (Figure ). Juices are mostly aqueous, while wine samples can contain up to 15 % ethanol, affecting retention of polar analytes. Trapping tests were conducted using standards dissolved H 2O/EtOH (85/15, v/v). Based on the predicted analyte charge state (Figure ) two different trapping mobile phases were tested, including 5 mM ammonium formate (pH 6.2) and 1% formic acid (pH 2.1). Figure presents a schematic of the column-switching system, where sample volumes ranging from 1 µL to 1 mL can be directly injected (Figure ). Among the four trap columns tested, the ReproSil-Pur 120 C18-AQ and Reprospher 100 C18/WCX provided the best results of the number of analytes retained and the signal intensities (Figure ). In contrast, the ReproSil 80 SCX performed poorly, with no trapping of dinotefuran, clothianidin, and thiamethoxam under both buffer conditions. Additionally, using 1% formic acid in the sample led to a loss of nitenpyram when using strong cation exchange or mixed-mode trapping columns (Figure ). Ultimately, the ReproSil-Pur 120 C18-AQ proved to be the most effective trapping column in both buffer conditions, in particular for nitenpyram (Figure ). On-line dilution was implemented prior to the trapping column to reduce the elution strength of wine samples that contain ethanol. The injection flow rate was set to 0.1 ml/min and the dilution flow rate ranged between 0.1 and 1 ml/min, resulting in a dilution ratio from 1 to 10 without loss of analytes (Figure ). The trapping time was set to 1 min and the largest washing volume of 1.1 ml allowed to remove polar compounds (Figure ). The online dilution allows for refocusing of early eluting analytes such as nitenpyram (Figure ). Pesticide residue analysis was conducted on 21 fruit and vegetable juices. Across all juice samples, twenty-one different pesticides, mostly fungicides, were detected and confirmed, with different frequencies. A summary is presented in Table and their occurrence in Figure where pyrimethanil, boscalid, metalaxyl, tebuconazole and carbendazim occurring at least in five samples. As a note two neonicotinoids acetamiprid and imidacloprid, controversial pesticides with country-specific regulations, were found three and one times, respectively in apple juices.