A green-analytical chemistry method for agrochemical-residue analysis in vegetables

• A green analytical chemistry chromatographic method for agrochemicals is proposed.
• The coupling to chemometric calibration renders a simple and safe protocol.
• The dual detection offers versatility to the method.
• Fluorescence-elution time second-order data are obtained at two excitation wavelengths.
• Multivariate curve resolution allows the quantification in very interfering media.

Ten agrochemicals, including fungicides, insecticides, herbicides and a plant growth regulator, were quantified at part per billion levels in complex matrices using a green-analytical chemistry (GAC) method. Liquid chromatography with dual UV/diode array (DAD) and fluorescence (FLD) detections was carried out in a single run, and the second-order DAD-elution time and FLD-elution time data obtained were treated with MCR-ALS (multivariate curve resolution/alternating least-squares) algorithm. In this way, while analytes are measured through their more appropriate (absorbance and/or fluorescence) signals, chemometric treatment of the corresponding matrices allows the resolution of total or partial overlapped bands, and to overcome the presence of interferences in real samples. In this work, FLD-elution time second-order data were obtained for the first time at two excitation wavelengths, improving the sensitivity of fluorescent analytes. The approach was successfully applied to in land cultivated vegetables, including mushroom, lettuce, alfalfa sprout, cucumber, and celery.