Ethephon is approved in the European Union as a plant growth regulator and used in plant protection products. The available methods for the assay of ethephon in pesticide formulations demand decomposition of ethephon to ethene under alkaline conditions, and subsequently either titration by acidimetry or gas chromatography with flame ionization detection. The present work proposes two novel anion exchange high-performance liquid chromatographic methods with indirect spectrophotometric detection for the assay of ethephon in plant protection formulations, with a quick and simple sample preparation, involving only weighing and diluting the sample with water before injection. The study involved optimization of the pH, the concentration of a chromophore compound as the mobile phase modifier and the optimization of the mobile phase flow rate. The first method used a strong anion exchange column (250 mm × 4 mm, 10 µm, 300 Å) with isocratic elution with an aqueous mobile phase consisted of 1 mM potassium hydrogen phthalate at pH 7 by the addition of 0.6 M aqueous KOH using a 1.4 mL/min flow rate. The second approach also used a strong anion exchange column (250 mm × 4.6 mm, 5 µm, 80 Å) with isocratic elution with an aqueous mobile phase composed of 1.2 mM phthalic acid, 6 mM monopotassium phosphate and 4% (v/v) methanol at pH 2 by the addition of H₃PO₄ and 2 mL/min flow rate. The two methods were validated, applied in commercial samples and were shown to be equivalent after statistical comparison. They are considered applicable for the quality control of ethephon content in soluble concentrate formulations and surpass the existing laborious and time-consuming methods which demand decomposition of ethephon to ethene.

Sludge generated after washing of fruits and vegetables during agro-food processes is a complex matrix and selective methods for the identification and quantification of pesticides’ residues are necessary in order to achieve a sustainable and effective management of the total sewage. The present work describes the development and validation of a reliable, simple and fast analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 47 pesticides of different chemical classes, including organosphosphates, pyrethroids, neonicotinoids, triazoles and others, in sludge samples after QuEChERS sample preparation. The necessity of the individual steps of QuEChERS was investigated and the LC-ESI-MS/MS conditions were optimized to achieve maximum sensitivity of the target analytes. The method limits of detection (LODs) ranged between 0.0005 mg/kg (imidacloprid) and 0.05 mg/kg (beta cyfluthrin). The recoveries ranged between 71–120% and the repeatability of the method was ≤25% expressed as relative standard deviation. The method was applied to sludge samples generated after washing of fruits in an agro-fruit-packaging unit in Greece. The results showed the presence of 37 pesticides’ active substances with concentrations ranging from low ppbs, such as fludioxinil (5 μg/kg) up to low ppms such as beta cyfluthrin (3.5 mg/kg) and with their sum concentration reaching up to 19 mg/kg.

A rapid, simple, precise and accurate high performance liquid chromatographic (HPLC) analytical method was developed and validated for the determination of the active substances (a.s.) azoxystrobin, topramezone, acetamiprid, fluometuron and folpet in their respective commercially available formulations. The method was used for the analysis of samples under the frame of the national quality control program of plant protection products in the Greek market. Chromatographic separation of the active substances from additives and co-formulants is achieved using isocratic elution with acetonitrile and 0.1% phosphoric acid solution (60:40 v/v) at a flow rate of 0.4 mL min⁻¹ on a C₁₈ monolithic column (Chromolith Performance-RP18e 100 × 4.6 mm) and UV detection at 230 nm. Validation parameters of the method fulfilled acceptability criteria. Recovery of all individual compounds was in the range 97.8–100.9%. Precision expressed as relative standard deviation was lower than the theoretical values of the modified Horwitz equation. Correlation coefficients of linearity of response were better than 0.999. The benefits of the proposed method are significant reduction in analysis time and total cost since all analytes were determined with the same extraction procedures and chromatographic system. Analysis of real samples for all active ingredients confirmed fitness for purpose of the suggested method.