Authors:L. Velkoska-Markovska and B. Petanovska-Ilievska
This paper presents a new, simple, precise, and accurate rapid resolution liquid chromatography (RRLC) method for determination of an active ingredient malathion in the pesticide formulation. The analysis was performed on a Poroshell EC 120-C18 (50 mm × 3 mm, 2.7 μm) analytical column using isocratic elution with a mobile phase consisted of acetonitrile–water (50:50, v/v), a flow rate of 1 mL/min, a constant column temperature at 25 °C, and ultraviolet-diode array detection (UV-DAD) at 220 nm. The specificity, selectivity, linearity, precision, and accuracy were tested for the method validation according to the Collaborative International Pesticides Analytical Council (CIPAC) and Directorate General Health and Consumer Protection (SANCO) guidelines and all tested parameters were found within acceptance criteria. The obtained results indicated that the proposed method can be used for routine analysis of the active ingredient malathion in the pesticide formulation “Etiol tecni” following the CIPAC and SANCO rules. The run time of analysis under the stipulated chromatographic conditions was about 2.5 min, meaning that the proposed method requires a small volume (< 1.5 mL) of the organic solvent (acetonitrile) making it cost-effective.
Authors:L. Velkoska-Markovska, B. Petanovska-Ilievska, and L. Vodeb
A normal-phase high-performance liquid-chromatographic method has been developed for simultaneous quantitative analysis of phenmedipham, desmedipham, and ethofumesate in a pesticide formulation. Analysis was performed on a 25 cm × 0.4 cm, 5-μm particle, CN column with n-hexane-dichloromethane 40:60 (v/v) as mobile phase at a flow rate of 1 mL min–1. UV detection was performed at 270 nm; the constant column temperature was 25°C. The run time under these chromatographic conditions was less than 8 min. Calibration plots were linear in the concentration range 76–380 μg mL–1 for phenmedipham, 72–360 μg mL–1 for desmedipham, and 52–260 μg mL–1 for ethofumesate. Statistical evaluation by analysis of variance showed the intra-day repeatability (n = 8) and inter-day precision (n = 3) of the assay were satisfactory. The sensitivity of the method, as the limits of detection (LOD) and quantification (LOQ) for each active ingredient, was also determined.
Authors:L. Velkoska-Markovska, B. Petanovska-Ilievska, M. S. Jankulovska, and U. Ilievski
This study presents the development and validation of a new reversed-phase high-performance liquid chromatography (RP-HPLC) method for simultaneous determination of captan, folpet, and metalaxyl residues in table grape samples with ultraviolet–diode array detection (UV–DAD). Successful separation and quantitative determination of analytes was carried out on LiChrospher 60 RP-select B (250 × 4 mm, 5 μm) analytical column. Mixture of acetonitrile–0.1% formic acid in water (65:35, v/v) was used as a mobile phase, with flow rate of 1 mL/min, constant column temperature at 25 °C, and UV detection at 220 nm. The target residues were extracted with acetone by ultrasonication, followed by a cleanup using liquid–liquid extraction (LLE) and solid-phase extraction (SPE). The obtained values for multiple correlation coefficients (R2 > 0.90), relative standard deviation (RSD) of retention times, peak areas and heights (RSD ≤ 2.25%), and recoveries ranging from 90.55% to 105.40%, with RSD of 0.02% to 5.37%, revealed that the developed method has a good linearity, precision, and accuracy for all analytes. Hence, it is suitable for routine determination of investigated fungicides in table grape samples.