Dragana Šunjka

Application of liquid chromatography with diode-array detector for determination of acetamiprid and 6-chloronicotinic acid residues in sweet cherry samples.

SUMMARY A rapid and simple method for simultaneous determination of acetamiprid and its metabolite 6-chloronicotinic acid in sweet cherry samples has been developed. This residue analysis method is based on the reversed phase separation on C18 column with gradient elution. Analytes’ determination and quantification were performed by high performance liquid chromatography (HPLC) with diode-array detector and chromatograms were extracted at 230 nm. Extraction efficiency experiments demonstrated the ability of this method to extract neonicotinoids from sweet cherry samples. These insecticides were extracted with a mixture of acetonitril/0.1N ammonium-chloride (8/2, v/v). The average recoveries of acetamiprid and 6-chlornicotinic acid from sweet cherry samples were in the range of 95-101% and 73-83%, respectively, with the associated relative standard deviations (RSDs) <5%. Expanded measurement uncertainties for the analyzed compounds were 2.7 and 3.01%. The limit of quantification (LOQ) was 10 µg/kg and 30 µg/kg for acetamiprid and 6-chloronicotinic acid, respectively. Thus, the developed HPLC/DAD method can be considered a useful tool for sensitive and rapid determination of acetamiprid and 6-chloronicotinic acid. Hence, the method may find further application in the analysis of real sweet cherry samples contaminated with these insecticides at a ppb level.

Dissipation rate of acetamiprid in sweet cherries

Degradation of acetamiprid in sweet cherry samples was evaluated at several intervals from the product application until the end of the pre-harvest interval. An orchard of sweet cherries located at Stepanovicevo village near Novi Sad was used in this study. Acetamiprid was applied according to the manufacturer’s recommendation for protecting sweet cherries from their most important pests. Sweet cherry fruit samples were collected at eight intervals: immediately after acetamiprid application and 2, 4, 6, 8, 10, 12 and 14 days after application. The extraction of acetamiprid from sweet cherry samples was performed using a QuEChERS-based method. Determination was carried out using an HPLC-UV diode array detection system (Agilent 1100, United States) with an Agilent Zorbax Eclipse C18 column (50 mm C 4.6 mm internal diameter, 1.8 μm particle size). The method was subjected to a thorough validation procedure. The recovery data were obtained by spiking blank sweet cherry samples at three concentration levels (0.1-0.3 mg/ kg), yielding 85.4% average recovery. Precision values expressed as relative standard deviation (RSD) were below 1.61% for the intraday precision. Acetamiprid showed linear calibrations from 0.05 to 2.5 μg/ml with correlation coefficient (R2) of 0.995%. The limit of detection and limit of quantification were found to be 5 μg/kg and 14 μg/kg, respectively. The validated method was applied in the analysis of acetamiprid in sweet cherry samples. During the study period, the concentration of acetamiprid decreased from 0.529 mg/kg to 0.111 mg/kg. The content of acetamiprid in sweet cherry samples at the end of the pre-harvest interval was below the maximum permissible level specified by the Serbian and EU MRLs. [Projekat Ministarstva nauke Republike Srbije, br. TR31038: Development of chemical methods for analysis of the insecticide acetamiprid]

Some arguments in favor of a Myriophyllum aquaticum growth inhibition test in a water–sediment system as an additional test in risk assessment of herbicides

The present study compares the practicability, reproducibility, power, and sensitivity of a Myriophyllum aquaticum growth inhibition test in a water-sediment system with the recently accepted Myriophyllum spicatum test in an equivalent testing system and the standard Lemna sp. test. Special consideration was given to endpoints based on M. aquaticum control plant growth and variability of relative growth rate and yield: shoot length, fresh weight, dry weight, and root weight. Sensitivity analysis was based on tests performed with 3,5-dichlorophenol, atrazine, isoproturon, trifluralin, 2,4-dichlorophenoloxyacetic acid, and dicamba. Growth rates for average M. aquaticum control plants were 0.119 d(-1) and 0.112 d(-1), with average estimated doubling time 6.33 d and 6.74 d for relative growth rate fresh weight and shoot length, respectively. Intrinsic variability of M. aquaticum endpoints was low: 12.9%, 12.5%, and 17.8% for relative growth rate shoot length, relative growth rate fresh weight and yield fresh weight, respectively. The power of the test was fairly high. When the most sensitive endpoints were used for comparison, the 2 Myriophyllum species were similarly sensitive, more sensitive (in the case of auxin simulators), or at least equally sensitive as Lemna minor to other tested herbicides. The M. aquaticum 10-d test with a 7-d exposure period in a water-sediment system has acceptable sensitivity and can provide repeatable, reliable, and reproducible results; therefore, it should not be disregarded as a good and representative additional test in environmental risk assessment.

Physioloigical and Morphological Parametrers of Cultivated Plants as Indicators of Water Quality

Summary By using biological assay in the laboratory were tested quality and impact of the water to the selected test plants: buckwheat (Fagopyrum esculentum) and cabbage (Brassica oleracea). Water was analyzed from two locations from the River Douro in Portugal. Physico-chemical analysis of general parameters in the water samples indicate that electrical conductivity and ammonium were detected in values exceeding MAC, according to Portuguese regulations on water quality. Also, in the analyzed samples of water in quantities that exceed the maximum allowable concentration values are: arsenic (As), selenium (Se), iron (Fe), magnesium (Mg). In tested samples several pharmaceuticals were detected. The obtained results indicate differences in tolerance of the test plants towards the quality of water. Physiological parameters (germination energy and germination) are not good indicators of water quality and more reliable can be considered some morphological traits (length, fresh and dry weight of root and shoot), that reacted in inhibition or stimulation, depending on water quality.

DISSIPATION RATE AND RESIDUES OF ACETAMIPRID AND IPRODIONE IN SWEET CHERRY FRUITS

A neonicotinoid insecticide acetamiprid and dicarboximide fungicide iprodione, are used in sweet cherry for control of the major pest (Rhagoletis cerasi L.) and pathogen (Monilia laxa). For the purpose of the safe consumption of agricultural products after pesticide application, studies on their dissipation kinetics are essential to work out their half-lives (DT50) and pre-harvest intervals (PHI). However, there is a lack of information on the persistence of acetamiprid and iprodione in sweet cherry fruits in different climatic conditions of production. Therefore, the objectives of this study were to investigate the dissipation and residues of acetamiprid and iprodione in sweet cherry fruits, as well as to evaluate the validity of prescribed PHI for these pesticides. Field experiments were conducted in a sweet cherry orchard, near Novi Sad, where acetamiprid and iprodione were applied at a recommended concentration. At various time intervals, from treatment to harvest, having in mind PHI (14 days for acetamiprid and 7 days for iprodione) representative samples of sweet cherry fruits were collected. Extraction of pesticides was carried out by QuEChERS method, followed by HPLC-DAD analysis. The method was validated in accordance with the SANCO/12571/2013 document and was used the determination of pesticides in real sweet cherry samples. During the study period, the concentration of acetamiprid and iprodione decreased from 0.52 mg/kg to 0.11 mg/kg and from 0.29 mg/kg to 0.07 mg/kg, respectively. The dissipation of acetamiprid and iprodione residues over the time fitted to the equation Ct=0.52-0.22t and Ct=0.29-0.20t, with DT50 of 3.15 and 3.47 days, respectively. Finally, the content of acetamiprid and iprodione in sweet cherry samples, at the end of PHI, were below the maximum allowed level specified by the Serbian (1.5 mg/kg and 3 mg/kg) and EU MRLs (1.5 mg/kg and 10 mg/kg).