Razgradnja acetamiprida u plodovima trešanja

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 Stepanovićevo 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 × 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.U cilju praćenja razgradnje acetamiprida u plodovima trešanja u periodu od primene preparata do isteka karence, izvršen je tretman preparatom na bazi ove aktivne materije u preporučenoj dozi. Ogled je postavljen u zasadu srednje kasne sorte trešnje na lokalitetu Stepanovićevo u okolini Novog Sada. Plodovi su uzorkovani osam puta - odmah nakon primene preparata, 2, 4, 6, 8, 10, 12 i 14 dana. Ekstrakcija acetamiprida iz trešanja izvedena je QuEChERS metodom. Za određivanje acetamiprida korišćena je tečna hromatografija sa DAD detektorom (Agilent 1100, United States) i Agilent Zorbax Eclipse C18 kolonom (unutrašnji prečnik 50 mm x 4.6 mm, veličina čestica 1.8 μm). Kao mobilna faza upotrebljeni su acetonitril i 1.5% rastvor CH3COOH (30/70), sa protokom 1 ml/min, temperaturom kolone 25 oC i injektovanom zapreminom 2,5 μl, dok je kao odgovarajuća talasna dužina usvojena vrednost od 254 nm. Validacija metode je u potpunosti sprovedena u skladu sa zahtevima standarda SANCO/12495/2011 (EU Commission Health and Consumer Protection Directorate- General, 2011). Prosečna vrednost prinosa ekstrakcije acetamiprida iz trešanja proverena na tri nivoa obogaćenja (0.1-0.3 mg/kg) iznosila je 85.4%. Preciznost merenja razmotrena proverom ponovljivosti određivanja acetamiprida izražena je relativnom standardnom devijacijom (RSD) sa vrednošću manjom od 1.61%. U opsegu masenih koncentracija acetamiprida od 0,05 do 2,5 μg/ml postignuta je dobra linearnost odziva detektora sa koeficijentom varijacije od 0,995%. Limit detekcije i kvantifikacije za određivanje acetamiprida u trešnjama prikazanom metodom iznose 5 μg/kg i 14 μg/kg. Tokom ispitivanog perioda koncentracija acetamiprida u trešnjama se smanjivala od 0,592 mg/kg neposredno nakon primene insekticida do 0,111 mg/kg po isteku karence od 14 dana. Analizom je utvrđeno da je sadržaj acetamiprida u uzorcima plodova trešnje nakon isteka perioda karence ispod maksimalno dozvoljene količine za ovu aktivnu materiju propisane Pravilnikom Republike Srbije (0,2 mg/kg) i Evropske Unije (1,5 mg/kg)

Physicochemical Changes of the Gluten-Free Rice-Buckwheat Cookies during Storage – Artificial Neural Network Model

The influence of storage time, temperature, and packaging on some physicochemical characteristics of gluten-free rice-buckwheat cookies was studied. Shelf life markers, such as water activity (aw), hydroxymethylfurfural (HMF), firmness, and color parameters were modelled in relation to different storage conditions. Principal component analysis was applied to study the similarity among samples according to the observed parameters. The mathematical model in the form of an artificial neural network was developed to predict the physicochemical parameters of cookies during 6-month storage. The most evident differentiation among samples was observed for color coordinate a*, aw , and HMF. Regarding the methods for determination of the parameters, priority should be given to the instrumental determination of color as the most convenient method. The processing of experimental data allowed the creation of useful mathematical model to be used in predicting the behavior of physicochemical changes of cookies by different factor combinations during storage

Potential health benefits of blueberry and raspberry pomace as functional food ingredients: Dietetic intervention study on healthy women volunteers

The fruit juice industry generates pomace as a valuable by-product especially rich in polyphenols, dietary fibers, vitamins, minerals, and unsaturated fatty acids. In the cookies used in this study, 30% of the gluten-free flour was replaced with dried and ground blueberry and raspberry pomace, rich source of polyphenols, dietary fibers, linoleic and alpha-linolenic acid. In order to examine whether the addition of blueberry and raspberry pomace in cookie formulation can have beneficial effects on certain blood parameters and anthropometric measurements, the designed cookies were tested in 20 healthy, normally fed female subjects, aged 30–50 years (41.35 ± 8.58 years) over four-week dietetic intervention study. Significant changes in the composition of fatty acids serum phospholipids, decrease in LDL-cholesterol level (20.16%), increase in adiponectin level (25.52%) and decrease in ALT and AST values were observed, thus indicating that inclusion of cookies containing blueberry and raspberry dried and ground pomace to usual diet might have positive effects on certain cardiovascular risk factors and liver function indicators

Antibakterijsko djelovanje mlijeka magarice na klinički izolat Klebsiella pneumoniae

The purpose of this study was to investigate the antibacterial activity of raw donkey milk toward the clinical isolate of Klebsiella pneumoniae at 9, 15 and 38 °C as well as to clarify the role of lysozyme, lactoferrin and calcium content in the antibacterial activity of donkey’s milk. The effects of contamination level and incubation period on this antibacterial activity were also examined. Antibacterial assays were performed by determing the bacterial count in intentionally contaminated (102, 103, 104 cfu/mL) donkey milk samples during 8 and 96 hours. Lab-on-a-chip electrophoresis and atomic absorption spectrometry were used for the determination of lysozyme, lactoferrin and calcium contents in donkey milk, respectively. The donkey milk samples showed varying degrees of antibacterial activity against the tested strain K. pneumoniae. The antibacterial synergism of lysozyme and lactoferrin was proven for this clinical strain as the samples with higher lactoferrin amount showed a stronger antibacterial activity. The correlation between calcium content and antibacterial activity of donkey milk samples was not established. Donkey milk showed stronger antibacterial potential at 15 °C compared to 9 °C, but this was limited by a higher growth rate of K. pneumoniae at 15 °C. The higher level of contamination resulted in a faster consumption of the antibacterial capacity of donkey milk. The artificial neural network model for prediction of K. pneumoniae count gave acurate fit to experimental data, showing a reasonably good (overall r2 for donkey milk was 0.986, with training error 4.67∙10-4, while r2 for nutrient broth was 0.982 and training error was 0.002).Svrha ovog istraživanja bila je utvrditi antibakterijsko djelovanje sirovog mlijeka magarice prema kliničkom izolatu Klebsiella pneumoniae pri 9, 15 i 38 °C, te razjasniti ulogu lizozima, laktoferina i kalcija u antibakterijskom djelovanju mlijeka magarice. Također su ispitani učinci razine kontaminacije i razdoblja inkubacije na navedenu antibakterijsku aktivnost. Antibakterijski testovi provedeni su određivanjem broja bakterija u ciljano kontaminiranim (102, 103, 104 cfu/ mL) uzorcima mlijeka magarice tijekom 8 i 96 sati. Lab-on-a-chip elektroforeza i atomska apsorpcijska spektrometrija korištene su za određivanje sadržaja lizozima, laktoferina i kalcija u mlijeku magarice. U ispitivanim uzorcima mlijeka magarice utvrđeni su različiti stupnjevi antibakterijske aktivnosti prema ispitivanom soju K. pneumoniae. Za ovaj klinički soj dokazan je antibakterijski sinergizam lizozima i laktoferina, jer su uzorci s većom količinom laktoferina pokazali jače antibakterijsko djelovanje. Korelacija između sadržaja kalcija i antibakterijske aktivnosti uzoraka mlijeka magarice nije utvrđena. Mlijeko magarice pokazalo je jači antibakterijski potencijal na 15 °C u usporedbi s antibakterijskim potencijalom na 9 °C, ali je on bio ograničen većom stopom rasta K. pneumoniae na 15 °C. Viša razina kontaminacije uzrokovala je bržu potrošnju antibakterijskog kapaciteta mlijeka magarice. Model umjetne neuronske mreže za predviđanje broja K. pneumoniae dobro se slagao s eksperimentalnim podacima (ukupni r2 za mlijeko magarice bio je 0,986, s pogreškom učenja od 4,67 10-4, dok je r2 za hranjivi medij bio 0,982, a pogreška učenja bila je 0,002)

Brašno - Kruh '15

Proceedings contains 28 original research articles presented at 8th International Congress Flour – Bread ’15 and 10th Croatian Congress of Cereal Technologists Brašno – Kruh ’1

Optimization of extraction and determination of neonicotinoids using liquid chromatography in selected samples

Insekticidi novije generacije, neonikotinoidi, odlikuju se specifičnim načinom  delovanja na nervni sistem insekata. Radi dobijanja što brže i kvalitetnije informacije o izloženosti životne sredine ovim insekticidima i količinama njihovih ostataka u hrani potrebno je raspolagati odgovarajućim instrumentalnim metodama za njihovo određivanje. Razvijene su i optimizovane analitičke metode zasnovane na tečnoj hromatografiji za određivanje sedam odabranih neonikotinoida (dinotefurana, nitenpirama, tiametoksama, klotianidina, imidakloprida, acetamiprida  i tiakloprida) u medu i likeru od meda. Ispitivana je mogućnost određivanja klotianidina pomoću tečne hromatografije visoke efikasnosti sa detektrorom od niza dioda (HPLC-DAD) primenom kombinacije tečno-tečne i ekstrakcije na čvrstoj fazi iz uzoraka meda. Na osnovu preliminarnih rezultata može se zaključiti da korišćenje  faznih-čvrsto kolona u kombinaciji sa tečno-tečnom ekstrakcijom dihlormetanom rezultira prihvatljivim prinosom klotianidina u uzorcima meda pri koncentraciji od oko 0,5 µg g-1 klotianidina. Radi dobijanja većih prinosa odabrana je disperzna tečno-tečna mikroekstrakcija (DLLME) kao tehnika pripreme uzoraka meda. Testirana je upotreba acetonitrila kao disperznog sredstva. Pored hloroforma, korišćen je i dihlormetan kao drugo ekstrakciono sredstvo, kako bi se  uporedila efikasnost ekstrakcije. Zabeleženi su prinosi klotianidina od 69,7 i 68,3%  u zavisnosti da li je korišćen hloroform, odnosno DHM kao rastvor za ekstrakciju. Može se zaključiti da je prinos ekstrakcije bio povoljniji pri odnosu 0,5 mL ACN i 2,0 mL DHM. Prinosi su se kretali od 68,4% do 92,1%, što je ukazalo da su parametri DLLME ekstrakcije optimalni. Kako bi se detaljnije ispitali ključni parametri DLLME tehnike, korišćena je metodologija površine odziva (RSM), kao i detekcija na osetljivijem kuplovanom masenom detektoru (MS/MS). Optimizovani su HPLC-MS/MS  parametri kako bi se obezbedilo zadovoljavajuće hromatografsko  razdvajanje i niske granice detekcije (GD, 0,5–1,0 μg kg-1) i određivanja (GO, 1,0–2,5 μg kg-1) ispitivanih neonikotinoida u medu. Upotrebom centralno kompozitnog dizajna konstruisani su kvadratni modeli ispitivanih faktora: zapremine ekstrakcionog (DHM, 1,0–3,0 mL) i disperznog (ACN, 0,0–1,0 mL) sredstva, izračunati statistički parametri i optimizovan proces DLLME upotrebom Derringer-ove funkcije poželjnih odgovora. Upotrebom MMC i SC krivih u opsegu GO–100,0 μg kg-1 ispitan je uticaj matriksa pri čemu zaključeno je da je najveći uticaj matriksa bio na odziv analitičkog signala nitenpirama, dinotefurana i klotianidina. Ispitani su prinosi odabranih neonikotinoida (R, 74,3–113,9%), kao i preciznost metode u uslovima ponovljivosti (RSD, 2,74– 11,8%) i intermedijerne reproduktivnosti (RSD, 6,64–16,2%). Brza (retenciona vremena 1,5–9,9 min) i osetljiva metoda, koja troši malu količinu rastvarača, primenjena je za ispitivanje 15 realnih uzoraka meda različitog cvetnog porekla. Rezultati su pokazali da ispitivani med nije sadržao ostatke ispitivanih neonikotinoida u koncentracijama iznad GD. Dalje istraživanje je bilo usmereno ka  razvijanju i optimizaciji HPLC-DAD analitičke metode upotrebom DLLME i QuEChERS tehnika za  pripremu uzoraka za određivanje 7 neonikotinoida u uzorcima meda. U ovom delu istraživanja optimizovani su i hromatografski parametri, upotrebom RSM sa Box-Behnken-ovim dizajnom i Derringer-ovom funkcijom poželjnih odgovora. Od  ispitivanih neonikotinoida dinotefuran i imidakloprid su bili u najvećoj meri izloženi uticaju matriksa, bez obzira na proceduru pripreme uzoraka. Može se istaći da je uticaj matriksa na analitički signal dinotefurana bio izraženiji u slučaju MS/MS, apostrofirajući manju robusnost ove metode određivanja. Prinosi neonikotinoida su  bili (R, 73,1–118,3%), preciznost u uslovima ponovljivosti (RSD, 3,28–10,40%) i intermedijerne reproduktivnosti (RSD, 6,45–17,70%), a granice detekcije (GD, 1,5–2,5 µg kg-1) i određivanja (GO, 5,0–10,0 µg kg-1). Metoda je primenjena za ispitivanje 7 neonikotinoida u 104 uzorkameda različitog cvetnog porekla sa  teritorije Autonomne Pokrajine Vojvodine. Detektovano je prisustvo tiakloprida, imidakloprida i tiametoksama u količinama koje su bile ispod MDK RS i EU. Analizirani su uzorci likera od meda - medice. Upoređivane su dve tehnike pripreme uzoraka, DLLME i QuEChERS i primenjeni optimizovani hromatografski  uslovi i MS/MS parametri. U slučaju nitenpirama, dinotefurana i tiametoksama uticaj matriksa bio je najizraženiji. Metoda je validovana određivanjem prinosa neonikotinoida (R, 69,2–113,4%), preciznosti u uslovima ponovljivosti (RSD, 3,21–12,81%) i intermedijerne reproduktivnosti (RSD, 9,11–16,63%), kao i granice detekcije (GD, 0,5–2,5 µg kg-1) i određivanja (GO, 1,0–10,0 µg kg-1). Analizom 10 komercijalno dostupnih likera od meda otkriveno je prisustvo klotianidina i tiakloprida, evčzokinotš z  na neophodnost daljeg kontrolisanja ovog proizvoda na prisustvo neonikotinoida. Ispitana je mogućnost uklanjanja odabranih neonikotinoida (dinotefurana, klotianidina i tiakloprida) iz vodene sredine (reke Dunav). Ispitivanje efikasnosti 6 različitih vrsta uklanjanja odabranih neonikotinoida (u prisustvu prirodne insolacije u laboratorijskim uslovima, sa dodatkom H2O2, sa dodatkom MWCNT, sa dodatkom MWCN+H 2O2, sa dodatkom Fe-MWCNT, sa dodatkom Fe-MWCNT+H2O2) vršeno je upotrebom prethodno razvijene HPLC-MS/MS metode. Krive uklanjanja odabranih neonikotinoida, pokazale su da tokom 60 minuta pri prirodnoj insolaciji  u laboratorijskim uslovima koncentracija smanjenje oko 25%. Analitički signal dinotefurana dobijen u prisustvu H2O2 pod istim uslovima ukazuje na uklanjanje ciljnog analita od oko 40%, tiakloprida od oko 70%, a klotianidina u potpunosti. Testirana je adsorpcija ciljnog analita na višezidnim ugljeničnim nanocevima (MWCNT). Ovim postupkom može da se ukloni oko 30% dinotefurana, oko 50% klotianidina i 60% tiakloprida. U kombinaciji sa H2O2 , MWCNT pokazuju bolju sposobnost uklanjanja za 15–50% u zavisnosti od ispitivanog neonikotinoida. Upotreba Fe-MWCNT i njihova kombinacija sa H2O2 otvorila je mogućnost za dalja  ispitivanja mehanizma uklanjanja. Ustanovljeno je nastajanje intermedijera kojima odgovaraju m/z od 117,5 i 140,6 u slučaju razgradnje dinotefurana u sistemima sa H2O2, MWCNT+H2O2, Fe-MWCNT+H2O2 i klotianidina u sistemu Fe-MWCNT+H2O2.Neonicotinoid insecticides, as one of the fastest growing new generation of insecticides, have contributed to a significant reduction of toxicity for the environment; therefore, monitoring and determination of trace levels of the neonicotinoids in honey are necessary and demands highly efficient, selective and sensitive analytical techniques. The objective of the present work was to develop a rapid, sensitive, optimized and accurate analytical method based on liquid chromatography for determining seven neonicotinoid insecticides, dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid and thiacloprid in honey and honey liqueur samples. The possibility for determination of clothianidin in honey samples was investigated by HPLC with a diode array detector (HPLC-DAD). Based on preliminary results, it can be concluded that the use of a solid-phase column in combination with a liquid-liquid extraction with dichloromethane results in an acceptable recovery of clothianidin in the samples with a clothianidin concentration of about 0.5 µg g-1. After obtaining low recovery of clothianidin, dispersed liquid-liquid microextraction (DLLME) was selected as a technique for the preparation of honey samples.. The adequacy of acetonitrile as a dispersing agent was investigated. Besides the chloroform, a dichloromethane was used as a second extracting agent , in order to compare the relative efficiency of the extraction solvents. It can be concluded that the extraction recovery (68.4–92.1%) was more favorable with the use of 0.5 mL ACN and 2.0 mL DHM. Furthermore, LC-MS/MS parameters were optimized to unequivocally provide good chromatographic separation, low detection (LOD, 0.5–1.0 μg L−1) and quantification (LOQ, 1.0–2.5 μg L−1) limits for acetamiprid, clothianidin, thiamethoxam, imidacloprid, dinotefuran, thiacloprid and nitenpyram in honey samples. Using different  types (chloroform, dichloromethane) and volumes of extraction (1.0–3.0 mL) and dispersive (acetonitrile; 0.0–1.0 mL) solvent and by mathematical modeling it was possible to establish the optimal sample preparation procedure. Matrix-matched calibration and blank honey sample spiked in the concentration range of LOQ–100.0 μg kg−1 were used to compensate the matrix effect and to fulfill the requirements of SANCO/12495/2011 for the accuracy (R 74.3–113.9%) and precision (expressed in terms of repeatability (RSD 2.74–11.8%) and within-laboratory reproducibility (RSDs  6.64–16.2%)) of the proposed method. The rapid (retention times 1.5–9.9 min), sensitive and low solvent consumption procedure described in this work provides reliable, simultaneous, and quantitative method applicable for the routine laboratory analysis of seven neonicotinoid residues in 15 real honey samples. Neonicotinoid  residues were not detected in any of the investigated samples. The objective of next study was to develop and optimize HPLC-DAD analytical method with dispersive liquid-liquid microextraction (DLLME) and QuEChERS sample preparation procedures for the simultaneously analysis of seven neonicotinoids in honey samples. The liquid chromatographic conditions were optimized by response surface methodology with Box-Behnken design and the global Derringer´s desirability. The optimized method was  validated to fulfill the requirements of SANCO/12495/2011 standard for both sample pretreatment procedures providing results for accuracy (R, 73.1–118.3%), repeatability (RSD, 3.28–10.40%) and within-laboratory reproducibility (RSD, 6.45–17.70%), limits of detection (LOD, 1.5–2.5 gµ kg-1) and quantification (LOQ, 5.0–10.0 µg kg-1). For the first time, more than 100 honey samples collected from all 7 counties of Autonomous Province of Vojvodina were analyzed. The presence of thiacloprid, imidacloprid and thiametoxam was discovered in a small number of samples. The objective of next study was to develop an optimized LC-MS/MS analytical method with DLLME and QuEChERS procedures for analysis of 7 neonicotinoids in honey liqueur. The method was validated to fulfill the requirements of SANCO/12495/2011 for both sample pretreatment procedures providing results for accuracy (R, 69.2–113.4% for DLLME; 71.8–94.9% for QuEChERS), precision (RSD expressed in terms of repeatability (3.21–10.20% for DLLME; 4.19–12.81% for QuEChERS) and within-laboratory reproducibility (9.11–16.63% for DLLME; 11.32–16.40% for QuEChERS)), limits of detection (LOD, 0.5–1.5 gµ L-1 for DLLME; 1.0–2.5 gµ L-1 for QuEChERS) and quantification (LOQ, 1.0–5.0 gµ L-1 for DLLME; 2.5–10.0 µg L-1 for QuEChERS). Analysis of real honey liqueur samples obtained from local markets showed the presence of clothianidin or thiacloprid in four of the analyzed samples, therefore implicating the necessity of ongoing control of this type of traditional product.  Removal of selected neonicitinoid insecticides - dinotefuran, clothianidin and thiacloprid using MWCNT and H2O2 from Danube water matrix was investigated.  Efficiency of different systems for neonicotinoids removal (under natural insolation in laboratory, with H2O2, with MWCNT, with MWCNT+ H2O2, with Fe-MWCNT, with Fe-MWCNT+H2O2) was evaluated with developed LC-MS/MS method. Analysis of degradation rates revealed loss of 25% of the initial neonicotinoid concentration under natural insolation in the laboratory conditions during 60 min. Addition of chemical agent H2O2 promoted loss of 40% of the initial dinotefuran, 70% of thiacloprid concentration and total removal of clothianidin under same conditions. With the addition  of MWCNT concentration of dinotefuran, clothianidin and thiacloprid decayed for 30, 50 and 60%, respectively. Iron modification of MWCNT in combination with H2O2 increased the removal rate of selected neonicotinoid for 15–50%. Presence of intermediates was discovered in systems of dinotefuran with H2O2, MWCNT+H2O2, e-MWCNT+H2O2 and of clothianidin in systems with Fe-MWCNT+H2O2 with m/z of 117,5 and 140,6.

Determination of pesticide residues in drainage water

Pesticides are used worldwide within agriculture to protect crops and ensure the quantity and quality of the harvest. However, intensive and inappropriate pesticides application can directly or indirectly affect different parts of the environment, especially water source. Besides the occurrence of pesticides in drinking water, control of pesticide presence in surface and groundwater is also very important. This primarily refers to the drainage water, river and groundwater, considering the importance of environmental protection and food safety production. The presence of pesticide residues in these matrices may cause yield reduction and decrease product quality, due to its uptake. Objectives of this study included drainage water investigations to identify residue levels of selected pesticides. The sampling was performed during June 2012. Water samples were taken from drainage canals, on twelve sampling points, in intensively cultivated regions of Serbia, Vojvodina Province. Pesticides were chosen based on the European Union Directive 2008/105/EC. This directive by Annex X defines the List of priority substances in the field of water policy. List includes 33 pollutant - 9 are pesticides. The extraction of pesticides from water was performed using 018 ENVI (TM) disc (47 mm). Prior to extraction disc was conditioned with 5 ml of methanol and 5 ml of deionized water. Afterward, water sample was filtered through the disc under vacuum. After drying under vacuum (25 degrees C for 1 h), pesticides were eluted from the disc with 5 ml of mixture of dichloromethane/n-hexane (40/60, v/v) and evaporated to dryness. The extract was dissolved in 1 ml of methanol, ultrasonically homogenized and analyzed. The pesticide residues concentrations analyzed by gas chromatography/electron capture detection with Ni-63. Identification is performed by the use of GC/MS. The mean recovery of this extraction method for all analyzed pesticides at 1 mu g/ml, 0.1 pg/ml and 0.01 pg/ml spiking levels was 93.6%, with associated standard deviations (RSD) of 2.7. The limit of quantification was 0.01 pg/ml. Method accuracy was quantified through measurement uncertainty estimate based on method validation data. The combined relative uncertainty for water samples was 0.481%, while the expanded uncertainty (Us) calculated as U-c=k*U-c, where k is the coverage factor with level of confidence of approximately 95% considering a coverage factor of 2 (EURACHEM/CITAC, 2000), was 0.962%. Obtained values of evaluated analytical parameters are completely in accordance with regulations for analysis of pesticides trace level. Described method was applied for determination of above mentioned pesticides in real water samples. Finally, acetochlor, alachlor and chlorpyrifos were detected in drainage water samples collected in the agricultural area of Serbia

Determination of the acetamiprid residues in selected vegetables and fruit

Increased use of pesticides has resulted in contamination of the environment causing also many associated long-term effects on human health. Therefore, validated analytical methods that produce reliable results for the assessment of pesticide residues in fruits and vegetables are highly needed. The main objective of this study was validation of the method for the analysis of acetamiprid in tomato and determination of its residues after the application at recommended rates under controlled conditions. Obtained results of acetamiprid half-life in tomato are compared with DTso in sweet cherry. For sample pre-treatment QUEChERS procedure was used. Insecticide determination and quantification were performed by HPLC with diode-array detection (Agilent 1100 Series) and Zorbax Eclipse C18 column (50 mm x 4.6 mm internal diameter, 1.8 pm particle size) This method fulfilled validation criteria described in the European Union guidelines (SANCO 12571/2013), by evaluating the accuracy, precision, linearity, limit of detection (LOD) and limit of quantification (LOQ), as well as matrix-effect (ME), The accuracy and precision were satisfactory, showing mean recovery values higher than 80% and precision below 20%, in all cases. The validated method was applied for the analysis of acetamiprid residues in real samples. Half-life of acetamiprid in tomato was 4.33 day and it is quite similar to DT, obtained in the experiment with sweet cherries. On the sixth day after the acetamiprid application residues in tornato were at MRL level, as well as in sweet cherries (according to Serbian MRL, 2010), while the PHI was 14 day