The aim of the research is to evaluate pesticide residue contamination of fresh and frozen fruits and vegetables, agricultural raw material, purchased from Polish farmers for production of frozen fruits and vegetables, and the estimation of the multiresidue method effectiveness expressed as the proportion of pesticides detected in food samples to the total number of pesticides analyzed by multiresidue methods. A total of 144 samples (of black currants, red currants, raspberries, cherries, strawberries, blackberries, cauliflowers and broccoli) were analyzed using LC-MS/MS method for the determination of 60 pesticides. QuEChERS extraction, matrix-matched calibration and dynamic multiple reaction monitoring method were used. Residues of 15 compounds, mainly fungicides and insecticides, were detected in 46 samples. The percentage of samples with residues above the maximum residue levels (MRL) was 15%, whereas samples with residues below MRL were 17%. A total of 13 samples contained more than one pesticide residue. Pesticide residues were detected most often in samples of black currants (50%), broccoli (36.4%), raspberries (29%) and red currants (21.8%). The most frequently detected pesticides were carbendazim and acetamiprid. The proportion of pesticides detected during our study to the total number of analyzed pesticides amounted to 25%. It was compared to literature findings. For three fourth of multiresidue methods, the proportion was below 50% for methods developed for the analysis of less than 100 pesticides, and below 30% for methods developed for the analysis of more than 100 pesticides. It appears that a lot of efforts and means is lost on pesticides never or rarely detected in examined samples. The workload and cost effectiveness of the development and application of multiresidue methods along with the range of pesticides covered by the method should be carefully and thoroughly considered anytime when a new method or workflow is developed. Including non-targeted screenings in pesticide residue control seems to be an alternative worth considering.
Propofol, 2,6-diisopropylphenol, seems to be a good candidate as a fish anaesthetic, however, no study regarding propofol influence on fish has yet been reported. The aim of this study was to examine propofol pharmacokinetics in rainbow trout (Oncorhynchus mykiss) following bath exposure. Fish (n = 100) were exposed to an aqueous propofol bath at 12 o C and 17 o C; propofol concentration in the bath was 10 mg L -1 . Plasma concentration-time profiles were determined using LC-MS, and pharmacokinetic parameters were calculated. Propofol was absorbed quickly at both temperatures. Its concentration reached 13.8±2.7 μg mL -1 and 16.1±2.1 μg mL -1 at 12 o C and 17 o C, respectively, during the first minute of exposure. Blood plasma propofol decreased rapidly to 6.8±0.7 μg mL -1 and 6.3±2.2 μg mL -1 at 12 o C and 17 o C respectively, during the first 10 minutes of the recovery. The half-life time of propofol was 1.5 h and 1.1 h at 12 o C and 17 o C, respectively. We found propofol anaesthesia in trout effective and safe. However, it caused a gradual decrease of respiratory rate, and therefore a specific anaesthesia protocol should be developed.
A spectrophotometric method based on the reduction of nitrates to nitrites was applied to the determination of the difference between total nitrate and nitrite contents in the extracts from the cucumber peel and flesh. The content of these ions was determined in glasshouse cucumbers and those grown in the open fields, both marketed in Poland. Nitrate and nitrite extraction was performed using the Griess diazotization reaction and carried out according to the ISO recommendation (ISO 6635, 1984). It was observed that the mean nitrate content in the peel was significantly higher (p < 0.0001) than the mean nitrate content in the flesh. It was also proved that cucumber peel accumulated nearly threefold higher amount of nitrates than the flesh. The nitrite concentrations in all tested samples were below the limit of quantification. Despite statistically significant differences in the nitrate contents between the peel and the flesh, no excessive levels were found. A comparison of the current results to those reported for Poland and other countries is also presented.
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