A multiresidue method for simultaneous determination of 10 dyes unauthorised for the use in laying hens was developed (Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red G, Sudan Orange G, Sudan Red 7B, Para-Red, Toluidine Red, Citrus Red). The dyes were extracted using liquid-liquid extraction with acetonitrile in the presence of anhydrous sodium sulphate, and cleaned using zirconium coated silica cartridges. After dilution with acetonitrile saturated with hexane:DMSO (8:2), samples were analysed using LC-MS/MS system with acetonitrile (A) and 0.1% formic acid (B) as a mobile phase in a gradient mode and C18 analytical column. The method was validated according to the requirements described in the Commission Decision 2002/657/EC: linearity (r ≥ 0.998), precision: repeatability (1.94%-10.02%), and within-laboratory reproducibility (4.66%-8.89%), recovery (97%-105%), decision limit CCα (5.33-6.50 μg/kg), and detection capability CCβ (6.18-7.50 μg/kg) were calculated. The developed method fulfilled all performance criteria and can be used in the official survey of dyes residues in food of animal origin.
Marta Piątkowska, Piotr Jedziniak, Małgorzata Olejnik, Konrad Pietruk, Jan Żmudzki and Andrzej Posyniak
Introduction: The paper presents the method of simultaneous determination of 10 illegal azo dyes in feed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry technique. Material and Methods: The dyes were extracted with hexane, evaporated to dryness, and analysed. Separation was achieved in 7 min in a gradient elution using acetonitrile (A) and 0.1% formic acid (B) as a mobile phase. Results: The validation results showed the repeatability of the method, which was evaluated at three levels (50, 500, and 5,000 μg/kg). All the matrix calibration curves for the working ranges were linear (R2 0.9904 to 1.0), the repeatability was between 2.1% and 24%, and recoveries ranged from 77.9% to 120%. The LOD and LOQ were at 1-2 and 5-10 μg/kg for different dyes, respectively. Furthermore, the method was applied in the homogeneity tests of the in-house prepared feed containing Sudan I at the levels of 0.5, 5, and 50 mg/kg. Conclusions: A sensitive, selective, and fast multiresidue method was successfully developed and validated. Its robustness was confirmed by the analysis of an experimental feed containing Sudan I.
Katarzyna Pietruszka, Marta Piątkowska and Piotr Jedziniak
Introduction: Ochratoxin A (OTA) is a toxic metabolite mainly produced by Aspergillus spp. and Penicillum spp. fungi. Research on the contamination of cereals, complete feeds, and tissues with this mycotoxin has indicated that it can be a toxicological problem impacting animal health and food safety in temperate climes. OTA contamination mainly besets the global pig industry, necessitating the monitoring of feeds and animal tissues. The aim of the study was to present the results of the official monitoring of OTA in animal tissues and feeds in Poland in 2014–2016 and determine the possible correlation between the presence of OTA in different types of samples.
Material and Methods: The presence of ochratoxin A was determined using accepted procedures based on liquid chromatography with fluorescence detection after immunoaffinity column clean-up. Determination of OTA was afforded in the range of 0.3 μg/kg to 300 μg/kg in complete feeds and from 0.2 μg/kg to 150 μg/kg in the kidneys, liver, and muscles.
Results: Over the three year span, about 23.5% of the animal tissues samples were contaminated by ochratoxin A. In the 2014 survey, 10% of the sample tissues contained 5–10 μg/kg (only one sample above 10 μg/kg), and in 2015 and 2016, 24% of samples showed levels above the limit of quantification 0.2 μg/kg, while none of the samples exceeded the established provisional action level of 5 μg/kg for animal tissues. The animal feed analysis showed that 9% was contaminated with ochratoxin A above the limit of quantification of 0.3μg/kg. In 2% of feed samples the OTA concentration was greater than 50 μg/kg.
Conclusion: The results confirm the appropriacy of OTA contamination monitoring and help to increase food safety.
Konrad Pietruk, Marta Piątkowska and Małgorzata Olejnik
Some azo dyes, including Sudans I–IV and Para Red, are genotoxic and may be biotransformed to cancerogenic aromatic amines. They are banned as food and feed additives, but their presence has been detected in food. Aromatic amines are also considered potentially toxic. Online EC–MS is a promising tool to study the transformation mechanisms of xenobiotics such as azo dyes. The aim of the study was to investigate emulation of how azo dyes are enzymatically transformed to amines with EC–MS.
Material and Methods
The reduction reactions of five azo dyes (Sudans I–IV and Para Red) were conducted using a glassy carbon working electrode and 0.1% formic acid in acetonitrile. Reduction results were compared with the literature and in silico to select preliminary candidates for metabolites. The LC-MS/MS method was used to confirm results obtained by electrochemical reactor.
A limited number of pre-selected compounds were confirmed as azo dyes metabolites – aniline for Sudan I, aniline and 4-aminoazobenzene for Sudan III, o-toluidine for Sudan IV, and 4-nitroaniline for Para Red. No metabolites were found for Sudan II.
Electrochemistry–mass spectrometry was successfully applied to azo dyes. This approach may be used to mimic the metabolism of azo dyes, and therefore predict products of biotransformation.
The aim of the study was to evaluate the influence of various chemical forms of iodine (I− and IO3−) and selenium (SeO32− and SeO42−) on the nutritional and health-promoting quality of carrot (Daucus carota L.) storage roots. The experiment (conducted in 2012-2014) comprised the soil fertilization of carrot ‘Kazan’ F1 in the following combinations: 1. Control, 2. KI, 3. KIO3, 4. Na2SeO4, 5. Na2SeO3, 6. KI + Na2SeO4, 7. KIO3 + Na2SeO4, 8. KI + Na2SeO3, 9. KIO3+ Na2SeO3. Iodine and selenium were applied twice: before sowing and as top dressing in a total dose of 5 kg I ha−1 and 1 kg Se ha−1. No significant influence of iodine and selenium fertilization was noted with respect to average root weight and leaf yield. Each year, the application of KI + Na2SeO4 negatively affected the content of glucose and total sugars in carrot. An increased sucrose level was noted in the roots of plants treated with KIO3 + Na2SeO4, with a total sugar concentration comparable to the control. Irrespective of the year, carrots fertilized with KI were characterized by the highest accumulation of nitrates (III) – NO2− in roots. The simultaneous introduction of iodine and selenium compounds (KI + Na2SeO4, KIO3 + Na2SeO4, KI + Na2SeO3 and KIO3 + Na2SeO3) into the soil reduced the content of nitrates (III) in carrot as compared to combinations with the individual application of these compounds. The influence of the tested factors on other analysed parameters (the content of dry weight, nitrates (V), chlorides, oxalates, citrates, free amino acids, carotenoids, phenolic compounds, phenylpropanoids, flavonols and anthocyanins as well as free radical scavenging activity (DPPH) was rather year-dependent.