2020-10-31. A linear regression was used and no ‘fit weighting’ was applied. LC‐MS grade acetonitrile was obtained from Biosolve (Valkenswaard, the Netherlands). The solvent was then evaporated to dryness in a SpeedVac concentrator (SVC100, Savant Instruments Inc., Farmingdale, NY, USA) and 100 μL of 0.03% acetic acid solution/acetonitrile 60/40 (v/v) was added to the tube. As there is no specific validation criteria for aldehydes in food or feed matrices, our work was based primarily on the Decision of the European Commission 2002/657/EC,21 a guideline used for the analysis of residues of veterinary drugs, which presents requirements concerning chromatographic techniques and mass spectrometry that can be applied here. The derivative forms of the aldehydes and the internal standards were detected using the multiple reaction monitoring (MRM) mode, with two transitions for each compound (Table 1). I know this method well. endstream endobj 931 0 obj <. Indeed, Figure 2 shows the chromatograms of aldehyde DNPH‐derivatives analyzed by LC‐MS in a blank Corn Flakes® cereals sample spiked with internal standards and a Corn Flakes® cereals sample spiked with internal standards and 0.4 mg/kg malondialdehyde (MDA), Crotonaldehyde (CRT), benzaldehyde (BNZ), 2,4‐nonadienal and 2,4‐decadienal, 0.16 mg/kg 4‐HHE and 4‐HNE and 0.5 mg/kg hexanal (HXL), which are the concentrations of the respective aldehydes in the first point of the matrix matched calibration curve. After checking that they were still suitable, the derivatization time and temperature were maintained at 60°C for 2 h, as previously optimized.26. 930 0 obj <> endobj Most of the published methods described to measure aldehydes in animal feed use a colourimetric method called the TBARS (thiobarbituric acid reactive species) method.18-20 However, this method lacks specificity because it measures the total content of aldehydes able to react with thiobarbituric acid, expressed in malondialdehyde content, instead of measuring each compound individually. formaldehyde-DNPH derivative in acetonitrile [2,14]. The DNPH reagent is highly reactive toward formaldehyde. In addition, during each of the three days of the validation, six ground Kellogg's® Corn Flakes® cereal samples were spiked with increasing concentrations of aldehydes to be used as calibration curves, leading to a total of 98 ground cereal samples. The precision (closeness of agreement between independent test results) of the method is evaluated through its repeatability (variation of the results obtained in a same series), expressed as a relative standard deviation or RSDr, and its intermediate precision (variation of the results obtained in different series), also expressed as relative standard deviation, and is often called RSDR. 2005-03-26. Structures of the 8 aldehydes analyzed: malondialdehyde (MDA), 4‐hydroxy‐2‐nonenal (4‐HNE), 4‐hydroxy‐2‐hexenal (4‐HHE), crotonaldehyde (CRT), benzaldehyde (BNZ), hexanal (HXL), 2,4‐nonadienal and 2,4‐decadienal. The best condition was obtained when 2 mL water were used as post‐derivatization solvent. Use the link below to share a full-text version of this article with your friends and colleagues. Contents. Selectivity and specificity were demonstrated by showing the absence of significant peak or chromatographic peak areas smaller than those of the corresponding peak in the first point of the calibration curve in the blanks and the presence of quantifiable peaks in the spiked samples. It is a member of phenylhydrazines and a C-nitro compound. These observations can be explained by the fact that 4‐HHE, 2,4‐decadienal and 2,4‐nonadienal are the three aldehydes quantified by using an internal standard which is not their isotopic analogue or the same molecule with an added methyl group and which has a behaviour different from the one of the analyzed aldehydes. The evaluated parameters were specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, using the concept of accuracy profiles. %PDF-1.6 %���� The analysis with the mass spectrometer was performed in MS/MS mode, with positive ionization for MDA and MeMDA and negative ionization for the other compounds. Also, less solvent is required for preparation of a stock solution. The best compromise between solubility and chromatographic peak areas was obtained for the 8 aldehydes with a DNPH concentration of 0.05 M in acetonitrile/acetic acid (9/1, v/v). The dotted external lines represent the acceptance limits. Results were calculated using Xcalibur Software (Thermo Fisher Scientific, Waltham, MA, USA). The tube was vortexed for 15 s and then centrifuged at 3700 g for 10 min on a REAX Top vortex from Heidolph (Schwabach, Germany) and a Minifuge T centrifuge from Heraeus (Hanau, Germany), respectively. The chemist performing this method must read the safety data sheets (SDS) to become familiar with the hazards before using these solvents in the laboratory. Ethanol absolute for analysis and trichloroacetic acid were from Merck (Darmstadt, Germany). Raw response data, without any correction, obtained for both calibration standards and spiked samples were computed using the validation software e‐Noval. Learn more. Because the cost of the stable isotope analogue of 4‐HHE was prohibitively high, 4‐HNE‐D3 was bought instead and used for 4‐HHE and 4‐HNE quantification. Prior to extraction, the addition of a post‐derivatization solvent to increase the aqueous phase was investigated. For validation purposes, it was decided to use ground Kellogg's® Corn Flakes® cereals to mimic animal feed in calibration curves and for the validation of the method, knowing that this cereal contains 0.9% fat only and is thus poorly sensitive to oxidation.
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