formaldehyde-DNPH derivative in acetonitrile [2,14]. The DNPH concentration (0.0125 M, 0.025 M, 0.05 M, 0.1 M, and 0.15 M), the solvent (acetonitrile, ethanol) and the type of acid (hydrochloride, acetic, sulphuric, and phosphoric acids) in the DNPH solution were tested. 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. For the 4‐HHE, 2,4‐decadienal and 2,4‐nonadienal, the lower 95% tolerance interval is higher than the acceptance limit of 50% for the “high” level of concentration (66.3, 139.2, and 108.5%, respectively). Kellogg's® Corn Flakes® cereals were bought in a local supermarket. An LC‐MS/MS method was developed for the analysis of potentially toxic aldehydes as markers of the lipid oxidation in animal feed. 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). The validation was performed according to the Commission Decision 2002/657/EC and following the most commonly used approaches.24, 25 The Commission Decision 2002/657/EC promotes the use of Certified Reference Materials (CRM) to validate an analytical method. Learn more. Methylmalondialdehyde (MeMDA) was synthetized from (dimethylamino)‐2‐methyl‐2‐propenal (DMP, Sigma‐Aldrich, St. Louis, MO, USA) according to the method described by Syslovã et al.23. Correspondence to: Caroline Douny, Department of Food Sciences, Laboratory of Food Analysis, FARAH ‐ Veterinary Public Health, University of Liège, Quartier Vallée 2, Avenue de Cureghem 10, Sart Tilman B43bis ‐ 4000 Liège, Belgium. Internal dashed lines represent the 95% β‐expectation tolerance interval (the result expected for a level included in the dosing range will fall in these limits, with a risk of 5% of being outside). Also, less solvent is required for preparation of a stock solution. 2,4-dinitrophenylhydrazine is a C-nitro compound that is phenylhydrazine substituted at the 2- and 4-positions by nitro groups. One gram (1 g) of mixed sample was weighed in a test tube, spiked with 200 μL of BHT solution (1 mg/mL in ethanol), 100 μL of the solution containing the six internal standards and 2200 μL water/ethanol 50/50 (v/v). Its molecular and crystal structure has been analyzed. Accuracy profiles computed for the aldehydes are shown in Figure 3. During the three days of the validation, 20 ground cereal samples were spiked only with internal standards to be used as ‘blank’ samples and 60 ground cereal samples were spiked with internal standards and three different concentrations (low, medium, high; n=20 for each concentration) of aldehydes (Table 2), which correspond to the first, the fourth, and the sixth point of the calibration curve, respectively. Dates: Modify . At 2.4 mg/m . Stock solution of malondialdehyde 1 mg/mL (MDA) was obtained by hydrolysis of 1,1,3,3‐Tetraethoxypropane (TEP) in trichloroacetic acid 5%. Create . Raw response data, without any correction, obtained for both calibration standards and spiked samples were computed using the validation software e‐Noval. The recovery (the proportion of the amount of analyte, added to the analytical portion of the test material, which is extracted and presented for measurement) ranged from 54% to 115% (Table 2). No solvent or 2 mL of water, ethanol, acetonitrile, ethanol/water 50/50 (v/v), and acetonitrile/water 50/50 (v/v) were tested. Stock solutions of 4‐hydroxy‐2‐hexenal (4‐HHE), 4‐hydroxy‐2‐nonenal (4‐HNE) and 4‐hydroxy‐2‐nonenal‐D3 (4‐HNE‐D3) were obtained from Cayman Chemicals (Ann Harbor, MI, USA). Limited Antioxidant Effect of Rosemary in Lipid Oxidation of Pan-Fried Salmon. The gradient elution conditions were from 40 to 65% of solvent A in 8.5 min and from 65 to 100% in 4 min; then, conditions were held for 7.5 min and the contribution of solvent A was decreased to 40% over 2 min and maintained for another 6 min reconditioning. The LOQ is defined here as the smallest quantity of the targeted substance in the sample that can be assayed under experimental conditions with well‐defined accuracy.32 The definition can also be applicable to the upper LOQ which is the highest quantity of the targeted substance in the sample that can be assayed under experimental conditions with well‐defined accuracy. State of art and best practices for fatty acid analysis in aquatic sciences. Safety & Documentation. Picograde hexane was from LGC Standard (Wesel, Germany). It does not represent any. Number of times cited according to CrossRef: Nonenzymatic oxygenated metabolite of docosahexaenoic acid, 4(RS)‐4‐F4t‐neuroprostane, acts as a bioactive lipid molecule in neuronal cells. The measurement uncertainty (MU) (a parameter that characterizes the dispersion of the values that could reasonably be attributed to the measurand) is expressed here as a relative expanded uncertainty (a percentage of the result) and is calculated from the total variance of the β‐expectation tolerance interval, using a coverage factor of 2. Log in or register to post comments; Tue, 04/07/2009 - 15:50 #2. The dotted external lines represent the acceptance limits. At a formaldehyde concentration of 1.2 mg/m. 3. and at 5% breakthrough, the Waters sampler had a capacity at <10% RH of 55 µg, and at >85% RH a capacity of 77 µg. 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. The capacity of DNPH-coated silica gel samplers was found to vary with relative humidity (RH) in addition to concentration of formaldehyde. 26 The sample matrix is very acidic (20% HCL, ph 0). 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. Derivatized standards were synthesized in our laboratory according to the derivation protocol explained in Section Sample preparation and infused directly in the mass spectrometer to optimize the MS tune parameters. 2,4-Dinitrophenylhydrazin e (DNPH), a hydrazine derivative, is a potential mutagenic agent. The proposed extractions were tested to extract the dinitrophenylhydrazone derivatives of the eight aldehydes of interest and five internal standards and four times 1 mL hexane showed the best results. used are acetonitrile, tetrahydrofuran, and methanol. The five other aldehydes were detected in Corn Flakes® cereals but their chromatographic peak areas were smaller than those of the corresponding peak in the first point of the calibration curve (Figure 2). Working off-campus? Methylcrotonaldehyde (MeCRT), benzaldehyde‐13C, hexanal‐D12, 4‐HNE‐D3 and methylmalondialdehyde (MeMDA) were used as internal standards in the quantitative analysis. The repeatability was between 2 and 14% and the intermediate precision was between 2 and 25% for the 8 aldehydes (Table 2). The filters were hydrophilic single use syringe filters (0.2 µm pore size, 25 mm, Chromafil) from Macherey‐Nagel (Düren, Germany). LODs (the smallest quantity of the targeted substance that can be detected but not accurately quantified in the sample) are calculated within the e‐Noval software by either dividing the lower LOQ by 3.3 or by adding three times the residual standard deviation obtained from an ANOVA test to the y intercepts of the calibration curves. While no official regulatory standards have been set for aldehydes in food or animal feed, acceptance limits (dotted external lines) were selected arbitrarily at 50% for all aldehydes except for 2,4‐nonadienal where the acceptance limits were selected at 70%. Separation was achieved on an Atlantis T3 C18 column (3 µm, 2.1 x 150 mm), with an Atlantis guard column T3 C18 (3 µm, 2.1 x 10 mm), both from Waters Corporation (Milford, MA, USA). Data generated during the validation of the method were processed with e‐Noval 3.0 software, from Arlenda (Liège, Belgium). Extractions of samples and injections of samples extracts were performed on three days. Aldehydes contained in edible oils of a very different nature after prolonged heating at frying temperature: Presence of toxic oxygenated α,β unsaturated aldehydes, Formation of toxic alkylbenzenes in edible oils submitted to frying temperature. According to several authors27-29 the malondialdehyde hydrazones could be extracted with two or four times 1 mL hexane. When a peak was detected, it was shown that it fulfilled the confirmation criteria detailed in Section Confirmation criteria (Figure 2). +49 (0) 34291 / 33 72 36 Dr. Analytical. Top. Indeed, those three compounds were either not detected or detected with their chromatographic peak areas close to those of the background noise peaks in Corn Flakes®. Subsequently, a validation protocol for the developed method was set‐up, based on various performance parameters. A mixture of the 8 aldehydes of interest at a concentration of 8 (4‐HHE and 4‐HNE), 25 (hexanal) and 20 ng/μL (for the 5 other aldehydes) was prepared in water/ethanol 50/50 (v/v). I know this method well. 930 0 obj <> endobj The LODs were found below the lowest spiked level for all compounds (Table 2). Water was of Chromanorm quality, while acetic acid 100% was of Normapur Quality and were both provided by VWR International (West Chester, PA, USA). Depending on the compounds, the lower and upper LOQ ranged respectively from 0.16 to 0.50 and 3.14 to 12.5 mg/kg (Table 2). %PDF-1.6 %���� Most of the other published methods described in the literature were not validated and demonstrated to be fit‐for‐use for food or feed matrices. The evaluated parameters were specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, using the concept of accuracy profiles. Six samples of ground Kellogg's® Corn Flakes® cereals were spiked with the internal standards solution and five of them with concentrations ranging from 0.16 to 4.0 mg/kg for 4‐HHE and 4‐HNE, 0.15 to 7.5 mg/kg for MDA, crotonaldehyde, benzaldehyde, 2,4‐decadienal and 2,4‐nonadienal and 0.5 to 12.5 mg/kg for hexanal.
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