动物饲料中氮/蛋白质含量检测方案(定氮仪)

智能文字提取功能测试中

thermoscientific Characterization of food and animal feed relatedproducts bv the Thermo Scientific FlashSmartElemental Analyzer Authors Dr. Liliana Krotz and Dr. Guido Giazzi Thermo Fisher Scientific， Milan， Italy Keywords Animal Feed， CHNS， Food Quality， Food Supplements， Labeling， QA/QC Goal To demonstrate the performanceof the Thermo ScientificFlashSmart Elemental Analyzerfor nitrogen/protein determinationin food and animal feed. Food and animal feed is made up of chemical compounds that determineflavor， color， texture and nutritional value， and are carefully regulated byfederal authorities and various international organizations to ensure that theyare safe to eat and are accurately labelled. One of the main analyses for quality control and R&D purposes is elementalcharacterization. The determination of nitrogen， carbon， hydrogen andsulfur， provides useful information on the characterization of these materials.It is therefore very important to have an accurate and precise technique，preferably automatic， that allows fast analysis with excellent reproducibility.The Thermo Scientific FlashSmartElemental Analyzer (Figure 1) copeseffortlessly with the wide array of laboratory requirements such as accuracy，precision and day to day reproducibility. Figure 1. Thermo Scientific FlashSmart Elemental Analyzer. Methods For CHNS determinations， the elemental analyzeroperates according to the dynamic flash combustion ofthe sample. The sample is weighed in a tin capsule andintroduced into the combustion reactor via theThermo ScientificMAS Plus Autosampler with oxygen.After combustion， the resultant gases are carried bya helium flow to a layer filled with copper， then sweptthrough a GC column that separates the combustiongases， finally being detected by a Thermal ConductivityDetector (TCD) (Figure 2). Total run time is less than10 minutes. For NCS or for sulfur only determination， thewater produced during combustion is adsorbed througha H，O trap before entering the GC column. For NC determination， after combustion， the producedgases are carried by a helium flow to a second reactorfilled with copper， then swept through a H，O trap， aGC column， before finally being detected by a thermalconductivity detector. Total run time is less than fiveminutes (see Figure 3). Figure 3. FlashSmart NC configuration. A complete report is automatically generated by theThermo Scientific"EagerSmart" Data Handling Softwareand displayed at the end of the analysis. Results Different food and animal feed related products with alarge range of elemental concentrations were analyzed invarious configurations， to show the performance of theinstrument in terms of repeatability. For the CHNS， NCS and sulfur only determinations， theaddition of Vanadium Pentoxide (oxygen donor) wasused for a complete conversion of the sulfur， and theinstrument was calibrated with the standards BBOT*and nicotinamide. For NC determination， acetanilideand aspartic acid were used as standards to calibratethe instrument. In all cases， K factor was used as thecalibration method. * BBOT： 2，5-Bis (5-tert-butyl-benzoxazol-2-yl) thiophene. Table 1 shows the CHNS data obtained from differentsample matrices. The weight of sample was 2-3 mgfor animal gelatines and food supplement A， 3-4 mgfor starch and food supplement C， 8-10 mg for foodsupplement B. No memory effect was observed when changing thesample nature， indicating complete combustion of allsamples with quantitative determination of the elements. Table 1.CHNS data. Sample N% RSD% C% RSD% H% RSD% S% RSD% Fish gelatine 16.24916.21216.189 0.185 43.02343.09943.051 0.089 6.9026.6086.586 2.632 0.3940.4080.408 2.004 Bovine gelatine 15.79615.83515.838 0.148 44.61544.64744.624 0.037 6.6236.6586.622 0.309 0.5310.5360.537 0.601 Porcine gelatine 16.08816.01616.043 0.226 44.46044.39744.379 0.096 6.6316.6596.582 0.585 0.5310.5360.537 0.970 Starch 2.5302.5162.5372.5202.528 0.329 31.00830.85031.00030.95630.967 0.204 5.3965.4565.4155.3735.310 1.004 0.3990.3960.3910.3920.398 0.902 Food supplement A 13.16813.16013.194 0.137 52.17952.08452.178 0.104 6.6656.6266.626 0.311 Food supplement B 0.0710.0710.073 1.109 8.01978.0251 8.0241 0.036 2.2072.1992.209 0.254 Food supplement C 0.3300.3320.329 0.533 40.61540.39640.630 0.323 6.2746.3316.323 0.488 0.3660.3680.357 1.581 Table 2 shows the NCS data obtained from differentsample matrices. The weight of the sample was3-4 mg. No memory effect was observed when changing thesample nature， indicating complete combustion of allsamples with quantitative determination of the elements. Table 3 shows the sulfur data obtained from differentsoya and maize samples. The weight of the sample was3-4 mg. Table 3. Sulfur data. Sample S% RSD% Soya 1 0.356-0.336-0.338-0.350-0.343-0.341 2.214 Soya 2 0.351-0.344-0.343 1.635 Soya 3 0.372-0.373-0.363 1.725 Soya 4 0.366-0.363-0.364 0.388 Maize 1 0.115-0.114-0.116-0.113-0.113-0.106 3.137 Maize 2 0.119-0.111 4.919 Maize 3 0.104-0.104 Maize 4 0.112-0.102 6.608 Maize 5 0.102-0.100 1.396 Table 4 shows the NC data of blood flour， meat flour andfood supplements. The weight of sample was 9-10 mgfor blood flour and meat flour while for food supplementsthe weight was 10-20 mg. Table 4. NC data. Sample N% RSD% C% RSD% Blood flour 14.53614.30714.427 0.797 48.79149.23849.052 0.458 Meat flour 7.2137.4747.385 1.804 32.00833.28732.722 1.963 Food supplement 1 5.7395.7475.744 0.071 14.59814.62314.612 0.084 Food supplement 2 11.36511.39111.369 0.123 45.62545.30345.343 0.385 Food supplement 3 5.8455.8315.863 0.269 17.12717.11517.161 0.138 Food supplement 4 3.6303.6133.634 0.310 37.09336.975 36.956 0.201 Conclusions The FlashSmart EA allows the quantitative recovery ofthe elements from any matrix with no memory effectobserved when changing the sample. The advantageof the FlashSmart EA lies in its ability to perform NCdetermination or simultaneous CHNS determinationin a single run. By a simple modification of the CHNSconfiguration， the analysis of NCS or sulfur only can beperformed using the same analytical conditions. 食品和动物饲料由决定味道、颜色、质地和营养价值的化学化合物组成，并由政府当局和各种国际组织严格监管，以确保它们食用安全，并贴上准确的标签。元素表征是质量控制和研发的主要分析之一，氮、碳、氢和硫的测定，为这些材料的表征提供了有用的信息。因此，需要有一个可以全自动、快速分析并提供准确性和重现性高的技术是非常重要的。热电FlashSmart N/protein杜马斯定氮仪可轻松满足各种实验室要求，如准确度、精密度和日常重现性。