Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumTable 3. Differences between repeated measurements for the gravimetric and TGAmethodMeanMeasurement 1 Measurement 2 t p SELGravimetric method8.10 8.13 0.13 0.894 0.22TGA method9.34 9.33 0.04 0.969 0.05CONCLUSIONComparison of the results of the gravimetric and TGA methods used for the determination ofcrude ash content in feedstuffs showed that the results for the TGA method had demonstratedbetter precision compared with the reference chemical method. Furthermore, the results ofthis study showed the existence of a certain bias between the results of two methods, wherethe gravimetric method produced results that were lower than the results obtained by thegravimetric method. The differences in obtained results may be affected by differentphysical nature of the methods, different equipment used, different measurementconditions, uncertainties of mass equipment and temperature controllers, computationeffects, operator effects or random variation. Further work should be performed in orderto identify the level of accuracy of these methods.ACKNOWLEDGEMENTSThis work was financed by the Ministry of Science and Technological Development,Republic of Serbia (Project No. 20066).REFERENCES1. Danzer, K: Analytical chemistry: theoretical and metrological fundamentals.Springer-Verlag Berlin, Heidelberg 2007, pp 65-100.2. Eurachem/CITAC Guide CG 4: Quantifying Uncertainty in AnalyticalMeasurement, Eurachem/CITAC Working Group, Eurochem, London (2000).3. Felsner, M.L., Cano, C.B., Matos, J.R., de Almeida-Muradian, L.B., Bruns,R.E: Optimization of thermogravimetric analysis of ash content in honey. JBraz Chem Soc, 15 (2004), 797-802.4. Hoffman, P. C: Ash content of forages, Focus on Forage, 7 (2005), 1-2.5. Hunt, L.A: Ash and energy content of material from seven forage grasses,Crop Sci, 6 (1966), 507-509.6. Jovanović, R., Dujić, D., Glamočić, D: Ishrana domaćih životinja. Stylos,Novi Sad, 2002.197