Comparing plastic syringes and disposable columns to extract n-alkanes in forage and concentrate feeds/Comparacao de seringas plasticas e colunas descartaveis para extracao de n-alcanos em forragens e concentrados

• Published in: Ciência rural 2010-08, Vol.40 (8), p.1844-1847
• Main Authors: de Oliveira, Dimas Estrasulas, Tedesch, Luis Orlindo
• Format: Article
• Language: eng ; spa
• Subjects: Analysis; análise; Chromatography; consumo; determinação de n-alcanos; digestibilidade; digestibility; hidrocarbonetos; hydrocarbons; Hypodermic needles; Hypodermic syringes; intake; n-alkane determination; Syringes
• ISSN: 0103-8478; 1678-4596

Saturated aliphatic hydrocarbons (n-alkanes) were extracted from feed, orts, and bovine fecal samples using disposable, plastic 5mL-syringes as an alternative material to disposable columns, which are normally used in the liquid-solid extraction phase of n-alkanes. For both methods, the n-alkane extracts (carbon chain length between 31 and 36 atoms) were identified using gas chromatography. The linear regression between methods were: 1) feces: column Alkane=2.63+0.92^syringeAlkane [[r.sup.2] = 0.94, square root of the mean square error (RMSE) = 13.7mg [kg.sup.-1], n=30] from which the intercept and the slope did not simultaneously differ from zero and unity (P>0.05), respectively; 2) feeds: column Alkane = 0.36 + 1.12 x syringeAlkane ([r.sup.2]=0.85, RMSE=1.9mg [kg.sup.-1], n=21) from which the intercept and the slope did not simultaneously differ from zero and unity (P>0.05), respectively; 3) orts: column Alkane=0.49+0.92^syringeAlkane ([r.sup.2]=0.98, RMSE=1.2mg kg'1, n=15) from which the intercept and the slope did not simultaneously differ from zero and unity (P>0.05), respectively. Materials with low concentration of nalkanes may affect the values obtained in both methods. These results suggested that disposable plastic syringes might be a viable alternative to columns thus, reducing analytical costs. Key words: analysis, digestibility, intake, hydrocarbons, n alkane determination N-alcanos foram extraidos de alimentos, sobras e fezes de bovinos com a utilizacao de seringas plasticas descartaveis de 5mL como um material alternativo as colunas descartaveis que sao normalmente utilizadas para a fase de extracao liquido-solido. Para ambos os metodos, os n-alcanos (cadeias de carbono entre 31 e 36 atomos) foram identificados usando cromatografia gasosa. As regressoes lineares entre metodos foram: 1) fezes: col-una Alcano = 2,63 + 0,92 x seringa Alcano [[r.sup.2] = 0,94, raiz do quadrado medio do erro (RMSE)=13,7mg [kg.sup.-1], n=30], em que o intercepto e o coeficiente angular nao diferiram simultaneamente de zero e um (P>0,05), respectivamente; 2) alimentos: coluna Alcano=0,36+1,12xseringa Alcano ([r.sup.2] = 0,85, RMSE=1,9mg kg1, n=21), em que o intercepto e o coeficiente angular nao diferiram simultaneamente de zero e um (P>0,05), respectivamente; 3) sobras: coluna Alcano=0,49+0,92^seringa Alcano ([r.sup.2]=0,98, RMSE = 1,2mg [kg.sup.-1], n=15), em que o intercepto e o coeficiente angular nao diferiram simultaneamente de zero e um (P>0,05), respectivam