Simultaneous Determination of Lactic Acid and Volatil Fatty Acids in Ox Rumen Juice by Ion Chromatography

Ion chromatography was applied to the simultaneous determination of 7 organic acids in rumen juice,including lactic acid,ethanoic acid,propanoic acid,iso-butanoic acid,n-butanoic acid,iso-pentanoic acid and n-pentanoic acid.The IonPac AS11-HC (4 mm×250 mm) was used as analytical column with IonPac AG11-HC (4 mm×50 mm) as protective column.Electric conductance detector with ASRS (4 mm) suppressor was used in the determinations.Sodium hydroxide solutions with different concentration were used as the mobile phase in the gradient elution.Linear relationships between the values of peak area and concentration of the above mentioned organic aicds were found in ranges of 0.36-36.0,0.10-50.0,0.11-23.0,0.05-8.7,0.15-36.0,0.11-19.0 and 0.06-23.5 mg·L-1 with their detection limits of 9.87,3.60,4.15,2.46,4.71,3.19,6.93 μg·L-1 respectively.As shown by the analytical results obtained by analysis of substantial sample of rumen juice,values of RSD′s (n=7) found from the analytical results were in the range of 1.73%-5.66%.