Gas chromatographic determination of water and ethanol in silage by internal standard method

Abstract

Water and ethanol contents of different silages were determined by solvent extraction gas chromatography. Methanol was used as internal standard. The gas chromatograph was equipped with thermal conductivity and hydrogen flame ionization detectors. Glass columns, length 1.5m, i.d. 2 mm, were packed with Chromosorb 101, 80/100 mesh size. Water and ethanol extractions of 10 silages and gas chromatographic runs of the extracts could be carried out daily. The methods are suitable for routine laboratory analysis and use of the internal standard allows the gas chromatographic runs to be performed faster and more accurately. The precisions of water and ethanol determinations were satisfactory, the mean relative standard deviation percents of 12 replicate analyses being respectively 0.22 and 2.55. Water content of silages was also determined by conventional forced-air oven drying at 105°C. When ethanol content of the silage was above 5 percent, there was a tendency for water contents obtained by the oven drying method to be over 5 percentage units greater than those obtained by solvent extraction gas chromatography. When the ethanol content was below 0.5 percent, high acetic acid and lactic acid contents with low pH resulted the same tendency, the difference between the methods varring from 0.5 to 2.2 percentage units.

Effect of lactic acid bacteria inoculants, formic acid, potassium sorbate and sodium benzoate on fermentation quality and aerobic stability of wilted grass silage

“…Dried samples were analysed for organic matter (OM), nitrogen (N), neutral detergent fibre (NDF) and for in vitro organic matter digestibility (OMD) by a modification of the method described by Nousiainen et al (2003). Fresh samples were stored frozen (-20°C) until analysed for buffering capacity, WSC and soluble N. Oven determined silage DM was corrected with an equation given by Huida (1982). Water extract of silage was measured for pH, WSC, lactic acid, ethanol, ammonia-N and for VFAs (acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acid).…”

Effects of restriction of silage fermentation with formic acid on milk production

“…Total N and soluble N concentrations in fresh silage samples were measured by the Kjeldahl method using Cu as a digestion catalyst and Tecator 1028 Distilling Unit. Silage ethanol concentration was determined according to Huida (1982). A modification of the method described by was used to measure in vitro OM digestibility of the forages.…”

Variability in the ranking of the three most-limiting amino acids for milk protein production in dairy cows consuming grass silage and a cereal-based supplement containing feather meal

“…Other analyses were for short-chain fatty acids, 8 water-soluble carbohydrate, 9 starch, 10 neutral-and acid-detergent ®bres, 11 lactic acid 12 and ethanol. 13 Milk samples were analysed for total solids gravimetrically, for fat by the Gerber method, for total protein (N Â 6.38) by a Kjeldahl procedure and for lactose polarimetrically.…”