Determination of organic acids in feedstuff, silage, haylage, and fermentates for biogas plants
To provide the proper conditions for silage or haylage storage in agriculture it is necessary to regularly monitor the formation of certain organic acids in it. For example, the formation of butyric acid can indicate spoiling of material. Formic or propionic acids can be artificially added to increase the nutritional quality.
The same materials and some other biodegradable waists (agricultural residues, sewage sludge, etc.) are also used in biogas plants, where the fermentation process must be carefully monitored, in particular, by the determining the certain organic acids.
The present method allows determination of some important organic acids like acetic, lactic, butyric, propionic, and formic in feedstuff additives, silage, haylage and in different biodegradable materials of biogas plants. Some other organic acids (oxalic, fumaric, etc.) can be also determined within this method.
The capillary electrophoresis method for the determination of organic acids is based on their differential migration and separation in a fused silica capillary under the influence of electric field. Sample pretreatment includes either just water extraction or sample distillation with steam. CE separation is completed within 5 minutes.
Identification and quantification of the analyzed organic acids is performed by measuring their intrinsic UV absorption at 190 nm.