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Frequently, there are bubbles in the titrator of the automatic Kjeldahl nitrogen analyzer. The elimination of bubbles greatly affects the titration accuracy. In general, if there are no special bubbles, the burette can be drained several times by repeatedly filling the titrator with a manual function. However, the actual operation often encounters a situation in which the bubbles are relatively large or difficult to drain. In the long-term experiment, it was found that the hydrochloric acid solution was taken out of the pipeline for feeding hydrochloric acid, and then filling the titrator in the manual mode completely solved the problem of air bubbles. Since the pipe is not placed in the hydrochloric acid solution, the titrator can only inhale air when it is filled with liquid. At this time, the bubbles in the titrator will disappear into the air, and the pipe will be returned to the hydrochloric acid solution to empty the titrator again. Liquid filling can completely solve the bubble problem. The automatic Kjeldahl nitrogen analyzer has the advantages of rapidity, accuracy, flexibility and reduced human error, but there are also deficiencies. Kjeldahl measurement of crude protein concentration of hydrochloric acid is usually 0.1 ~ 0.2mol / L, so the hydrochloric acid solution can not be stored for a long time, often need to be re-formulated, so you need to completely replace the original pipeline hydrochloric acid to replace the new hydrochloric acid Solution.
When emptying the original hydrochloric acid solution in the titrator empty by the automatic Kjeldahl analyzer, since the top of the titrator is a conical structure, the plunger inside the titrator can only rise, and there is still a part of the hydrochloric acid above the plunger cannot be completely Exhausting, although the concentration of hydrochloric acid will be close to the newly prepared concentration after repeated repeated liquid addition and emptying, there will still be some errors, which will have some impact on some of the more demanding assessments and comparisons. Some potentiometric titrator manufacturers have changed the way in which the titrator is drained upwards to drain down or to change the top of the titrator to a flat top to ensure complete replacement of the titrant. This may be an automatic Kjeldahl determinator. The instrument improvements provide a reference.
Determination of Crude Protein in Feed Using Automatic Kjeldahl Nitrogen Detector
The feed industry is undergoing rapid and continuous development, and the output of feedstuffs is constantly increasing. The protein content in feedstuffs is a very important standard. The determination of crude protein in feed can be roughly divided into two types: the Kjeldahl method and the automatic Kjeldahl method. Although Kjeldahl apparatus is simple in equipment and consumes less reagents, it has a relatively large influence on human factors. Although automatic Kjeldahl apparatus has a high degree of automation, the assay reagent consumption is relatively large. This article discusses the factors affecting the determination of feed protein commonly found in Kjeldahl (distillation) and Kjeldahl (automatic Kjeldahl), and provides references for crude protein assayers in feeds.