Grain, compound feeds or feed pellets occur in a variety of forms; compound feeds are usually inhomogeneous. Feedstuff is analyzed, for example, to determine the nutritional value, to detect hazardous substances or genetically modified ingredients. To ensure meaningful and reliable analysis results, representative and homogeneous samples are required. Therefore, sample preparation involves homogenization and size reduction of the material to a defined particle size. RETSCH laboratory mills are perfectly suited for this process.
How to turn a laboratory sample into a representative part sample with homogeneous analytical fineness -
Food occurs in a great variety of consistencies and is often inhomogeneous. Food testing labs require representative samples to produce meaningful and reproducible analysis results. Therefore, food samples must be homogenized and pulverized to the required analytical fineness, ideally with as little time and effort as possible. Furthermore, reliable analytical results can only be obtained if the entire sample preparation process is carried out reproducibly.
Rock salt and sea salt not only consist of sodium chloride but may also contain other minerals and silicates, depending on the mining area and method. To analyze the composition of salt, the sample needs to be sufficiently homogenized, considering that larger
lumps of rock salt are usually very inhomogeneous. The element concentrations in salt are usually very low so that it is frequently necessary to process amounts in the kilogram range. The Rotor Beater Mill SR 300 easily pulverizes charges of several kilogram
and is therefore ideally suited for this application.
A typical laboratory sample of coal often consists of 10 kg or more. Depending on the type of coal, each sample piece may have dimensions of 150 mm x 70 mm x 70 mm or even more. When dealing with rather inhomogeneous materials like lignite it is not sufficient to take one of the big lumps and crush it to obtain a few grams which can then be used for analytical processes such as the determination of the calorific value or sulfur content. One piece of coal taken randomly from the laboratory sample will never entirely represent the original sample; using such a sample for analysis will therefore lead to unreliable results which cannot be reproduced.
In the book "Ideas and Applications Toward Sample Preparation for Food and Beverage Analysis," (ISBN 978-953-51-3686-6), edited by Mark T. Stauffer, RETSCH has published a chapter on reliable sample preparation of food samples. This chapter describes the process of turning a laboratory sample into a representative part sample with homogeneous analytical fineness by choosing the most suitable mill. Important aspects of size reduction and homogenization are explained, a variety of application examples is given, and specific applications such as cryogenic grinding are discussed in detail.
Reliable and accurate analysis results can only be guaranteed by reproducible sample preparation. This consists of transforming a laboratory sample into a representative part sample with homogeneous analytical fineness. Retsch offers a comprehensive range of the most modern mills and crushers for coarse, fine and ultra-fine size reduction of almost any material. The product range also comprises a wide choice of grinding tools and accessories which helps to ensure contamination-free preparation of a great variety of sample materials. The selection of the correct grinding tool depends on the sample material and the subsequent method of analysis. Different grinding tools have different characteristics, such as required energy input, hardness or wear-resistance.
A variety of methods can be used to analyze solid materials. What they all have in common is the necessity to use a representative, homogeneous analysis sample which needs to have a particular fineness, depending on the analytical method used. The size reduction and homogenization of solids is usually carried out with laboratory crushers and grinders.
A faultless and comparable analysis is closely linked to an accurate sample handling. Only a sample representative of the initial material can provide meaningful analysis results. Rotating dividers and rotary tube dividers are an important means to ensure the representativeness of a sample and thus the reproducibility of the analysis. Correct sample handling consequently minimizes the probability of a production stop due to incorrect analysis results. Thus correct sample handling is the key to effective quality control.
Why Size Reduction? A reliable and accurate analysis can only be guaranteed by reproducible sample preparation. The "Art of Milling" describes the process of turning a laboratory sample into a representative part sample with homogeneous analytical fineness.