20 ANALYTICAL AND LABORATORY EQUIPMENT
The importance of being well prepared
Dan Crothers looks at how laboratory paddle blenders have offered fast reliable homogenisation for a wide range of laboratory samples.
S Fig. 1. The Stomacher 400 Circulator.
ample preparation is a critical step in all safety analyses. High quality sample preparation is vital to the ultimate delivery of good quality, accurate results and, therefore, should be a key consideration when analysing samples for safety purposes. Numerous industriesdepend on rapid and safe sample preparation techniques for production and quality monitoring in order to be able to intervene when required in active processes, while minimising downtime.
Be prepared For example, food materials are inherently variable, therefore it is essential that this variability, both within and between samples, is minimised as greatly as possible prior to microbiological analyses with proper sampling and also sample pre-treatment techniques.
Following the use of appropriate statistical methods to obtain representative and replicate samples, the resulting sample then requires an efficient sample pre-treatment procedure to ultimately deliver rapid, reliable and reproducible analytical results within given limits and
tolerances. To achieve this, material must be made less heterogeneous by reducing the particle weight and size within the primary sample. Tis enables smaller subsamples to be taken for a representative analysis of the whole and also ensure maximal organism recovery. Furthermore, if organisms are not released from the sample matrix via homogenisation, they will not grow or multiply in any subsequent culturing or selective isolation procedure. Consequently, another key issue to be addressed by a sample preparation method is the easy elimination of the potential for any cross-contamination between samples, thereby ensuring accurate results.
Finally, in addition to delivering a contaminant-free, reproducibly homogenised sample when reducing a food sample, the durability and
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