What you need to know about collecting aliquots and homogenizer bags

In a laboratory context, an aliquot is a portion taken from a liquid or solid volume, identically representing the initial product – its composition as well as its physical and chemical properties – for analysis purposes.

Understanding the homogenization process

For a successful aliquot, it is important to material in a homogenizer in order to evenly distribute all particles in the sample. Homogenization is therefore a process in which a product is pulverized to create the desired proportionate mixture. Without this crucial step, the aliquot cannot be a completely reliable representation of the for example, food is tested to ensure that it is safe for consumption, according to the standards established by the relevant governmental authority.

The result of the crushing is a homogeneous mixture which must then be filtered to separate the liquids and solids. The aliquot is taken from the liquid portion, using a glass pipette. The sample must be meticulously filtered and separated to ensure that the aliquot is accurate and efficiently collected and that the pipette is not blocked by any solid particles. A good filtration system must therefore be put in place to make sure that the final result will be optimal

Several homogenization techniques are employed, depending on the machine used or the type of sample under study. For solid or semi-solid samples, the result is usually obtained by strong vibrations, hammer blows or pressure rollers. It is therefore essential for the material being analyzed to be securely contained in a bag that is strong enough not only to prevent cross-contamination but also to withstand brute force of the crushing process and thus prevent material from leaking into the homogenizer. In addition, without the use of bags, the samples submitted successively into a homogenizer and then subjected to crushing and sieving would inevitably be exposed to cross-contamination.

How to optimize aliquot collection

As with any scientific process that must adhere to a rigorous methodology, there are several challenges facing laboratory analyzers, including any of the following:

• The homogenization process leaves particles large enough to clog the pipette;
• The contents are mixed or separated properly;
• The sample or filter bag is punctured during the process;
• The sample is compromised by cross-contamination.

An aliquot collection process that is not optimized for good results inevitably incurs costs, in terms of the materials and human resources used, until the desired result is obtained. Of course, if the contents of a filter bag break in the homogenizer, the homogenizer will have to be cleaned thoroughly to avoid cross-contamination. And that’s an expensive headache you can certainly avoid!

The FILTRA BAG – an innovative solution

Traditionally, filter bags were made of natural fibre mesh, often resulting in disparities, especially due to the disproportionate yarns used and the size of the filter holes. In addition, some fibres may react with the chemical components in the crushed sample, thus distorting the result. The invention of synthetic materials has provided a solution to these problems. Our FILTRA BAG blender bags are efficiently produced with an outer polyethylene/PET membrane, which eliminates any risk of piercing the walls during crushing. In addition, the full-size filter membrane allows bacteria to circulate between compartments while keeping larger residues separate.

They are also manufactured in a way that protects organic samples from the evaporative properties that can be caused by the heat generated during the crushing process. Homogenization is therefore easy and safe for the content. Our bags are designed to facilitate the analyzer’s work from start to finish: samples are placed on one side of the bag, and the aliquot is taken on the other side of the central filtering wall, letting through only the liquid and retaining any solid on the other side. Moreover, the size of the FILTRA BAG filtration holes, which have a pore diameter of 330 microns, is controlled and ensures unparalleled precision for all your solid or semi-solid samples.

In addition, choosing FILTRA BAGs means you are investing in a product that will facilitate the entire aliquot collection process, while also making the most of your materials, equipment and valuable staff time.