Solutions and powders for the laboratory
Laboratory solutions and powders are the support reagents that surround an assay: dilution and wash buffers, stabilisers for antibodies and conjugates, blocking agents, bovine serum albumin and powders to be weighed for in-house formulations. They do not generate the signal, but they decide how much of the signal is noise. In the CABRU catalogue the category brings together the 63 references from Candor Medix Biochemica, the albumin from Solabia and the formulations from G Biosciences, which include 206 buffer references and 166 ready-to-use solutions.
Blocking, stabilising, diluting: three distinct jobs
A blocker occupies the free sites of the solid surface so that the antibody does not stick to them: it acts before incubation and is the remedy for diffuse background. A stabiliser works on the protein instead, keeping antibody and conjugate active during storage and in dilute solution, where a protein at low concentration tends to adsorb onto the walls and denature. The diluent sits in between: it brings the antibody to working concentration while suppressing its non-specific binding. In the Candor range, 39 references are declared compatible with the whole set of immunological methods — western blot, ELISA, IHC, IP, immunofluorescence and array — in working sizes of 50, 125 and 500 ml.
The choices most often got wrong
| Choice | Options | Criterion |
|---|---|---|
| Blocking agent | BSA, skimmed milk, protein-free blockers | Milk does not go with anti-phospho antibodies; a protein-free blocker is needed when the antibody recognises BSA or when working in biotin-streptavidin |
| BSA grade | Fraction V, protease free, IgG free, fatty-acid free | Chosen by what has to be absent: proteases, residual immunoglobulins, bound fatty acids |
| Preservative | Sodium azide, alternatives, none | Azide inhibits peroxidase: it does not belong in diluents for HRP conjugates |
| Supply form | Ready-to-use solution, powder to be weighed | Powder leaves concentration and pH free; a solution removes the weighing error and is traceable to a batch |
Pack sizes and storage
Solabia albumin is offered in three sizes — 100 g, 500 g and 1 kg — in protease-free fraction V quality. Protein powders are hygroscopic: keep them closed, in a dry environment, and bring them to room temperature before opening, to avoid the condensation that compromises weighing and solubility. Preservative-free buffers are made fresh or kept refrigerated for the period stated on the datasheet; those containing a preservative should be checked against the detection chemistry before use. The full list, with codes and pack sizes, is in the product catalogue; for a reference that is not listed, CABRU checks availability among the manufacturers it represents.