ROMIL solvents, acids and reagents are manufactured to a very high degree of purity, so much so that impurities can become more apparent when compared with lesser ‘analytical’ grades. Indeed, it is this purity that allows today’s analysts to rapidly identify and determine components in their sample, without wasting time on resolving true sample signals from a background of reagent impurities.
But to maintain the original high degree of purity certain procedures should be observed with regard to storage and handling. For example, impurities can form due to thermal or photolytic decomposition as well as through formation of free radicals. Adverse reactions with atmospheric oxygen can produce dangerous peroxides and dryness can be degraded by contamination with atmospheric moisture. Effects of this kind differ from product to product and can be more noticeable over a period of time, especially when combining the sensitivity of modern analytical instrumentation with the very high purity of ROMIL laboratory products.
At ROMIL we minimise these problems by manufacturing and filling under an inert atmosphere of dry nitrogen. An ‘expiry date’ or ‘shelf life’ is established for each product in order to guarantee to users a certain period of time when the product will give optimum performance. Furthermore, our stock rotation policy ensures that only the freshest manufactured batches are released for sale thus prolonging the period of ‘useful life’. This means that when we supply a product with, for example, a 2 years shelf life it means exactly that. The shelf life has not been degraded, say, for 18 months, whilst sitting in our warehouse, leaving only 6 months for the customer to use it.
So to obtain the best performance from ROMIL products they should be used within the defined period of time and stored in such a way that minimises impurity build-up. To prevent contamination it is good practice to dispense from the container rather than withdraw product with pipettes or other glassware. Do not return unused material and always replace the original closure immediately after use. Partially-used bottles of solvents should be purged with dry nitrogen or other inert gas before replacing the cap in order to maintain the optimum UV transparency. Pack sizes should be chosen appropriate to the method. Whilst large containers may be suitable for HPLC gradients or for extraction prior to GC, smaller bottles are more suited to purely spectroscopic applications which consume much less solvent. Smaller pack sizes are also worth considering for those products which may deteriorate on atmospheric exposure.
Certified reference solutions and volumetric reagents should be gently shaken before use to maintain homogeneity which can be degraded due to water condensation on the inner surface of the container. This will also address striaition effects which may develop on long term storage.
We recommend that products are kept in a cool and dry place, preferably in the dark and certainly out of direct sunlight. The solvent or acid cupboard below the laboratory bench is ideal and indeed modern safety regulations require that such chemicals are stored in appropriate cupboards whilst not in use. Long-term exposure to excessively warm temperatures should be avoided. In general, a comfortable ambient room temperature (15-25°C) for laboratory personnel is fine for most products but where special storage conditions are required, such as refrigeration, this is stated on the label.
Information regarding stability and storage of reagents is an integral requirement of modern Good Laboratory Practice (GLP) and ISO 17025 management. These quality systems are designed to ensure that data from laboratory studies is both reliable and reproducible. All ROMIL bottles carry a batch number for unique identification purposes and to help customers comply with GLP requirements our labels also bear the following additional information on stability and storage:
- date of QC test
- recommended expiry date or shelf life
- special storage conditions, if any
- a space for recording the date opened
|Relatively 'unstable' materials||In addition to the above, the following information is given for products which may deteriorate faster after the container seal is opened:|
- recommended expiry date or shelf life (after opening)
Note that the shorter shelf life after opening must run within the unopened period otherwise it should be reduced accordingly. For example, if the recommended expiry after opening is 3 months then if the bottle is opened, say, 2 months from the expiry date, then the expiry after opening is reduced to 2 months.
It is not to be assumed that products suddenly become unuseable after the expiry date. Rather, the user should make a judgement based on knowledge and experience as to whether the product can continue to be used for the technique in mind. One way to do this would be to re-test the key purity parameters as defined on the label or specified in a written method. Record the results in the laboratory journal and annotate the product label. But even so, a high purity solvent or acid should still be suitable for less demanding applications beyond its recommended shelf life.
We are proud that ROMIL, during the mid 1980s, were the first to introduce such an enhancement to the labelling of laboratory chemicals. Whilst this has now become an industry standard requirement, the clarity of the ROMIL approach and system of shelf life control continues to far exceed all others.