Your reagents should do ‘Exactly what they say on the tin.’  This only happens though if you look after them in the way the manufacturer states on their data sheets. We have all been guilty of using reagents past their expiration date.  Usually we can get away with it, but there are a few things to beware of. Manufacturers guarantee their reagents but only if you have stored and handled them according to their recommendations.

Buffers

Take care to look at the manufacturer’s protocol and chat to your lab mates.  You can make up some buffers in advance and store them in the fridge/freezer,  but some need to be made up fresh.  Don’t forget to label the bottle with your initials and the date.  Also beware of inflicting too many freeze/thaw cycles on your reagents.  To avoid this, make up your buffers and aliquot them and freeze them in individual vials containing enough for one day’s experiments. Make sure your freezer isn’t a frost-free freezer that undergoes freeze/thaw cycles, which could adversely affect your reagents.

Caution: If your buffers have precipitated, this is usually an indication that you have done something wrong. Have you made up your stock with the wrong buffer? Has it been stored incorrectly? Is it past its useful life?

Antibodies

Antibodies are very expensive.  If you treat them badly by storing them incorrectly or by contaminating them, then it is a costly mistake. Each antibody has a unique shelf- life and different storage conditions. So make sure you store them as stated by the manufacturer.  Often that means keeping them at the correct temperature in a dark vial.

When kept at room temperature, antibodies (and other reagents) can become contaminated by microbial growth, which could affect their effectiveness. For long-term storage (e.g. in the freezer), many manufacturers recommend storing them concentrated in aliquots in volumes greater than 10ml. Dilute antibody solutions (<1mg/ml) are more prone to inactivation and there can also be physical loss of the antibody as the antibody can bind to the storage vessel surfaces.

If you are using a fluorescently-conjugated antibody, then make sure you store them in a dark vial or wrap them in foil. This will help prevent any photo-bleaching of the fluorochrome. This is particularly important when using tandem dyes (dyes made up of a donor and acceptor fluorochrome).

Also if you have a precious experiment, you might want to keep a stock of your own antibodies separately to prevent one of your colleagues accidently contaminating them with a unclean tip.

Viability Dyes

Many of the fixable live/dead dyes that are available are best stored frozen, but again it might be worth storing them in aliquots to prevent freeze/thawing of your dyes.

Take Home Message on How to Store Your Reagents

Always check the data sheet, follow the manufacturers storage recommendations and use some common-sense.   Also check how much reagent is left in the bottle before you start out on your mammoth experiment. You don’t want to run out!!

Remember that although using the dregs of your reagents may save some money, if it means not getting optimal results, repeating the whole experiment will end up costing you so much more.