SPI-CHEM™ Glutaraldehyde
To ship refrigerated or to not ship refrigerated
To ship refrigerated or not:
There is a split in our industry as to whether glutaraldehyde needs to be
shipped refrigerated or not. There are some who claim that it does and they
present their supporting data to back up that philosophy. Certainly some
chemicals most certainly should always be shipped refrigerated, for example,
L. R. White resin and
colloidal gold products, but we do not
believe that EM grade glutaraldehyde, if distilled to the purity of the
SPI-Chem glutaraldehyde does not require refrigerated shipment.
There are several reasons why SPI Supplies does not treat EM grade
glutaraldehyde as a "cold ship" product. First, and not necessarily in
order of importance, has to do with the mechanism of aging of the aqueous
glutaraldehyde solution. There is agreement that when impurities are
present, the polymerization (e.g. aging) process speeds up. There is some
disagreement as to just what are these impurities, and whether the process
is described as being "autocatalytic" or not, but as the purification of the
material gets better and better, the aging process becomes slower and slower.
Obviously, glutaraldehyde with a better starting purity will have a longer
shelf life than one that is not so pure.
On the other hand, as the temperature becomes higher and higher, and of
course, it does not matter whether the higher temperature occurs during
shipment or during storage, the aging process will speed up. We would
expect that the Arrhenius equation would hold, meaning that for every
increase in temperature of 10 C°, the rate will increase by an order of
magnitude (e.g. factor of 10 times).
We know from experience that SPI-Chem EM grade glutaraldehyde stored for one
year at room temperature will still be quite acceptable for use in EM
studies, and indeed SPI Supplies guarantees the SPI-Chem EM grade
glutaraldehyde product for one year when stored under those conditions. So
the real question is, what is the risk to product integrity if shipment is
made in the summer from SPI to a customer. And our experience spanning a
period of over twenty years suggests that the impact on the shipment is nil.
We have a few theories of our own as to why this concern about shipment on
summer days when in fact the experience has been that shipping on such days,
unrefrigerated, does not pose any risk to the product. For one thing, some
of the most often cited studies of the negative impact of temperature on
product integrity described testing done at 200° and even 370°C. These
temperatures are just not realistic in real life exposure when in transit.
Even on the most hot of summer days, at 40°C, because of the insulating
characteristics of the packaging materials used in the shipment of SPI
products, some number of hours would be needed before the contents of the
parcel came to equilibrium with the ambient temperature on the outside.
Even for international shipment, to tropical climates, since these shipments
travel ways by courier, when in transit and when cleared through customs,
they are normally now seeing an air conditioned environment. Of course the
delivery truck is not normally air conditioned, but then again the residence
time is not very long once sent out for delivery.
Another factor in all of this is the impact of the new electronic technology
on international shipments and the way goods are cleared through customs.
This is done today, in most countries, electronically, on the basis of the
paperwork, and parcel are usually "already cleared" by the time the plane
arrives, so any residence time spent in a distribution center indeed is
very short.
So having said all of that, we have always believed that the
"customer is king". Whatever the customer wants, the customer gets...
so that if you as our customer don't want to buy into the above cited
argument, and wish to have your EM grade glutaraldehyde shipped as a
refrigerated shipment, we certainly can do that, and you would be charged
additional for that service.
But the important thing is that you would be making that decision yourself
and you would be specifying, on your order for EM grade glutaraldehyde, that
the shipment be made as a refrigerated shipment.
Storage temperature:
Despite the fact that we will guarantee the SPI-Chem EM grade glutaraldehyde
for one year when stored at room temperature, we still recommend
refrigeration for long term storage. Prior to shipment from SPI Supplies,
the product is kept at low temperature under refrigeration. Because of our
high turnover of the product, the residence time in our own inventory is
rarely more than thirty days.
Rejeuvenation of aged glutaraldehyde:
Sometimes a customer is faced with having to dispose of some glutaraldehyde
that has gone bad. Naturally we hope that this would not have been SPI-Chem
glutaraldehyde, but in any case, there is the alternative of recycling to
disposal as a hazardous waste.
Yes, while it can be messy and time consuming, in some environments,
recycling and bringing the spoiled glutaraldehyde back up to EM standards
is an option. There are two approaches to purification, one being the
original method, that is, the use of charcoal, and the other being vacuum
distillation, but which requires special equipment. Probably today, the
vacuum distillation method is a bit better, but for many years, the charcoal
approach was more than acceptable, with the charcoal serving to remove the
dimers, trimers, and higher molecular weight chains that were formed from
the monomer.
Protocol for purification:
1] Mix the concentrated liquid glutaraldehyde solution with 1g of activated
charcoal per 100 ml of liquid.
2] Allow to stand for 30 minutes
3] Vacuum filter through a Whatman #1filter.
4] This should be repeated three times.
5] Bottle or ampoule under dry nitrogen and then store at 4°C (39°F)
6] Repeat once a year or more often if the solution, which should be clear,
developes a turbidity or precipitate.
Make sure all appropriate safety precautions are taken. As indicated, this
can be messy and take a lot of time and resources. Clearly, this should be
considered only when the circumstances dictate such action, such as the
costs of hazardous waste disposal.
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Saturday July 05, 2008
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