Guidelines concerning the handling of chemicals

It is important that one be fully informed as to the specific dangers of the substances one is using, only in this case can one use them safely.

Storage of sensitive and dangerous substances

Basically the contents of all containers must be clearly marked and the necessary hazard instructions and symbols should be affixed to the container. If this has not already been done by the manufacturer or seller, then it may be of use to affix information concering the origins or quality of the substance to the container.

Toxic or very toxic substances (symbol T or T+) must according to law be stored in a locked hazardous substance cabinet. Also other dangerous substances should be stored there. It is important that larger quantities of flammable or oxidizing substances not be stored near the workplace. One should also pay attention that substances which can intensely react with one another, such as acids and alkalies, not be stored next to one another.

The appropriate container

Basically one should not use any containers which are intended for the use of the storage of foodstuffs or which could otherwise lead to a mix-up!

Liquids are best kept in narrow necked containers, commonly called bottles. It is recommended to store dangerous liquids in plastic bottles in order to avoid accidents due to the breakage of glass bottles. The plastic cannot of course be destroyed by the substance. Some substances, e.g. aromatic compounds or sulphuric acid, are only allowed to come into contact with specific plastics, one should inform oneself at the time of purchase of a plastic container as to its resistence to different substances. Alkalies corrode glass, one should therefore store it in alkali-resistant plastic (e.g. polyethylene, PE). For substances which are needed frequently but only in limited quantities it is recommended that these be stored in pipette bottles. One should be aware of the fact that certain substances corrode or swell the rubber stopper.

Wide necked containers are appropriate for solids. Plastic is lighter than glass and rarely breaks, therefore it is generally preferable. Photosensitive substances must be kept in opaque plastic containers or in brown glass containers.

The right quantity

Air or water sensitive substances should be kept at the working place in small quantities. If one constantly opens a larger container the substance can become unusable over time, and one has to then throw away a good part of it. The same is true for dangerous substances, especially liquid ones, for by doing this one can limit the seriousness of an accident due to spillage or to breakage of the container. The container should basically be chosen not to be inordinately large in relationship to the quantity of the substance which is to be stored within it. In the case of liquid dangerous substances one should leave at least one-tenth of the bottle volume free, in order to avoid spillage when pouring. Inflammable or oxidizing substances should always only be stored in small quantities near the working place.

Pouring and decanting of chemicals

As a matter of principle all technical aids used such as funnels, spatulas, etc., must be clean! They are to be cleaned immediately after each usage. Syringes and pipettes are to be rinsed thoroughly. If they have been used for water insoluble substances, then ethyl alcohol or acetone is to be used, and afterwards they are to be rinsed with water.

In the process of decanting larger quantities of substances, as well as in the case of smaller quantities of especially dangerous substances, one should place a easily cleanable tablet underneath in order to avoid a contamination of the working place. This is in particular necessary if the work surface consists of wood or similiarly difficult to clean materials.

If one pours a liquid out of a bottle one has at the ready a paper towel in order to absorb any drops which drip down from the bottle. One takes the bottle in the hand such that any liquid dripping down and any drops do not get on to the hands. If one fills a liquid into a test tube or any other narrow necked vessel, then one places this in a stand, or holds it with a test tube holder. In order to transfer smaller amounts of dangerous liquids one uses as a matter of principle a (also clean on the outside) pipette or syringe. One should take into account that heavy liquids (especially concentrated acids) can pearl out of pipettes on their own. For this one uses pipettes with an especially narrow opening or a syringe with a stainless steel needle.

To pour liquids or solids into narrow necked containers one uses a funnel.

One transfers small amounts of solids with a spatula, in this process it is easy to lose some of it. Therefore, one should minimize the distance between the container from which the substance is taken and the container into which the substance is to go. For larger amounts a spool is appropriate.

Health protection

If using volatile substances one should always provide for good ventilation. Highly or extremely flammable substances (danger symbol F or F+) can form an explosive atmosphere, when using these substances one should not only provide for good ventilation but also extinquish all sources of ignition. See also Fire Protection. Some substances (e.g. mercury, hydrogen flouride) are so poisonous that they can only be used with a very efficient exhaust hood! Better it would be to forgo using such compounds.

In the usage of corrosive or hot substances, and really better in any work with chemicals, it is imperative to wear protective goggles. They should offer protection on all sides, normal glasses are not sufficient. This is the most important safety precaution of all, the loss of an eye can happen all too quickly and unexpectedly, yet this can be easily avoided!

One always wears in the laboratory work clothes, everyday clothing does not offer good protection and it is a bother when it becomes damaged. As a matter of principle one should avoid synthetic fibers, as these are easily inflammable and can therefore also cause severe injuries. A robust cotton lab coat is flame resistant and offers good protection, because it absorbs many dangerous substances before they get to the skin. In the case of a dangerous contamination the lab coat should, of course, be taken off quickly.

Gloves are to be treated with caution, no glove offers protection against all substances. Especially the cheap and easily available latex gloves are only very briefly effective and are at any rate soon penetrated by most liquids. A thick model offers generally more protection, but the loss of feeling and precision is in turn itself dangerous. One should not count on gloves to prevent skin contact with dangerous substances, potentially one does not notice the contamination because of them!

If one works with bare hands, then one should wash these regularly. In the case of contact with a dangerous substance then best to do this at once. Inasmuch as through these substances, as well as due to other circumstances in the laboratory, the skin is strongly affected, the use of a protective ointment, expediently of a silicone base, is strongly recommended. After work one should perhaps apply a skin cream.

I hope that it is obvious from common sense, but still one can mention it: one is not to work in socks or even worse barefoot! The footwear used should be impervious and allow stability, an adequate protection against mechanical impact is certainly also useful.

With experiments in which a very bright light or UV radiation is produced or utilised, one should use aside from the customary safety goggle sunglasses with UV protection. In the case of strong radiation (e.g. burning of magnesium, thermite reaction) it is advisable to use safety goggles for gas welding, many models of which can replace the usual safety goggle. In contrast to welding goggles one sees with these goggles adequately under normal lighting circumstances.

Medical care in the case of accident

As a matter of principle every measure must, of course, be taken to avoid accidents. It is particularly advised to perform experiments in the smallest possible scale, as well as to consider the use of less dangerous substitutes. Furthermore with regard to chronic harm it is recommended to minimize the use of volatile poisons as well as to always provide for adequate ventilation.

In the case of poisoning of any type, also with larger cuts or burns, one should as a precaution consult with a doctor in any case, or in acute and bad cases call the emergency physician. In the case of poisoning it is helpful to be able to exactly inform the doctor as to what has caused the poisoning, perhaps showing the label.

In the case of smaller cuts one has band-aids at the ready, also for burns as well as burn ointment (believe me, you will need it!).

In the case of contact with dangerous substances a quick washing off with water is usually (but not always) a good way to limit damage, in contact with acids or alkalies diluted acid or lye can be helpful. It cannot be generally recommended to clean off organic substances with solvents, as these can even reinforce the absorption by the body.

If despite all cautionary measures there is an occurence of eye damage a longer period of rinsing of the eye (for at least 5 minutes) is in most cases called for, by all means seek help immediately.