ABC of Safety in the Biological Sciences
Mineral acids are said to be responsible for more accidents in the laboratory than any other liquids.18 Acids and their vapours are corrosive and can produce severe damage to eyes and body tissues. All concentrated acids are dangerous but hydrofluoric acid, in particular, is extremely corrosive and toxic as a liquid or vapour.
Of the more commonly used acids sulphuric acid needs to be handled with extreme care as it reacts violently with water. When diluting an acid always add acid to water and never pour water into acid. When handling acids always wear a long sleeved laboratory coat or gown, rubber gloves pulled over the sleeve of the coat or gown and full face protection. Use a fume hood and ensure that it is working correctly.
Great care needs to be taken if a stopper is found to be firmly fixed in the neck of a bottle. This often occurs with concentrated acids, particularly when glass stoppers are used in glass bottles.
The safe procedure to follow when removing
a problem stopper is as follows:
1. Stand the bottle in a large sink.
2. Cover the stopper and the neck of the bottle with a cloth.
3. Gently tap the stopper. If the stopper in the bottle is glass use another glass stopper to tap it with. The two glass stoppers set up a resonance which is often successful in loosening the jammed stopper.
4. If these measures fail it will be necessary to break the neck of the bottle after scoring around it with a glass file. A point of hot glass applied to the score mark will cause the neck to break cleanly.
A releasing solution19 can be applied to the stopper although this normally takes several hours to be effective.
Absolute ethanol 2 parts
Glycerin 1 part
Sodium chloride 1 part
Bottles containing acid should be transported in carriers designed for that purpose. These have a cap which locks in place over the bottle holding it firmly and securely. Carriers are manufactured from acid resistant low density polyethylene and are designed to contain a spill should this occur.
When pouring acids never place the stopper from the bottle on a bench top but rather hold the stopper in the crook of your hand and replace once pouring is complete.
Pour acids slowly. Do not discharge in spurts. Wear rubber gloves to avoid drips which run down the side of the bottle. After pouring flush the outside of the container with water before storing. Immediately flush any splashes that occur with water and neutralise with a solution of 10% sodium bicarbonate.
Acids rapidly destroy paper labels on bottles. Although etched labels are recommended paper labels coated with a thin layer of paraffin wax or Teflon are suitable.
Concentrated acids and alkalis are incompatible and contact between them can be explosive. These agents should not be stored adjacent to each other. Some acids when mixed together are also incompatible (see Incompatible Chemicals).
Acids are best stored in cabinets designed to contain spills should a bottle break (see acid storage cabinet). Suitable cabinets have glass reinforced cement in the base.
A face mask, eye protection and rubber gloves along with appropriate body protection are essential before attempting to clean up a moderate spillage. Breathing apparatus is required with some types of acid spills, for example hydrochloric acid. Spread sodium bicarbonate liberally over the splash area and when neutralised mop up cautiously with plenty of water. Commercial products for use in acid spills are also available.
If spills occur on the body immediately drench the affected area with water. An emergency shower should be used for all but minor spills. After drenching remove clothing and thoroughly wash the affected areas.
A magnesia/glycerol paste can be applied to any skin affected areas, however blisters and burns will require medical attention.20
If acids are ingested give water to drink followed by milk of magnesia. If only the mouth is involved flush thoroughly with water followed by milk of magnesia.20
If acid vapours are inhaled rest and warmth are required, however if exposure is severe it is necessary to seek medical advice.20