A Guide to Handle Acid (Safety) in The Laboratory

In terms of acidity, a chemical compound is considered acidic when it has a pH below 7. The lower the pH value, the higher its acidity. In laboratory testing, acids can generally be classified as either strong acids or weak acids.

Acidic liquids can be hazardous to humans because they may cause tissue damage and serious health effects upon exposure. Therefore, before handling or testing acidic compounds, you must wear appropriate personal protective equipment (PPE) that meets industrial safety standards. In Indonesia, laboratory safety procedures generally follow applicable SNI standards.

Characteristics of Acidic Compounds

Acidic compounds can be divided into two types: strong acids and weak acids. The two have different characteristics.

Strong acids have a higher degree of ionization, while weak acids have a lower degree of ionization. The degree of acid ionization can be determined using the Ka value, which indicates the strength of an acid.

a. Hydrochloric Acid

Hydrochloric acid, or HCl, is a strong acid commonly used in metal purification, electroplating, and boiler descaling. It can also be used as a catalyst and as a raw material for producing dyes.

Hydrochloric acid is produced by dissolving hydrogen chloride in water. When hydrogen chloride gas enters water, water molecules accept a hydrogen ion from HCl, separating it from the chlorine atom. The ionization process can be represented as follows:

HCl + H₂O → H₃O⁺ + Cl⁻

When preparing 5 M HCl for laboratory use, the concentration of the solution must be adjusted through dilution. For example, to prepare 5 M HCl from a 12 M stock solution, the dilution ratio is 5/12 = 0.416.

This means that approximately 0.416 parts of concentrated HCl and 0.584 parts of water are required to prepare a 5 M HCl solution. In other words, to prepare 100 mL of 5 M HCl from a 12 M stock solution, approximately 42 mL of HCl and 58 mL of water would be required.

b. Nitric Acid

Nitric acid has the chemical formula HNO₃. This highly corrosive acid is used in various industrial and laboratory applications.

In laboratories, nitric acid is commonly used to digest samples for ICP-MS analysis. Nitric acid is available in various concentrations, including:

• 70% nitric acid, commonly used for laboratory applications.

• 90% nitric acid, used in certain industrial and fertilizer-related applications.

• 98% nitric acid, used in specialized industrial applications, including as a component in rocket propellant systems.

c. Aqua Regia

Aqua regia is a highly corrosive acidic solution capable of dissolving noble metals such as gold and platinum. It is generally prepared by combining concentrated hydrochloric acid (approximately 37%) and concentrated nitric acid (approximately 70%).

Aqua regia is useful for several applications, including:

1. Cleaning laboratory glassware contaminated with metals.

2. Removing stubborn chemical contaminants.

3. Cleaning containers used for thermogravimetric analysis.

4. Cleaning NMR tubes.

How to Store Acids in the Laboratory

Acids can react dangerously if they are not stored properly. Therefore, proper storage procedures are essential.

First, store acids in appropriate chemical containers designed for laboratory use. This helps prevent contamination and chemical reactions caused by unsuitable containers. Never store acids in food or beverage containers.

Protect chemical storage containers from heat sources, direct sunlight, and open flames. Store them at an appropriate room temperature in a well-ventilated area and follow the storage requirements specified in the relevant Safety Data Sheet (SDS).

HSE or Occupational Safety When Using Acids in the Laboratory

Acids are corrosive substances that can harm people when they come into direct contact with the skin, eyes, or other parts of the body. Therefore, anyone working in an acid laboratory should understand the following health, safety, and environmental (HSE) procedures.

a. Personal Protective Equipment

The following PPE should be used when handling acids:

• Safety goggles

• Laboratory coat

• Nitrile gloves

• Protective footwear

• Safety shoes

• Tyvek sleeves

b. Engineering Controls

Appropriate engineering controls can help minimize exposure to hazardous chemicals. These may include:

• Fume hoods

• Protective shields

• Chemical workbenches

• Laminar flow benches

• Refill stations

c. Training Requirements

Personnel should receive appropriate training on laboratory cleaning and safety procedures before and after using the laboratory.

Training may include:

• Chemical hygiene

• ICP-MS Clean Lab SOP

• Milli-Q SOP

• Pipette SOP

• Plastic Acid Leaching SOP

d. Emergency Equipment

Emergency equipment should be readily available to respond to incidents involving acid exposure.

• Eyewash stations

• First-aid kits

• Safety showers

• Chemical spill kits

The Importance of Acid Handling Simulations in the Laboratory

Acid handling simulations are conducted to help laboratory personnel understand how to safely use chemicals in the laboratory, particularly corrosive substances that may pose serious hazards.

The purpose of these simulations is to teach laboratory staff how to use appropriate protective equipment, handle and mix acidic compounds safely, respond to chemical exposure or accidents, and dispose of acidic waste properly.

What to Do if You Are Exposed to Acid

Accidental exposure to acidic substances can occur during laboratory work. Therefore, it is important to take appropriate action immediately to minimize potential harm.

The following are general actions that can be taken in the event of an acid-related laboratory accident, based on occupational health and safety procedures:

1. Report every laboratory accident, such as spills or broken equipment, as well as injuries such as punctures or burns, to the laboratory staff immediately.

2. If an acidic chemical comes into contact with the eyes or skin, immediately flush the affected area with running water for at least 20 minutes and seek assistance from the laboratory supervisor or trained personnel.

3. If a chemical splashes onto the body, remove contaminated clothing or the laboratory coat and use the available safety shower.

4. If a chemical is inhaled, immediately move the affected person to an area with fresh air.

5. If an acidic chemical is swallowed, seek immediate medical attention, particularly if the person develops symptoms or feels unwell.

6. Do not induce vomiting unless specifically instructed by a medical professional or poison-control service. Follow the relevant Safety Data Sheet (SDS) and emergency medical guidance.

7. If the lips or tongue are exposed to an acidic chemical, rinse the mouth thoroughly with water and seek medical assistance.

8. Never pipette chemical solutions by mouth. Always use an appropriate pipette or pipetting device.

9. For minor thermal burns, cool the affected area with clean, cool running water and seek appropriate medical attention. Do not apply chemicals or home remedies to serious burns unless instructed by a healthcare professional.

10. For serious burns, immediately seek professional medical treatment.

11. If you are injured by broken laboratory glassware, clean and treat the wound appropriately and seek medical attention if the bleeding does not stop or if the wound is serious.

12. Never pick up broken glassware with bare hands. Use a brush, tongs, or another appropriate tool.

13. Dispose of broken laboratory glassware in a designated sharps or broken-glass container.

14. If a chemical spill occurs, use an appropriate chemical absorbent or spill kit according to the chemical's SDS and the laboratory's spill-response procedure.

15. Allow the absorbent to react or collect the chemical as instructed by the spill-response procedure, then clean the area and dispose of the contaminated material in the designated chemical-waste container.

16. In the event of an electrical accident, disconnect the power supply from a safe location before attempting to assist the victim. Contact emergency medical personnel immediately. If the person is unconscious and not breathing normally, trained personnel should begin CPR and use an automated external defibrillator (AED) if available and appropriate.

Acids are chemical substances that can cause serious harm if they are not handled properly. Following established procedures and wearing appropriate PPE are essential steps for minimizing the risk of laboratory accidents.

Be Careful When Handling Acids

Acids must be handled with extra care to prevent accidents and minimize risks to yourself and others.

If you are exposed to an acid, follow the appropriate emergency procedures immediately and seek assistance from trained laboratory personnel or medical professionals.

Stay safe!