Correct Cleaning Method of Laboratory Utensils

Clean laboratory glassware is a prerequisite for obtaining correct experimental results; therefore, cleaning laboratory glassware is an important preparatory step before experiments. Below, we share how to properly clean laboratory glassware, hoping it will be helpful.

I. Routine Washing Method (General Containers)

1. Wash hands with soap before cleaning laboratory glassware.

2. First, rinse away dust with tap water, then use a brush dipped in detergent solution to carefully scrub the inner and outer surfaces. Rinse with water while scrubbing until no detergent residue remains.

3. Rinse 3-5 times with tap water, then rinse 3 times with deionized water.

4. For laboratory glassware that is difficult to scrub, soak it in detergent solution first, then rinse with water. Clean glassware should be free of water droplets inside and out, and any residual water on the walls should be neutral according to an indicator.

5. Scouring powder should not be used to clean graduated glassware or the inner walls of glass instruments to prevent scratching the glass.

II. Washing of Vessels Made of Different Materials

1. Silver, nickel, and iron vessels can be melted with NaOH, or briefly soaked in a 1:3 dilute HCl solution followed by rinsing with water.

2. Agate vessels should not be soaked. Wash with detergent first, then rinse with water and air dry upside down. Do not tumble dry.

3. Plastic, porcelain, and glass vessels can be soaked in dilute HCl and then rinsed.

III. Washing of Special Vessels

1. Sand core funnels should be cleaned with hot HCl or chromic acid solution while filtering, followed by sequential rinsing with tap water and distilled water. After use, sand core funnels should be dissolved with appropriate detergents for different precipitates before rinsing. After cleaning, they can be dried in a drying oven at 120℃, but water droplets must be removed before drying to prevent the filter from cracking. Special care should be taken to prevent dust from entering the cleaned sand core funnel.

2. After standard cleaning and assembly, complete sets of glassware should be steam-washed for a period of time before use. Glass containers used for trace and micro-analysis should be soaked in HNO3 at a ratio of 1:1 to 1:9 and then washed using conventional methods.

3. Heavily soiled containers generally require initial pretreatment with HNO3 soaking; once the washing solution is determined, increasing the soaking time and heating/boiling can enhance the washing effect; use an ultrasonic cleaner.

IV. Cleaning of Special Stains

1. Rust and scale should be cleaned with dilute HCl or dilute HNO3;

2. Containers containing potassium permanganate should be cleaned with hydrochloric acid solution of stannous chloride or sulfuric acid solution containing oxalic acid;

3. Insoluble silver salts should be washed with sodium thiosulfate or ammonia;

4. Aluminum salts, quinoline phosphomolybdate, and white MoO3 should be cleaned with dilute NaOH solution;

5. Potassium tetraphenylborate should be cleaned with acetone;

6. Containers with fatty stains should be wiped or soaked with organic solvents such as gasoline, toluene, acetone, alcohol, or dichloromethane.

V. Washing of Containers Containing Toxic and Hazardous Substances

1. When washing containers used for analyzing carcinogenic substances or highly toxic substances such as cyanide, to prevent harm to the human body, they should be soaked in a detergent solution that destroys these harmful substances before washing.

2. Containers used for analyzing cyanide can be disinfected by soaking in a 3% NaOH solution, followed by regular cleaning.

3. Glass containers used for analyzing benzo[a]pyrene should be soaked in a 20% HNO3 solution for 24 hours, then rinsed with tap water to remove residual acid, and then cleaned using regular methods.

VI. Washing and Treatment of Sampling Containers for Different Projects

1. Containers for water samples used to detect heavy metals should be soaked in 1:4 HNO3 for at least 24 hours, then cleaned using standard methods.

2. Containers for water samples used to detect trace organic matter should be washed with chromic acid solution, dried, and then shaken with purified hexane to remove organic contaminants from the container walls. Alternatively, they can be soaked in potassium permanganate solution and then rinsed thoroughly with tap water and purified water.

3. Containers for water samples used to detect anionic surfactants should be scrubbed with detergent, shaken with methanol for 1 minute, and then rinsed thoroughly with tap water and purified water in sequence. Containers for water samples used to detect microorganisms should be washed using standard methods, and glassware should be sterilized by placing them in an autoclave and heating to 121°C for 15 minutes. Plastic containers should be immersed in 0.5% peracetic acid solution for 10 minutes or sterilized at low temperature in ethylene oxide gas.

4. Polypropylene heat-resistant plastic containers can be autoclaved at 121℃ for 15 minutes.

5. Containers for mercury testing should be thoroughly rinsed with 1:3 HNO3 and soaked for several hours, then rinsed thoroughly with tap water and ultrapure water. Containers for trace sulfate samples should not be washed with sulfuric acid-containing cleaning solutions.

6. Containers for chromium testing should not be washed with hydrochloric acid or potassium dichromate cleaning solutions.

7. Containers for phosphate testing should not be washed with phosphorus-containing cleaning solutions.

8. Containers for ammonia and Kjeldahl nitrogen testing should be rinsed with ammonia-free water at the end.

VII. Drying of Glassware

Glassware can be dried using methods such as air drying, oven drying, blowing dry, and baking dry.

Precautions:

1. Never use the drying method to dry any measuring instruments.

2. When drying, proceed from bottom to top to prevent water dripping back from the mouth of the bottle and causing the glass to crack.

3. The drying method is only suitable for hard glassware. Some glassware, such as cuvettes, colorimetric tubes, weighing bottles, reagent bottles, etc., must never be dried using the drying method.

4. Place clean glassware upside down in a glassware cabinet, with clean filter paper lining the cabinet shelves. Close the cabinet door tightly to prevent dust accumulation.

The above is a summary of the correct cleaning methods for laboratory glassware compiled by the marketing department of Sichuan Youpu Ultrapure Technology. For more details, please call our 24-hour nationwide customer service hotline 400-884-6567.