Glass instruments commonly used in laboratories such as beakers, test tubes, burettes, pipettes, volumetric flasks, etc. The instrument will be stained with oil, scale, rust, etc. during use. If it is not cleaned in time, it will cause errors in results and even have extremely adverse effects on the life and performance of the instrument. Therefore, the glass instruments used in chemical experiments must be cleaned.
1、Some glassware washing methods
First, we divide the instruments into two categories:
One type is a brush that can be washed: a test tube, a beaker, a reagent bottle, a conical flask, a measuring cylinder, and the like;
(1) Wash with water
Select a suitable brush according to the characteristics of the glass instrument to be washed, such as a tube brush, a beaker brush, a flat brush, a burette brush, and the like. Washing with a brush and rubbing water can dissolve the soluble substances, and can also remove the dust and insoluble matter attached to the glass instrument, but often can not wash off the oil and organic matter.
(2) Wash with detergent
You can use a brush to pick up the detergent (such as washing powder) and carefully brush the inner and outer walls (especially the inner wall) of the glass instrument. In order to improve the washing efficiency, the detergent can be formulated into a 1% to 5% aqueous solution, and the glass instrument to be washed is heated and immersed. After a while, brush again with a brush.
The other type is a small-mouth glass measuring device that cannot be washed with a brush; a pipette, a pipette, a volumetric flask, etc.;
(1) Small-mouth glass measuring devices such as pipettes, pipettes, and volumetric flasks should be soaked in cold water immediately after use. Do not let the contaminated materials dry up.
After the work is completed, rinse with running water to remove the attached reagents, proteins, and other substances. After drying, soak in chromic acid washing solution for 4-6 hours or overnight, then rinse thoroughly with tap water, then rinse with distilled water or deionized water for 2-3 times, and place it on the measuring rack to dry naturally.
In an emergency, it can be oven-dried at 80 ° C or below, or add a small amount of absolute ethanol or methanol, ether, or other solvents to the measuring device, slowly rotate it to cover the inner wall of the container, then pour it out, then blow-dry or Drying with negative pressure can achieve the purpose of rapid drying. (This method is cumbersome to clean and requires the professional operation to clean, which is dangerous)
(2) Cleaning with a laboratory-specific ultrasonic cleaner.
The laboratory-specific ultrasonic cleaner adopts the principle of a high-efficiency ultrasonic cavitation effect. The water molecules oscillate in the glass instrument and shake off the dirt on the surface of the instrument. Under the action of the ultrasonic cleaning machine, it has a quick cleaning corner and gap, which replaces the traditional manual scrubbing. Not in place.
Finally, just use the instrument to dry and use it again. (This cleaning method can effectively avoid contact with chemical liquids, which is a safer cleaning method)
Tip: Do not wipe the glassware with your hands, cloth, or paper to avoid re-contamination.
2、Choose the right detergent
Under normal circumstances, the commercially available synthetic detergent can be used to clean the glass instrument. When the inner wall of the instrument is provided with insoluble matter and cannot be cleaned with synthetic detergent, the appropriate detergent should be selected according to the nature of the attached material.
If the attached material is an alkaline substance, dilute hydrochloric acid or dilute sulfuric acid may be used to dissolve the attached matter and dissolve;
If the attached substance is an acidic substance, a sodium hydroxide solution may be used to cause the attached matter to react and dissolve; if the attached matter is If it is not soluble in acid or alkali, but it is soluble in some organic solvents, use this kind of organic solvent as detergent to dissolve the attached matter.
If the attached matter is If it is not soluble in acid or alkali, but it is soluble in some organic solvents, use this kind of organic solvent as detergent to dissolve the attached matter.
Several examples are given: white deposits on the inner wall of the container for long-term lime water, using dilute hydrochloric acid as a detergent; iodine sublimation test, purple-black iodine attached to the bottom of the container containing iodine, immersed in potassium iodide solution or alcohol;
There are dark brown deposits on the container wall of Jiusheng potassium permanganate solution. Concentrated hydrochloric acid can be used as a detergent. The inner wall of the instrument is equipped with a silver mirror and nitric acid is used as a detergent. The inner wall of the glassware is stained with grease and hot soda solution. Carry out cleaning.
In the laboratory, there is also a specially prepared washing liquid that can be reused many times.
For inconvenient cleaning with a brush to clean the dish, the following cleaning solution can be prepared for chemical cleaning. For the analysis of certain trace metals, the vessel needs to be at a certain concentration of hydrochloric acid, nitric acid solution or inclusion. Soak the solution in the mixture for a considerable period of time, remove the metal ions adsorbed on the surface, and then rinse with distilled water.
Polyethylene, polyvinyl chloride, and PTFE vessels can also be cleaned in the same way, but attention should be paid to the fact that plastic products are easily deformed by heat, easily scratched by hard objects, and sensitive to many organic solvents.
1. Chromic acid washing solution: Weigh 92g of dihydrate sodium dichromate dissolved in 460mL of water, then inject 800mL of sulfuric acid. The other formula is to inject 1L of sulfuric acid into 35mL of saturated sodium dichromate solution.
When the lotion is used until it turns green, it loses its washing ability. When using the chromic acid washing solution, the washed dish should have less water, preferably dry, to avoid dilution of the washing liquid and reduce efficiency. Dichromate can also be used. Potassium replaces sodium dichromate, but the former has a lower solubility. The container washed with chromic acid wash solution should be rinsed thoroughly with clean water to remove possible chromium ions.
2. Alkaline potassium permanganate washing solution. Weigh 4.0g potassium permanganate, put it in a 250mL beaker, weigh 10.0g sodium hydroxide, put it in the same beaker, weigh 100mL distilled water, add it in several times. Stir constantly, so that potassium permanganate and sodium hydroxide are fully dissolved.
Carefully transfer the dissolved portion into a 200 mL brown reagent bottle, and repeat this operation until all the potassium permanganate is dissolved. Rinse the beaker repeatedly with distilled water and rinse. Pour the solution into the brown reagent bottle until there is no purple color on the inner wall of the beaker.
Finally, dilute to 100mL with the remaining distilled water, cover the stopper, shake well, stick the label, and spare. It is suitable for washing the oily glassware, but The remaining manganese dioxide needs to be washed with hydrochloric acid or hydrochloric acid plus hydrogen peroxide.
3. Sodium hydroxide (potassium) ethanol solution: Add about 1L of 95% ethanol to 120mL aqueous solution containing 120g sodium hydroxide (potassium), which becomes a detergent with strong detergency and long-term exposure of glass grinding It is easily damaged in this lotion.
4. Sulfuric acid and fuming nitric acid mixture: suitable for special oily, dirty glassware.
5. Trisodium phosphate solution: Dissolve 57 g of trisodium phosphate and 28 g of sodium oleate in 470 mL of water. To remove the carbon residue on the glassware, the vessel can be soaked in the solution for a few minutes, and then the residue is removed with a brush. ~150g / L sodium hydroxide (potassium) solution also has the same effect.
6. 10g / L EDTA 20g / L sodium hydroxide solution: Soak the washed glassware with this solution, can remove some trace metal ions adsorbed on the surface of the container.
7. Hydrochloric acid solution: a mixture of hydrochloric acid and two parts of ethanol to wash the utensils stained with organic reagents.
8. Acidic oxalic acid lotion. Weigh 10g of oxalic acid or 1g of hydroxylamine hydrochloride dissolved in 20% of 100mL hydrochloric acid solution. For inorganic pollutants (such as potassium permanganate, ferric iron) contaminated with oxides and soluble in water, etc. This dish can be used for utensils.
3 、Master the operation method of the washing glass instrument
For simple instruments with easy-to-remove substances, such as test tubes, beakers, etc., use a test tube brush to pick up synthetic detergents. When rotating or moving the tube brush up and down, use appropriate force to avoid damage to the instrument and scratching the skin.
Then rinse with tap water. When the instrument is inverted, the wall of the device forms a uniform water film, with no drops of water, and it will be washed when it does not flow down.
For glass equipment with difficult to remove attachments, after using the appropriate detergent to dissolve the attachments, remove the washing residue, brush with a test tube, and finally rinse with tap water.
Some glassware instruments with relatively fine structure and complexity cannot be brushed with a brush, such as a volumetric flask, a pipette, etc., and can be dipped with a washing liquid.
For limited space, the acid burette is taken as an example. The washing operation is as follows: When washing starts, first check whether the rubber disk on the piston is fastened to prevent slipping and damage during washing; pay attention to whether there is leakage or blockage, and if so, adjust it.
Close the piston, inject 2-3 ml of washing liquid into the burette, slowly tilt the burette to the level, and slowly rotate the burette, so that the inner wall is completely immersed in the washing liquid. Raise the burette, then unscrew the piston and release the washing liquid. The person in the piston can also be washed.
Finally, it is flushed with tap water and also released from the tip of the piston. It is not necessary to save time to pour liquid from the upper nozzle.
Washing standards are as described above.
4、Timely washing of glass instruments
Timely washing of the glass instrument is conducive to the selection of a suitable detergent because it is easy to judge the nature of the residue at that time. In some chemical experiments, the residual liquid after the reaction is poured out in time, and there is no hard-to-remove deposit on the inner wall of the instrument, but it is left for a while.
After the volatile solvent escapes, the residue adheres to the inner wall of the instrument, making the washing difficult. There are also some substances that can react with the instrument itself, and if not washed in time, the instrument will be damaged or even scrapped.
5, other matters needing attention
Do not blindly mix various reagents for detergent use, and do not use any reagents to wash glass instruments. This not only wastes drugs but also is prone to danger.
As a Chinese laboratory glassware manufacturer, WUBOLAB caters to your glassware procurement requirements.
