Cleaning standard for laboratory glassware
1. cleanser and its scope of use
The most commonly used cleaners are soap, soap liquid (special products), detergent, decontamination powder, lotion, organic solvent and so on.
Soap, liquid soap, washing powder, and detergent powder, used for glassware, can be directly brushed with a brush such as beakers, flasks, bottles; lotion for the inconvenience of glassware for many, such as washing brush buret, pipette flask, distillation instrument, and other special shapes, also used for scaling washing for a long time without the cup apparatus and brush at.
The washing glassware used for washing liquid is to use the chemical reaction of the lotion itself and the dirt to remove the dirt. So we need a full opportunity to soak; the organic solvent is to belong to some type of greasy dirt, while the use of organic solvent can be washed to remove the effect of dissolving grease, or with the help of some organic solvents can play a special fast and mixed with water, rinse with water will not wash away the glassware. Such as toluene, xylene, and gasoline can wash the grease, alcohol, ether, and acetone and washed glassware can be rinsed with water.
2. kinds of washing liquid and matters of attention to use
Washing liquid is called lotion for short, and there are various kinds of lotion according to different requirements. Some of the more commonly used descriptions are as follows
1. strong acid oxidizing agent Lotion
The strong acid oxidant lotion is made up of a K2Cr2O7 and a concentrated sulphuric acid (H2SO4). K2Cr2O7 in an acidic solution, has a strong oxidation ability, and less corrosion of the glass instrument ps. So this lotion is the most widely used in the laboratory.
In the use of this lotion should be careful not to splash on the body, in order to prevent “burn” to break clothes and damage the skin. Pour lotion to wash glassware, should make the instrument Biquan pause again after weeks of immersion into the lotion bottle.
The first time with a small amount of water washing equipment just after washing wastewater, do not fall in the pool and the sewer, long will sink and sewer corrosion, should be poured into the waste water tank, centralized treatment.
2. Alkaline lotion
The alkaline lotion is used to wash the oil-contaminated dirt, which is used for a long time (more than 24 hours) or soaking. From the alkali solution for the instrument, wear latex gloves, so as not to burn the skin.
Commonly used alkali washing fluid is sodium carbonate solution (Na2CO3, namely soda ash), sodium bicarbonate (Na2HCO3, sodium bicarbonate), sodium phosphate (Na3PO4, three phosphate sodium), sodium hydrogen phosphate two sodium (Na2HPO4) solution and so on.
The steps and requirements of the washing glass instrument
1. Constant washing glassware
When washing the glassware, you should first wash the hand with soap, so that the grease on the hand is attached to the instrument, and the difficulty of washing is increased. If the instrument is stored for a long time with dust ash, wash it away with clean water first, and then wash or wash the cleaning agent according to the requirement.
If you use detergent powder, dip the brush in a small amount of decontamination powder, brush the instrument inside and outside, then rinse it with water and flush it to the naked eye to see no decontamination powder. Then wash it with tap water for 3~6 times, and then do more than three times with distilled water. A fine, clean glass instrument should be suspended from the water. If still can catch on the water, still need to wash.
When rinsed with distilled water, it is necessary to use the method of flushing the wall along the wall and fully concussion, and the instrument after rinsing through the distilled water should be examined by the indicator as neutral.
2. the glass instrument for trace metal analysis is soaked in 1:1~1:9HNO3 solution and then washed by constant method.
3. for fluorimetric analysis, the glass instrument should avoid washing powder (because the detergent contains fluorescent brighteners, which will bring errors to the analysis results).
The glassware that should be used frequently in the experiment should be cleaned and dried up after each experiment. For different experiments, there are different requirements for drying. For general quantitative analysis, beakers, tapered bottles, and other instruments can be used fine, but many instruments for food analysis are dry, some require no watermarks, and others require no water. The drying apparatus should be carried out according to the different requirements.
The main drying methods of the instrument are five main types:
1. Drying:
Wash the instrument to control the water, put it in the oven to dry, oven temperature of 105~110 C drying for about 1 hour. Can also be placed in the drying infrared drying box. This method is suitable for general instruments. The weighing bottle and so on should be cooled and preserved in the dryer after drying. The solid glass plug and thick wall instrument should be heated and the temperature can not be overheated so as not to break. The measure can not be put in an oven drying.
The cleaning apparatus can be dried in an electrothermal drying box (oven), but the water should be cleaned as far as possible before it is put in. When the instrument is placed, attention should be paid to making the mouth of the instrument down (the instrument that is not stable after the inversion should be flat). The lowest in the electric heating drying box and put an enamel plate, from the instrument to receive the drops of water droplets, not to the electric wire, so as not to damage the electric wire.
2. dry:
Pan can be placed in a beaker or asbestos net with a small fire to dry. The tube can be directly used in small fire dry operation, The tube is slightly inclined pipe down, is not time to move back and forth in the water.
3. Dry:
Wash the glassware can be inverted in the experimental instruments in the clean cabinet frame (glassware inverted posterior instability of the measuring cylinder, it should be flat), and let it dry naturally.
4. Blow dry:
Blow the glassware dry with compressed air or a blower.
5. Drying in organic solvents:
Some measuring instruments with scale can not be dried by heating. Otherwise, the precision of the instrument will be affected. We can use some volatile organic solvent (such as alcohol or alcohol and acetone mixture) to wash the instrument (amount), the instrument tilt rotation instrument, the wall of water mixed with organic solvent, and then pour out, a small amount of residual liquid mixture in the instrument, soon the volatile drying apparatus.
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