Note on the use of laboratory glassware, what are you ignoring

Ding, ding, bang, broke another one, and this is one of the most familiar tools in our lab, glassware. How to clean glasswares and how to dry.

There is manything you should pay attention to during the use, do you know?

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  1. The use of common glassware

(I) Pipette

1. Classification: Single mark pipette (called big belly pipette), graduated pipette (incomplete discharge type, complete discharge type, blow-out type)

  1. Single mark pipette is used to pipette a certain volume of solution accurately.The diameter of the marking part of the single-marked pipette is small and the accuracy is high; The indexing pipette has a large diameter and the accuracy is slightly worse. Therefore, when measuring an integer volume of the solution, the corresponding size is usually used Single mark pipette instead of indexing pipette.
  1. Operation:

Pipetting:  for the experiment requiring high accuracy, wipe the residual water from the tip of the pipe with a filter paper, then rinse the water inside and outside the tip of the pipe with the waiting liquid for three times to ensure that the concentration of the removed operating solution remains unchanged.Be careful not to reflux the solution to avoid dilution and contamination of the solution.

When pipetting the solution to be aspirated, insert the tip of the tube 1-2cm below the liquid surface (too deep, too much solution adheres to the outer wall of the tube; too shallow: suction empty after the liquid level drops).

Reading: The line of sight is on the same level as the lowest point of the meniscus of the solution.

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Release: the tip of the tube touches the inside of the vessel so that the vessel is tilted and the tube is upright.

Left free along the wall: Before the pipette is removed from the receiving container, wait for 3 secords to ensure that the liquid flows out completely.

(2) volumetric flask

It is mainly used to prepare a solution of accurate concentration.

Before using volumetric flasks, check whether the volume of volumetric flasks is consistent with that required; Brown volumetric flasks should be used for the preparation of light soluble substances. Whether the grinding plug or plastic plug leaks water.

1. Leakage test: add tap water to the area near the label line, plug the cork tightly, press the plug with the forefinger, stand the bottle upside down for 2 minutes, and use dry filter paper to check whether there is water seepage along the gap of the bottle mouth.If there is no water leakage, rotate the cork 180° and stand on its head for another 2 minutes to check.

2. Notes:

Glass rods must be used when transferring solutions to volumetric flasks;

Do not hold the bottle in the palm of your hand to avoid liquid expansion;

When the volume in the volumetric flask reaches about 3/4, shake the volumetric bottle for several times (do not reverse), to make the solution mix well. Then put the volumetric bottle on the table and slowly add water until it is close to the line 1cm, waiting for 1-2 minutes to leave the solution sticking to the wall of the bottleneck. Add water to the lowest point below the bending liquid level and tangent to the mark;

The hot solution should be cooled to room temperature before being injected into the volumetric flask, otherwise the volume error may be caused.

The volumeter bottle cannot hold the solution for a long time, especially the lye, which will corrode the glass and make the cork stick and unable to open;

When the volumetric bottle is used up, rinse it out with water.

If it is not used for a long time, wash and blot it dry and pad it with paper.

  1.  Washing method

Whether all kinds of glassware used in physical and chemical laboratory are clean often affects the reliability and accuracy of analysis results, so it is very important to ensure that the glassware used is clean.

There are many ways to wash glassware, which should be selected according to the requirements of the test, the nature of the dirt and the pollution degree. The measuring device that needs to measure the solution accurately, it is not easy to use the brush when cleaning, because the brush is used for a long time, it is easy to wear the inner wall of the measuring device, and the material to be measured is not accurate.

Glass ware cleanliness inspection: the inner wall should be completely moistened by water without beads.

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Cleaning method

(1) Brush with water;

(2) Wash with detergent or soap solution (this method is not recommended for chromatography or mass spectrometry experiments, surfactants are not easy to clean, which may affect the experimental results);

(3) Use chromium lotion (20g potassium dichromate is dissolved in 40g heated and stirred water, and then 360g industrial concentrated hydrochloric acid is slowly added): it has a strong ability to remove oil from organic matter, but it is highly corrosive and has certain toxicity. Pay attention to safety;

(4) Other lotions;

Alkaline potassium permanganate lotion: 4g potassium permanganate is dissolved in water, 10g potassium hydroxide is added and diluted with water to 100ml. Used to clean oil stains or other organic substances.

Oxalic acid lotion: 5-10g oxalic acid is dissolved in 100ml water, and a small amount of concentrated hydrochloric acid is added. This solution is used to wash the manganese dioxide produced after potassium permanganate washing.

Iodine-potassium iodide lotion (1g iodine and 2g potassium iodide are dissolved in water and diluted with water to 100ml): used to wash the dark brown residual dirt of silver nitrate.

Pure pickling solution: 1:1 hydrochloric acid or nitric acid. Used to remove trace ions.

Alkaline lotion: 10% sodium hydroxide aqueous solution. The effect of degreasing by heating is better.

Organic solvents (ether, ethanol, benzene, acetone): used to wash away oil stains or organic substances dissolved in the solvent.

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3. Drying

The glassware should be washed and dried for later use after each test. Different tests have different requirements for the degree of dryness of glass instruments. For example, the triangular flask used for titrating acidity can be used after washing, while the triangular flask used in fat determination requires drying. The instrument should be dried according to different requirements.

(1) Airing dry: if you don’t need it urgently, it can be dried upside down;

(2) Drying: It can be dried in an oven at 105-120℃ (the measuring device cannot be dried in an oven);

(3) Blow-drying: hot air can be used to dry in a hurry (glass appliance dryer).

Of course, if you want a safe and efficient cleaning and drying method, you can also choose a laboratory glassware washer produced by XPZ. It can not only ensure the cleaning effect, but also save time, effort, water and labor. The laboratory glassware washer produced by XPZ adopts the latest international cleaning technology. It can complete automatic cleaning, disinfection and drying with one button, bringing you a new experience of efficiency, speed and safety. The integration of cleaning and drying not only improves the level and efficiency of experiment automation, but also greatly reduces pollution and damage during work.

Post time: Aug-06-2020