Steps of washing glassware and drying method

1. Common washing equipment

(1) When washing the instrument, first wash your hands with soap to prevent oil stains on your hands from attaching to the instrument and increase the difficulty of washing. If the instrument is stored for a long time with dust and dust, rinse it off with clean water first, and then use a cleaning agent to scrub or wash it as required. If using decontamination powder, dip the brush in a small amount of decontamination powder, brush the inside and outside of the instrument, and then rinse with water until the decontamination powder is invisible to the naked eye, wash with tap water for 3~6 times, and then rinse with distilled water More than three times. A thin and clean glass instrument should not hold water droplets. If the water drops can still be caught, it still needs to be washed again. When rinsing with distilled water, use the method of flushing along the wall and fully shake it. The instrument after rinsing with distilled water should be neutral when checked with an indicator.

(2) For glass instruments for trace metal analysis, use 1:1~1:9HNO3 solution to soak, and then wash in the usual way.

(3) When performing fluorescence analysis, glass instruments should avoid washing with washing powder (because washing powder contains fluorescent whitening agent, it will bring errors to the analysis results).

(4) When analyzing carcinogens, appropriate washing and night soaking should be selected, and then washing according to the usual method.

2. Drying of glass instruments

Instruments that should be used frequently for experiments should be cleaned and dried for later use after each experiment. Different experiments have different requirements for drying. Generally, the beakers, conical flasks and other instruments used for quantitative analysis can be used when they are clean. However, many of the instruments used for food analysis require dryness, and some require no water marks. The requirements are anhydrous. The instrument should be dried according to different requirements.

(1) Dry

The instrument that is not urgently needed can be rinsed with distilled water and placed upside down in a dust-free place to control the moisture, and then dried naturally. The instrument can be placed on a shelf with dowels or a glass cabinet with ventilation holes.

(2) Drying

The cleaned instrument is dewatered and dried in an oven at 105~110℃ for about 1 hour. It can also be dried in an infrared lamp drying box. This method is applicable to general instruments. After drying, weighing bottles should be cooled and stored in a desiccator. When drying instruments with solid glass plugs and thick walls, the temperature should be raised slowly and the temperature should not be too high to avoid cracking. Do not put the measuring device in the oven to bake.

The hard test tube can be heated and dried with an alcohol lamp. It is necessary to bake it from the bottom with the mouth of the tube down to prevent the water droplets from flowing back and bursting the test tube. After baking until there is no water droplets, move the mouth of the test tube upward to remove the moisture.

(3) Dry by hot (cold) wind

For instruments that are eager to dry or larger instruments that are not suitable for being placed in the oven, blow-drying can be used. Usually use a small amount of ethanol, acetone (or finally ether) into the instrument that has been dewatered and shake it, then blow it with a hair dryer, and start blowing with cold air for 1 to 2 minutes. When most of the solvent is evaporated, blow in hot air to Completely dry, and then use cold air to blow away the residual steam so that it will not condense in the container again.