glass labware

Quartz glass labware features an extremely low coefficient of thermal expansion, high temperature resistance, excellent chemical stability, superior electrical insulation, low and stable ultrasonic delay performance, the best ultraviolet spectral transmission performance, as well as visible and near-infrared spectral transmission performance. It also has mechanical properties superior to those of ordinary glass

Instruments made of glass are called glass labware. A large number of glass labware are used in laboratories because glass has high chemical stability, thermal stability, good transparency, certain mechanical strength and good insulation performance. Glass labware made by taking advantage of the excellent properties of glass is widely used in various laboratories, such as chemical laboratories, medical testing laboratories, biological laboratories, scientific research laboratories and teaching laboratories. Glass labware has good chemical stability, but it is not absolutely immune to erosion; rather, the degree to which it is eroded meets certain standards. It is a problem to be noted in trace analysis that trace ions enter the solution due to the erosion of glass and neutralize the ions to be analyzed adsorbed on the glass surface in the solution. HF acid strongly corrodes glass, so experiments involving HF acid cannot be conducted with glassware. Alkaline solutions, especially concentrated or hot ones, cause obvious corrosion to glass. If the glass labware used for storing alkali solution is a ground glass instrument, the ground glass will stick together and cannot be opened. Therefore, glass containers cannot store alkaline solutions for a long time.

Classification of Quartz glass labware:
1.Conveying and shut-off devices, such as glass joints, interfaces, valves, plugs, pipes and rods, etc.

2.Containers, such as dishes, bottles, beakers, flasks, troughs, test tubes, etc.

3.Basic operation instruments and devices. The basic operations include absorption, drying, distillation, condensation, fractionation, evaporation, extraction, purification, filtration, liquid separation, stirring, crushing, centrifugation, gas generation, chromatography, combustion, combustion analysis, etc.

4.Measuring instruments, such as flow, specific gravity, pressure, temperature, surface tension and other measuring instruments, as well as measuring vessels, droppers, pipettes, syringes, etc.

5.Physical measuring instruments, such as those for testing color, light, density, electrical parameters, phase change, radioactivity, molecular weight, viscosity, particle size, etc.

6.Chemical element and compound determination instruments, such as arsenic, carbon dioxide, elemental analysis, functional group analysis, metal element, sulfur, halogen and water determination instruments, etc.

7.Material testing instruments, such as those for measuring atmosphere, explosives, gases, metals and minerals, mineral oil, building materials, water quality, etc.

8.Food, pharmaceutical and biological analysis instruments, such as food analysis, blood analysis, microbial culture, microscope accessories, serum and vaccine tests, urine tests and other analysis instruments

The general washing steps for quartz glass labware

In the experiment, various quartz glass labware will be used. Whether these quartz glass labware are clean or not will directly affect the accuracy of the experimental results. Therefore, the quartz glass labware must be cleaned thoroughly before the experiment.

For common quartz glass labware, such as beakers, flasks, conical flasks, test tubes and measuring cylinders, a brush can be used to scrub from the outside to the inside with water. This can remove water-soluble substances, some insoluble substances and dust. If there are oil stains or other organic substances, they can be washed with scouring powder, soap powder or detergent. Scrub with a brush dipped in scouring powder or detergent, then rinse thoroughly with tap water, and finally rinse the inner wall 2 to 3 times with distilled water or deionized water. The inner walls of the cleaned quartz glass labware should be evenly wetted by water without water streaks and without water droplets adhering. In organic experiments, ground-glass quartz glass labware is often used. When cleaning, it is necessary to protect the ground-glass joint and avoid using detergents instead of cleaning agents.

For quartz glass labware that is difficult to clean with a brush or cannot be cleaned thoroughly with a brush, such as burettes, volumetric flasks, pipettes, etc., usually, detergent is poured or sucked into the container and soaked for a period of time. Then, the detergent in the container is poured into the storage bottle for later use, and then rinsed with tap water and deionized water.

The sand core glass filter must be cleaned immediately after use. For the different sediment remaining in the filter sand core, appropriate detergent should be used to first dissolve the solid sediment on the surface of the sand core. Then, the residual sediment in the sand core should be repeatedly removed by vacuum washing with detergent. After that, it should be rinsed clean with distilled water, dried at 110℃, and stored in a dust-proof cabinet.

2 Washing methods for hard-to-clean dirt

Washing of crystals and precipitates: When sodium hydroxide or potassium hydroxide absorbs carbon dioxide from the air to form carbonates, or when there are precipitates of copper hydroxide or iron hydroxide, they can be soaked in water for several days, then washed with dilute acid to form substances soluble in water, and finally rinsed with water. If there are organic matter precipitates, they can be washed with boiled organic solvents or sodium hydroxide solutions.

Washing of residual amalgam: Mercury forms metal alloys (amalgam) with some metals and adheres to the glass wall to form dark stains. The amalgam can be dissolved in a 10% nitric acid solution by volume and then washed off with water.

Washing of drying oil, grease and paint: Ammonia water or chloroform can be used for washing. Unhardened grease can be washed with organic solvents. Kerosene can be washed with hot soapy water. Viscous oil can be washed by soaking in a hot sodium hydroxide solution.

Cleaning of stains: The white stains on the glass are formed due to long-term alkali storage and corrosion by alkali. The yellowish-brown rust spots adhering to the glass can be washed away with hydrochloric acid solution. The turbid produced during the electrolysis of lead acetate can be washed with acetic acid. Brown manganese dioxide spots can be washed with ferrous sulfate, hydrochloric acid or oxalic acid solution. Ink stains on the glass can be washed off with soda or sodium hydroxide solution.

Washing of silver salt stains: For silver chloride and silver bromide stains, sodium thiosulfate solution can be used. For silver mirrors, hot dilute nitric acid solution can be used to generate silver nitrate that is easily soluble in water for cleaning.