Biological and chemical laboratories handle different chemicals, reagents, and samples for various experiments. Using equipment made up of plastics is not practical in many instances because plastic can melt or have adverse reactions with the chemical. The use of glassware is applicable for storing chemicals or performing different experiments.
The glass used in constructing the glassware is either borosilicate or soda-lime glass. The soda-lime is less tolerant to chemicals and has lesser hydrolytic resistance. So, soda-lime glassware is used as a storage container. Borosilicate glass can tolerate chemicals like acids, halogens, and organic solvents. Only acids like hydrofluoric heated phosphoric acids or strong alkaline solutions can cause corrosion in the glass. That is why borosilicate glass is preferred over soda-lime glass.
Laboratories that use glassware are microbiology, clinical or diagnostic, chemistry, and different biological laboratories. Glassware commonly used in these laboratories are Petri dishes, beakers, conical (Erlenmeyer) flasks, funnel, cylinders, etc.
List of Glassware Used in Laboratory
Glassware is used to store chemicals (liquid or solid), prepare reagents, mix chemicals, and perform different experiments.
Petri dish is glassware used in different biological laboratories, especially microbiology laboratories, to culture bacteria, fungi, or cell lines. The Petri dish is a shallow, circular, and transparent glassware invented by the scientist Richard Julius Petri. It is usually covered with a transparent lid slightly larger in diameter.
The types of Petri dish differs extensively based on their size. The diameter ranges from 30 mm to 200 mm. The standard diameter used is 90 mm.
Beakers are cylindrical containers used to hold chemicals and liquids in laboratories. It is called a beaker due to a beak-like spout at the top to prevent spilling while pouring fluids.
These are available in various sizes. Volumetric markings are present in the beaker, but these are not precise. The beakers are of two types; low form or Griffin beakers and tall or Berzelius beakers. The tall-form beakers have handles for easy pouring, but handles may be absent in low-form ones.
Test tubes or sample tubes are cylindrical glassware with finger-length used to collect, heat, or gently mix samples/chemicals in laboratories. Test tubes can withstand high temperatures due to the borosilicate or quartz glass used for their construction. These are round at the bottom, and the top is open.
These are used in chemistry and biological laboratories for conducting different experiments. In diagnostic laboratories, these help in the collection of samples and for storing chemicals. The use of color-coded lids is popular in clinical laboratories.
A conical or Erlenmeyer flask, named after the inventor German chemist Emil Richard August Carl Erlenmeyer, is glassware shaped like a cone with a flat bottom and cylindrical neck. These are used as reaction flasks, especially during titration or making culture media manually. Like beakers, these also have markings that are not accurate.
Erlenmeyer flask is available in various sizes based on volume/size and mouth. The size of the conical flask available is 25 ml, 50 ml, 100 ml, 125 ml, 150 ml, 250 ml, 300 ml, 500 ml, 100 ml, 2000 ml, 3000 ml, 4000 ml, 5000 ml, and 6000 ml. Two types of flasks based on the mouth are; wide mouth and narrow mouth.
Graduated pipettes are glassware with graduation marks for precise measurements. It is used to transfer liquids, draw up samples or chemicals, and do many more experiments. The pipettes are cylindrical tube-like structures. Some graduated pipettes have a bulb in between and a marking on the top part that indicates its volume capacity. Others have markings at an interval of 0.1 to 1 ml, depending on the pipette size.
A volumetric burette is a laboratory glassware that is graduated and is used in titration. It is a long cylindrical tube-shaped instrument that is pointed at the bottom. There is a stop cock in the bottom of the burette to control the flow of the liquid. It is of two types; gas and liquid volumetric burette. The liquid falls due to gravity when the valve is opened. In the case of a gas volumetric burette, the stop cock is at the top. The tube is filled with water or mercury and connected to a reservoir with fluid at the base. The gas is collected by displacement of the liquid.
Round bottom flask
As the name suggests, it is a flask with a round or circular base or bottom. These flasks are used for distillation and gas preparation in the laboratory. While working with a round bottom flask, a cork ring is required to keep it upright. Likewise, while performing the experiment stand is used to hold it.
It is made up of borosilicate glass and is available in various sizes. The neck of the round bottom flask can be narrow, wide, or have a ground glass joint. Likewise, the number of necks can also vary from single, twin, and triple-necked.
A volumetric flask is laboratory glassware used for precise measurements at a specific temperature. The base of the volumetric flask is flat, and the bottom is shaped like a pear. The neck is long and cylindrical, with a calibrated marking for the volume it can measure.
It is used for preparing molar solutions in the laboratory for various analyses. The apparatus is available in different volumes from 1 ml to 2000 ml. These are not graduated, so they lack graduation marks.
A slide or microscope slide is a thin piece of glass 3 by 1 inch in size. It is used to hold samples and specimens for viewing under a microscope. The slide can be either plain or frosted at the end. The frosted glass slide is used in the preparation of blood smears.
The glass slide is used in staining biological specimens before observing them under the microscope. It is widely used in diagnostic, microbiological, botanical, and zoology laboratories.
Stirring or glass rods are laboratory glassware used for mixing liquids. It is made up of solid borosilicate glass. Another use of a stirring rod is in spreading bacterial culture in solid growth media and conducting various tests. It is made up of a single piece of thin glass. It is usually 10-40 cm long and 0.5 cm in diameter.
Glass tubes are hollow cylindrical glassware used for tubing purposes. It is used to make a delivery tube and transfer reagents.
Cutting of the glass tube in the laboratory is done using triangular files. Heating over the Bunsen burner helps bend the glass tube into the desired shape. Hence these are used in the laboratory preparation of gases.
A graduated or measuring cylinder is a glassware used in the laboratory for measuring the volume of liquids. It is available in different sizes. It is a long cylinder. It has horizontal graduation marks for precisely measuring the volume. The upper part of the cylinder is open and has a spout or beak-like shape for easy pouring. Some have ground joint glass and can be closed by using a stopcock.
Accuracy classes available for graduated cylinders are of two types; class A and B. Class is two times more accurate than class B. The graduation mark can be single- or double-scaled. Calibration is done either to deliver (TD) or to contain (TC).
Funnels are laboratory glassware that is used for filtering and transferring purposes. It has a narrow neck that allows only specific volumes of chemicals to flow through. Using filter paper helps in performing filtration in the laboratory. It is also used for transferring fine-graded chemicals and liquids from one container to another. Using these kinds of funnel help avoid spillage in the laboratory. Other experiments where funnels are used are separating mixed compounds by evaporation and condensation.
This bottle is constructed using borosilicate glass which is topped by a stopper. It is also called graduated or media bottles. The primary purpose of this bottle is to store reagents and solutions in the laboratory.
A glass retort is an airtight vessel used for distillation purposes. It has a spherical or circular container with a narrow and downward-facing neck. The open end has a stopper made up of glass to make it airtight. The slim neck acts as a condenser during distillation.
Specific gravity bottle
The specific gravity, density, or relative-density bottle is used in determining the densities of liquid. The density helps in calculating the specific gravity of the liquid. These are made up of glass and have caps to prevent evaporation. Some bottles have graduated necks that help in easy measurements. The size and shapes of this bottle vary widely.
McCartney bottles are glassware with aluminum or plastic caps used as culture media in microbiological laboratories. These are wide mouth thick glass containers. The lids are sealed to create an airtight environment inside the bottles. These bottles are autoclavable.
A distillation or distilling flask is a glassware used in the laboratory to separate two different liquids of different boiling points. The flask has round bottom for even heat dispersion, a long neck, and a sidearm for condensation. Flask with two or more necks is also available for complex distillation.
Flat bottom flask
Flat-bottom flasks are made of borosilicate glass and are used for boiling. The shape of the vessels resembles the round bottom flask, except its base is flat instead of rounded. It has a similar neck to that of the round bottom flask.
Ebulliometer are glassware designed to measure the temperature of different liquids by measuring the vapor-liquid equilibrium. There are two types of ebulliometer based on the principle used to measure the equilibrium; isothermal or isobaric ebulliometer. Swietoslawski ebulliometer, based on the isobaric method, has four major parts; boiler, thermowell, Cotterell pumps, and condenser. Besides the above parts, a stirring pump is present in an isothermal ebulliometer.
Abderhalden’s drying pistols
Abderhalden’s drying pistols are laboratory glassware used to dry out or remove water molecules and impurities from the samples. Earl Abderhaldem provided a brief description of this pistol. The apparatus has two barrels; the inner is connected to the vacuum source with the help of a trap, and the outer barrel is connected to the condenser and round bottom flask. This apparatus helps in the desiccation of heat-sensitive compounds when desiccators are ineffective.
Desiccators are laboratory glassware used to dry wet substances or store substances that are sensitive to moisture. The desiccators are more effective when used with a vacuum. It has different parts like lid, base, and stopcocks. The caps are sealed tight. There are different types of desiccators; vacuum, automatic, gas, and purge desiccators.
Watch, or clock glass, is a concave glass used in evaporating liquid in a chemistry laboratory by placing it on top of a beaker with boiling water. It is also used to hold solid substances and as a cover for beakers.
Cleaning of Laboratory Glassware
Glass equipment is preferred over plastic because it is reusable, durable, easy to clean, and appropriate for almost all experiments. So, cleaning laboratory glassware properly after every use is essential to avoid cross-contamination. Solids can deposit in the base of the glassware, small ions can firmly adhere to the surface of the glassware, or organic materials can bond with the glass. So, prepper solvent, surfactant, and cleaning methods are vital for reusing glassware.
General cleaning method
- Cleaning general laboratory apparatus
- Remove any remnant liquid or solid deposits in the glass and wipe any greasy substances using acetone and clean clothes.
- Wash the glassware gently in soapy water.
- Use a brush or cleaning pad to remove any residues.
- Rinse with water, followed by rinsing with deionized water. The deionized water forms a sheet in the glass. If this sheet is not obtained, follow an aggressive cleaning technique.
- In the case of burettes, pipettes, tubes, and volumetric flasks, rinse with the solution to be added thoroughly before use.
- Dry using acetone and dispose of it in the organic waste container.
- Cleaning glassware with microbiological media
Mild cleaning method
Solid brittle deposits are removed by scraping using brushes, whereas soft deposits like grease will not entirely be removed by scrubbing. There are also areas in glass where brushes or clothes cannot reach.
Soak in gentle solvents like deionized water, dilute surfactants, concentrated weak acids, dilute phosphate, carbonates, or ammonia, and protein or saccharide solutions hydrolyzing enzymes for long periods can help.
The soaking action is benefitted from a simple mechanical process like stirring, shaking, and sonication.
Another method of cleaning is using organic solvents. Moistening a cloth with organic solvent for an easily accessible surface or agitating solvent inside the container is two methods commonly used. However, organic solvents are flammable and toxic, so proper ventilation, wearing gloves, and personal protective equipment is advised.
Aggressive cleaning method
Even after using organic solvents and mild cleaning methods, residues may not be removed. So removing adhered material is done either by oxidizing the residues or removing the top silicon layer.
Oxidizing contaminants from glassware is done by using various solutions like aqua regia, piranha solutions, fully concentrated sulfuric acids, pyrosulfuric acid, and chromic acid solution. Aqua regia is an aqueous nitric and hydrochloric acid solution in a 1:3 ratio.
The chromic acid solution is prepared by adding solid chromium (IV) oxide, potassium dichromate, or potassium chromate to the sulfuric acid. Piranha solution is a mixture of hydrogen peroxide the fully concentrated sulfuric acid. Fuming sulfuric acid has sulfur trioxide (10-20%) that makes pyrosulphuric acid.
The glass used to make the glassware has polysilicate solids and oxides. It also has sodium or potassium. The surface of the glass binds with hydroxyl and oxide, which is attached to silicon. Sometimes these surface functional groups bind to the contaminant, which is hard to remove with simple solvents. So, the silica layer is removed. The removal is done by soaking the glassware for a certain period in dilute hydrofluoric acid or base like potassium and sodium hydroxide in either ethanol or isopropanol.
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