General Laboratory Techniques

Centrifugation is a lab method used to separate parts of a mixture. A centrifuge spins samples at very high speed. This creates centrifugal force, which moves denser particles away from the axis of rotation and lighter particles toward it.

As the sample spins, the denser material can settle at the bottom of the tube. This solid layer is called a pellet. The liquid left above it is the supernatant, and both parts can be processed or analyzed further.

The video also explains how to use a...

A microplate reader measures signals from samples in a multiwell plate. It is a multimodal instrument, so it can record absorbance, fluorescence, and luminescence. This makes it useful for running several experiments at the same time.

Multiwell plates are a key part of the setup. They let many tests be performed at once in separate wells. The assay, or test procedure, can include standards, samples, a blank, and positive and negative controls. These controls help show that the assay is working...

Preparing solutions with accurate measurements is an important lab skill in biological research. A solution is a homogeneous mixture formed when a solute dissolves in a solvent. Solutions are usually identified by their components and by their concentration.

Concentrated solutions can be made less concentrated by dilution. The video also shows serial dilution, which is a step-by-step way to dilute a solution. These methods help students prepare solutions with the right strength for an...

Preparing aqueous lab solutions is a basic skill used in many biology and chemistry experiments. A solution is a uniform mixture made when a solute dissolves in a solvent, which is the main liquid. The amount of solute in a solution is called its concentration.

The procedure begins with calculating and measuring the correct amount of solute for the needed volume. The solute is then dissolved in purified water to make a water-based, or aqueous, solution. For biological use, the pH may also be...

The micropipettor is a lab tool for moving very small amounts of liquid. It helps users transfer microvolumes of liquid solutions with accuracy. In school and research labs, it is used when careful sample handling matters.

Micropipettors come in several sizes. They can measure volumes from 0.5 to 5000 µl. Each instrument uses one of three disposable tip sizes, and the tip must match the micropipettor for proper use.

A micropipettor works by displacing air from the pipette shaft. This creates...

Serological pipettes are lab tools for moving milliliter volumes of liquid. They are commonly used for amounts from less than 1 mL up to 50 mL. In many labs, they help students handle liquids carefully and accurately.

These pipettes may be sterile plastic and disposable, or glass that can be sterilized and reused. Both kinds work with a pipet-aid. The pipet-aid helps with aspiration, which means drawing liquid up, and dispensation, which means releasing it.

The same pipet-aid can be used with...

The Bunsen burner is a common lab tool used to make a hot, sootless, non-luminous flame. It was named after and co-designed by Robert Bunsen in 1854. In school science labs, it gives students a steady source of heat for careful work.

A Bunsen burner works by controlling how gas and oxygen mix in its central barrel before combustion, or burning. That mixing helps ignite the flame. By adjusting the burner, you can change both the size of the flame and its temperature.

The flame can also create...

Lab hoods are protective enclosures used for many science experiments. They help shield samples from the environment and can also protect the researcher from hazardous or infectious material. The term hood can include a laminar flow bench, a fume hood, a tissue culture hood, or a biosafety cabinet.

These hoods work on the principle of laminar flow, which means air moves in a smooth, controlled stream. They also share a similar setup. A hood usually has a window sash and protective glass...

Analytical balances measure sample mass with very high precision in the laboratory. These instruments can read down to ten thousandths or even hundred thousandths of a gram. A triple beam balance is another common scale. It uses counterweights on three rider beams to balance the sample in the pan.

Modern analytical balances work with electronic sensors instead of rider beams. They are built to measure a substance accurately. Because they are so sensitive, many include a draft shield. The...

The spectrophotometer is a common tool for measuring how much light a chemical sample absorbs. Spectrophotometry is the quantitative measurement of light absorption by passing a beam of light through a sample. It is used often in scientific research.

This page reviews the key ideas behind the instrument, including transmittance, absorbance, and the Beer-Lambert Law. Transmittance is the light that passes through a sample. Absorbance is the light the sample takes in. These ideas help explain...

Histology studies cells and tissues with the help of a light microscope. To do that well, the sample must be prepared first. The exact method depends on the sample’s size and hardness, and it also depends on what staining steps or other later uses are planned.

Preparation usually starts with fixation. Fixation is the step that stops the sample from breaking down after cells die and release enzymes. This helps keep the tissue intact for the next steps.

After fixation, the sample is placed in...

Fluorescent labels make tiny parts of a sample easier to see with a light microscope. Fluorescence microscopy combines normal magnification with fluorescence, which is the absorbance and emission of a small range of light wavelengths by a fluorophore. A fluorophore is a fluorescent molecule that gives off light after it absorbs light.

This imaging method needs more than a basic light microscope. It uses a strong light source, specialized filters, and a way to label the sample with fluorescence.

A light microscope uses lenses and light to enlarge small specimens. It can magnify a sample to as much as a thousand times its original size. Scientists use it in many fields to see details that are too small to view with the naked eye.

At its simplest, a light microscope has a clear lens that magnifies the sample and a light source that illuminates it. Most light microscopes are more complex. They contain several carefully tuned lenses with tightly controlled dimensions inside the microscope...

Keeping lab samples cold is an important part of sample preservation in biomedical research. Scientists use extreme cold to protect laboratory samples, specimens, and reagents during experiments and between them. The right cooling method depends on the experimental need and how long the material must stay cold.

Ice and dry ice are common cooling agents for short-term cooling. They help keep samples cold during an active experiment. The video also explains the physical properties of these...

Laboratory heating helps match the temperature to the job. Many assays run at room temperature, or RT, which is about 20 to 25°C. Some steps, however, need controlled heat instead of room temperature.

Cells may need to be cultured near body temperature, which is about 37°C. Protein structure can be modified at temperatures above 56°C. Reagents and solutions may also be heated to around 100°C.

The video also shows how to measure temperature in a stirring liquid. It explains the proper way to...