General Laboratory Techniques

The centrifuge is an instrument used in nearly every research lab across the globe. Centrifugation is the process by which a centrifuge is used to separate components of a complex mixture. By spinning laboratory samples at very high speeds, the components of a given mixture are subjected to centrifugal force, which causes more dense particles to migrate away from the axis of rotation and lighter ones to move toward it. These particles can sediment at the bottom of the tube into what’s...

The microplate reader is a multimodal instrument that allows for a variety of experiments to be performed and measured simultaneously. Microplate readers can make absorbance, fluorescence and luminescence measurements. Multiwell plates are integral to the microplate reader and allow for many experiments to be performed at once. Regardless of the assay type, experiments on the plate reader utilize a standard curve to determine the experimental values. This curve uses samples of known...

Solutions are utilized to some degree in almost all biological research applications. Therefore understanding how to measure and manipulate them is imperative to any experiment. In this video, concepts in preparing solutions are introduced. Solutions consist of a solute dissolved in solvent to yield a homogeneous mixture of molecular substances. Solutions are generally identified by their components and corresponding concentrations. Concentrated solutions are diluted through various...

The ability to successfully make solutions is a basic laboratory skill performed in virtually all biological and chemical experiments. A solution is a homogenous mixture of solute dissolved in bulk liquid known as the solvent. Solutions can be described by their solute concentration, a measure of how much solute is present per unit of solution. In this video, a step-by-step procedure for how to make a water-based, or aqueous, solution for biological applications is presented. The video...

The micropipettor is a common laboratory instrument used for transferring microvolumes of liquid solutions. Micropipettors come in a range of sizes for the accurate movement of volumes between 0.5 and 5000 μl and each instrument requires one of three different sized disposable tips. Micropipettors work by displacing air from the pipette shaft, allowing the liquid to be drawn into the resulting vacuum. Their uses include transferring cell suspensions for a variety of cell-based assays, loading...

The serological pipette is frequently used in the laboratory for transferring milliliter volumes of liquid, from less than 1 ml to up to 50 ml. The pipettes can be sterile, plastic, and disposable or sterilizable, glass and reusable. Both kinds of pipettes use a pipet-aid, for the aspiration and dispensation of liquids. Different sizes of pipettes can be used with the same pipet-aid for a variety of experimental assays. For example, serological pipettes are useful for mixing chemical solutions...

The Bunsen burner, named after and co-designed by Robert Bunsen in 1854, is a common laboratory instrument that produces a hot, sootless, non-luminous flame. The Bunsen Burner allows for precise regulation of the mixing of gas and oxygen in its central barrel before combustion, which ignites the flame. By manipulating the Bunsen burner, both the size and temperature of the flame can be controlled. Among other uses, the heat of a Bunsen burner flame can be used to create a convection current,...

Hoods are a common class of instrument, which act as a protective enclosure for various types of laboratory experiments. They serve to shield experimental samples from the environment, as well as to protect the researcher from hazardous or infectious samples. “The Hood” is a term that can include laminar flow benches, fume hoods, as well as tissue culture hoods or biosafety cabinets. All hoods operate based on the principle of laminar flow and have the same basic components, including a...

The analytical balance is the common piece of equipment in the scientific laboratory. These highly precise instruments can measure down to ten thousandths or even hundred thousandths of a gram. The triple beam balance is a type of scale that uses counterweights on a three rider beams to counterbalance the sample in the pan. On the other hand, modern analytical balances use a complex system of electronic sensors to accurately mass a substance. The analytical balance is so sensitive that it...

The spectrophotometer is a routinely used instrument in scientific research. Spectrophotometry is the quantitative measurement of how much a chemical substance absorbs light by passing a beam of light through the sample using a spectrophotometer. In this video, basic concepts in spectrophotometry, including transmittance, absorbance and the Beer-Lambert Law are reviewed in addition to the components of the spectrophotometer. These concepts provide a foundation for how to determine the...

Histology is the study of cells and tissues, which is typically aided by the use of a light microscope. The preparation of histological samples can vary greatly based on the inherent properties of the samples such as size and hardness as well as expected post-processing which includes planned staining techniques or other down-stream applications. As described in this video, specimen preparation typically begins with a fixation procedure to prevent degradation of the sample by naturally...

Fluorescence microscopy is a very powerful analytical tool that combines the magnifying properties of light microscopy with visualization of fluorescence. Fluorescence is a phenomenon that involves absorbance and emission of a small range of light wavelengths by a fluorescent molecule known as a fluorophore. Fluorescence microscopy is accomplished in conjunction with the basic light microscope by the addition of a powerful light source, specialized filters, and a means of fluorescently...

The light microscope is an instrument used by researchers in many different fields to magnify specimens to as much as a thousand times their original size. In its simplest form, it is composed of a clear lens that magnifies the sample and a light source to illuminate it. However, most light microscopes are much more complex and house numerous fine-tuned lenses with tightly controlled dimensions all within the body of the microscope itself and in components such as the objectives and eyepieces.

Preservation of laboratory samples, specimens, and reagents using extreme cold is routinely performed in biomedical research labs. This video will discuss some of the methods for keeping laboratory samples cold and will explain the correct cooling method to use for each experimental requirement. For example, cooling agents, such as ice and dry ice, are typically used when keeping samples cold during experiments. This video discusses the physical properties of the most commonly used cooling...

Although many experimental assays are performed at room temperature (RT; ~20-25°C), it is not uncommon for experiments, or parts of experiments, to require some type of temperature regulation. This video discusses the different reasons for and temperatures at which a scientist may want to “keep things warm”. For example, sometime, cells need to be cultured in an environment close to body temperature (~37°C), protein structure needs to be modified (>56°C), or reagents and solutions need to...