Lab techniques pillar · 26 definitions
Laboratory & analytical techniques
Clear, citable definitions of the techniques scientists use to separate, identify, measure and image samples — spectroscopy, chromatography, mass spectrometry, electrophoresis, PCR, microscopy and imaging. Explained at the physics-and-chemistry-of-the-measurement level, accurate and strictly non-clinical.
Separating and identifying molecules
Much of analytical science is about pulling a mixture apart and working out what is in it. Chromatography — including HPLC and gas chromatography — separates components, while mass spectrometry and NMR spectroscopy identify them. Titration remains a fundamental way to measure concentration.
Working with biological molecules
Biology has its own toolkit. Gel electrophoresis separates DNA, RNA and proteins by size; the western blot and ELISA detect specific proteins using antibodies; PCR amplifies DNA; and flow cytometry analyses cells one at a time.
Imaging and measurement physics
Imaging methods make the invisible visible. Light and electron microscopy resolve fine structure, while MRI and ultrasound are explained here purely as measurement physics. The definitions below cover the separation, detection and imaging methods that produce research data.
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Laboratory & analytical technique definitions
Spectroscopy
What is spectroscopy?
Spectroscopy is the study of how matter absorbs, emits, or scatters electromagnetic radiation as a function of wavelength. Measuring these interactions reveals the structure, composition, and concentration of a sample.
Read →Mass spectrometry
What is mass spectrometry?
Mass spectrometry measures the mass-to-charge ratio of ions to identify and quantify the molecules in a sample. Components are ionised, separated by an analyser, and counted by a detector.
Read →Chromatography
What is chromatography?
Chromatography separates the components of a mixture by their differing affinities for a stationary phase versus a moving mobile phase. Components travel at different speeds and emerge separately.
Read →HPLC
What is HPLC?
HPLC (high-performance liquid chromatography) separates compounds in solution by pumping a liquid mobile phase under high pressure through a tightly packed column, resolving complex mixtures with high precision.
Read →Gas chromatography
What is gas chromatography?
Gas chromatography (GC) separates volatile compounds by carrying them in an inert gas through a column, where each compound is retained for a characteristic time before reaching the detector.
Read →Gel electrophoresis
What is gel electrophoresis?
Gel electrophoresis separates DNA, RNA, or proteins by driving them through a porous gel with an electric field, so molecules sort by size and charge as smaller ones travel further.
Read →Western blot
What is a Western blot?
A Western blot is a research method that detects a specific protein in a sample by separating proteins by electrophoresis, transferring them to a membrane, and probing with antibodies that bind the target.
Read →ELISA
What is ELISA?
ELISA (enzyme-linked immunosorbent assay) is an antibody-based laboratory assay that detects and quantifies a target molecule by linking its capture to an enzyme that produces a measurable colour change.
Read →PCR (technique)
What is PCR as a laboratory technique?
PCR is a laboratory technique that amplifies a chosen DNA sequence by repeated thermal cycling, doubling the target with each cycle so a tiny amount of DNA becomes millions of copies.
Read →Microscopy
What is microscopy?
Microscopy is the use of lenses or beams of radiation to magnify objects too small for the eye, resolving fine detail in cells, materials, and structures by gathering and focusing light or electrons.
Read →Electron microscopy
What is electron microscopy?
Electron microscopy uses a focused beam of electrons instead of light to image specimens, achieving far higher resolution and revealing structures down to the near-atomic scale.
Read →Titration
What is titration?
Titration is a quantitative chemical analysis that finds the concentration of a solution by reacting it with a standard solution of known concentration until the reaction just reaches its endpoint.
Read →MRI
What is MRI? (the measurement physics)
MRI is an imaging technique whose physics rests on nuclear magnetic resonance: hydrogen nuclei in a strong magnetic field absorb and re-emit radio waves, and these signals are reconstructed into an image.
Read →Ultrasound
What is ultrasound? (the measurement physics)
Ultrasound imaging sends high-frequency sound waves into a medium and times their echoes from boundaries to build an image; the physics is the emission, reflection, and timing of sound.
Read →Flow cytometry
What is flow cytometry?
Flow cytometry analyses cells one at a time as they flow in single file past a laser, measuring light scatter and fluorescence to characterise and, in FACS, physically sort them.
Read →NMR spectroscopy
What is NMR spectroscopy?
NMR spectroscopy determines molecular structure by observing how atomic nuclei in a magnetic field absorb and re-emit radio waves; tiny differences in resonance frequency, the chemical shift, reveal each atom's environment.
Read →Distillation
What is distillation?
Distillation separates the components of a liquid mixture by exploiting their different boiling points: the mixture is heated to vaporise the more volatile component, and the vapour is then cooled and condensed back into a purer liquid.
Read →Centrifugation
What is centrifugation?
Centrifugation separates the components of a mixture by spinning it at high speed, so that denser particles are driven outward to form a pellet while lighter material stays in the supernatant above.
Read →UV-Vis spectroscopy
What is UV-Vis spectroscopy?
UV-Vis spectroscopy measures how much ultraviolet and visible light a sample absorbs at each wavelength; because absorbance is proportional to concentration through the Beer-Lambert law, it is widely used to quantify substances.
Read →Infrared spectroscopy
What is infrared spectroscopy?
Infrared spectroscopy measures how a sample absorbs infrared light; because chemical bonds absorb at frequencies that match their vibrations, the resulting spectrum identifies the functional groups present in a molecule.
Read →X-ray diffraction
What is X-ray diffraction?
X-ray diffraction (XRD) determines the arrangement of atoms in a crystal by measuring how X-rays scatter from its regularly spaced planes; the directions of the diffracted beams follow Bragg’s law and reveal the crystal structure.
Read →Thin-layer chromatography
What is thin-layer chromatography?
Thin-layer chromatography (TLC) separates compounds on a thin layer of adsorbent coated on a plate; a solvent rises through the layer, carrying compounds different distances, and each is characterised by its Rf value.
Read →LC-MS
What is LC-MS?
LC-MS couples liquid chromatography, which separates the components of a sample in solution, with mass spectrometry, which identifies and quantifies them by mass-to-charge ratio, combining separation and identification in one analysis.
Read →GC-MS
What is GC-MS?
GC-MS couples gas chromatography, which separates volatile compounds in the gas phase, with mass spectrometry, which identifies each compound by its mass spectrum, combining separation and confident identification in one run.
Read →Cell culture
What is cell culture?
Cell culture is the laboratory practice of growing cells outside their original organism under controlled conditions, supplying the nutrients, temperature, and environment they need so researchers can study and manipulate them.
Read →Immunohistochemistry
What is immunohistochemistry?
Immunohistochemistry (IHC) is a laboratory method that detects specific molecules within a tissue section using labelled antibodies, so the location of a target can be seen directly against the tissue’s structure under a microscope.
Read →Common questions
Lab techniques FAQ
What is spectroscopy?+
Spectroscopy is the study of how matter interacts with electromagnetic radiation. By measuring the light a substance absorbs or emits at different wavelengths, scientists can identify materials and determine their structure and concentration. It is one of the most widely used families of analytical technique.
What is the difference between chromatography and mass spectrometry?+
Chromatography separates the components of a mixture by their differing movement through a stationary phase. Mass spectrometry identifies and measures components by their mass-to-charge ratio. They are often combined — for example GC-MS or LC-MS — so that compounds are first separated and then identified.
How does an MRI work?+
Magnetic resonance imaging uses a strong magnetic field and radio waves to detect signals from hydrogen nuclei in the body, which a computer reconstructs into detailed images. These pages explain the physics of the measurement; they do not interpret images or provide medical advice.
Is this a clinical or diagnostic resource?+
No. These pages explain how laboratory and imaging techniques work as measurement methods. They are not medical, diagnostic or screening advice and do not interpret what any test or scan result means for an individual.
How does this relate to CASRAI standards?+
CASRAI is a research-standards body. Analytical techniques produce the measurements behind much of science, and their value depends on careful method documentation and reproducibility — the research-data standards that let results be compared and reused.
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