Editing High-performance liquid chromatography (section)

===Detectors===
HPLC detectors fall into two main categories: universal or selective. Universal detectors typically measure a bulk property (''e.g.'', [[refractive index]]) by measuring a difference of a [[physical property]] between the mobile phase and mobile phase with solute while selective detectors measure a solute property (''e.g.'', [[Ultraviolet–visible spectroscopy|UV-Vis absorbance]]) by simply responding to the physical or [[chemical property]] of the solute.<ref>{{Cite book|title=Principles and practice of modern chromatographic methods|last=K.|first=Robards|date=1994|publisher=Elsevier/Academic Press|others=Haddad, P. R., Jackson, P. E.|isbn=9780080571782|location=Amsterdam|oclc=815471219}}</ref> HPLC most commonly uses a [[spectrophotometer|UV-Vis absorbance detector]]; however, a wide range of other [[chromatography detector]]s can be used. A universal detector that complements UV-Vis absorbance detection is the [[charged aerosol detector]] (CAD). A kind of commonly utilized detector includes refractive index detectors, which provide readings by measuring the changes in the refractive index of the eluant as it moves through the flow cell. In certain cases, it is possible to use multiple detectors, for example [[Liquid chromatography–mass spectrometry|LCMS]] normally combines UV-Vis with a mass spectrometer.

When used with an electrochemical detector (ECD) the HPLC-ECD selectively detects [[neurotransmitters]] such as: [[norepinephrine]], [[dopamine]], [[serotonin]], [[glutamate]], GABA, [[acetylcholine]] and others in neurochemical analysis research applications.<ref>{{Cite web|url=https://www.amuzainc.com/eicom-electrochemical-detection-ecd-fundamentals/|title=Electrochemical Detection (ECD) Fundamentals|website=Amuza Inc}}</ref> The HPLC-ECD detects neurotransmitters to the [[femtomolar]] range. Other methods to detect neurotransmitters include liquid chromatography-mass spectrometry, ELISA, or radioimmunoassays.