Editing Analytical chemistry (section)

== Instrumental methods ==
{{Main|Instrumental analysis}}
[[File:Analytical instrument.png|thumb|upright=1.2|Block diagram of an analytical instrument showing the stimulus and measurement of response]]

=== Spectroscopy ===
{{further|Spectroscopy}}
Spectroscopy measures the interaction of the molecules with [[electromagnetic spectrum|electromagnetic radiation]]. Spectroscopy consists of many different applications such as [[atomic absorption spectroscopy]], [[emission spectroscopy|atomic emission spectroscopy]], [[ultraviolet-visible spectroscopy]], [[X-ray spectroscopy]], [[fluorescence spectroscopy]], [[infrared spectroscopy]], [[Raman spectroscopy]], [[dual polarization interferometry]], [[nuclear magnetic resonance spectroscopy]], [[photoemission spectroscopy]], [[Mössbauer spectroscopy]] and so on.

=== Mass spectrometry ===
{{further|Mass spectrometry}}
[[File:1 MV accelerator mass spectrometer.jpg|thumb|An [[Accelerator mass spectrometry|accelerator mass spectrometer]] used for [[radiocarbon dating]] and other analysis]]
Mass spectrometry measures [[mass-to-charge ratio]] of molecules using [[Electric field|electric]] and [[magnetic field]]s. In a mass spectrometer, a small amount of sample is ionized and converted to gaseous ions, where they are separated and analyzed according to their [[mass-to-charge ratio]]s.<ref name=":0" /> There are several ionization methods: [[electron ionization]], [[chemical ionization]], [[electrospray ionization]], fast atom bombardment, [[matrix-assisted laser desorption/ionization]], and others. Also, mass spectrometry is categorized by approaches of mass analyzers: [[magnetic-sector]], [[quadrupole mass analyzer]], [[quadrupole ion trap]], [[time-of-flight mass spectrometry|time-of-flight]], [[Fourier transform ion cyclotron resonance]], and so on.

=== Electrochemical analysis ===
{{further|Electroanalytical method}}
Electroanalytical methods measure the [[electric potential|potential]] ([[volts]]) and/or [[electric current|current]] ([[Ampere|amps]]) in an [[electrochemical cell]] containing the analyte.<ref>{{cite book|last1=Bard|first1=Allen J.|last2=Faulkner|first2=Larry R.|year=2000|title=Electrochemical Methods: Fundamentals and Applications|location=New York|publisher=John Wiley & Sons|edition=2nd|isbn=0-471-04372-9}}{{page needed|date=January 2014}}</ref><ref>{{cite book|last1=Skoog|first1=Douglas A.|last2=West|first2=Donald M.|last3=Holler|first3=F. James|year=1988|title=Fundamentals of Analytical Chemistry|location=New York|publisher=Saunders College Publishing|edition=5th|isbn=0030148286}}{{page needed|date=January 2014}}</ref>  These methods can be categorized according to which aspects of the cell are controlled and which are measured.  The four main categories are [[Ion selective electrode|potentiometry]] (the difference in electrode potentials is measured), [[coulometry]] (the transferred charge is measured over time), [[amperometry]] (the cell's current is measured over time), and [[voltammetry]] (the cell's current is measured while actively altering the cell's potential).

[[Potentiometry]] measures the cell's potential, [[coulometry]] measures the cell's current, and [[voltammetry]] measures the change in current when cell potential changes.<ref>{{Cite book|last=Skoog|first=Douglas A. |title=Fundamentals of analytical chemistry|date=1996|publisher=Saunders College Pub|author2=Donald M. West |author3=F. James Holler|isbn=0-03-005938-0|edition=7th |location=Fort Worth|oclc=33112372}}</ref><ref>{{Cite book |last=Bard |first=Allen J. |title=Electrochemical methods : fundamentals and applications |author2=Larry R. Faulkner |date=2001 |publisher=Wiley |isbn=0-471-04372-9 |edition=Second |location=Hoboken, NJ |oclc=43859504}}</ref>

=== Thermal analysis ===
{{further|Calorimetry|Thermal analysis}}
Calorimetry and thermogravimetric analysis measure the interaction of a material and [[heat]].

=== Separation ===
[[File:TLC black ink.jpg|thumb|Separation of black ink on a [[thin-layer chromatography]] plate]]
{{further|Separation process|Chromatography|Electrophoresis}}
Separation processes are used to decrease the complexity of material mixtures.  [[Chromatography]], [[electrophoresis]] and  [[Field Flow Fractionation|field flow fractionation]] are representative of this field.

==== Chromatographic assays ====
{{further|Chromatography}}
Chromatography can be used to determine the presence of substances in a sample as different components in a mixture have different tendencies to adsorb onto the stationary phase or dissolve in the mobile phase. Thus, different components of the mixture move at different speed. Different components of a mixture can therefore be identified by their respective [[Retardation factor|R<sub>''ƒ''</sub> values]], which is the ratio between the migration distance of the substance and the migration distance of the solvent front during chromatography.
In combination with the instrumental methods, chromatography can be used in quantitative determination of the substances. Chromatography separates the analyte from the rest of the sample so that it may be measured without interference from other compounds.<ref name=":0" /> There are different types of chromatography that differ from the media they use to separate the analyte and the sample.<ref>{{Citation |last=Poole |first=C. F. |title=CHROMATOGRAPHY |date=2000-01-01 |url=https://www.sciencedirect.com/science/article/pii/B0122267702000211 |encyclopedia=Encyclopedia of Separation Science |pages=40–64 |editor-last=Wilson |editor-first=Ian D. |place=Oxford |publisher=Academic Press |language=en |isbn=978-0-12-226770-3 |access-date=2022-10-07}}</ref> In [[Thin-layer chromatography]], the analyte mixture moves up and separates along the coated sheet under the volatile mobile phase. In [[Gas chromatography]], gas separates the volatile analytes. A common method for chromatography using liquid as a mobile phase is [[High-performance liquid chromatography]].

=== Hybrid techniques ===
Combinations of the above techniques produce a "hybrid" or "hyphenated" technique.<ref name="pmid6353577">{{cite journal |doi=10.1126/science.6353577|bibcode = 1983Sci...222..291W |title=Hyphenated techniques for analysis of complex organic mixtures |year=1983 |last1=Wilkins |first1=C. |journal=Science |volume=222 |issue=4621 |pages=291–6 |pmid=6353577 }}</ref><ref name="pmid9008869">{{cite journal |doi=10.1002/(SICI)1096-9888(199701)32:1<64::AID-JMS450>3.0.CO;2-7 |title=High-performance Liquid Chromatography/NMR Spectrometry/Mass Spectrometry:Further Advances in Hyphenated Technology |year=1997 |last1=Holt |first1=R. M. |last2=Newman |first2=M. J. |last3=Pullen |first3=F. S. |last4=Richards |first4=D. S. |last5=Swanson |first5=A. G. |journal=Journal of Mass Spectrometry |volume=32 |pages=64–70 |pmid=9008869 |issue=1|bibcode=1997JMSp...32...64H }}</ref><ref name="pmid9253184">{{cite journal |doi=10.1016/S0021-9673(97)00325-7 |title=Chromatographic and hyphenated methods for elemental speciation analysis in environmental media |year=1997 |last1=Ellis |first1=Lyndon A |last2=Roberts |first2=David J |journal=Journal of Chromatography A |volume=774 |pages=3–19 |pmid=9253184 |issue=1–2}}</ref><ref name="pmid12462614">{{cite journal |doi=10.1016/S0021-9673(02)01228-1 |title=Hyphenated techniques in anticancer drug monitoring |year=2002 |last1=Guetens |first1=G |last2=De Boeck |first2=G |last3=Wood |first3=M |last4=Maes |first4=R.A.A |last5=Eggermont |first5=A.A.M |last6=Highley |first6=M.S |last7=Van Oosterom |first7=A.T |last8=De Bruijn |first8=E.A |last9=Tjaden |first9=U.R |journal=Journal of Chromatography A |volume=976 |pages=229–38 |pmid=12462614 |issue=1–2}}</ref><ref name="pmid12462615">{{cite journal |doi=10.1016/S0021-9673(02)01227-X |title=Hyphenated techniques in anticancer drug monitoring |year=2002 |last1=Guetens |first1=G |last2=De Boeck |first2=G |last3=Highley |first3=M.S |last4=Wood |first4=M |last5=Maes |first5=R.A.A |last6=Eggermont |first6=A.A.M |last7=Hanauske |first7=A |last8=De Bruijn |first8=E.A |last9=Tjaden |first9=U.R |journal=Journal of Chromatography A |volume=976 |pages=239–47 |pmid=12462615 |issue=1–2}}</ref>  Several examples are in popular use today and new hybrid techniques are under development. For example, [[gas chromatography-mass spectrometry]], gas chromatography-[[infrared spectroscopy]], [[liquid chromatography-mass spectrometry]], liquid chromatography-[[NMR spectroscopy]], liquid chromatography-infrared spectroscopy, and capillary electrophoresis-mass spectrometry.

Hyphenated separation techniques refer to a combination of two (or more) techniques to detect and separate chemicals from solutions. Most often the other technique is some form of [[chromatography]]. Hyphenated techniques are widely used in [[chemistry]] and [[biochemistry]]. A [[Slash (punctuation)|slash]] is sometimes used instead of [[hyphen]], especially if the name of one of the methods contains a hyphen itself.

=== Microscopy ===
[[File:3D-SIM-3 Prophase 3 color.jpg|thumb|[[Fluorescence microscope]] image of two mouse cell nuclei in [[prophase]] (scale bar is 5 μm)<ref>{{cite journal |doi=10.1126/science.1156947 |title=Subdiffraction Multicolor Imaging of the Nuclear Periphery with 3D Structured Illumination Microscopy |year=2008 |last1=Schermelleh |first1=L. |last2=Carlton |first2=P. M. |last3=Haase |first3=S. |last4=Shao |first4=L. |last5=Winoto |first5=L. |last6=Kner |first6=P. |last7=Burke |first7=B. |last8=Cardoso |first8=M. C. |last9=Agard |first9=D. A. |last10=Gustafsson |first10=M. G. L. |last11=Leonhardt |first11=H. |last12=Sedat |first12=J. W. |journal=Science |volume=320 |issue=5881 |pages=1332–6 |pmid=18535242 |pmc=2916659|bibcode = 2008Sci...320.1332S }}</ref>]]
{{further|Microscopy}}
The visualization of single molecules, single cells, biological tissues, and [[nanomaterial]]s is an important and attractive approach in analytical science.  Also, hybridization with other traditional analytical tools is revolutionizing analytical science.  [[Microscopy]] can be categorized into three different fields: [[optical microscopy]], [[electron microscopy]], and [[scanning probe microscopy]].  Recently, this field is rapidly progressing because of the rapid development of the computer and camera industries.

=== Lab-on-a-chip ===

{{further|Microfluidics|Lab-on-a-chip}}
Devices that integrate (multiple) laboratory functions on a single chip of only millimeters to a few square centimeters in size and that are capable of handling extremely small fluid volumes down to less than picoliters.