partition chromatography

The process of separating mixtures of chemical compounds by passing them through a column that contains a solid stationary phase that was eluted with a mobile phase (column chromatography) was well known at that time.{{cite journal |last1=Pakhomov |first1=V. P.|title=Chromatography in Pharmaceutical Chemistry (100 Years of the Discovery of Chromatography by M. S. Tswett) |journal=Pharmaceutical Chemistry Journal|volume=37 |issue=8 |year=2003 |pages=451–452 |doi=10.1023/A:1027324501053 |s2cid=22507057 }} Chromatographic separation was considered to occur by an adsorption process whereby compounds adhered to a solid media and were washed off the column with a solvent, mixture of solvents, or solvent gradient. In contrast, Martin and Synge developed and described a chromatographic separation process whereby compounds were partitioned between two liquid phases similar to the separatory funnel liquid-liquid separation dynamic. This was an important departure, both in theory and under equilibrium conditions.{{cite journal |last1=Schindler |first1=Hans |title=Notes on the history of the separatory funnel |journal=Journal of Chemical Education |date=November 1957 |volume=34 |issue=11 |pages=528 |doi=10.1021/ed034p528 |bibcode=1957JChEd..34..528S }} Martin and Synge initially attempted to devise a method of performing a sequential liquid-liquid extraction with serially connected glass vessels that functioned as separatory funnels. The seminal article presenting their early studies described a rather complicated instrument that allowed partitioning of amino acids between water and chloroform phases. The process was termed "counter-current liquid-liquid extraction."{{cite journal |last1=Martin |first1=A. J. P. |last2=Synge |first2=R. L. M. |title=Separation of the higher monoamino-acids by counter-current liquid-liquid extraction: the amino-acid composition of wool |journal=Biochemical Journal |date=1 January 1941 |volume=35 |issue=1–2 |pages=91–121 |doi=10.1042/bj0350091 |pmid=16747393 |pmc=1265473 }} Martin and Synge described the theory of this technique in reference to continuous fractional distillation described by Randall and Longtin.{{cite journal |last1=Randall |first1=Merle |last2=Longtin |first2=Bruce |title=Separation Processes: General Method of Analysis |journal=Industrial & Engineering Chemistry |date=September 1938 |volume=30 |issue=9 |pages=1063–1067 |doi=10.1021/ie50345a028 }} This approach was deemed too cumbersome, so they developed a method of absorbing water onto silica gel as the stationary phase and using a solvent, such as chloroform, as the mobile phase.{{cite journal |last1=Whelan |first1=William J. |title=Partition Chromatography Revisited |journal=IUBMB Life |date=1 May 2001 |volume=51 |issue=5 |pages=329–330 |doi=10.1080/152165401317190851 |pmid=11699880 |doi-access=free }} This work was published in 1941 as "a new form of chromatogram employing two liquid phases."{{cite journal |last1=Martin |first1=A. J. P. |last2=Synge |first2=R. L. M. |title=A new form of chromatogram employing two liquid phases. A theory of chromatography. 2. Application to the micro-determination of the higher monoamino-acids in proteins |journal=Biochemical Journal |date=1 December 1941 |volume=35 |issue=12 |pages=1358–1368 |doi=10.1042/bj0351358 |pmid=16747422 |pmc=1265645 }} The article describes both the theory in terms of the partition coefficient of a compound, and the application of the process to the separation of amino acids on a water-impregnated silica column eluted with a water:chloroform:n-butanol solvent mixture.

The previously described work of Martin and Synge impacted the development of the previously known column chromatography and inspired new forms of chromatography such as countercurrent distribution,{{cite journal |last1=Craig |first1=Lyman C. |title=Identification of small amounts of organic compounds by distribution studies: II. Separation by counter-current distribution |journal=Journal of Biological Chemistry |date=October 1944 |volume=155 |issue=2 |pages=519–534 |doi=10.1016/S0021-9258(18)51183-2 |doi-access=free }} paper chromatography,{{cite journal |doi=10.1042/bj0380224|title=Qualitative analysis of proteins: A partition chromatographic method using paper|year=1944|last1=Consden|first1=R.|last2=Gordon|first2=A. H.|last3=Martin|first3=A. J. P.|journal=Biochemical Journal|volume=38|issue=3|pages=224–232|pmid=16747784|pmc=1258072}} and gas-liquid chromatography which is more commonly known as gas chromatography. The modification of silica gel stationary phase led to many creative ways of modifying stationary phases in order to influence the separation characteristics. The most notable modification was the chemical bonding of alkane functional groups to silica gel to produce reversed-phase media.{{cite journal |last1=Horvath |first1=C. |last2=Melander |first2=W. |title=Liquid Chromatography with Hydrocarbonaceous Bonded Phases; Theory and Practice of Reversed Phase Chromatography |journal=Journal of Chromatographic Science |date=1 September 1977 |volume=15 |issue=9 |pages=393–404 |doi=10.1093/chromsci/15.9.393 }} The original problem that Martin and Synge encountered with devising an instrument that would employ two free-flowing liquid phases was solved by Lyman C. Craig in 1944, and commercial counter-current distribution instruments were used for many important discoveries.{{Cite journal| pages = 49–77| last = Moore| first = Stanford| title = Lyman Creighton Craig 1906-1974| journal = National Academy of Sciences Biographical Memoirs| access-date = 2016-02-26| date = 1978| url = http://www.nasonline.org/member-directory/deceased-members/20000680.html}} The introduction of paper chromatography was an important analytical technique which gave rise to thin-layer chromatography.{{cite journal |last1=Martin |first1=A J P |title=Partition Chromatography |journal=Annual Review of Biochemistry |date=June 1950 |volume=19 |issue=1 |pages=517–542 |doi=10.1146/annurev.bi.19.070150.002505 |pmid=14771840 }} Finally, gas-liquid chromatography, a fundamental technique in modern analytical chemistry, was described by Martin with coauthors A. T. James and G. Howard Smith in 1952.{{cite journal |last1=James |first1=A. T. |last2=Martin |first2=A. J. P. |last3=Smith |first3=G. Howard |title=Gas-liquid partition chromatography: the separation and micro-estimation of ammonia and the methylamines |journal=Biochemical Journal |date=1 October 1952 |volume=52 |issue=2 |pages=238–242 |doi=10.1042/bj0520238 |pmid=13018213 |pmc=1197975 }}

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Category:Chromatography