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Thin-layer chromatography
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<h2 id="procedure">Procedure</h2> <p>The process for TLC is similar to <a href="/facts/Paper_chromatography/1qDcbIp0">paper chromatography</a> but provides faster runs, better separations, and the choice between different stationary phases.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> Plates can be labelled before or after the chromatography process with a pencil or other implement that will not interfere with the process.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p><p>There are four main stages to running a thin-layer chromatography plate:<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p><p>Plate preparation: Using a capillary tube, a small amount of a concentrated solution of the sample is deposited near the bottom edge of a TLC plate. The <a href="/facts/Solvent/LoMPMz8S">solvent</a> is allowed to completely evaporate before the next step. A <a href="/facts/Vacuum_chamber/9LkgL4qm">vacuum chamber</a> may be necessary for non-volatile solvents. To make sure there is sufficient compound to obtain a visible result, the spotting procedure can be repeated. Depending on the application, multiple different samples may be placed in a row the same distance from the bottom edge; each sample will move up the plate in its own "lane." </p> <p>Development chamber preparation: The development solvent or solvent mixture is placed into a transparent container (separation/development chamber) to a depth of less than 1 centimetre. A strip of filter paper (aka "wick") is also placed along the container wall. This filter paper should touch the solvent and almost reach the top of the container. The container is covered with a lid and the solvent vapors are allowed to saturate the atmosphere of the container. Failure to do so results in poor separation and non-reproducible results. </p><p>Development: The TLC plate is placed in the container such that the sample spot(s) are not submerged into the mobile phase. The container is covered to prevent solvent evaporation. The <a href="/facts/Solvent/LoMPMz8S">solvent</a> migrates up the plate by <a href="/facts/Capillary_action/aa60yQ32">capillary action</a>, meets the sample mixture, and carries it up the plate (elutes the sample). The plate is removed from the container before the solvent reaches the top of the plate; otherwise, the results will be misleading. The <i>solvent front</i>, the highest mark the solvent has travelled along the plate, is marked. </p><p>Visualization: The solvent evaporates from the plate. Visualization methods include UV light, staining, and many more. </p> <h2 id="separation-process-and-principle">Separation process and principle</h2> <p>The separation of compounds is due to the differences in their attraction to the stationary phase and because of differences in solubility in the solvent.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> As a result, the compounds and the mobile phase compete for binding sites on the stationary phase.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> Different <a href="/facts/Chemical_compound/37FXqqtv">compounds</a> in the sample mixture travel at different rates due to the differences in their <a href="/facts/Partition_coefficient/D4aTlBal">partition coefficients</a>.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> Different solvents, or different solvent mixtures, gives different separation.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> The <a href="/facts/Retardation_factor/20xwIh1W">retardation factor</a> (<i>R</i>f), or <i>retention factor</i>, quantifies the results. It is the distance traveled by a given substance divided by the distance traveled by the mobile phase. </p> <p>In <a href="/facts/Normal_phase_chromatography/UNT9jPp0">normal-phase</a> TLC, the stationary phase is <a href="/facts/Chemical_polarity/KlIJ0zjB">polar</a>. Silica gel is very common in normal-phase TLC. More polar compounds in a sample mixture interact more strongly with the polar stationary phase. As a result, more-polar compounds move less (resulting in smaller <i>R</i>f) while less-polar compounds move higher up the plate (higher <i>R</i>f).<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> A more-polar mobile phase also binds more strongly to the plate, competing more with the compound for binding sites; a more-polar mobile phase also dissolves polar compounds more.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> As such, all compounds on the TLC plate move higher up the plate in polar solvent mixtures. "Strong" solvents move compounds higher up the plate, whereas "weak" solvents move them less.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> </p><p>If the stationary phase is non-polar, like <a href="/facts/Reversed-phase_chromatography/nc0XW7CL">C18</a>-functionalized silica plates, it is called <a href="/facts/Reversed-phase_chromatography/nc0XW7CL">reverse-phase</a> TLC. In this case, non-polar compounds move less and polar compounds move more. The solvent mixture will also be much more polar than in normal-phase TLC.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> </p> <h3>Solvent choice</h3> <p>An <a href="/facts/Eluotropic_series/ns3pIr7e">eluotropic series</a>, which orders solvents by how much they move compounds, can help in selecting a mobile phase.<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> Solvents are also divided into solvent selectivity groups.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> Using solvents with different elution strengths or different selectivity groups can often give very different results.<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a><a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> While single-solvent mobile phases can sometimes give good separation, some cases may require solvent mixtures.<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> </p><p>In normal-phase TLC, the most common solvent mixtures include ethyl acetate/hexanes (<a href="/facts/Ethyl_acetate/om0PFI7S">EtOAc</a>/<a href="/facts/Hexane/JxPecNPt">Hex</a>) for less-polar compounds and methanol/dichloromethane (<a href="/facts/Methanol/EIfpoNCg">MeOH</a>/<a href="/facts/Dichloromethane/mHyeTD2D">DCM</a>) for more polar compounds.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> Different solvent mixtures and solvent ratios can help give better separation.<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> In reverse-phase TLC, solvent mixtures are typically water with a less-polar solvent: Typical choices are water with tetrahydrofuran (<a href="/facts/Tetrahydrofuran/P5t6SkMK">THF</a>), acetonitrile (<a href="/facts/Acetonitrile/fNpbvRp6">ACN</a>), or methanol.<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> </p> <h2 id="analysis">Analysis</h2> <p>As the chemicals being separated may be colourless, several methods exist to visualise the spots: </p> <ul><li>Placing the plate under <a href="/facts/Blacklight/pAQ4hnUq">blacklight</a> (366 nm light) makes fluorescent compounds glow</li> <li>TLC plates containing a small amount of <a href="/facts/Fluorescent/qsJVT2qP">fluorescent</a> compound (usually <a href="/facts/Manganese/j9ELd1TL">manganese</a>-activated <a href="/facts/Willemite/Gem8lHSH">zinc silicate</a>) in the adsorbent layer allow for visualisation of some compounds under UV-C light (254 nm). The adsorbent layer will fluoresce light-green, while spots containing compounds that absorb UV-C light will not.<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a></li> <li>Placing the plate in a container filled with <a href="/facts/Iodine/JlfMecMf">iodine</a> vapours temporarily stains the spots.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> They typically become a yellow or brown colour.</li> <li>The TLC plate can either be dipped in or sprayed with a stain and sometimes heated depending on the stain used. Many stains exist for a large range of chemical moieties but some examples include:<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a><a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a><a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> <ul><li><a href="/facts/Potassium_permanganate/nyjjuDlo">Potassium permanganate</a> (no heating, for oxidisable groups)</li> <li><a href="/facts/Ninhydrin/IS1y8CkG">Ninhydrin</a> (heating, amines and amino-acids)</li> <li>Acidic <a href="/facts/Vanillin/mBmdAn7I">vanillin</a> (heating, general reagent)</li> <li><a href="/facts/Phosphomolybdic_acid/7CDInQf1">Phosphomolybdic acid</a> (no heating, general reagent)</li></ul></li> <li>In the case of lipids, the chromatogram may be transferred to a <a href="/facts/Polyvinylidene_fluoride/9LXbA0M4">polyvinylidene fluoride</a> membrane and then subjected to further analysis, for example, <a href="/facts/Mass_spectrometry/RH5WBHJ2">mass spectrometry</a>. This technique is known as <a href="/facts/Far-eastern_blot/xgEqXBwj">far-eastern blot</a>.<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a></li></ul> <h2 id="plate-production">Plate production</h2> <p>TLC plates are usually commercially available, with standard particle size ranges to improve <a href="/facts/Reproducibility/yh5pawMj">reproducibility</a>.<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> They are prepared by mixing the adsorbent, such as <a href="/facts/Silica_gel/qrNxnft5">silica gel</a>, with a small amount of <a href="/facts/Chemically_inert/oglbxzgk">inert</a> binder like <a href="/facts/Calcium_sulfate/mTD8oGaH">calcium sulfate</a> (gypsum) and water.<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> This mixture is spread as a thick slurry on an unreactive carrier sheet, usually <a href="/facts/Glass/hezRsAGf">glass</a>, thick aluminum foil, or plastic. The resultant plate is dried and <i>activated</i> by heating in an oven for thirty minutes at 110 °C.<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> The thickness of the absorbent layer is typically around 0.1–0.25 mm for analytical purposes and around 0.5–2.0 mm for preparative TLC.<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a> Other adsorbent coatings include <a href="/facts/Aluminium_oxide/wXM9P6pI">aluminium oxide</a> (alumina), or <a href="/facts/Cellulose/wYPafTU0">cellulose</a>.<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a> </p> <h2 id="applications">Applications</h2> <h3>Reaction monitoring and characterization</h3> <p>TLC is a useful tool for reaction monitoring.<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> For this, the plate normally contains a spot of starting material, a spot from the reaction mixture, and a co-spot (or cross-spot) containing both.<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a><a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> The analysis will show if the starting material disappeared and if any new products appeared.<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a> This provides a quick and easy way to estimate how far a reaction has proceeded. In one study, TLC has been applied in the screening of <a href="/facts/Organic_reaction/SESmeGWm">organic reactions</a>.<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a> The researchers react an <a href="/facts/Alcohol_(chemistry)/Y0SCTDkh">alcohol</a> and a <a href="/facts/Catalysis/LPBS7TQC">catalyst</a> directly in the co-spot of a TLC plate before developing it. This provides quick and easy small-scale testing of different <a href="/facts/Reagent/c3GLInCu">reagents</a>. </p> <p>Compound characterization with TLC is also possible and is similar to reaction monitoring. However, rather than spotting with starting material and reaction mixture, it is with an unknown and a known compound. They may be the same compound if both spots have the same <i>R</i>f and look the same under the chosen visualization method. However, co-elution complicates both reaction monitoring and characterization. This is because different compounds will move to the same spot on the plate. In such cases, different solvent mixtures may provide better separation.<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a> </p> <h3>Purity and purification</h3> <p>TLC helps show the purity of a sample. A pure sample should only contain one spot by TLC. TLC is also useful for small-scale purification.<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a> Because the separated compounds will be on different areas of the plate, a scientist can scrape off the stationary phase particles containing the desired compound and dissolve them into an appropriate solvent.<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> Once all the compound dissolves in the solvent, they filter out the silica particles, then evaporate the solvent to isolate the product. Big preparative TLC plates with thick silica gel coatings can separate more than 100 mg of material.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a> </p><p>For larger-scale purification and isolation, TLC is useful to quickly test solvent mixtures before running <a href="/facts/Column_chromatography/fPNBKwx8">flash column chromatography</a> on a large batch of impure material.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a><a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> A compound <a href="/facts/Elution/ns3pIr7e">elutes</a> from a column when the amount of solvent collected is equal to 1/<i>R</i>f.<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a> The <a href="/facts/Elution/ns3pIr7e">eluent</a> from <a href="/facts/Column_chromatography/fPNBKwx8">flash column chromatography</a> gets collected across several containers (for example, test tubes) called fractions. TLC helps show which fractions contain impurities and which contain pure compound. </p><p>Furthermore, two-dimensional TLC<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> can help check if a compound is stable on a particular stationary phase. This test requires two runs on a square-shaped TLC plate. The plate is rotated by 90º before the second run. If the target compound appears on the diagonal of the square, it is stable on the chosen stationary phase. Otherwise, it is decomposing on the plate. If this is the case, an alternative stationary phase may prevent this decomposition.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> </p><p> TLC is also an analytical method for the direct separation of <a href="/facts/Enantiomer/wjPv5J3y">enantiomers</a> and the control of enantiomeric purity, e.g. active pharmaceutical ingredients (<a href="/facts/Active_Pharmaceutical_Ingredient/oeDx5S19">APIs</a>) that are chiral.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a></p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Column_chromatography/fPNBKwx8">Column chromatography</a></li> <li><a href="/facts/HPTLC/al9Meaf2">HPTLC</a></li> <li><a href="/facts/Radial_chromatography/nSht5JnK">Radial chromatography</a></li> <li>Chiral thin-layer chromatography</li></ul> <h2 id="bibliography">Bibliography</h2> <ul><li>F. Geiss (1987): Fundamentals of thin layer chromatography planar chromatography, Heidelberg, Hüthig, <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 3-7785-0854-7</li> <li>Justus G. Kirchner (1978): Thin-layer chromatography, 2nd edition, Wiley</li> <li>Joseph Sherma, Bernard Fried (1991): Handbook of Thin-Layer Chromatography (= <i>Chromatographic Science.</i> Bd. 55). Marcel Dekker, New York NY, <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 0-8247-8335-2.</li> <li>Elke Hahn-Deinstorp: <i>Applied Thin-Layer Chromatography. Best Practice and Avoidance of Mistakes.</i> Wiley-VCH, Weinheim u. a. 2000, <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 3-527-29839-8</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Harry W. Lewis & Christopher J. Moody (13 Jun 1989). Experimental Organic Chemistry: Principles and Practice (Illustrated ed.). WileyBlackwell. pp. 159–173. ISBN 9780632020171. <a href="9780632020171" target="_blank">9780632020171</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Zhang, Meizhen; Yu, Qian; Guo, Jiaqi; Wu, Bo; Kong, Xianming (2022-11-28). "Review of Thin-Layer Chromatography Tandem with Surface-Enhanced Raman Spectroscopy for Detection of Analytes in Mixture Samples". Biosensors. 12 (11): 937. doi:10.3390/bios12110937. ISSN 2079-6374. PMC 9687685. PMID 36354446. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9687685" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9687685</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Zhang, Meizhen; Yu, Qian; Guo, Jiaqi; Wu, Bo; Kong, Xianming (2022-11-28). "Review of Thin-Layer Chromatography Tandem with Surface-Enhanced Raman Spectroscopy for Detection of Analytes in Mixture Samples". Biosensors. 12 (11): 937. doi:10.3390/bios12110937. ISSN 2079-6374. PMC 9687685. PMID 36354446. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9687685" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9687685</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Silver, Jack (2020-12-08). "Let Us Teach Proper Thin Layer Chromatography Technique!". Journal of Chemical Education. 97 (12): 4217–4219. Bibcode:2020JChEd..97.4217S. doi:10.1021/acs.jchemed.0c00437. ISSN 0021-9584. S2CID 226349471. <a href="https://doi.org/10.1021%2Facs.jchemed.0c00437" target="_blank">https://doi.org/10.1021%2Facs.jchemed.0c00437</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>A.I. Vogel; A.R. Tatchell; B.S. Furnis; A.J. Hannaford & P.W.G. Smith (1989). Vogel's Textbook of Practical Organic Chemistry (5th ed.). Longman Scientific & Technical. ISBN 978-0-582-46236-6. <a href="978-0-582-46236-6" target="_blank">978-0-582-46236-6</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Jork, H., Funk, W., Fischer, W., Wimmer, H. (1990): Thin-Layer Chromatography: Reagents and Detection Methods, Volume 1a, VCH, Weinheim, ISBN 3-527-278834 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Thin Layer Chromatography: How To http://www.reachdevices.com/TLC.html <a href="http://www.reachdevices.com/TLC.html" target="_blank">http://www.reachdevices.com/TLC.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Silver, Jack (2020-12-08). "Let Us Teach Proper Thin Layer Chromatography Technique!". Journal of Chemical Education. 97 (12): 4217–4219. Bibcode:2020JChEd..97.4217S. doi:10.1021/acs.jchemed.0c00437. ISSN 0021-9584. S2CID 226349471. <a href="https://doi.org/10.1021%2Facs.jchemed.0c00437" target="_blank">https://doi.org/10.1021%2Facs.jchemed.0c00437</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Thin Layer Chromatography: How To http://www.reachdevices.com/TLC.html <a href="http://www.reachdevices.com/TLC.html" target="_blank">http://www.reachdevices.com/TLC.html</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Reich, E.; Schibli A. (2007). High-performance thin-layer chromatography for the analysis of medicinal plants (Illustrated ed.). New York: Thieme. ISBN 978-3-13-141601-8. <a href="978-3-13-141601-8" target="_blank">978-3-13-141601-8</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Reich, E.; Schibli A. (2007). High-performance thin-layer chromatography for the analysis of medicinal plants (Illustrated ed.). New York: Thieme. ISBN 978-3-13-141601-8. <a href="978-3-13-141601-8" target="_blank">978-3-13-141601-8</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Thin Layer Chromatography (TLC): Principle with animation <a href="http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/" target="_blank">http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Thin Layer Chromatography (TLC): Principle with animation <a href="http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/" target="_blank">http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Thin Layer Chromatography (TLC): Principle with animation <a href="http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/" target="_blank">http://pharmaxchange.info/press/2012/11/thin-layer-chromatography-tlc-principle-with-animation/</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Dolan, John W. (31 May 2006). "The Power of Mobile Phase Strength". LCGC North America. LCGC North America-06-01-2006. 24 (6): 570–578. Retrieved 30 March 2023. <a href="https://www.chromatographyonline.com/view/power-mobile-phase-strength" target="_blank">https://www.chromatographyonline.com/view/power-mobile-phase-strength</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Dolan, John W. (31 May 2006). "The Power of Mobile Phase Strength". LCGC North America. LCGC North America-06-01-2006. 24 (6): 570–578. Retrieved 30 March 2023. <a href="https://www.chromatographyonline.com/view/power-mobile-phase-strength" target="_blank">https://www.chromatographyonline.com/view/power-mobile-phase-strength</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Johnson, Andrew R.; Vitha, Mark F. (2011-01-28). "Chromatographic selectivity triangles". Journal of Chromatography A. EDITORS' CHOICE V. 1218 (4): 556–586. doi:10.1016/j.chroma.2010.09.046. ISSN 0021-9673. PMID 21067756. <a href="https://www.sciencedirect.com/science/article/pii/S0021967310012823" target="_blank">https://www.sciencedirect.com/science/article/pii/S0021967310012823</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Santiago, Marina; Strobel, Scott (2013-01-01), "Chapter Twenty-Four - Thin Layer Chromatography", in Lorsch, Jon (ed.), Cell, Lipid and Carbohydrate, Methods in Enzymology, vol. 533, Academic Press, pp. 303–324, doi:10.1016/b978-0-12-420067-8.00024-6, ISBN 978-0-12-420067-8, PMID 24182936, retrieved 2023-03-29 <a href="978-0-12-420067-8" target="_blank">978-0-12-420067-8</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Johnson, Andrew R.; Vitha, Mark F. (2011-01-28). "Chromatographic selectivity triangles". Journal of Chromatography A. EDITORS' CHOICE V. 1218 (4): 556–586. doi:10.1016/j.chroma.2010.09.046. ISSN 0021-9673. PMID 21067756. <a href="https://www.sciencedirect.com/science/article/pii/S0021967310012823" target="_blank">https://www.sciencedirect.com/science/article/pii/S0021967310012823</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>Snyder, Lloyd R.; Kirkland, Joseph J.; Dolan, John W. (2009-11-11). Introduction to Modern Liquid Chromatography. Hoboken, NJ, USA: John Wiley & Sons, Inc. doi:10.1002/9780470508183.app1. ISBN 978-0-470-50818-3. <a href="978-0-470-50818-3" target="_blank">978-0-470-50818-3</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>"SiliaPlate - TLC Practical Guide". SiliCycle. March 28, 2023. <a href="https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide" target="_blank">https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>Dickson, Hamilton; Kittredge, Kevin W.; Sarquis, Arlyne M. (1 July 2004). "Thin-Layer Chromatography: The "Eyes" of the Organic Chemist". Journal of Chemical Education. 81 (7): 1023. Bibcode:2004JChEd..81.1023D. doi:10.1021/ed081p1023. ISSN 0021-9584. <a href="https://pubs.acs.org/doi/abs/10.1021/ed081p1023" target="_blank">https://pubs.acs.org/doi/abs/10.1021/ed081p1023</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>"SiliaPlate - TLC Practical Guide". SiliCycle. March 28, 2023. <a href="https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide" target="_blank">https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>Jork, H., Funk, W., Fischer, W., Wimmer, H. (1990): Thin-Layer Chromatography: Reagents and Detection Methods, Volume 1a, VCH, Weinheim, ISBN 3-527-278834 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>Thin Layer Chromatography stains http://www.reachdevices.com/TLC_stains.html <a href="http://www.reachdevices.com/TLC_stains.html" target="_blank">http://www.reachdevices.com/TLC_stains.html</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>Jork, H., Funk, W., Fischer, W., Wimmer, H. (1994): Thin-Layer Chromatography: Reagents and Detection Methods, Volume 1b, VCH, Weinheim <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>O. Kaynar; Y. Berktas (2010-12-01). "How To Choose The Right Plate For Thin-Layer Chromatography?". Reviews in Analytical Chemistry. 29 (3–4): 129–148. doi:10.1515/REVAC.2010.29.3-4.129. ISSN 2191-0189. S2CID 94158318. <a href="https://doi.org/10.1515%2FREVAC.2010.29.3-4.129" target="_blank">https://doi.org/10.1515%2FREVAC.2010.29.3-4.129</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>O. Kaynar; Y. Berktas (2010-12-01). "How To Choose The Right Plate For Thin-Layer Chromatography?". Reviews in Analytical Chemistry. 29 (3–4): 129–148. doi:10.1515/REVAC.2010.29.3-4.129. ISSN 2191-0189. S2CID 94158318. <a href="https://doi.org/10.1515%2FREVAC.2010.29.3-4.129" target="_blank">https://doi.org/10.1515%2FREVAC.2010.29.3-4.129</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>Tables showing the thickness value of commercial regular and preparative Thin Layer Chromatography plates <a href="http://www.materialharvest.com/welcome/silica_products/tlc_plates.html" target="_blank">http://www.materialharvest.com/welcome/silica_products/tlc_plates.html</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>O. Kaynar; Y. Berktas (2010-12-01). "How To Choose The Right Plate For Thin-Layer Chromatography?". Reviews in Analytical Chemistry. 29 (3–4): 129–148. doi:10.1515/REVAC.2010.29.3-4.129. ISSN 2191-0189. S2CID 94158318. <a href="https://doi.org/10.1515%2FREVAC.2010.29.3-4.129" target="_blank">https://doi.org/10.1515%2FREVAC.2010.29.3-4.129</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>Dickson, Hamilton; Kittredge, Kevin W.; Sarquis, Arlyne M. (1 July 2004). "Thin-Layer Chromatography: The "Eyes" of the Organic Chemist". Journal of Chemical Education. 81 (7): 1023. Bibcode:2004JChEd..81.1023D. doi:10.1021/ed081p1023. ISSN 0021-9584. <a href="https://pubs.acs.org/doi/abs/10.1021/ed081p1023" target="_blank">https://pubs.acs.org/doi/abs/10.1021/ed081p1023</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>"SiliaPlate - TLC Practical Guide". SiliCycle. March 28, 2023. <a href="https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide" target="_blank">https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>"SiliaPlate - TLC Practical Guide". SiliCycle. March 28, 2023. <a href="https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide" target="_blank">https://www.silicycle.com/ca/products/thin-layer-chromatography-tlc-plates/siliaplate-tlc-practical-guide</a> <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>TLC plates as a convenient platform for solvent-free reactions Jonathan M. Stoddard, Lien Nguyen, Hector Mata-Chavez and Kelly Nguyen Chem. Commun., 2007, 1240–1241, doi:10.1039/b616311d <a href="/wiki/Chem._Commun." target="_blank">/wiki/Chem._Commun.</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>Bickler, Bob (22 November 2022). "Why is Solvent Evaluation by TLC Important for Good Flash Chromatography Results?". Biotage. Retrieved 1 April 2022. <a href="https://selekt.biotage.com/blog/why-is-solvent-evaluation-by-tlc-important-for-good-flash-chromatography-results" target="_blank">https://selekt.biotage.com/blog/why-is-solvent-evaluation-by-tlc-important-for-good-flash-chromatography-results</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>Wing, R. E.; Bemiller, J. N. (1972-01-01), Whistler, Roy L.; BeMiller, James N. (eds.), "[8] - Preparative Thin-Layer Chromatography", General Carbohydrate Method, Academic Press, pp. 60–64, doi:10.1016/b978-0-12-746206-6.50015-1, ISBN 978-0-12-746206-6, retrieved 2023-04-01 <a href="978-0-12-746206-6" target="_blank">978-0-12-746206-6</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>Wing, R. E.; Bemiller, J. N. (1972-01-01), Whistler, Roy L.; BeMiller, James N. (eds.), "[8] - Preparative Thin-Layer Chromatography", General Carbohydrate Method, Academic Press, pp. 60–64, doi:10.1016/b978-0-12-746206-6.50015-1, ISBN 978-0-12-746206-6, retrieved 2023-04-01 <a href="978-0-12-746206-6" target="_blank">978-0-12-746206-6</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>Wing, R. E.; Bemiller, J. N. (1972-01-01), Whistler, Roy L.; BeMiller, James N. (eds.), "[8] - Preparative Thin-Layer Chromatography", General Carbohydrate Method, Academic Press, pp. 60–64, doi:10.1016/b978-0-12-746206-6.50015-1, ISBN 978-0-12-746206-6, retrieved 2023-04-01 <a href="978-0-12-746206-6" target="_blank">978-0-12-746206-6</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>Snyder, Lloyd R.; Kirkland, Joseph J.; Dolan, John W. (2009-11-11). Introduction to Modern Liquid Chromatography. Hoboken, NJ, USA: John Wiley & Sons, Inc. doi:10.1002/9780470508183.app1. ISBN 978-0-470-50818-3. <a href="978-0-470-50818-3" target="_blank">978-0-470-50818-3</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></p></li> <li id="fn:53"><p>Bickler, Bob (13 November 2020). "Invest 10 minutes on TLC and save a day of grief". Retrieved 30 March 2023. <a href="https://selekt.biotage.com/blog/invest-10-minutes-on-tlc-and-save-a-day-of-grief" target="_blank">https://selekt.biotage.com/blog/invest-10-minutes-on-tlc-and-save-a-day-of-grief</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></p></li> <li id="fn:54"><p>Fair, Justin D.; Kormos, Chad M. (2008-11-21). "Flash column chromatograms estimated from thin-layer chromatography data". Journal of Chromatography A. 1211 (1): 49–54. doi:10.1016/j.chroma.2008.09.085. ISSN 0021-9673. PMID 18849041. <a href="https://www.sciencedirect.com/science/article/pii/S0021967308016683" target="_blank">https://www.sciencedirect.com/science/article/pii/S0021967308016683</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></p></li> <li id="fn:55"><p>Stahl, Egon (1969), Stahl, Egon (ed.), "Apparatus and General Techniquesss in TLC", Thin-Layer Chromatography: A Laboratory Handbook, Berlin, Heidelberg: Springer, pp. 52–86, doi:10.1007/978-3-642-88488-7_3, ISBN 978-3-642-88488-7, retrieved 2023-03-29 <a href="978-3-642-88488-7" target="_blank">978-3-642-88488-7</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></p></li> <li id="fn:56"><p>"Thin Layer Chromatography: A Complete Guide to TLC". Chemistry Hall. 2020-01-02. Retrieved 2020-01-30. <a href="https://chemistryhall.com/thin-layer-chromatography/" target="_blank">https://chemistryhall.com/thin-layer-chromatography/</a> <a href="#fnref:56" class="footnote-back-ref">↩</a></p></li> <li id="fn:57"><p>Bhushan, R.; Tanwar, S. J. Chromatogr. A 2010, 1217, 1395–1398. (doi:10.1016/j.chroma.2009.12.071) <a href="/wiki/Ravi_Bhushan" target="_blank">/wiki/Ravi_Bhushan</a> <a href="#fnref:57" class="footnote-back-ref">↩</a></p></li> </ol>