{"id":14912,"date":"2019-04-04T15:31:25","date_gmt":"2019-04-04T13:31:25","guid":{"rendered":"https:\/\/www.rct-online.de\/magazin\/?p=14912"},"modified":"2026-03-26T11:37:41","modified_gmt":"2026-03-26T10:37:41","slug":"cas-numbers","status":"publish","type":"post","link":"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/","title":{"rendered":"CAS Numbers"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_73 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/#The_Birth_Certificates_of_Chemical_Substances\" title=\"The Birth Certificates of Chemical Substances\">The Birth Certificates of Chemical Substances<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/#The_Chemical_Abstracts_Service_CAS\" title=\"The Chemical Abstracts Service (CAS)\">The Chemical Abstracts Service (CAS)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/#The_CAS_Number\" title=\"The CAS Number\">The CAS Number<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/#The_CAS_Database_in_Practice\" title=\"The CAS Database in Practice\">The CAS Database in Practice<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/cas-numbers\/#Outlook\" title=\"Outlook\">Outlook<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"The_Birth_Certificates_of_Chemical_Substances\"><\/span>The Birth Certificates of Chemical Substances<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\"><strong>In chemical research \u2013 and especially in the development of new chemical products \u2013 detailed knowledge of the properties of the raw and auxiliary materials used is an essential prerequisite. When conducting literature searches, reviewing patents, or browsing databases, one almost always encounters the so-called CAS numbers alongside the usual substance data. The following article explains how they are created and what they mean.<\/strong><\/p>\n<p style=\"text-align: justify;\">According to the latest figures from the American Chemical Society (ACS), more than 140 million chemically defined substances are currently known \u2013 and the number continues to grow daily. These substances are mainly published in scientific journals and patent documents and are increasingly indexed in databases that serve as information tools. However, many of these databases are field-specific and therefore not comprehensive.<\/p>\n<p style=\"text-align: justify;\">One example is the extensive GESTIS database, which is maintained by the German Social Accident Insurance. It mainly focuses on substances relevant to occupational safety and accident prevention. This can be compared to national occupational safety databases or toxicological information systems available in other European countries.<\/p>\n<blockquote>\n<p style=\"text-align: justify;\">GESTIS, for instance, lists pure water (H<sub>2<\/sub>O) but not its isotopic analogues: so-called <em>heavy water<\/em>, deuterium oxide (D<sub>2<\/sub>O), and radioactive tritium oxide (T<sub>2<\/sub>O).<\/p>\n<\/blockquote>\n<h2><span class=\"ez-toc-section\" id=\"The_Chemical_Abstracts_Service_CAS\"><\/span>The Chemical Abstracts Service (CAS)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">The most comprehensive database for chemical research is provided by the Chemical Abstracts Service (CAS), based in Columbus, Ohio, USA. Established in 1965, CAS serves as a classic reference database for literature searches.<\/p>\n<p style=\"text-align: justify;\">This service is operated by the American Chemical Society (ACS), the world\u2019s largest professional organisation for chemistry, which evaluates global scientific literature and records every newly identified substance.<\/p>\n<p style=\"text-align: justify;\">In addition to English abstracts of collected scientific articles, the CAS database offers direct links to the original publications. It contains nearly all scientific literature on chemistry, biochemistry, polymer technology, and materials science dating back to 1907.<\/p>\n<figure id=\"attachment_3485\" aria-describedby=\"caption-attachment-3485\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3485 size-full\" title=\"American Chemical Society headquarters in Washington, D.C.\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/American-Chemical-Society-Gebaeude.jpg\" alt=\"American Chemical Society headquarters in Washington, D.C.\" width=\"600\" height=\"396\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/American-Chemical-Society-Gebaeude.jpg 600w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/American-Chemical-Society-Gebaeude-300x198.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/American-Chemical-Society-Gebaeude-310x205.jpg 310w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-3485\" class=\"wp-caption-text\">Headquarters of the American Chemical Society (ACS) in Washington, D.C. | By AgnosticPreachersKid &#8211; Own work, CC BY-SA 3.0, https:\/\/commons.wikimedia.org\/w\/index.php?curid=10689881<\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"The_CAS_Number\"><\/span>The CAS Number<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">A CAS number (Chemical Abstracts Service Registry Number) is the unique registration number assigned to each individual substance entry in the CAS database. It provides a clear numerical identifier for every chemical substance. The numbers are issued sequentially and bear no intrinsic relation to the properties or structure of the compound itself. In this sense, the CAS number functions as a \u201cbirth certificate\u201d for each known chemical substance.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/bottles-carboys-and-accessories\/29663\/narrow-neck-bottle-made-of-ldpe\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3501 size-full\" title=\"Narrow-Neck Bottle made of LDPE | translucent | natural-coloured | with tight screw cap\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/enghalsflasche-aus-ldpe.jpg\" alt=\"Narrow-Neck Bottle made of LDPE \" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/enghalsflasche-aus-ldpe.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/enghalsflasche-aus-ldpe-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/bottles-carboys-and-accessories\/29718\/jerrycan-made-of-pp-stackable\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3502 size-full\" title=\" Jerrycan made of PP | stackable | transparent | thick-walled and place-saving at the same time\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/kanister-aus-pp-baukastensystem.jpg\" alt=\"kanister-aus-pp-baukastensystem\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/kanister-aus-pp-baukastensystem.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/kanister-aus-pp-baukastensystem-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center><\/p>\n<p style=\"text-align: justify;\">The CAS number consists of up to ten digits divided into three blocks (e.g. 9 8 7 6 5 4 3 \u2013 2 1 \u2013 0). The first two blocks represent the registration entry; the last digit is a check digit that verifies the validity of the entry. \u00a0It is calculated as the last digit of the weighted sum of all preceding digits in the CAS Registry Number, using the following formula:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3476 size-full\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/04\/R.png\" alt=\"R\" width=\"161\" height=\"48\" \/><\/p>\n<p style=\"text-align: justify;\">For example, for the polymer polypropylene (PP) with CAS Registry Number 9003-07-0, the check digit 0 results from the following calculation (from right to left):<\/p>\n<p>R = (1 x 7) + (2 x 0) + (3 x 3) + (4 x 0) + (5 x 0) + (6 x 9) = 70<\/p>\n<p style=\"text-align: justify;\">Since the sum R = 70, the check digit is 0. Thus, the complete CAS number for polypropylene (PP) is 9003-07-0.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"The_CAS_Database_in_Practice\"><\/span>The CAS Database in Practice<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">The CAS database provides information on virtually every chemical substance known to date \u2013 including minerals, polymers, alloys, proteins, and DNA sequences. It also contains all known information about the chemical elements, each uniquely documented by its CAS number, for example: oxygen (CAS number 7782-44-7), chlorine (CAS number 7782-50-5), lead (CAS number 7439-92-1), and radioactive plutonium (CAS number 7440-07-5).<\/p>\n<figure id=\"attachment_3489\" aria-describedby=\"caption-attachment-3489\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3489 size-full\" title=\"Periodic Table of Elements\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/Periodensystem-der-Elemente.jpg\" alt=\"Periodic Table of Elements\" width=\"600\" height=\"385\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/Periodensystem-der-Elemente.jpg 600w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/Periodensystem-der-Elemente-300x193.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-3489\" class=\"wp-caption-text\">\u00a9 Humdan \u2013 stock.adobe.com<\/figcaption><\/figure>\n<p>Even recently synthesized, artificial elements have been added to the CAS Registry. The element Tennessine (Ts), first produced in 2010 with atomic number 117, has the CAS number 87658-56-8.<\/p>\n<p style=\"text-align: justify;\">Likewise, the superheavy synthetic element Oganesson (Og), with the to date highest atomic number of\u00a0 118, is registered under 54144-19-3. Its existence, first reported in 2006, was debated for years until it was officially confirmed by the International Union of Pure and Applied Chemistry (IUPAC) in 2015.<\/p>\n<figure id=\"attachment_3487\" aria-describedby=\"caption-attachment-3487\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3487 size-full\" title=\"Three Isotopes of Hydrogen\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/wasserstoff-isotope.jpg\" alt=\"Three Isotopes of Hydrogen\" width=\"600\" height=\"320\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/wasserstoff-isotope.jpg 600w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/wasserstoff-isotope-300x160.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/wasserstoff-isotope-310x165.jpg 310w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-3487\" class=\"wp-caption-text\">\u00a9 Balint Radu \u2013 stock.adobe.com<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Unlike many other databases, the CAS Registry also includes isotopic analogues of compounds. This can be illustrated using water:<\/p>\n<p style=\"text-align: justify;\">Pure water (H\u2082O) has the CAS number 7732-18-5, while so-called &#8220;heavy water&#8221; (D\u2082O), in which hydrogen is replaced by its heavier isotope deuterium (D), is registered under CAS number 7789-20-0. Water (T\u2082O) formed from the heaviest of the three hydrogen isotopes, radioactive tritium (T), has the CAS number 1494-65-9.<\/p>\n<p style=\"text-align: justify;\">The CAS Registry is updated daily, making it the most comprehensive information source worldwide for chemists, product developers, engineers, and decision-makers in industry. Access is available through the SciFinder\u00ae software via the Chemical Abstracts Service website. Using a CAS number, users can directly retrieve substance-specific information and related literature references.<\/p>\n<p><center><a style=\"outline-width: 0px !important; user-select: auto !important;\" href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/dishes-and-crucibles\/29782\/evaporating-dish-made-of-ptfe-with-spout\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3506 size-full\" title=\"Evaporating Dish made of PTFE - with spout | very sturdy &amp; stable | in slightly conical design\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/abdampfschale-aus-ptfe-mit-ausguss.jpg\" alt=\"Evaporating Dish made of PTFE - with spout\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/abdampfschale-aus-ptfe-mit-ausguss.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/abdampfschale-aus-ptfe-mit-ausguss-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/metering-facilities-and-metering-devices\/pipette-and-accessories\/29943\/universal-bulb-pipette-made-of-pp\"><img loading=\"lazy\" decoding=\"async\" class=\"Vollpipette aus PP alignnone wp-image-3507 size-full\" title=\"Universal Bulb Pipette made of PP | transparent, permanently coloured ring mark (blue) and marking.\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/universal-vollpipette-aus-pp.jpg\" alt=\"Universal Bulb Pipette made of PP \" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/universal-vollpipette-aus-pp.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/universal-vollpipette-aus-pp-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center>However, access to the CAS Registry is restricted to registered users, and the linked publications are available only via paid access. However, this cost is justified by the scope and reliability of the data provided.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Outlook\"><\/span>Outlook<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">The number of new substances continues to rise. In the late 1960s, only about one million substances were known and registered; ten years later, the number had grown to five million, and by the early 2000s it exceeded twenty million. Today, over 140 million substances are recorded in the CAS Registry \u2013 and there is no end in sight.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/filtration\/prefilters-and-filter-holders\/30795\/filter-holder-made-of-pc\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3511 size-full\" title=\"Filter Holder made of PC | for ultrapurification and sterile filtration of small volumes | particularly economic in price\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/filterhalter-aus-pc.jpg\" alt=\"Filter Holder made of PC\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/filterhalter-aus-pc.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/filterhalter-aus-pc-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/tubes-hoses\/tubings-and-pipes-made-of-rigid-plastics\/pe-tubing\/28748\/hdpe-chemical-tubing\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3512 size-full\" title=\"HDPE Chemical Tubing | high density | good weldable (laboratory and container building) | hardly absorbs water\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/hdpe-chemieschlauch.jpg\" alt=\"hdpe-chemieschlauch\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/hdpe-chemieschlauch.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2019\/05\/hdpe-chemieschlauch-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center><\/p>\n<p style=\"text-align: justify;\">One major reason is that since the mid-1990s, biologically relevant compounds such as DNA sequences and proteins have been included in the registry, accounting for a large share of new entries. Still, continuous research in classical areas of chemistry \u2013 including pharmaceuticals, medical chemistry, polymer science, agriculture, and food chemistry \u2013 will keep contributing new substances in the future.<\/p>\n<p style=\"text-align: justify;\">Whether these substances find practical application or not is irrelevant: the CAS Registry records everything new, even if some entries may seem abstract or theoretical, like those for the synthetic elements. In this way, knowledge once gained is never lost.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Birth Certificates of Chemical Substances In chemical research \u2013 and especially in the development of new chemical products \u2013 detailed knowledge of the properties of the raw and auxiliary materials used is an essential prerequisite. When conducting literature searches, reviewing patents, or browsing databases, one almost always encounters the so-called CAS numbers alongside the &hellip;<\/p>\n","protected":false},"author":4,"featured_media":11852,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,3028,2748,3029],"tags":[3438,3442,3433,3431,3443,3434,2750,3432,3436,2947,3441,3437,2948,3435,3444,3439,2774,2775,3445,3440],"class_list":["post-14912","post","type-post","status-publish","format-standard","has-post-thumbnail","","category-all-articles","category-alle-beitraege-en","category-materials-in-chemistry","category-werkstoffe-in-der-chemie-en","tag-canister","tag-cas-en","tag-cas-number","tag-cas-numbers","tag-chemical-abstracts-service-en","tag-chemical-elements","tag-chemical-hoses","tag-evaporating-dishes","tag-filter-holder","tag-hdpe-en","tag-hydrogen","tag-isotopes","tag-ldpe-en","tag-narrow-neck","tag-pc-en","tag-periodic-table","tag-pp-en","tag-ptfe-en","tag-universal-en","tag-volumetric-pipettes"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.1 - 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