Editing PH meter (section)

==History==
[[File:Here's the new Beckman Pocket pH Meter 2012.002 b49f13 001.tif | thumb|right| "Here's the new Beckman Pocket pH Meter", 1956]]

The concept of pH was defined in 1909 by [[S. P. L. Sørensen]], and electrodes were used for pH measurement in the 1920s.<ref name=Determinants>{{cite book|last1=Travis|first1=Anthony S.|last2=Schröter|first2=H.G.|last3=Homburg|first3=E. |author3-link=Ernst Homburg|last4=Morris|first4=P.J.T.|title=Determinants in the evolution of the European chemical industry : 1900-1939 : new technologies, political frameworks, markets and companies|date=1998|publisher=Kluwer Acad. Publ.|location=Dordrecht|isbn=978-0-7923-4890-0|page=332|url=https://books.google.com/books?id=gvP7CAAAQBAJ&pg=PA332|access-date=29 May 2015}}</ref>

In October 1934, [[Arnold Orville Beckman]] registered the first patent for a complete chemical instrument for the measurement of pH, U.S. Patent No. 2,058,761, for his "acidimeter", later renamed the pH meter. Beckman developed the prototype as an assistant professor of chemistry at the [[California Institute of Technology]], when asked to devise a quick and accurate method for measuring the acidity of [[lemon]] juice for the [[California Fruit Growers Exchange]] ([[Sunkist Growers, Incorporated|Sunkist]]).<ref name="hundred"/>{{rp|131–135}}

On April 8, 1935, Beckman's renamed [[National Technical Laboratories]] focused on the manufacture of scientific instruments, with the Arthur H. Thomas Company as a distributor for its pH meter.<ref name="hundred">{{cite book | isbn = 978-0-941901-23-9 |author1=Arnold Thackray |author2=Minor Myers, Jr. |name-list-style=amp |others = foreword by James D. Watson. | year = 2000 | publisher = Chemical Heritage Foundation | location = Philadelphia, Pa. | title = Arnold O. Beckman : one hundred years of excellence}}</ref>{{rp|131–135}} In its first full year of sales, 1936, the company sold 444 pH meters for $60,000 in sales.<ref name="Landmarks"/> In years to come, the company sold millions of the units.<ref name=Chicago>{{cite news|last=Luther|first=Claudia|title=Arnold O. Beckman, 104|url=https://www.chicagotribune.com/2004/05/19/arnold-o-beckman-104/|access-date=8 March 2014|newspaper=Chicago Tribune News|date=May 19, 2004}}</ref><ref name=Jaehnig>{{cite book|last1=Jaehnig|first1=Kenton G.|title=Finding Aid to the Beckman Historical Collection 1911 - 2011 (Bulk 1935 - 2004 )|url=http://othmerlib.sciencehistory.org/record=b1072260~S6|website=Science History Institute|quote="Click on 'Beckman Historical Collection Finding Aid' to go to full document."|access-date=30 October 2015}}</ref> In 2004 the Beckman pH meter was designated an [[National Historic Chemical Landmarks|ACS National Historic Chemical Landmark]] in recognition of its significance as the first commercially successful electronic pH meter.<ref name="Landmarks">{{cite web |url = http://www.acs.org/content/acs/en/education/whatischemistry/landmarks/beckman.html |title = Development of the Beckman pH Meter |publisher = American Chemical Society |work = National Historic Chemical Landmarks |access-date= March 25, 2013}}</ref>

The [[Radiometer (company)|Radiometer]] Corporation of Denmark was founded in 1935, and began marketing a pH meter for medical use around 1936, but "the development of automatic pH-meters for industrial purposes was neglected. Instead American instrument makers successfully developed industrial pH-meters with a wide variety of applications, such as in breweries, paper works, alum works, and water treatment systems."<ref name=Determinants/>

In the 1940s the electrodes for pH meters were often difficult to make, or unreliable due to brittle glass. Dr. [[Werner Ingold]] began to industrialize the production of single-rod measuring cells, a combination of measurement and reference electrode in one construction unit,<ref>15.3.1957: English Patent – Measuring assemblies for the determination of ion concentrations and redox potentials, particularly suitable for carrying out measurements at elevated temperatures. Patent No. 850177</ref> which led to broader acceptance in a wide range of industries including pharmaceutical production.<ref>Dr. A. Fiechter, Dr. W. Ingold und A. Baerfuss, Chemie-Ingenieur-Technik 10 (1964) 1000-1004: "Die pH-Kontrolle in der mikrobiologischen Verfahrenstechnik"</ref>

Beckman marketed a portable "Pocket pH Meter" as early as 1956, but it did not have a digital read-out.<ref>{{cite web |title=Here's the new Beckman Pocket pH Meter |date= 1956 |url=https://digital.sciencehistory.org/works/4q77fr32b |website=Science History Institute |access-date=6 August 2019}}</ref>
In the 1970s Jenco Electronics of [[Taiwan]] designed and manufactured the first portable digital pH meter.  This meter was sold under the label of the [[Cole-Parmer|Cole-Parmer Corporation]].<ref name="Buie">{{cite web|last1=Buie|first1=John|title=Evolution of the pH Meter|url=http://www.labmanager.com/lab-product/2010/10/evolution-of-the-ph-meter|website=Lab Manager|access-date=October 7, 2010}}</ref>