Primary standard


Primary standard

In metrology, a primary standard is a standard that is accurate enough that it is not calibrated by or subordinate to other standards. A primary standard in chemistry is a reliable, readily quantified substance. Features of a primary standard include:

1. High purity
2. Stability (low reactivity)
3. Low hygroscopicity and efflorescence
4. High solubility (if used in titration)
5. High equivalent weight

Some examples of primary standards according to the European Pharmacopoeia 5, ch. 4.2:

*Arsenic trioxide for making sodium arsenite solution for standardisation of sodium periodate solution (until Ph. Eur. 3, Appendix 2001 also for iodine and cerium(IV) sulfate solutions, since Ph. Eur. 4, 2002 standardised by sodium thiosulfate)
*Benzoic acid for standardisation of waterless basic solutions: ethanolic sodium and potassium hydroxide, TBAH, and alkali methanolates in methanol, isopropanol, or DMF
*Potassium bromate (KBrO3) for standardisation of sodium thiosulfate solutions
*Potassium hydrogen phthalate (usually called KHP) for standardisation of aqueous base and perchloric acid in acetic acid solutions
*Sodium carbonate for standardisation of aqueous acids: hydrochloric, sulfuric acid and nitric acid solutions (but not acetic acid)
*Sodium chloride for standardisation of silver nitrate solutions
*Sulfanilic acid for standardisation of sodium nitrite solutions
*Zinc powder, after being dissolved in sulfuric or hydrochloric acid, for standardisation of EDTA solutions

External links

* [http://www.chemistry.adelaide.edu.au/external/soc-rel/content/standard.htm Analytical Standards] Primary standard is used in titration.

A primary standard must contain the following,1. high purity2. atmospheric stability3. absence of hydrate water4. modest cost5. reasonable solubility6. reasonably high molar mass

Source : Skoog, West, Holler, Crouch "Fundamentals of Analytical Chemistry" Brooks/ Cole. California, 2004

ource

*Skoog and West. Fundamentals of Analytical Chemistry. (3rd ed.) Holt, Rinehart, and Winston, 1976.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • primary standard — pirminis etalonas statusas T sritis automatika atitikmenys: angl. primary standard vok. Primärnormal, n; Primärstandard, m rus. первичный эталон, m pranc. étalon primaire, m …   Automatikos terminų žodynas

  • primary standard — pirminis etalonas statusas T sritis Standartizacija ir metrologija apibrėžtis Patvirtintas arba plačiai pripažintas kaip geriausių metrologinių savybių etalonas, kurio vertė nustatoma nesiremiant kitais to paties dydžio etalonais. atitikmenys:… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • primary standard — pirminis etalonas statusas T sritis chemija apibrėžtis Patvirtintas ar plačiai pripažintas etalonas, kurio vertė nustatoma nesiremiant kitais to paties dydžio etalonais. atitikmenys: angl. primary standard rus. первичный эталон …   Chemijos terminų aiškinamasis žodynas

  • primary standard — pirminis etalonas statusas T sritis fizika atitikmenys: angl. primary standard vok. Primärnormal, n; Urmaß, n; Urnormal, n rus. первичный эталон, m; первоначальный эталон, m pranc. étalon primaire, m …   Fizikos terminų žodynas

  • primary standard solution — pirminis etaloninis tirpalas statusas T sritis Standartizacija ir metrologija apibrėžtis Tirpalas, kuriame reikiama analičių koncentracija gaunama pasvertame tirpiklyje tirpinant pasvertą žinomos sudėties ir grynumo medžiagos kiekį. atitikmenys:… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • primary standard solution — pirminis etaloninis tirpalas statusas T sritis chemija apibrėžtis Tirpalas, kuriame reikiama analičių koncentracija gaunama pasvertame tirpiklyje tirpinant pasvertą žinomos sudėties ir grynumo medžiagos kiekį. atitikmenys: angl. certified… …   Chemijos terminų aiškinamasis žodynas

  • primary standard solution — pirminis etaloninis tirpalas statusas T sritis fizika atitikmenys: angl. primary certified reference solution; primary standard solution vok. primäre Standardlösung, f rus. первичный стандартный раствор, m; первичный эталонный раствор, m pranc.… …   Fizikos terminų žodynas

  • Standard solution — is a chemical term which describes a solution of known concentration. The concentration of the solution is normally expressed in units of moles per Litre (mol/L, often abbreviated to M for molarity). Standard solutions are normally used in… …   Wikipedia

  • Primary instrument — A primary instrument is a scientific instrument, which by its physical characteristics is accurate and is not calibrated against anything else. A primary instrument must be able to be exactly duplicated anywhere, anytime with identical… …   Wikipedia

  • primary certified reference solution — pirminis etaloninis tirpalas statusas T sritis Standartizacija ir metrologija apibrėžtis Tirpalas, kuriame reikiama analičių koncentracija gaunama pasvertame tirpiklyje tirpinant pasvertą žinomos sudėties ir grynumo medžiagos kiekį. atitikmenys:… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.