--- title: How can the exact concentration of glycol in a coolant be determined? description: Why refractometer readings can mislead, and how gas chromatography (GC) determines the exact glycol concentration and true freezing point. --- [Skip to content](https://faq.invicta.no/faq-en/how-can-the-exact-concentration-of-glycol-in-a-coolant-be-determined#main-content) - [English](https://faq.invicta.no/faq-en/how-can-the-exact-concentration-of-glycol-in-a-coolant-be-determined) - [Norsk](https://faq.invicta.no/faq/hvordan-kan-man-avdekke-nøyaktig-konsentrasjon-av-glykol-i-en-kjølevæske) English Show submenu for translations [![Invicta\_logo\_blue](https://faq.invicta.no/hs-fs/hubfs/Invicta_logo_blue.png?width=70&height=102&name=Invicta_logo_blue.png)](https://www.invicta.no) - [Hjem](https://www.invicta.no/) - [Bransjer](https://www.invicta.no/#bransjer) - [Analysetjenester](https://www.invicta.no/#tjenester) - [Ilum Access Kundeportal](https://access.ilum.no/login) Open main navigation Close main navigation - [Hjem](https://www.invicta.no/) - [Bransjer](https://www.invicta.no/#bransjer) - [Analysetjenester](https://www.invicta.no/#tjenester) - [Ilum Access Kundeportal](https://access.ilum.no/login) - - [English](https://faq.invicta.no/faq-en/how-can-the-exact-concentration-of-glycol-in-a-coolant-be-determined) - [Norsk](https://faq.invicta.no/faq/hvordan-kan-man-avdekke-nøyaktig-konsentrasjon-av-glykol-i-en-kjølevæske) English Show submenu for translations How can we help you? - There are no suggestions because the search field is empty. 1. [Invicta FAQ](https://faq.invicta.no/faq-en?hsLang=en) 2. [Products and analysis types](https://faq.invicta.no/faq-en/products-and-analysis-types?hsLang=en) 3. [Coolant analysis](https://faq.invicta.no/faq-en/products-and-analysis-types?hsLang=en#coolant-analysis) # How can the exact concentration of glycol in a coolant be determined? ## Analysis with GC-FID A refractometer reading will only work if there is one type of glycol, i.e. you will get a reading regardless of what has been mixed into the coolant, but the freezing point that is read off will not be correct. For example, if 5% vodka and 10% ethylene glycol are mixed with water, a refractometer may tell you that the freezing point is -19°C and 23% glycol. This is incorrect. The exact concentration of glycol is determined by analysis with Gas Chromatography (GC). The freezing point can then be calculated based on the measured amount of glycol. 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