Metrohm has described a system and method to provide automatic determination of hydroxyl number (HN) according to ASTM E 1899-08 and DIN 53240-2.
The hydroxyl number is defined as the mg of KOH equivalent to the hydroxyl content of 1g of sample.
The system used to carry out the test consists of: the Metrohm 814 USB sample processor; 905 Titrando; 800 Dosino; Solvotrode and Tiamo software.
The method suggested in ASTM E 1899-08 is based on the reaction of the primary and secondary hydroxyl groups with excess toluene-4-sulfonyl-isocyanate (TSI) to form an acidic carbamate.
The latter can then be titrated in a non-aqueous medium with the strong base tetrabutyl-ammonium hydroxide.
The method suggested in DIN 53240-2 is based on the catalysed acetylation of the hydroxyl group.
After hydrolysis of the intermediate, the remaining acetic acid is titrated in a non-aqueous medium with alcoholic KOH solution.
The Metrohm system automates these two methods for determining polyols and oxooils.
Because it eliminates tedious and time-consuming manual tasks, it offers an immediate return-on-investment to laboratories that analyse a large number of samples per day, the company claimed.
All Metrohm systems come with a three-year warranty.
