A defined number of tablets is directly weighed out into the sample vessel. After positioning the samples on the sample rack, all relevant analysis data such as weight, position and identification of the sample are entered into the sample data table of the tiamo™ software. Prior to comminution, the sample is transported to the second workstation where 60ml methanol is added.

Subsequently the Polytron comminutes the tablet for 90s at 25,000rpm; comminution of three tablets requires a comminution time of 120s. 10ml water is added to the homogenised sample. Using the 809 Titrando and the Solvotrode, benzbromaron is titrated with sodium hydroxide solution (1 mol/L). While the benzbromaron sample is being titrated, cleaning is performed fully automatically in the external rinsing station.

Benzbromaron titration

Benzbromaron is a weak acid whose pKa (4.50) is comparable to that of acetic acid (4.75). After loss of the hydrogen ion, the negative charge at the oxygen atom is delocalised around the ring. The more stable the ion is, the more likely it is to form. Hence, titration with strong bases is a convenient method for benzbromaron determination.

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