Simple rugged non-aqueous potentiometric titration assay for urea

The US Pharmacopeia specifies a Kjeldahl distillation for the assay of urea, which is a time consuming, laborious and technique-oriented test. Other tests with similar complications include diazotization and urease enzyme methods. A typical quality control assay test would be a titration; however, an aqueous titration is not feasible owing to the neutral character of urea in aqueous media. The literature also refers to non-aqueous titrations but reproducibility is a major shortcoming. This paper describes a simple straightforward non-aqueous titration which is 100% accurate (based on recovery data), with a precision of <0.4% RSD.