Which method is described as expensive and sensitive for urea determination?

• A. Direct Chemical/Fearon
• B. Indirect Enzymatic
• C. Colorimetric
• D. Gravimetric

Answer: (B)

The concept here is that urea measurement methods differ in both cost and sensitivity, and enzymatic approaches often offer higher sensitivity thanks to enzyme specificity, but come with higher expense and complexity. Indirect enzymatic assays use a urease-driven reaction to split urea into detectable products, typically measuring the released ammonia or the reaction’s downstream signal. Because the enzyme reacts specifically with urea and under controlled conditions can detect very low concentrations with good precision, this approach is highly sensitive. The trade-off is cost and practicality: enzymes and their stabilizers, along with the need to maintain optimal temperature, pH, and sometimes proprietary reagents, push the price up and require more careful handling. In contrast, direct chemical methods can be simpler and cheaper but are more prone to interference from other substances and generally offer lower sensitivity. Gravimetric methods, while robust, are laborious and not suitable for routine high-throughput measurements, and colorimetric techniques vary in cost and can suffer from matrix effects.