In the Jaffe method, the kinetic improvement involves measuring absorbance at which?

• A. A single fixed time point
• B. Between two points
• C. At every minute for an hour
• D. Continuous real-time monitoring

Answer: (B)

In the kinetic Jaffe method, the focus is on the rate of color development rather than a single end-point. By measuring how absorbance changes between two time points, you obtain a slope that corresponds to the amount of creatinine present. This two-point (rate) approach helps minimize interference from substances that may react with picrate or affect the color at a fixed time, giving a more accurate and robust estimate of creatinine concentration. Reading at a single fixed time point can be biased by timing and non-specific reactions, and continuous real-time monitoring is more data-heavy and not necessary. So, using two points to determine the change in absorbance over time is the best approach.