FTIR Analysis of Mouse Urine Urea Using IR Cards

Abstract

Urea in mouse urine results from the normal breakdown and use of protein. A variation in its content may indicate a change in the way the mouse's metabolism, liver, and kidney are functioning. To demonstrate the feasibility of using FTIR–IR cards for urine urea analysis, urine samples were obtained from two control females and four pregnant mice during their pregnancy. An internal standard, potassium thiocyanate (KSCN), was added to each of the urine samples in a 3:1 ratio. Dry urea/KSCN films were obtained by spreading the urine/KSCN samples onto the polyethylene windows of the IR cards. Sample transmission spectra were obtained using a Genesis II FTIR spectrometer (Mattson). Urea content was indicated by the ratio of the peak due to urea at 3458 cm⁻¹ to the peak due to KSCN at 2060 cm⁻¹. The urea molarities were determined based on a FTIR analysis of a set of standard urea/KSCN solutions. Results showed that the urea content remained at a constant level for the control mice: (3.9 ± 0.2) M for control mouse 215c and (3.1 ± 0.2) M for control mouse 219c. However, a large variation in urea content was observed for the pregnant mice right before and right after their deliveries.

Keywords:

• IR cards
• Metabolism
• KSCN solutions
• Urea