Team:Brown-Stanford/Lab/Protocols/Conductivity

Conductivity Measurements of Ureolysis

(Guided by conductivity protocol of [Whiffen et al. (2004)])

Reagents/supplies

• Cell culture(s), 5 mL per culture of known cell density
• 1.5M Urea, 30 mL per culture
• Conductivity meter

Protocol

1. Before beginning, equalize the temperatures of both the 1.5M urea solution and the liquid cultures are made constant; changes in temperature can have large effects on the conductivity of ionic solutions, and a change in temperature may overshadow the increase in conductivity due to ureolysis
2. Calibrate conductivity meter
3. Take background measurements of the conductivity of both staring solutions
4. Add 30 µL of 1.5M urea to each cell culture. Measure conductivity at prescribed intervals

Calculations

• Urea hydrolyzed (mM) = Conductivity (mS/cm) x 11.11 at 25˚C