Rapid spectrophotometric pH measurements based on the dual-wavelength technique.
A spectrophotometric method for the measurement of pH in solutions of lidocaine hydrochloride (Xylocaine) for injection is presented. 4-Nitrophenol is used as an indicator for determinations of pH in the range 6.5-7.0. The method was found to be faster than the conventional potentiometric method, mainly due to the utilization of a computer-controlled photodiode array spectrophotometer for the measurements. A further advantage with the spectrophotometric method is that errors arising from varying liquid junction potentials are avoided.
Johansson
P A
PA
Astra Pharmaceutical Production AB, Analytical Control, S-151 85 Södertälje, Sweden.
Ostling
G
G
Drakenberg
J
J