Anions in high purity, boiler feed and nuclear reactor cooling waters - Determination of Anions in Natural and Treated Waters - page 610

Cyclohexylamine 10 <1 <1

Hydrazine 1 <1 <1

H 2 SO 4 10 <1 <1

Na 2 1+ SO 3

5 4.4 4.5

Fe 2+ , Cu 2+ , Zn 2+

1+1+1 −2.9 <1

Ca 2+ , Mg 2+ , K +

2+2+20 1.5 <1

0 2 −4 <1 -

a If the other substances had no effect the results would have been expected to fall within the
limits of 0 ±1.2 and 50±3.4µg L −1 at the 95% confidence level
Source: Reproduced with permission from the Electrochemical Society Inc., USA [14]

jacket, the correlation coefficient between EMF and concentration was always greater
than 0.99. The sensitivity (0.18mV µg L −1 of chloride at 25°C and 0.4-0.5mV µg L −1 of
chloride at 4°C) was about 10 times greater than that of the silver-silver chloride
electrode. Total standard deviations at 10, 5 and 2µg L −1 of chloride were 0.4, 0.5 and

0.3µg L −1 of chloride respectively.
Potentials were measured with a digital pH meter reading to 0.1mV and displayed on a
chart recorder. Two types of ion selective electrodes were used, those made from
Radiometer F3012 Universal electrodes, and the Ionel Model SL-01 (Ionel electrodes,
Mount Hope, Ontario, Canada). Both have membranes made of a mixture of mercury(II)
sulphide and mercury(II) chloride. In the electrode developed at CERL, the mixture is
used to impregnate a graphite PTFE electrode, while in the Ionel electrode the mixture is
hot pressed into a disc. The reference electrode was a mercury-mercury(I) sulphate
electrode with a 0.5mol L −1 sodium sulphate filling solution (instead of the usual 1mol
L −1 solution, which would have precipitated at the lowest operating temperature of 4°C).
The reservoir containing the filling solution and the reference element could be raised to
0.5m above the remote liquid junction, which was of the ground glass sleeve type.
The chloride electrode and the remote junction were housed in a flow cell fitted with a
water jacket through which thermostatically controlled water was circulated by means of
a Techne C-100 thermocirculator operated in conjunction with a Techne Model 1000
chiller unit. The remote junction was in a separate compartment downsteam of the
chloride electrode compartment, which contained a magnetic stirrer bar. The flow cell
was painted black to exclude light.
A Technicon Model 1 proportioning pump delivered the solutions to the flow cell,
pumping the sample or standard solutions at 3.9ml min−1 and the acid reagent solution at
0.8ml min −1 . Air was injected at 1ml min−1 to improve mixing. The air-segmented
mixture of sample and reagent solutions passed through a glass mixing coil to a T-piece,
from which the air and a portion of the solution were extracted at 1.6ml min −1 . The rate
of delivery of solution to the flow cell was, therefore, 4.1ml min −1 . The pump tubes were
made of PVC, but the transmission lines were made of PTFE.
Before entering the cell, the solution passed through a short length of stainless steel
tubing, which was connected to the chassis ground terminal on the pH meter. A stainless