Nova-Tech pH 310 - Manual (Page 21)

41
40
pH electrode activation (for glass bodied electrodes only) W
ARNING:
Only qualified persons pr
oficient with the safe handling of danger
ous
chemicals should perform the pr
ocedur
e below
. Pr
ovide pr
oper containers, fume
hoods, ventilation, and waste disposal. Safety goggles and pr
otective clothing must
be worn while performing this pr
ocedur
e. If possible, r
eplace with another electr
ode
instead of performing this r
eactivation pr
ocedur
e.
1.
Dip or stir the pH electrode
in alcohol for 5 minutes.
2.
Leave the electrode in tap water
for 15 minutes.
3.
Dip and stir the electrode
in concentrate acid (such as HCl or H
2 SO
4 ) for five
minutes.
4.
Repeat step 2.
5.
Dip and stir in strong base
(NaOH) for five minutes.
6.
Leave for 15 minutes
in distilled or deionized water
.
7.
Now test with standard calibration buf
fer solutions
to see if the electr
ode yields
acceptable r
esults.
Y
ou may r
epeat step 3 thr
ough 6 up to thr
ee times for better
response. If the r
esponse does not impr
ove, then your electr
ode is no longer
functioning. Replace with a new electr
ode—call your OAKT
ON Distributor for mor
e
information.
9. Probe Care and Maintenance
Since your pH electr
ode is susceptible to dirt and contamination, clean it every one
to thr
ee months depending on the extent and condition of use.
NOTE:
for specialty electr
ode car
e, consult the instr
uction manual included with
your electr
ode.
pH electrode storage For best r
esults, always keep the pH bulb wet. Use the pr
otective electr
ode storage
bottle or r
ubber cap filled with OAKT
ON
electr
ode storage solution to stor
e your
electr
ode (see page 45 for or
dering information).
Also, you can stor
e in a pH 4 buf
fer
with 1/100 part of saturated KCl. Other pH buf
fers ar
e OK for storage, but NEVER
use distilled water for storage. After measuring 1.
Rinse the pH electr
ode and r
efer
ence junction in de-ionized water
.
2.
Store the electrode as recommended above in “pH electrode storage,” or as recommended by the manufacturer
.
3.
Prior to next use, rinse the liquid junction with de-ionized water and tap dry— never wipe electrode.
NOTE:
If this does not r
estor
e electr
ode to normal r
esponse, see “Reactivating the
pH electr
ode” section below
.
pH electrode cleaning Salt deposits:
dissolve the deposits by immersing the electr
ode in tap water for ten
to fifteen minutes. T
en thor
oughly rinse with distilled water
.
Oil/grease film:
wash electr
ode pH bulb gently in some deter
gent and water
. Rinse
electr
ode tip with distilled water or use a general purpose electr
ode cleaner (see
page 40 for or
dering information).
Clogged reference junction:
heat a diluted KCl solution to 60 to 80°C. Place the
sensing part of the electr
ode into the heated solution for about 10 minutes.
Allow the
electr
ode to cool in some unheated KCl solution.
Protein deposits:
pr
epar
e a 1% pepsin solution in 0.1 M of HCl. Set the electr
ode in
the solution for five to ten minutes. Rinse the electr
ode with distilled water
.
Reactivating the pH electrode If stor
ed and cleaned pr
operly
, your pH electr
ode should be r
eady for immediate
use. However
, a dehydrated bulb may cause sluggish r
esponse. T
o
r
ehydrate the
bulb, immerse the electr
ode in a pH 4 buf
fer solution for 10 to 30 minutes. If this
fails, the electr
ode r
equir
es activation.
Never touch or rub glass bulb. Contact
builds up an electrostatic charge.
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