Hanna Instruments HI 931100 - Manual (Page 10)

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MAGNETIC STIRRER
HI 190M
POWER
SPEED
ON
OFF MAX
FILTERED
SOLUTION
6. Wait for the reading to stabilize, i.e. no drift
should be observed for at least a couple of
minutes. Note the measured value.
7. Since the dilution rate is 1/10, the reading in the
g/L range has to be divided by 100 to get the
actual reading of NaCl (per gram of cheese or
meat), or the value can be considered directly
expressed in % of NaCl.
Note: A response time of 10 to 15 minutes for the
first measurement of cheese or meat, is the
correct expected time for the electrode to
stabilize. Next measurements of cheese or
meat samples will require shorter response
time (less than 2 minutes). Do not rinse the
sodium electrode between subsequent mea-
surements since contamination is negligible.
IONIC STRENGTH ADJUSTER (ISA)
When the NaCl concentration of the sample is lower
than 5 g/L, it is recommend to use the HI 7090 ISA
solution. In such case, calibration should be per-
formed with standard solution containing 2% of ISA.
ISA (Ionic Strength Adjuster) = 50% of NH
4
Cl 4M +
50% of NH
4
OH 4M (use 2 mL of ISA every 100 mL
of sample).
HOW TO MEASURE SODIUM CHLORIDE IN
CHEESE AND MEAT (HI 931100)
1. Grind a sample of cheese or meat.
2. Pour a quantity (X g) in a glass beaker. Add
(X) x 10 mL of deionized water (note: ignoring
water content of cheese and meat).
3. Cover the beaker to prevent any spilling during
stirring, place the beaker on a hot plate stirrer
and agitate the sample at 40-50°C (104-122°F)
for 15-20 minutes.
4. Let the sample cool to the ambient temperature,
then filter it.
5. Dip the FC 300B sodium electrode into the fil-
tered sample. The tip of the electrode should be
immersed for approximately 2.5 cm/1" (i.e. the
electrode junction must be completely immersed)
without touching the bottom of the beaker. Dur-
ing measurement, the sample should be gently
stirred (100 rpm).
SPECIAL APPLICATIONS &
ADDITIONAL INFORMATION