Hach-Lange ISECL18103 User Manual - Manual (Page 12)

Message or symptom Possible cause Action
Temperature out of range
Calibration temperature value is
outside of range Make sure that the sample temperature is within the
range of the probe.
Make sure that the temperature sensor is working
correctly.
Measured temperature is outside
the range of the probe. Make sure that the standard temperature is within
the range of the probe.
Make sure that the temperature sensor is working
correctly.
Check standard temperature value
is outside of range Make sure that the check standard temperature is
within the range of the probe.
Below detection limit
Measurement is not quantifiable with
current saved calibration (based on
IUPAC-defined practical detection
limit). Perform a new calibration. Check that sample
concentration is bracketed between two standard
solution values (if within linear range).
Re-run calibration and measurement, optimizing
meter settings for slope acceptance and stabilization
criteria for expected sample concentration.
Re-run calibration and sample measurement with
the tips for low-level measurement.
Measurement value is outside of
range. Make sure sample is within the range of the probe.
Check probe response
To make sure there is a probe response, measure the probe potential (in mV) of two
Chloride Standard Solutions that are above and below the expected sample
concentration. For example, use 100 and 1000 mg/L Chloride Standard Solutions. The
two solutions should have potentials (difference in mV readings) that are 57 mV apart at
25 ºC (within the slope limits of the method is acceptable). Both solutions should be
above 7 mg/L Chloride.
Check accuracy of sample reading
To make sure the sample measurement is accurate, add a spike of Chloride Standard
Solution with the volumetric pipet. Refer to
Table 3 and formulas to calculate the percent
of recovery.
Typically a percent of recovery of 100% ±5% is a good indication that the instrument,
technique and the sample do not contribute to measurement errors.
Table 3 Spike reference
Measured sample concentration Volume of standard at add Concentration of standard
1 to 2 mg/L 0.5 mL 100 mg/L
3 to 6 mg/L 1.0 mL 100 mg/L
7 to 15 mg/L 0.3 mL 1000 mg/L
15 to 30 mg/L 0.5 mL 1000 mg/L
30 to 60 mg/L 1.0 mL 1000 mg/L
Percent recovery
Use the following formula to calculate the percent recovery when the sample volume is
25 mL:
E = (C x V
1
) / V
2
R = (A / (E + S)) x 100
• S = mg/L of Chloride in sample (before spike)
• C = concentration of standard used for spiking (mg/L)
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