Hach ISENA381 Series User manual

DOC022.53.80027
ISENA381
05/2021, Edition 5
User Manual

Table of Contents
Section 1 Product overview................................................................................. 3
Section 2 Specifications........................................................................................ 3
Section 3 Safety information............................................................................... 4
3.1 Intended use ....................................................................................................... 4
3.2 Use of hazard information..................................................................................... 4
3.3 Precautionary labels............................................................................................. 5
3.4 Product hazards.................................................................................................... 5
Section 4 Preparation for use.............................................................................. 5
Section 5 Calibration............................................................................................... 8
5.1 Calibration notes ................................................................................................. 8
5.2 Calibration procedure........................................................................................... 9
Section 6 Sample measurement..................................................................... 10
6.1 Sample measurement notes ............................................................................. 10
6.2 Sample measurement procedure....................................................................... 10
6.3 Interferences ..................................................................................................... 11
Section 7 Verify the calibration........................................................................ 12
7.1 Verification procedure......................................................................................... 12
Section 8 Maintenance......................................................................................... 13
8.1 Clean the probe.................................................................................................. 13
8.2 Fill the probe....................................................................................................... 13
8.3 Replace the filling solution.................................................................................. 14
8.4 Storage............................................................................................................... 14
Section 9 Troubleshooting ............................................................................... 16
9.1 Slope check........................................................................................................ 17
9.2 Standard additions check................................................................................... 17
Section 10 Consumables..................................................................................... 18
10.1 Accessories...................................................................................................... 18
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Table of Contents
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Section 1 Product overview
The Intellical ISENA381 series probes are digital, combination ion-selective electrodes (ISE) that
measure the concentration of sodium in wastewater, drinking water and general water samples. The
probes are refillable and have a built-in temperature sensor and a double ceramic pin for a reference
junction. A 59-mL bottle of electrode filling solution is supplied with the probe. Refer to Figure 1.
Figure 1 Probe overview
1 Probe soaker bottle with storage solution 5 Cable
2 Glass bulb, reference junction and
temperature sensor
6 Probe soaker bottle holder
3 Filling-hole plug 7 Electrode filling and storage solution
4 Protective tape and filling hole 8 Dispensing cap
Section 2 Specifications
Specifications are subject to change without notice.
Specifications Details
Probe type Digital, combination ion selective probe with a double junction,
refillable junction reference and a built-in temperature sensor
Measurement range 0.023 mg/L (1x10–6 M) to 23,000 mg/L (1 M) Na+
Accuracy ±0.02 mV or 0.05% (the larger value)
Electrode resistance < 800 MΩ at 25 °C (77 °F)
Reference type Ag/AgCl
Reference junction Double ceramic porous pin junction
Slope –59 mV/pNa (90 to 110% at 25 °C (77 °F) per Nernstian theoretical
value)
Linear region 1.4 mg/L to 23,000 mg/L Na+
Temperature accuracy ±0.3 °C (±0.54 °F)
Temperature sensor type 30 kΩ NTC thermistor
Operating temperature 0 to 50 °C (32 to 122 °F)
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Specifications Details
Storage temperature 5 to 40 °C (41 to 104 °F)
Response time in linear region 1 to 2 minutes in sample concentration > 1.4 mg/L
Minimum sample volume 25 mL
Minimum immersion depth 25.4 mm (1 in.)
Electrode filling solution 0.02 M NH4Cl
Storage solution Long-term storage: 0.02 M NH4Cl
Short-term storage: User-prepared solution of 100-mg/L sodium
standard solution and one sodium ISA powder pillow per 25 mL
Sensor material pH glass
Cable connection M12 digital output and connector
Dimensions Diameter: 12 mm (0.47 in.)
Length: 175 mm (6.9 in.) total; 103 mm (4.1 in.) below head
Cable length: ISENA38101: 1 m (3.3 ft); ISENA38103: 3 m (9.8 ft)
Warranty 1 year on the probe. This warranty covers manufacturing defects,
but not improper use or wear.
Certifications CE, FCC/ISED
Section 3 Safety information
3.1 Intended use
The Intellical probes are intended for use by individuals who measure water quality parameters in the
laboratory. The Intellical probes do not treat or alter water.
3.2 Use of hazard information
D A N G E R
Indicates a potentially or imminently hazardous situation which, if not avoided, will result in death or
serious injury.
WARNING
Indicates a potentially or imminently hazardous situation which, if not avoided, could result in death
or serious injury.
CAUTION
Indicates a potentially hazardous situation that may result in minor or moderate injury.
N O T I C E
Indicates a situation which, if not avoided, may cause damage to the instrument. Information that
requires special emphasis.
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3.3 Precautionary labels
Read all labels and tags attached to the instrument. Personal injury or damage to the instrument
could occur if not observed. A symbol on the instrument is referenced in the manual with a
precautionary statement.
Electrical equipment marked with this symbol may not be disposed of in European
domestic or public disposal systems. Return old or end-of-life equipment to the
manufacturer for disposal at no charge to the user.
3.4 Product hazards
CAUTION
Chemical exposure hazard. Obey laboratory safety procedures and wear all of the
personal protective equipment appropriate to the chemicals that are handled. Refer to
the current safety data sheets (MSDS/SDS) for safety protocols.
CAUTION
Chemical exposure hazard. Dispose of chemicals and wastes in accordance with local,
regional and national regulations.
CAUTION
Personal injury hazard. Glass components can break. Handle with care to prevent cuts.
Section 4 Preparation for use
N O T I C E
Make sure to remove the protective tape from the filling hole of new probes. A probe with a blocked
filling hole will not operate correctly.
New probes are filled with electrolyte filling solution and have a soaker bottle that contains storage
solution to keep the glass bulb and reference junction hydrated. Prepare the probe for calibration and
measurement as follows.
1. Prepare the sodium (ISA) rinse solution as follows:
a. Pour a minimum of 25 mL of deionized water into a wash bottle.
b. Add one sodium ISA powder pillow (0.4 g) for each 25 mL of deionized water and mix. For
example, to prepare 200 mL of sodium ISA rinse solution, refer to Figure 2.
2. Remove the protective tape from the filling hole. Refer to Figure 3.
3. Rinse the reference junction and glass bulb with the prepared sodium ISA rinse solution. Blot dry
with a lint-free cloth. Do not use deionized water.
4. If the inner filling solution is low, add more filling solution. Refer to Fill the probe on page 13.
5. Condition the probe as follows:
a. Dissolve one Sodium Ionic Strength Adjustor (ISA) Powder Pillow in 25 mL of a 100 mg/L
sodium standard solution.
b. Open the filling hole.
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c. Put the probe in the prepared solution and soak the probe for 1 hour or more (8 hours for best
results).
Note: If probe stabilization is slow after storage, condition the probe for 1 hour or more (8 hours for best results)
in 25 mL of a 100 mg/L sodium standard solution that contains one Sodium Ionic Strength Adjustor (ISA)
Powder Pillow.
6. Make sure that the meter has the correct date and time settings. The service-life time stamp in
the probe comes from the date and time settings in the meter.
Note: Some meters automatically open the date and time settings when the meter starts for the first time, or
after battery replacement.
7. Connect the probe to the meter.
8. Open the filling hole before use. Keep the level of the electrolyte filling solution above the level of
the measurement liquid during use. Refer to Figure 4.
Figure 2 Prepare 200 mL sodium ISA rinse solution
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Figure 3 Remove the protective tape
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Figure 4 Probe position during use
1 Filling hole in open position 3 Level of calibration solution or sample
2 Level of electrolyte filling solution
Section 5 Calibration
The procedure that follows is applicable to meters that can connect to Intellical ISE probes. Refer to
the applicable meter documentation for meter operation and probe-specific settings.
5.1 Calibration notes
Read the notes that follow before calibration.
• Use only the prepared sodium ISA rinse solution to rinse the probe. Refer to Preparation for use
on page 5.
• For calibrations with low-level standards (<1 mg/L), use plastic beakers.
• Measure the standard solutions from lowest to highest concentration for best results.
• Keep all of the solutions (standard solutions and samples) at the same temperature (± 2 °C
(± 3.6 °F)) for best results.
• Stir the standards and samples at a slow and constant rate to prevent the formation of a vortex.
• Use the default calibration options or change the options in the probe settings menu.
• Use the single display mode for calibration when more than one probe is connected to the meter (if
applicable).
• Calibrate the probes and verify the calibration regularly for best results. Use the meter to set
calibration reminders.
• The calibration data is stored in the probe. When a calibrated probe is connected to a different
meter with the same calibration options, a new calibration is not necessary.
• Air bubbles below the sensor when in solution can cause a slow response or error in the
calibration. Make sure to remove air bubbles during calibration.
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5.2 Calibration procedure
1. Go to the
calibrate menu.
Select the probe, if
applicable. The
display shows the
standard solutions to
use for calibration.
2. Add 25 mL of
each standard
solution to different
beakers.
3. Add one Sodium
Ionic Strength
Adjustor (ISA)
Powder Pillow to
each 25 mL of
standard solution.
4. Add a stir bar to
the first standard
solution. Put the
standard solution on
an electromagnetic
stirrer. Stir at a
moderate rate.
5. Open the filling
hole.
6. Rinse the probe
with the prepared
sodium ISA rinse
solution. Dry the
probe with a lint-free
cloth. Do not use
deionized water.
7. Put the probe in
the standard solution
with the sensor fully
submerged. Do not
put the probe on the
bottom or sides of
the beaker.
8. Shake the probe
from side to side to
remove air bubbles.
9. Stir for 30 to
60 seconds, then
read the sodium
concentration of the
standard solution.
10. Do steps 3
through 9 to read the
value of the
remaining standard
solutions.
11. Save the
calibration.
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Section 6 Sample measurement
The procedure that follows is applicable to meters that can connect to Intellical ISE probes. Refer to
the applicable meter documentation for meter operation and probe-specific settings.
6.1 Sample measurement notes
Read the notes that follow before sample measurements.
• Rinse the probe with the prepared sodium ISA rinse solution and dry with a lint-free cloth between
measurements to prevent contamination. Use only the prepared sodium ISA rinse solution to rinse
the probe. Refer to Preparation for use on page 5.
• For measurements below 1 mg/L, use plastic beakers.
• If the stabilization time is long, try a different stir rate and make sure to condition the probe. Use a
standard solution (with ISA) that is near in concentration to the samples to be measured.
• Keep all of the solutions (standard solutions and samples) at the same temperature (± 2 °C
(± 3.6 °F)) for best results.
• If complete traceability is necessary, enter a sample ID and operator ID before measurement.
Refer to the meter manual for instructions.
• Stir the standards and samples at a slow and constant rate to prevent the formation of a vortex.
• The meter automatically saves the measurement data when the user manually reads each data
point and when the meter is set to read at regular intervals. The user must manually save each
data point when the meter is set to read continuously.
• Air bubbles below the sensor can cause a slow response or error in the measurement. Make sure
to remove air bubbles before and during measurements.
6.2 Sample measurement procedure
1. Pour 25 mL of
fresh sample into a
50‑mL beaker.
2. Add one Sodium
Ionic Strength
Adjustor (ISA)
Powder Pillow.
3. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
4. Open the filling
hole.
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5. Rinse the probe
with the prepared
sodium ISA rinse
solution. Dry the
probe with a lint-free
cloth. Do not use
deionized water.
6. Put the probe in
the sample with the
sensor fully in the
sample. Do not put
the probe on the
bottom or sides of
the beaker.
7. Shake the probe
from side to side to
refresh the reference
junction and remove
air bubbles.
8. Stir for 30 to
60 seconds, then
read the sodium
concentration of the
sample. The display
shows the value
when the reading is
stable.
6.3 Interferences
The sensing element will measure some other ions that are known to interfere with the method. The
probe response to other ions usually increases the mV potential and causes a positive error. The
response to other ions can be semi-quantitatively calculated through the Nikolsky equation, an
extended Nernst equation:
E = Eº + (RT/(zF))ln[aNa + KNax × ax]
Where
• ax = the activity of the interfering ion
• KNax = the selectivity coefficient for the interfering ion relative to the primary ion
The primary interferences for sodium ion-selective electrodes are silver and hydrogen ions. The
sodium ISA increases the pH, which decreases interference from the hydrogen ion. If the sample
contains high levels of interferences, soak the probe in 1 M sodium chloride to remove the ions from
the glass membrane.
If the samples are very acidic or have a high buffer capacity, make sure that the sample pH is above
9 after the ISA is added. If necessary, add a known quantity of ammonium hydroxide (NH4OH) to the
calibration standards and the samples to increase the pH. The ammonium ion NH4+ has a low
selectivity coefficient and does not interfere.
The ions that interfere in sodium determinations are given for molar concentrations of all ions. The
smaller the value of the selectivity coefficient, the lower the interference. Approximate values of
selectivity coefficients (K) are ordered from highest to lowest in Table 1.
Table 1 Interferences
Interference Selectivity coefficient
Silver (Ag+) >1000
Hydrogen ion (H+) 20 (reduced by ISA addition)
Lithium (Li+) 0.01
Potassium (K+) 0.001
Thallium (Tl+) 0.0002
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Section 7 Verify the calibration
Measure the value of a fresh standard solution at regular intervals to make sure the result is
accurate. The meter compares the expected standard solution value to the measured value and
accepts or rejects the measurement. The user can change the standard solution and acceptance
criteria for verification in the probe-specific settings.
Note: Password protection may prevent access to the acceptance criteria.
7.1 Verification procedure
1. Go to the
verification menu.
The display shows
the standard solution
to use for
verification.
Note: Menu name for
HQd meters: Run check
standard.
2. Pour 25 mL of the
standard solution
into a 50‑mL beaker.
3. Add one Sodium
Ionic Strength
Adjustor (ISA)
Powder Pillow.
4. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
5. Open the filling
hole.
6. Rinse the probe
with the prepared
sodium ISA rinse
solution. Dry the
probe with a lint-free
cloth. Do not use
deionized water.
7. Put the probe in
the standard solution
with the sensor fully
in the solution. Do
not put the probe on
the bottom or sides
of the beaker.
8. Shake the probe
from side to side to
remove air bubbles.
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9. Stir for 30 to
60 seconds, then
read the value of the
standard solution.
The meter accepts
or rejects the result.
Section 8 Maintenance
Regular maintenance is necessary for the best accuracy, stabilization time and life of the probe.
Keep the probe in the recommended storage solution between measurements.
8.1 Clean the probe
Clean the probe regularly to remove mineral or sample buildup on the sensing element. Symptoms of
contamination:
• Incorrect or irregular readings
• Slow stabilization times
• Calibration errors
• Sample material stays on the probe
1. Rinse the probe with the prepared sodium ISA rinse solution. Dry the probe with a lint-free cloth.
Do not use deionized water.
2. Soak the glass bulb for 12 to 16 hours in Hach Electrode Cleaning Solution.
3. Soak the probe for 1 minute in 25 mL of a 100-mg/L sodium standard solution that contains one
Sodium Ionic Strength Adjustor (ISA) Powder Pillow.
4. Rinse the probe with tap water, then rinse with the prepared sodium ISA rinse solution.
8.2 Fill the probe
Add electrolyte filling solution to the probe regularly to make sure that the electrolyte flows from the
probe to the sample. Refer to Figure 5. Refer to Specifications on page 3 for the correct filling
solution.
Note: If the dispensing tip becomes clogged, remove the dispensing tip and soak the tip in warm ISA rinse solution.
Fully dry and assemble the tip.
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Figure 5 Fill the probe
8.3 Replace the filling solution
If the filling solution becomes contaminated, replace the filling solution.
1. Tilt the probe and open the filling hole.
2. Use a plastic transfer pipet to remove the contaminated solution from the filling hole. Discard the
solution.
3. Rinse the inner probe three times with deionized water.
4. Rinse the inner probe three times with new filling solution.
5. Fill the probe with new filling solution. Refer to Fill the probe on page 13.
8.4 Storage
N O T I C E
Probes can become permanently damaged if kept in a storage solution that is not specified by the
manufacturer. Use only the specified storage solution.
For short-term storage (24 hours or less), the probe can stay in a solution of 100 mg/L Na+ standard
solution with one Sodium Ionic Strength Adjustor (ISA) Powder Pillow. Do not store the probe in
deionized water or in samples.
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For long-term storage (more than 24 hours), close the filling hole and put the soaker bottle with
0.02 M NH4Cl on the probe. Refer to Figure 6. Keep the probe in a vertical position with the sensor
and reference junction below the liquid level in the soaker bottle. Add 0.02 M NH4Cl to the soaker
bottle if necessary.
Note: Before use after long-term storage, condition the probe in 25 mL of a 100 mg/L Na+ standard solution with
one Sodium ISA pillow (0.4 g) for 8 hours or more.
Figure 6 Probe storage
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Section 9 Troubleshooting
Refer to Table 2 for general troubleshooting information. To check the probe performance, refer to
Slope check on page 17. To check the accuracy of sample measurements, refer to Standard
additions check on page 17.
Table 2 Troubleshooting information
Problem Possible cause Solution
Decreased probe performance
causes slow stabilization and
prevents accurate calibrations or
measurements.
The glass sensor is dirty. Clean and condition the probe.
Refer to Clean the probe
on page 13.
The filling solution has
contamination.
Replace the filling solution. Refer
to Replace the filling solution
on page 14.
The reference junction is
clogged.
Fully rinse the reference junction
with sodium ISA rinse solution.
Shake the probe down to remove
air bubbles.
The probe is not conditioned
to the sample sufficiently.
Condition the probe. Refer to
Preparation for use on page 5.
The glass bulb has become
dry.
Soak the probe tip in 25 mL of
100 mg/L sodium standard
solution with one sodium ISA
powder pillow for 8 hours or
more.
Sample properties cause slow
stabilization or inaccurate
measurements.
The sample pH with ISA is
less than pH 9.
Make sure that the sample pH
after the ISA is added is higher
than pH 9. Make sure to add one
ISA pillow per 25 mL of sample.
The sample temperature is
low, or there is a large
temperature difference
between samples.
Increase the sample temperature
or adjust the temperature of
different samples to be the same
(within 2 °C (3.6 °F)).
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Table 2 Troubleshooting information (continued)
Problem Possible cause Solution
Procedure problem causes slow
stabilization and prevents
accurate calibrations or
measurements.
The filling hole is closed. Open the filling hole during use.
The stir speed is too slow or
too fast.
Try a different stir speed.
Air bubbles are around or
below the probe tip.
Carefully tap or shake the probe
to remove air bubbles.
Magnetic stirrers can
become warm and increase
the solution temperature.
Put a piece of insulating material
between the stirrer and beaker.
The ISA was not added. Add one ISA powder pillow to
each 25 mL of sample and
standard solution.
An incorrect standard
solution was used or the
standard solution has
contamination.
Use the specified standard
solution of good quality.
The protective tape was not
removed from the filling
hole.
Remove the tape from the filling
hole. Refer to Preparation for use
on page 5.
9.1 Slope check
Use the mV value of two standard solutions to make sure the probe gives the correct slope.
1. Prepare two standard solutions that are ten times apart in concentration (e.g., 10 mg/L and
100 mg/L Na+). Select standard solutions with a concentration above and below the typical
sample concentration. Use a minimum concentration of 1.4 mg/L.
2. Use the measurement procedure to add the ISA and measure the mV value of each standard
solution.
3. Calculate the difference in the mV value of the two standard solutions to find the slope. If the
probe is in good condition, the slope will be 59 mV (within the ± slope limits of the method) at
25 °C (77 °F).
9.2 Standard additions check
To make sure that the sample measurement is accurate, add a small volume of a standard solution
to the sample and calculate the percent recovery. The sample with the known volume of standard
solution is known as a spiked sample.
1. Use the measurement procedure to measure the concentration of a 25-mL sample.
2. Use a pipet to add the applicable volume of standard solution to the sample. Refer to Table 3.
Table 3 Standard solution volumes and concentrations
Measured sample
concentration
Volume of standard to
add
Concentration of standard
solution
1 to 2 mg/L 0.5 mL 100 mg/L Na+
3 to 6 mg/L 1.0 mL 100 mg/L Na+
7 to 15 mg/L 0.3 mL 1000 mg/L Na+
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Table 3 Standard solution volumes and concentrations (continued)
Measured sample
concentration
Volume of standard to
add
Concentration of standard
solution
15 to 30 mg/L 0.5 mL 1000 mg/L Na+
30 to 60 mg/L 1.0 mL 1000 mg/L Na+
3. Measure the concentration of the spiked sample.
4. Calculate the expected (theoretical) concentration of the spiked sample:
CE = (CS x VS/VT) + (CSS x VSS/VT)
Where:
• CE = expected (theoretical) concentration of the spiked sample
• CS = concentration of the sample (mg/L) before the standard solution was added
• CSS = concentration of the standard solution (mg/L)
• VS = sample volume (mL) before the standard solution was added
• VSS = volume of the standard solution (mL)
• VT = total volume (standard solution volume (mL) + sample volume)
5. Calculate the percent recovery of the standard addition. A percent recovery of 100 (±5)% is an
indication that the sample measurements are accurate.
Percent recovery = CM/CE x 100
Where:
• CM = measured concentration of the sample after the addition of the standard solution
• CE = expected (theoretical) concentration of the sample after the addition of the standard
solution
Section 10 Consumables
Note: Product and Article numbers may vary for some selling regions. Contact the appropriate distributor or refer to
the company website for contact information.
Description Quantity Item no.
Sodium/Potassium Ionic Strength Adjustor (ISA) Powder
Pillows 100/pkg 4451569
Electrode filling solution, 0.02 M NH4Cl 59 mL 2965126
Sodium standard solution, 10 mg/L as Na 1 L 2835153
Sodium standard solution, 100 mg/L as Na 500 mL 2318149
Sodium standard solution, 1000 mg/L as Na 500 mL 1474949
10.1 Accessories
Description Quantity Item no.
Beaker, polypropylene, 50 mL, low form 1 108041
Disposable wipes, 11 x 22 cm 280/pkg 2097000
Wash bottle, polyethylene, 500 mL 1 62011
Probe stand for standard Intellical probes 1 8508850
Soaker bottle for probe storage 1 5192900
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