Hach ISEF121 Series User manual

DOC022.53.80028
ISEF121
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............................................................................................. 4
3.4 Product hazards.................................................................................................... 5
Section 4 Preparation for use.............................................................................. 5
Section 5 Calibration............................................................................................... 5
5.1 Calibration notes ................................................................................................. 5
5.2 Calibration procedure........................................................................................... 6
Section 6 Sample measurement....................................................................... 7
6.1 Sample measurement notes ............................................................................... 7
6.2 Sample measurement procedure......................................................................... 7
6.3 Low-level measurements...................................................................................... 8
6.4 Interferences ....................................................................................................... 8
Section 7 Verify the calibration.......................................................................... 9
7.1 Verification procedure........................................................................................... 9
Section 8 Maintenance........................................................................................ 10
8.1 Clean the probe.................................................................................................. 10
8.2 Storage............................................................................................................... 10
Section 9 Troubleshooting ............................................................................... 11
9.1 Slope check........................................................................................................ 12
9.2 Standard additions check................................................................................... 12
Section 10 Consumables..................................................................................... 13
10.1 Accessories...................................................................................................... 13
1

Table of Contents
2

Section 1 Product overview
The Intellical ISEF121 series probes are digital, combination ion-selective electrodes (ISE) that
measure the concentration of fluoride in wastewater, drinking water and general water samples. The
probes have a built-in temperature sensor, a non-refillable gel reference and non-replaceable
membranes. Refer to Figure 1.
Figure 1 Probe overview
1 Sensing element 3 Sensor protection cap
2 Reference junction 4 Cable
Section 2 Specifications
Specifications are subject to change without notice.
Specifications Details
Probe type Digital combination probe with a non-refillable reference junction
and a built-in temperature sensor
Measurement range 0.01 mg/L (5x10–7 M) to 19,000 mg/L (1 M) F–
Accuracy ±0.02 mV or 0.05% (the larger value)
Sample pH range pH 4 to 8 (must be pH 5.0 to 5.5 after the addition of Fluoride ISA)
Reference type Ag/AgCl
Reference junction Single junction (annular porous PTFE)
Slope 59 mV/pF (90 to 110% at 25 °C (77 °F) in linear range per
Nernstian theoretical value)
Linear region 0.1 mg/L to 19,000 mg/L F–
Temperature accuracy ±0.3 °C (±0.54 °F)
Temperature sensor type 30 kΩ NTC thermistor
Operating temperature 5 to 50 °C (41 to 122 °F)
Storage temperature 5 to 35 °C (41 to 95 °F)
Response time in linear region < 60 seconds (application dependent)
English 3

Specifications Details
Minimum sample volume 25 mL
Minimum immersion depth 25.4 mm (1 in.)
Body material (standard) Epoxy
Sensor material Solid-state LaF3 crystal
Reference electrolyte Non-refillable Dritek gel reference element
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: ISEF12101: 1 m (3.3 ft); ISEF12103: 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.
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.
4 English

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.
Section 4 Preparation for use
Prepare the probe for calibration and measurement as follows.
1. Remove the sensor protection cap from the probe.
2. Rinse the probe with deionized water. Blot dry with a lint-free cloth.
3. Condition the probe before use. To condition the probe, soak the probe in approximately 25 mL of
the lowest concentration standard solution used for calibration for 30 to 60 minutes. Do not add
the ISA to the standard solution.
Note: Condition the probe each day for 15 to 30 minutes or for 30 to 60 minutes after long-term storage.
4. 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.
5. Connect the probe to the meter.
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 plastic containers during calibration and measurements. Glass containers can cause
inaccurate measurements.
• 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.
English 5

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 plastic
beakers.
3. Add one Fluoride
Ionic Strength
Adjustor (ISA)
Powder Pillow to
each 25 mL of
standard solution.
Note: As an alternative,
add 5 mL of Fluoride
ISA 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. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
6. 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.
7. Shake the probe
from side to side to
remove air bubbles.
8. Stir for 30 to
60 seconds, then
read the fluoride
concentration of the
standard solution.
9. Do steps 3
through 8 to read the
value of the
remaining standard
solutions.
10. Save the
calibration.
6 English

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.
• Use plastic containers during calibration and measurements. Glass containers can cause
inaccurate measurements.
• Rinse the probe with deionized water and dry with a lint-free cloth between measurements to
prevent contamination.
• If the stabilization time is long, try a different stir rate and make sure to condition the probe.
• 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 plastic
beaker.
2. Add one Fluoride
Ionic Strength
Adjustor (ISA)
Powder Pillow.
Note: As an alternative,
add 5 mL of Fluoride
ISA Solution.
3. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
4. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
English 7

5. 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.
6. Shake the probe
from side to side to
refresh the reference
junction and remove
air bubbles.
7. Stir for 30 to
60 seconds, then
read the fluoride
concentration of the
sample. The display
shows the value
when the reading is
stable.
6.3 Low-level measurements
Use the guidelines that follow for measurements at low concentrations (<1 mg/L F–).
• Use plastic containers during calibration and measurements. Glass containers can cause
inaccurate measurements.
• Clean the probe regularly as specified in Maintenance on page 10.
• Soak the probe in the lowest concentration standard solution for 1 hour maximum before
calibration and measurement.
• Use the meter to set the stability criteria for the probe to a low value.
• Stir the standards and samples at a slow and steady rate to prevent the formation of a vortex.
• Use a dilute ionic strength adjustor (ISA) solution for calibration and measurements:
1. Dissolve the contents of one ionic strength adjustor powder pillow in 50 mL of deionized water.
2. Add 5 mL of the dilute (ISA) solution to each 25 mL of standard solution or sample.
Note: The ISA is not necessary when all of the conditions that follow apply:
• The sample does not contain interferences.
• The sample pH is within the range given in the specifications.
• Omission of the ISA is accepted by the regulatory reporting agency (if the measurement is for regulatory
reporting).
6.4 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
Cations and most anions do not interfere with the fluoride measurements. Anions commonly
associated with fluoride (chloride (Cl–), bromide (Br–), sulfate (SO42–), bicarbonate (HCO3–),
phosphate (PO43–) and acetate (C2H3O2–)) do not interfere with the probe operation.
Hydroxide ions (OH–) interfere with the probe response when the pH is higher than pH 8. Some ions,
such as carbonate (CO32–) or phosphate (PO43–), increase the pH, which increases the hydroxide
(OH–) interference, but the ions do not directly interfere. Hydroxide ions (OH–) interfere with the
8 English

probe response when the level of hydroxide is more than 10% of the level of fluoride. The error
increases with an increase in pH and a decrease in fluoride.
When the Fluoride ISA is added to standards and samples, the pH is buffered between 5.0 and 5.5,
which prevents interference from hydroxide ion.
The selectivity coefficient is the approximate apparent increase in the measured concentration that is
caused by one unit of the interfering ion (e.g., 1 unit of OH– increases the fluoride concentration by
0.1). The approximate selectivity coefficients for some ions with the Intellical Fluoride ISE are shown
in Table 1.
Table 1 Interferences
Interference Selectivity coefficient
Hydroxide (OH–) 0.1 (below pH 8)
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 plastic
beaker.
3. Add one Fluoride
Ionic Strength
Adjustor (ISA)
Powder Pillow.
Note: As an alternative,
add 5 mL of Fluoride
ISA Solution.
4. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
English 9

5. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
6. 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.
7. Shake the probe
from side to side to
remove air bubbles.
8. 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 clean 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 deionized water. Dry the probe with a lint-free cloth.
2. Clean the sensing element as follows:
a. Lightly polish the sensing element with a small quantity of plain fluoride toothpaste (no teeth
whiteners or abrasives). Use a circular movement and polish until the sensing element is
clean.
b. Fully rinse with deionized water.
c. Soak the probe in isopropyl alcohol for 30 minutes.
d. Rinse the probe with deionized water.
e. Condition the probe. Refer to Preparation for use on page 5.
3. Soak the probe for 30 minutes in a 1-mg/L fluoride standard solution.
8.2 Storage
Keep the sensor protection cap on the probe during storage to prevent damage to the sensing
element.
Note: Make sure to condition the probe after long-term storage. Refer to Preparation for use on page 5.
1. Rinse the probe with deionized water. Dry the probe with a lint-free cloth.
2. Make sure that the probe sensor is dry, then install the sensor protection cap. Refer to Product
overview on page 3.
10 English

Section 9 Troubleshooting
Refer to Table 2 for general troubleshooting information. To check the probe performance, refer to
Slope check on page 12. To check the accuracy of sample measurements, refer to Standard
additions check on page 12.
Table 2 Troubleshooting information
Problem Possible cause Solution
Decreased probe performance
causes slow stabilization and
prevents accurate calibrations or
measurements.
The probe has contamination
on the sensing element.
Clean and condition the probe.
Refer to Clean the probe
on page 10.
The reference junction is
clogged.
Fully rinse the reference junction
with deionized water. 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.
Sample properties cause slow
stabilization or inaccurate
measurements.
The sample pH with ISA is
incorrect.
Make sure that the sample pH
after the ISA is added is
between 5.0 and 5.5. Make sure
to add one ISA pillow to each
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)).
Procedure problem causes slow
stabilization and prevents
accurate calibrations or
measurements.
Air bubbles are around or
below the probe tip.
Carefully tap or shake the probe
to remove air bubbles.
The ISA was not added. Add one ISA powder pillow to
each 25 mL of sample and
standard solution.
The stir speed is too slow or
too fast.
Try a different stir speed.
Magnetic stirrers can
become warm and increase
the solution temperature.
Put a piece of insulating material
between the stirrer and beaker.
An incorrect standard
solution was used or the
standard solution has
contamination.
Use the specified standard
solution of good quality.
Too much time passed after
the ISA was added.
Measure the sample or standard
solutions immediately after the
ISA is added.
English 11

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., 1 mg/L and
10 mg/L F–). Select standard solutions with a concentration above and below the typical sample
concentration. Use a minimum concentration of 1 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 F–
3 to 6 mg/L 1.0 mL 100 mg/L F–
7 to 15 mg/L 0.3 mL 1000 mg/L F–
15 to 30 mg/L 0.5 mL 1000 mg/L F–
30 to 60 mg/L 1.0 mL 1000 mg/L F–
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
12 English

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.
Fluoride Ionic Strength Adjustor Powder Pillows 100/pkg 258999
Fluoride Ionic Strength Adjustor Solution 3.78 L 2829017
Fluoride Standard Solution, 0.5 mg/L as F 500 mL 40505
Fluoride Standard Solution, 1 mg/L as F 500 mL 29149
Fluoride Standard Solution, 2 mg/L as F 500 mL 40520
Fluoride Standard Solution, 5 mg/L as F 500 mL 2797149
Fluoride Standard Solution, 10 mg/L as F 500 mL 35949
Fluoride Standard Solution, 100 mg/L as F 500 mL 23249
Wash bottle, polyethylene, 500 mL 1 62011
Disposable wipes, 11 x 22 cm 280/pkg 2097000
Beaker, 30 mL, plastic, colorless 80/pkg SM5010
Beaker, 100 mL, polypropylene 1 108042
Probe stand for standard Intellical probes 1 8508850
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
English 13

14 English

*DOC022.53.80028*
HACH COMPANY World Headquarters
P.O. Box 389, Loveland, CO 80539-0389 U.S.A.
Tel. [phone]
[phone] (U.S.A. only)
Fax [phone]
[email protected]
www.hach.com
HACH LANGE GMBH
Willstätterstraße 11
D-40549 Düsseldorf, Germany
Tel. [phone]
Fax [phone]
[email protected]
www.de.hach.com
HACH LANGE Sàrl
6, route de Compois
1222 Vésenaz
SWITZERLAND
Tel. [phone]
Fax [phone]
© Hach Company/Hach Lange GmbH, 2010-2011, 2013, 2021.
All rights reserved.