YSI 6 series User Manual page 90

Sondes
CHLORIDE
When selecting ISE5-CL-, you will be given the choice of 1-point, 2-point, or 3-point calibrations for your
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chloride (Cl ) sensor. The procedure is identical to that for the ammonium sensor, except that the calibrant
values are in mg/L of Cl instead of NH
for chloride that are 10 times greater than for ammonium and nitrate. Thus, the low calibration value
should be 10 mg/L and the high calibration value should be 1000 mg/L Cl-. The difference is due to the
fact that the effect of contamination of standards from inadvertent leakage of chloride ion from either the
DO probe or the reference junction of the pH probe will be less significant at higher concentrations.
NOTE: YSI strongly recommends the use of the 3-point protocol to ensure the best possible performance
from all ISE sensors (ammonium, nitrate, and chloride)
OPTIC TURBIDITY
NOTE: Before calibrating your 6026 or 6136 turbidity sensor, pay particular attention to the following
cautions:
 To properly calibrate YSI turbidity sensors, you MUST use standards that have been prepared
according to details in Standard Methods for the Treatment of Water and Wastewater (Section 2130 B).
Acceptable standards include (a) formazin prepared according to Standard Methods; (b) dilutions of
4000 NTU formazin concentrate purchased from Hach; (c) Hach StablCal
denominations; and (d) AMCO-AEPA standards prepared specifically for the 6026 and 6136 by either
YSI or approved vendors who are listed on the YSI website (www.ysi.com). STANDARDS FROM
OTHER VENDORS ARE NOT APPROVED FOR THE YSI TURBIDITY SYSTEM AND THEIR
USE WILL LIKELY RESULT IN BOTH CALIBRATION ERRORS AND INCORRECT FIELD
READINGS.
 For AMCO-AEPA standards, the value entered by the user during the calibration protocol is
DIFFERENT depending on which sensor (6026 or 6136) is being calibrated. This reflects the
empirically determined fact that 6026 and 6136 sensors that have been calibrated to the same value in
the primary standard formazin, will have different responses in suspensions of the AEPA-AMCO
beads. This effect is likely due to the larger optical cell volume of the 6136. Thus, for example, the
label of the YSI 6073 turbidity standard bottle indicates that the value of the standard is 100 NTU
when used for calibration of the 6026 sensor, but 126 NTU when used to calibrate the 6136.
Note that the phenomenon of a sensor-specific formazin/AEPA-AMCO ratio is well known for sensors
other than the 6026 and 6136.
 The details below are relevant to the calibration of both turbidity sensors offered by YSI – 6026 and
6136. However, to calibrate a 6136 sensor, you should have Version 2.16 or later installed in your
sonde.
 If you are calibrating a 6136 turbidity sensor you MUST use either a black bottomed calibration cup or
laboratory glassware with the probe guard installed for the calibration. See Section 2.6.1 above for details.
Failure to carry out the calibration properly can result in inaccurate readings, particularly water of very
low turbidity.
 Before proceeding with the calibration, be certain that the probe compartment of the sonde has been
cleaned and is free of debris. Solid particles from this source, particularly those carried over from past
deployments, will contaminate the standards during your calibration protocol and cause either
calibration errors and/or inaccurate field data.
YSI Incorporated Environmental Monitoring Systems Operations Manual
-N. IMPORTANT: We recommend that the user employ standards
4
Section 2
TM
standards in various NTU
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