Xylem 6-Series Multiparameter - Manual (Page 93)

Sondes Section 2
YSI Incorporated Environmental Monitoring Systems Operations Manual 2-87
To calibrate your 6131 Blue-Green Algae-Phycocyanin (BGA-PC) sensor, select BGA-PC cells/mL in the
initial calibration routine. There will be a choice of 1-point or 2-point options. The 1-point selection is
normally used to zero the fluorescence probe in a medium that is BGA-free. If you use this method, you
will either choose to utilize the default sensitivity for BGA-PC in the sonde software or to update a
previous 2-point calibration. Usually you will place the sonde in clear water, and input 0 µg/L at the screen
prompt. After pressing Enter the screen will display real-time readings allowing you to determine when
the BGA-PC readings have stabilized. Press Enter after the readings have stabilized to confirm the
calibration and zero the sensor. Then, as instructed, press any key to return to the Calibrate menu.
Note: For the 2-point calibration described below, a standard of known fluorescence is required. Two
general types of standards can be used: (a) phytoplankton suspensions of known BGA-PC content, and (b)
dye solutions whose fluorescence can be correlated to that of BGA-PC. The user is responsible for
determining the BGA-PC content of algal suspensions by using standard cell counting techniques. See
Section 5.16, Principles of Operation of this manual for more information about BGA-PC standards.
Select the 2-point option to calibrate the BGA-PC probe using two calibration standards. In this case, one
of the standards must be clear water (0 µg/L) and the other should be in the range of the suspected BGA-PC
content at the environmental site.
To begin the calibration, immerse the sonde in the 0 cells/mL standard, as instructed, and press Enter. It is
mandatory that the 0 cells/mL standard be calibrated first. The screen will display real-time readings that
will allow you to determine when the readings have stabilized. Pressing Enter will confirm the first
calibration. Following the instructions on the screen, place the sonde in the second BGA-PC standard,
input the correct value in cells/mL, press Enter, and view the stabilization of the values on the screen in
real-time. After the readings have stabilized, press Enter to confirm the calibration. Then, as instructed,
press any key to return to the Calibrate menu.
For all BGA-PC calibration procedures, be certain that the standard and sensor are thermally equilibrated
prior to proceeding with the calibration
CAUTION: To be assured of the accuracy for field measurements made with your BGA-PC sensor, you
must either initially calibrate the sensor using an algal suspension of known BGA-PC content or post
calibrate your sensor in a spreadsheet by comparing the fluorescence values obtained in field studies with
those obtained by laboratory analysis for chlorophyll on grab samples collected during the field study. The
use of chemical dye standards for “calibration” of the sensor may not result in accurate correlation between
fluorescence and actual BGA-PC readings and is designed primarily to evaluate the sensor for drift. See
Section 5.16. Principles of Operation for more information on the proper calibration of your BGA-PC
sensor.
OPTIC BGA-PE
To calibrate your 6132 Blue-Green Algae-Phycoerythrin (BGA-PE) sensor, select BGA-PE cells/mL in the
initial calibration routine. There will be a choice of 1-point or 2-point options. The 1-point selection is
normally used to zero the fluorescence probe in a medium that is BGA-free. If you use this method, you
will either choose to utilize the default sensitivity for BGA-PE in the sonde software or to update a
previous 2-point calibration. Usually you will place the sonde in clear water, and input 0 µg/L at the screen
prompt. After pressing Enter the screen will display real-time readings allowing you to determine when
the BGA-PE readings have stabilized. Press Enter after the readings have stabilized to confirm the
calibration and zero the sensor. Then, as instructed, press any key to return to the Calibrate menu.
Note: For the 2-point calibration described below, a standard of known fluorescence is required. Two
general types of standards can be used: (a) phytoplankton suspensions of known BGA-PE content, and (b)
dye solutions whose fluorescence can be correlated to that of BGA-PE. The user is responsible for