YSI 9600 - Manual (Page 91)

any source of their choosing as long as the chemicals are (a) identical in formulation and (b) equivalent in
purity – ACS Reagent Grade or better. An appropriate quantity of the reagents should be purchased based
on the frequency of deployment of your 9600. The cadmium used in the system MUST be purchased from
YSI in the form of a packaged column assembly.
What equipment do I need to make up the solutions for the 9600?
The following equipment should be available to users of the 9600. YSI does not supply this equipment,
but will help users in recommending a source for its purchase.
• Graduated Plastic Bottles with 2 L capacity (at least 6)
• Volumetric Flask for 1000 mL (at least 1) of solution.
• Adjustable pipetter for 0-1 mL volumes (at least 1)
• Glass pipets of various denominations (depending on standard concentrations required)
• Laboratory balance with weighing accuracy of 0.01 g
CALIBRATION OF THE 9600
How is the 9600 calibrated?
Part of the reagent package of the 9600 is a standard (usually 1 or 2 mg/L in nitrate-N) and a blank
(purified water with no nitrate present). These reagents are run through the system periodically during a
deployment providing on-board calibration that compensates for any instrument drift. These calibration
points are used to convert the optical readings from actual samples into nitrate values in mg/L nitrate-N.
This calibration protocol is transparent to the user.
How often are the calibration standards run as part of a field study?
The frequency of calibration is a user-selectable parameter. YSI generally recommends that calibration be
carried out at least once every 24 hours and preferably every 12 hours.
Do the calibration points displace actual data points?
Generally not. For sample intervals of 30 minutes or greater, the calibration is run between data points and
no readings are displaced. For a sample interval of 15 minutes, each calibration routine (standard and
blank) displaces one data point.
What concentration of calibration standard should I use for my field studies?
For your initial deployment, YSI recommends using a standard that is 1mg/L in nitrate-nitrogen (nitrate-N).
This standard will assure readings that are accurate to 5 % of the reading or 0.2 mg/L whichever is greater,
for the nitrate concentrations in most environmental water (0-6 mg/L of nitrate-N). If the water at your site
is known to consistently contain concentrations of nitrate higher than 6 mg/L, then you can either accept a
lower accuracy using the 1 mg/L nitrate-N standard or use a higher standard concentration such as 6 mg/L
nitrate-N which will assure accuracy of +/- 10 % of the reading in the higher range.
YSI Environmental 91 Model 9600 Nitrate Monitor