YSI ProDSS Meter Calibration and Maintenance
K:\Streamkeepers\Monitoring\Eqpt & supplies\Calibration-Maintenance\SOPs\YSI ProDSS maint-
cal SOP's
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5.
Take the 1st pipette out of the manganous sulfate solution. Check and make sure it is filled
with approximately 2 mL of solution and then add it to the BOD #1 bottle by immersing the
tip of the pipette into the sample before injecting the solution. Make sure when you add
solution you do not squeeze any air bubbles into the sample. Keep squeezing the top of the
pipette when you replace it in the sulfate solution so that it will be filled for the next time.
6.
Take the 2nd pipette out of the alkaline-azide solution, check and make sure it has
approximately 2 mL of solution and add it to the BOD #1 bottle using the same procedure as
before.
7.
Adding these solutions turns the water brown and chemically converts the free oxygen into a
manganese precipitate which falls to the bottom of the bottle. Put the glass stopper in the
BOD bottle and invert slowly a couple of times to mix the contents. The solution is now
stable.
8.
Repeat all the sampling steps for the other two BOD bottles.
9.
Record the time the samples were taken on the data sheet.
WINKLER TITRATIONS IN THE LABORATORY
Equipment for completing Winkler titrations:
•
Graduated cylinder burette with stopcock at bottom, 25 mL/ with 3-way stopcock
•
Volumetric burette, 10 mL with 3-way stopcock or 10 mL pipette with bulb on the end
•
3 Erlenmeyer flasks, 250 mL (number them-sample 1, 2, & 3)
•
Volumetric pipette 10 mL stored in “Streamkeepers” cardboard tube at back of counter
•
3 BOD bottles and glass stoppers
•
Plastic caps for each BOD bottle
•
Manganous sulfate solution with its eyedropper (2 mL pipette)
•
Alkali-iodate-azide reagent with its eyedropper (2 mL pipette)
•
Pipette suction/dispenser bulb
•
Magnetic stirrer
•
Stirring bars (one for each sample)
•
203 mL Volumetric flask (plastic flask cut to hold exactly 203 mL when completely
filled above the top; a rubber gasket around the top helps to deliver this flask’s contents
into the Erlenmeyer flasks)
•
Concentrated sulfuric acid
•
2 mL disposable pipette stored in glass jar, for acid transfer
•
Aqueous starch solution preserved with salicylic acid
•
Squirt bottle (250 mL) with starch solution
•
Sodium thiosulfate, 0.025 M (Check pull date – shelf life critical)
•
Potassium bi-iodate, 0.025 M (Check date – good 18mos from mfr.)
•
Rubber apron
•
Nitrile gloves
•
Acid face shield
•
Ensure all liquids are within the expiration date and there is enough quantity to complete
all 3 samples.
