Chapter 5
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Orion AQUAfast Reagent Chemistry Instructions for Orion AquaMate
78
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Orion AquaMate Spectrophotometer User Manual
Thermo Scientific
AC2009 Fluoride SPADNS Liquid Test
SPADNS Method
0.05 – 2 mg/l F
1.
Load and run the AC2009 method.
2.
Fill a clean AQUAfast 24mm round vial, Cat. No. AC2V24, with exactly 10 ml of deionized
water. Close the vial tightly with the cap. Wipe the exterior of the vial.
3.
Place the vial into the holder in the sample chamber and close the chamber door.
4.
Press the Measure Blank function key to measure the blank.
5.
Open the sample chamber door and remove the vial from the holder.
6.
Add exactly 2 ml SPADNS Solution to the vial. CAUTION: The vial will be filled to the top.
7.
Close the vial tightly with the cap and swirl or invert several times to mix the contents. Wipe
the exterior of the vial.
8.
Place the vial into the holder in the sample chamber and close the chamber door.
9.
Press the Measure Rgnt Blank function key to measure the reagent blank.
10.
Open the sample chamber door and remove the vial from the holder.
11.
Empty the vial, thoroughly rinse the vial and cap several times and then fill the vial with
exactly 10 ml of sample.
12.
Add exactly 2 ml SPADNS Solution to the vial. CAUTION: The vial will be filled to the top.
13.
Close the vial tightly with the cap and swirl or invert several times to mix the contents. Wipe
the exterior of the vial.
14.
Place the vial into the holder in the sample chamber and close the chamber door.
15.
Press the Measure Sample function key to display the result in mg/l fluoride.
Notes:
•
Reverse color methods use a reagent that, when prepared with samples, deceases in color
as the concentration of the species being measured in the samples increases. Reverse
color methods require the use of both a blank and a reagent blank. The blank is a clear
solution (deionized water) with zero absorbance. The reagent blank is a mixture of the
reagent and deionized water and provides a zero concentration point with the darkest color
(highest absorbance). The color of samples prepared with the reagent will decrease as the
concentration increases for this method.
•
The same batch of SPADNS reagent solution must be used for testing (reagent blank and
sample measurement) and one point calibration procedures. The one point calibration
process needs to be performed for each new batch of SPADNS reagent solution (see
Standard Methods 20
th
ed., 1998, APHA, AWWA, WEF 4500 F
-
D, 4.a).