LaMotte SMART Spectro Spectrophotometer - Manual (Page 255)

FORMAZIN STOCK SOLUTION
The turbidity calibration curve for this instrument was prepared by using formazin
solutions as a reference. A 4000 FTU standard solution is available (Order Code
6195-H, 60 mL) that can be diluted with low turbidity water to prepare solutions
within the test range.Dilutions from this stock solution should be prepared fresh
daily with low turbidity water.
Alternatively, a stock turbidity solution of 400 NTU can be prepared by observing
safety precautions and carefully following the procedure below.
Preparation of Formazin Stock Solution
1. Dissolve 1.000 g of Hydrazine Sulfate in deionized water and dilute to the mark
in a 100 mL volumetric fl ask.
2. Dissolve 10.00 g of hexamethylenetetramine in deionized water and dilute to
the mark in a 100 mL volumetric fl ask.
3. Mix 5 mL of each solution in a 100 mL volumetric fl ask and allow to sit
undisturbed for 24 hours at 25 +/- 3 °C.
4. At the end of the waiting period, dilute to the mark with deionized water and
mix. Store in amber glass.
5. The concentration of this stock solution is 400 FTU. This stock solution is stable
for one month. Dilutions from this stock solution should be prepared fresh daily
with low turbidity water.
TURBIDITY SMART Spectro Test Procedures 09.14
Test P
rocedures