GE Analytical Instruments ©2006 13-7 DLM 14291 Rev. A
• Dilute to the mark with nitrate-free, deionized water.
• Invert the flask several times until the solid dissolves.
• Transfer the stock solution to air-tight storage container.
• Calculate the concentration of the stock solution. For NaNO
3
, the
concentration is:
Conc. of Stock = (mgNaNO
2
/85 mg/mmol)/10 mL x 1000 mL/L
Use this stock 100 mM standard to prepare dilutions to construct a standard
curve for the NOA. The concentrations of the dilutions will depend on the
nitrate levels in the samples. Prepare dilutions that contain nitrate at
concentrations greater than the samples, concentrations less than the samples
and concentrations approximately the same as the samples. For most cell
culture work, nitrate concentrations will be in the nanomolar to micromolar
range. Analysis of standard solutions containing 10 nM, 50 nM, 100 nM, 1 µM, 5
µM, 10 µM, 50 µM and 100 µM will allow construction a calibration curve
suitable for most samples. For urine and other samples that contain high levels
of NO, the standard curve may be extended to include standards with nitrate
concentrations greater than 100 µM.
Preparation of Dilute Standards
The best way to prepare dilute standards is by serial dilution. The containers
for the dilute standards must be free of nitrate contamination (rinse with
nitrate-free water before use). Microfuge tubes (1.5 mL) or similar disposable
containers are suitable containers. To prepare the 1 mL of the dilute standards:
• Arrange 7 or 8 tubes in a rack and add 900 µL of nitrate-free water to each
tube.
• Set one tube aside and label the tube Water Blank.
• Add 100 µL of the stock solution to the first tube, mix thoroughly and label
the tube 10 mM (Note: the actual concentration will depend on the
To Next Page
Loading...
Need help?
General
