Nitrates samples were analyzed on a Lachat Quik-Chem 8000, following Quik-Chem Method 31-107-04-1-C.

 

2000.  Diamond, David H.  Determination of nitrate and/or nitrite in brackish or seawater by flow injection analysis colorimetry.     Quik-Chem Method 31-107-04-1-C.  Zellweger Ananlytics, Lachat Instrument Division, 6645 West Mill Road, Milwaukee, WI 53218. 

 

Summary:  Samples are passed through a copperized cadmium column to reduce nitrate to nitrite.  The nitrite (both original and reduced nitrate) is determined by diazotizing with sulfanilamide and coupling with N-(1-napthyl)-ethylenediamine dihydrochoride to form a highly colored azo dye which is measured colorimetrically.

 

Working Range: 5-50μm, MDL 0.12μm

 

Standard Preparation:

50mM stock standard-in a 1 liter volumetric flask dissolve 0.5055g dried (1hour at 60°C) potassium nitrate (KNO3) into about 800ml distilled water.  Dilute to 1 liter with DI water and invert several times to mix.  Can be stored refrigerated for up to 3 months.

 

50μm Working Stock Standard-In 1 L volumetric dilute 10ml 50mM stock to mark with DI water, invert to mix.

 

Working Standards (Prepare Daily): 

50μm-dilute 250ml 50μm working stock std. with 0ml DI water

25μm-dilute 125ml 50μm working stock std. with 125ml DI water  

10μm-dilute 50ml 50μm working stock std. with 200ml DI water

5μm-dilute 25ml 50μm working stock std. with 225ml DI water

0μm-250ml DI water