Green Nitrate Method

May 18, 2012 Final Method Update rule lists Chinchilla Scientific Easy (1– Reagent) Nitrate Method as an approved method for nitrate, and nitrite combined nitrate nitrite analysis under 40 CFR Part 136.3.

After review of validation data, The USEPA approved the use of the new non-hazardous nitrate method.  The USEPA determined that the method meets all requirements at 40 CFR Part 136 for measurement of nitrate and nitrite singly or combined in water and wastewater.

The method was also approved on August 3, 2009 (Federal Register / Vol. 74, No. 147 / Rules and Regulations) for drinking water compliance monitoring.  The USEPA determined that the methods is “equally effective” as current Safe Water Drinking Act (SWDA) methods for nitrate.  The new method meets all requirements at 40 CFR Part 141 for measurement of nitrate and nitrite singly or combined in drinking water.

Several methods exist for the determination of nitrate in aqueous solutions.  However, the most commonly performed USEPA approved methods are problematic and can be unreliable.  USEPA methods 353.1 nitrate Hydrazine reduction and 353.2 nitrate Cadmium reduction are carcinogenic and highly toxic.  Hazardous waste is generated when performing these methods and disposal is costly.  Other methods performed by ion chromatography (IC) and ion selective electrode (ISE) are slow and can have issues when performing analysis on samples with high ionic strength, such as wastewater, ground water, and soil extracts.  The new Chinchilla Scientific Easy (1– Reagent) Nitrate Method was developed to eliminate the problems associated with these traditional methods and improve performance.

The new Chinchilla Scientific Easy (1 – Reagent) Nitrate Method utilizes a “green” non-hazardous reducing agent which eliminates hazardous waste generation and exposure to carcinogens such as hydrazine and cadmium.  The method has greater linear range and better detection limits than commonly performed methods.  The validation study conducted by Chinchilla Scientific used a method range of 0.050 – 10.0 mg/L and consistently achieved a method detection limit (MDL) of 0.011 mg/L or better.  The method also has flexibility to work at lower and higher ranges, simply by adjusting the sample to reagent ratio.  Other issues like matrix interference and poor recovery are eliminated.  Regardless of the sample matrix, recovery of nitrate to nitrite is consistently between 95% to 105%.  Analytical costs associated with performing the new method are greatly reduced.  Unlike costly enzymatic tests, the Chinchilla Scientific reagent “R1” costs range from 1.5 to 4 cents per test depending on how the method is run.