EDTA column comparison in a sensitive method

Method Conditions:

Column: Cogent HPS C8™, 5μm, 120Å 
Catalog No.: 75008-15P
Dimensions: 4.6 x 150mm
Solvents: A.98% DI H2O/ 2% acetonitrile/ 0.1% acetic acid pH 3.5/ 2
g/L tetrabutylammonium sulfate
Temperature: 40°C
LOQ: 0.2μg/mL
Detection: 258 nm
Peak: 1. Water (solvent front)
          2. EDTA Fe3+  
Injection Volume: 2ul
Injection vol.: 20μL
Flow rate: 2 mL/min

Discussion: EDTA does not have a significant chromophore, so to achieve UV detection this method uses a pre column reaction of a solution of ferric chloride with the sample. The resulting EDTA/Fe3+ has significant UV absorbance making this a very sensitive method. Excellent peak shapes and selectivity make the Cogent HPS C8 a great choice for this method. EDTA is extremely difficult to analyze by itself however in its complexed form, it chromatographs well from matrices such as river sediment and other solutions.

Note: EDTA is a synthetic metal complexing reagent that is used in a wide variety of industrial applications. Used a preservative, it has very low biodegradability thus remains in the environment for long periods of time. Found in sewer water, freshwater and ground water, it re-solubilizes precipitated toxic metals back into solution where they can be ingested by plants and animals.

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