Nitriloacetic acid, determination

The interference caused by chloride ion, Fe(III), and Cu(II) in the determination of nitriloacetic acid and EDTA in natural waters was removed by pre-treating samples (pH > 4) with cation exchangers. Some samples required additional treatment with an anion exchanger (pH 1). The analytes were complexed with Bi (III) before being determined by differential pulse anodic stripping voltammetry at the hanging mercury drop electrode (vs. Ag/AgCl. The detection limit was 0.1 pg/L for EDTA. 

Warren and Malec [80] determined nitriloacetic acid and related amino polycarboxylic acids (iminodiacetic acid, glycine and sarcosine in inland waters and sewage effluents by converting to the butyl or A-trifluoracetyl esters followed by chromatography on dual glass U-shaped columns (1.9mx2mm) packed with 0.65% of ethanediol adipate on acid-... 

Reichert and Linckens [83] have reviewed gas chromatographic methods for the determination of nitriloacetic acid in potable waters. They point out that esterification of the nitriloacetic acid is required to enable it to be volatilised in the gas-liquid chromatographic column, and they compared a range of esterification reagents and conditions for simplicity and speed of operation. The method chosen involved treatment of a concentrated sample with a mixture of -propanol-acctyl chloride (10 1) and the resulting nitroacetic acid-propyl ester injected into a column, which was fitted with a nitrogen-sensitive detector. The detection limit for nitriloacetic acid in potable water is about lpgL-1. 

Other organic compounds that have been determined in sewage effluents include the following (see Table 15.13) hydrocarbons, alcohols, carboxylic acids, esters, chlorobenzenes, nitrosamines, ethylene diamine tetraacetic acid, nitriloacetic acid, organophosphorus compounds, linear alkyl benzene sulphonates, methyl mercaptan, polychlorobiphenyls and chlorinated insecticides. 

Gas chromatography has been applied to the determination of a wide range of organic compounds in trade effluents including the following types of compounds which are reviewed in Table 15.15 aromatic hydrocarbons, carboxylic acids aldehydes, non ionic surfactants (alkyl ethoxylated type) phenols monosaccharides chlorinated aliphatics and haloforms polychlorobiphenyls chlorlignosulphonates aliphatic and aromatic amines benzidine chloroanilines chloronitroanilines nitrocompounds nitrosamines dimethylformamide diethanolamine nitriloacetic acid pyridine pyridazinones substituted pyrrolidones alkyl hydantoins alkyl sulphides dialkyl suphides dithiocaibamate insecticides triazine herbicides and miscellaneous organic compounds. 

The biochemical reaction performed by the methyltransferase appears to be metal dependent, as determined by chemical inhibition studies, but the exact identity of this metal has yet to be defined [41]. EDTA treatment had no inhibitory effect on Stel4p, but incubation of the protein with 10 - 50 mM of the metal chelating agent 1,10-phenanthroline eliminated catalytic activity [37,41]. Additionally, even more hydrophobic metal sequesterants such as zincon [37], lysine nitriloacetic acid (Lys-NTA) [42], and cholesteryl-Lys-NTA [43] also inhibited the methyltransferase but at much lower concentrations. Together, these data suggest that the metal ion may be buried in a hydrophobic region of the enzyme. 

The denticity of the ligands in the intermediates of equations (2) and (3) is difficult to determine, though attempts have been made in certain systems, for example in nitriloacetate exchange. Any of the paths described above may be acid catalysed, as is illustrated in, for example, edta exchange studies. ... 

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