A subset of compounds (2,4-D; 2,4-DP; MCPA; MCPP; 2-phenyl
phenate; triclosan) were quantified by negative electrospray ionization (ESI -).
The PH stands for
Phenate Hexamine and came into use in 1915.
Analytical methods: Quantification during reduction of substrate concentrations (N[H.sub.4.sup.+] y N[O.sup.2.sub.-]) and increases in the products (N[O.sub.2.sup.-]) was carried out using the 4 500--N[H.sub.4.sup.+]-F
phenate method for ammonium, and the 4 500--NO-2-B colorimetric method for nitrite in samples taken from the systems every eight days (Eaton, Clesceri, & Greenberg, 1995).
These additives include zinc dialkyldithiophosphate, which contains zinc, sulfur, and phosphorous; calcium
phenate, which contains calcium; and molybdenum disulfide, which contains molybdenum and sulfur.
Ammonium-nitrogen (N[H.sub.4.sup.+]-N) and nitrite-nitrogen (N[O.sub.2.sup.-]-N) were determined by the
phenate method and colorimetric diazotization method, respectively.
Nutrients such as nitrite and ammonium were determined by cadmium reduction and
phenate methods respectively.
Nitrate-N and TAN were measured by the cadmium reduction method (Method 4500 Nitrate) and automated
phenate method (Method 4500 Ammonia G), respectively (Rice et al.
N[H.sub.3]-Nwas measured with Standard
Phenate Method.