A method is reported for the determination of cyromazine and melamine residues in soil. Soil samples are extracted twice via mechanical shaking, each time with 70% acetonitrile/30% 0.050 M ammomium carbonate for 30 min. An aliquot portion of the pooled extracts is subjected to strong cation exchange (SCX) purification on AG 50W-X4 resin. Final analysis is accomplished using liquid chromatography-ultraviolet (LC-UV) detection at a wavelength of 214 nm. Confirmatory analyses can be performed using gas chromatography-mass selective detection (GC-MSD) in the selected ion monitoring (SIM) mode. The limit of detection (LOD) is 2.5 ng injected and the limit of quantification (LOQ) is 10 ppb when using LC-UV for the analysis of N-cyclopropyl-1,3,5-triazine-2,4, 6-triamine (cyromazine) and 1,3,5-triazine-2,4,6-triamine (melamine). The LOD is 0.050 ng injected and the LOQ is 10 ppb when using GC-MSD for confirmatory analyses. The mean procedural recoveries were 97 and 95% and the standard deviations were 16 and 11% for cyromazine and melamine, respectively (n = 24), when using LC-UV. The mean procedural recoveries were 107 and 92% and the standard deviations were 9.9 and 16% for cyromazine and melamine, respectively (n = 29), when using GC-MSD. The method validation study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160. The method also passed an Independent Laboratory Validation (ILV) as per U.S. EPA FIFRA Subdivision N.
Kansas 66045. acid, and one or more phenyl hydroxyl groups that may become methylated to produce methoxy groups. Phenolic acids commonly occur as esters and/or ethers in combination with various sugars and aliphatic or aromatic acids and hydroxy acids. Most plant phenolic acids are derivatives of either benzoic (benzenecarboxylic; Cg-C^o r cinnamic (phenylpropanoid or phenylacrylic; C6-C3) acids (Roston and Kissinger, 1982).
Two methods of mineral extraction for citrus juices were investigated: dry ashing in a muffle furnace and wet ashing in a microwave oven. Elemental concentrations were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). For reference, a synthetic multielement mixture was prepared and analyzed. Results for the multielement solution using wet ashing in a microwave oven or drv ashing in a muffle furnace differed by less than 10% from those for an undigested, but diluted solution. An exception was boron, of which 9G% was lost in the muffle furnace. Grapefruit iuice analvsis showed differences in concentration of less than 10% for all elements. Orange juice samples, however, showed greater losses for Na (16%), Si (13%), and Sn (11%) with the dry ashing method.
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