Nature of the residues

Anilide herbicides are metabolized in plants via cleavage of acylamide moiety. 

Handbook of Residue Analytical Methods for Agrochemicals. 2003 John Wiley Sons Ltd. 

The definition of residues for selective anilides in plant samples is summarized 

Clomeprop Parent and 2-(2,4-dichloro-3-methylphenoxy)propionic acid 

Naproanilide Parent, 2-(2-naphthoxy)propionic acid and methyl 2-(2-naphthoxy)propionate 

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The Action of Heat.—We will assume in the first 1 ic,. S7. plate that the substance is homogeneous and consists of a single individual. Heat a portion on platinum foil and notice if it volatilises, chars, or burns with a clear, luminous, non-Iuminous (aliphatic), or smoky (aromatic) flame. Determine the nature of the residue, if any, when the carbon has burnt away. 

Polyelectrolytes are classified into three main groups nonionic, anionic, and cationic depending upon the nature of the residual charge on the polymer in aqueous solution as shown in Table 1. 

In a discussion of these results, Bertrand et al. [596,1258] point out that S—T behaviour is not a specific feature of any restricted group of hydrates and is not determined by the nature of the residual phase, since it occurs in dehydrations which yield products that are amorphous or crystalline and anhydrous or lower hydrates. Reactions may be controlled by interface or diffusion processes. The magnitudes of S—T effects observed in different systems are not markedly different, which indicates that the controlling factor is relatively insensitive to the chemical properties of the reactant. From these observations, it is concluded that S—T behaviour is determined by heat and gas diffusion at the microdomain level, the highly localized departures from equilibrium are not, however, readily investigated experimentally. 

Ammonium salts of the zeolites differ from most of the compounds containing this cation discussed above, in that the anion is a stable network of A104 and Si04 tetrahedra with acid groups situated within the regular channels and pore structure. The removal of ammonia (and water) from such structures has been of interest owing to the catalytic activity of the decomposition product. It is believed [1006] that the first step in deammination is proton transfer (as in the decomposition of many other ammonium salts) from NH4 to the (Al, Si)04 network with —OH production. This reaction is 90% complete by 673 K [1007] and water is lost by condensation of the —OH groups (773—1173 K). The rate of ammonia evolution and the nature of the residual product depend to some extent on reactant disposition [1006,1008]. 

Another complicating characteristic of materials from the environment is that the size and nature of the residue to be analyzed in the mass spectrometer will change from sample to sample. To determine if this might have an effect on the observed TCDD signal, we analyzed identical samples of TCDD with differing amounts of squalane, a saturated hydrocarbon selected as a model for residues obtained from standard extraction and cleanup procedures. As is indicated in Table I (Part A), there was... 

Unfortunately, AB and CD are often far from parallel as a consequence of the complicated nature of the residual current in polarography (cf., pp. 118-121), where one has to deal with at least two or three factors, as follows. 

The mechanism of bound residue formation is better understood today due to the use of advanced extraction, analytic, and mainly spectroscopic techniques (e.g., electron spin resonance, ESR nuclear magnetic resonance, NMR Fourier transform infrared spectroscopy), methods that are applied without changing the chemical nature of the residues. 

An assessment of the rates and duration of phenolic acid production from a residue is an important first step. Laboratory and field studies for assessing the dynamics of phenolic acid production must include considerations of the nature of the residue, soil properties, nutrient status of the system, microbial biomass interrelationships, temperature, moisture, residue placement in or on the soil, and other factors that relate to the field. Soil properties in the field are especially important when organic residues are incorporated. When soils are wet, such as those with more than -0.02 MPa water potential, oxygen diffusion is impeded and anaerobic conditions prevail, especially in soils that are high in clay content. Under these circumstances, microbial byproducts change dramatically and one result, for example, is an increase in the production of phenolic acids. Phenolic acid production is also affected by temperature (22) and soil fertility status (23). While the C H ratio of an organic residue may influence the rate of its decomposition and, hence, the rate of phenolic acid production, the... 

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