Purposeful degradation definition

Oxime carbamates are generally applied either directly to the tilled soil or sprayed on crops. One of the advantages of oxime carbamates is their short persistence on plants. They are readily degraded into their metabolites shortly after application. However, some of these metabolites have insecticidal properties even more potent than those of the parent compound. For example, the oxidative product of aldicarb is aldicarb sulfoxide, which is observed to be 10-20 times more active as a cholinesterase inhibitor than aldicarb. Other oxime carbamates (e.g., methomyl) have degradates which show no insecticidal activity, have low to negligible ecotoxicity and mammalian toxicity relative to the parent, and are normally nondetectable in crops. Therefore, the residue definition may include the parent oxime carbamate (e.g., methomyl) or parent and metabolites (e.g., aldicarb and its sulfoxide and sulfone metabolites). The tolerance or maximum residue limit (MRL) of pesticides on any food commodity is based on the highest residue concentration detected on mature crops at harvest or the LOQ of the method submitted for enforcement purposes if no detectable residues are found. For example, the tolerances of methomyl in US food commodities range from 0.1 to 6 mg kg for food items and up to 40 mg kg for feed items. ... 

For the purposes of this discussion, then, the following definitions will be used (examples are given below the set of definitions). Let P be the parent drug and I be the impurity or degradation product. Assume that MP0 and MPx are the mass of parent compound (and other starting reactants) initially and at time X, respectively MI>0 and Mi x are the total mass of impurities initially and at time X, respectively. Similarly, APj0, NP>X, N o, and Ntx are the analogous number of moles of each. 

Another problem is the ease with which a DSC apparatus degrades. Briefly, after it is used for a long time, it begins to produce noise, such that no definite DSC curve can be obtained. This may be attributable to the contamination of cell holders by gas from samples. The authors have conducted experiments with sealed cells by passing nitrogen gas through them, but contamination and its related noise production could not be avoided. For a time, a DTA apparatus considered less prone to contamination was borrowed from Nippon Kayaku Co., Ltd. and used for investigative purposes. 

Analytical pyrolysis is by definition the characterization of a material (or a chemical process) by chemical degradation reactions induced by thermal energy. It consists of a collection of techniques involving pyrolysis performed with the purpose of obtaining analytical information on a given sample. The type of analytical information can be... 

---