Identification in corn

Multiple development was traditionally performed manually. It consists of repeated developments of a plate in the same direction with the same solvent over the same distance. The result is narrower bands and improved resolution and detection sensitivity. The Rf values become very precise and are adequate enough for identification. A variation of this method is automated multiple development (AMD) and shows promising future. The HPTLC/AMD method was used to monitor phenylureas, carbamates and triazines in drinking water. HPTLC can also be performed using polar modified stationary phases to separate pesticides in various foodstuffs such as triazines in corn, asparagus, tomatoes, grapes and potatoes [14]. 

Corn-based foods followed by fumonisin B2 (FB2).The problems and risks associated with fumonisin contamination have resulted in the development of precise, reliable and sensitive methods for its determination in corn and corn-based foods (Magan Olsen, 2004, as cited in Silva et al., 2009). Therefore, the quality parameters in the analysis of FBI and FB2 in corn-based products obtained with LC with fluorescence detector have been investigated (Silva et al, 2009). Furthermore, a comparison study between fluorescence detector (FD), mass spectrometry, and tandem mass spectrometry with a triple quadrupole (QqQ) analyzer using an electrospray ionization interface for the determination of fumonisin B1 and B2 in corn-based products has been performed. A comparative study of the three LC detectors, FD, single quadrupole, QqQ for the analysis of fumonisins in corn samples has been performed. The response achieved by the three detectors was sensitive enough to study the maximum contents established by the EU legislation. These LC detectors would be appropriate for quantification purposes but the acquisition of at least two transitions achieved with QqQ provided a univocal identification. 

Pyridines and pyrimidines were patented separately, to complete an impressive array of protection for the heterocyclic triketones [35]. Nevertheless, after the first patent appeared regarding this novel substance class, most of the major companies started programs in the field. There were basically two strategies Some companies searched for novel diones that were at the time outside the scope of the Zeneca published patents, while other companies searched for novel aromatic acids. For example, Sandoz (now Syngenta) concentrated on the search for novel diones, and several compounds containing bicyclo[3.2.1]octane-2.4-dione, such as 29 [36, 37] and 30 [38], as well as the oxazinedione types (31) [39, 40], were important compounds for use in corn (Fig. 4.3.5). A collaboration between Sandoz and SDS Biotech has also led to the identification of proform triketones containing bicyclo[3.2.1]octane-2.4-diones for use in rice, such as benzobicyclon (9) [41]. 

Corcuera, L. J. (1974) Identification of the major active component present in corn extracts inhibitory to soft rot, Erwinia species. PhD thesis. Univ. Wisconsin, Madison. 

The discovery that crop tolerance for a particular herbicide could be enhanced has led to the identification of many compounds that antidote the herbicidal effect of the thiolcarbamate herbicides. iV,A/ -Diallyl-dichloroacetamide was the first material commercialized with thiocarbamate herbicides for use in corn. This same concept also has application for other types of herbicides. Also it was discovered that repeated application of the same thiolcarbamate led to rapid microbial degradation of the material in the soil. Addition of extenders to the thiolcarbamate herbicide counteracted with degrading effect of the microorganisms in the treated soil. 

Other groups of substances have been noted, but further investigation is needed to ascertain their identification among the surest ones, we would mention plastoquinones with a structure close to that of vitamin Ki, detected in chloroplasts (Kegel, 1962) and in olive oil (Therrault, 1963) a group of phenolic substances, whose presence has been observed in at least two oils [in parsley oil, the myristicin (Privett et al., 1963), and in olive oil, the oleoeuropein (Vazquez Romero et al., 1961)] and the vinylic esters and esters of diols (propane-1,2- and 1,3-diol, butane-1,3- and 1,4-diol) these last are found in corn seeds and consequently in the oil also (Bergelson et al., 1966). 

Liu DL, Christians NE (1994) Isolation and identification of rootinhibiting compounds from corn gluten hydrolysate. J Plant Growth Reg 1 227-230 Luo SM, Lin XL, Zeng RS, Kong CH, Cao PR (1995) Allelopathy of tropical plants in agroecosystem of South China. Ecol Sci 2 114-128... 

These are some examples of the use of i.r. spectra in the analysis and identification of carbohydrates in foods and natural products. Very often, these spectroscopic techniques are complementary to others, such as the study of aldobiouronic acids obtained by hydrolysis of peach-gum polysaccharides by their optical rotations and their i.r. spectra.100 However, the i.r. results appear to be sufficiently reliable to be used in the detection of traces of fructose and glucose, and to determine the d.e. (dextrose equivalent) of corn syrups, as well as the quantitative carbohydrate content in different products.101... 

There is hope that insect sex lures can be used to disrupt the mating pattern of insects and thereby control insect population. This approach to pest control has important advantages over conventional insecticides in that the chemical lures are specific for a particular species also they are effective in remarkably low concentrations and are relatively nontoxic. There are problems, however, not the least of which is the isolation and identification of the sex attractant that is produced by the insects only in minute quantities. Also, synergistic effects are known to operate in several insect species such that not one but several pheromones act in concert to attract the opposite sex. Two notable pests, the European corn borer and the red-banded leaf roller, both use cis-11-tetradecenyl ethanoate, 32, as the primary sex attractant, but the pure cis isomer is ineffective unless a small amount of trans isomer also is present. The optimum amount appears to be between 4% and 7% of the trans isomer. 

Kingan T. G., Bodnar W. M. and Hunt D. F. (1995) The loss of female sex pheromone after mating in the corn earworm moth Helicoverpa zea identification of a male pheromonostatic peptide. Proc. Nat. Acad. Sci. USA 92, 5082-5086. 

Interest in the influence of lipids on pyrazine formation has recently been generated by the identification of long-chain alkyl-substituted heterocyclic compounds in foods and in model systems. Pyrazines in this category include 2-heptylpyrazine isolated from french fried potato flavor (7), and 2-methyl-3(or 6)-pentylpyrazine and 2,5-dimethyl-3-pentylpyrazine, isolated from extruded zein/corn amylopectin/corn oil systems (8, 9). Only the involvement of lipids or lipid-decomposition products in the formation of these compounds could account for the long-chain alkyl substitution on the pyrazine ring. 

Volatile compounds generated by model systems of zeln, corn amylopectin and corn oil extruded at barrel temepratures of 120°C and 165°C were analyzed by GC and GC/MS. The largest quantities of lipid oxidation products were detected in systems containing all three components. In each system, the quantity of 2,4-deca-dienal was low relative to the quantities of hexanal, heptanal and benzaldehyde. Identification of the Maillard reaction products, 2-methyl-3(or 6)-pentyl-pyrazine, 2-methyl-3(or 6)-hexylpyrazine and 2,5-di-methyl-3-pentylpyrazine, suggested that lipid-derived aldehydes might be involved in the formation of substituted pyrazines. 4-Methylthiazole was identified as a major decomposition product of thiamin when corn meal containing 0.5% thiamin was extruded at a final temperature of 180°C. 

Davis, C. S., Ni, X. Z., Quisenberry, S. S. and Foster, J. E. 2000. Identification and quantification of hydroxamic acids in maize seedling root tissue and impact on western corn rootworm (Coleoptera Chrysomelidae) larval development. J. Econ. Entomol. 93, 989-992... 

Hydrolysed protein preparations have been used to attract various insects. The general subject of insect attractant use both in nature and by man is introduced, with particular reference to the Tephritid family of fruit flies. The work of the Biocommuni-cation Chemistry Research Unit on the identification of the active attractant compounds in the hydrolysed corn protein, Nu-Lure Insect Bait (NLIB) is discussed. Different isolates have been obtained by running simultaneous steam distillation-extractions (SDE) under vacuum and atomospherlc pressure and under basic and acidic conditions. Chemical fractionation of these isolates has also been accomplished. Chemical identification by gas chromatography/mass spectrometry (gc/ms) is discussed. 

Although Table 1 lists the fatty acid compositions of various lipids, this is not the only or the final arbiter of their classification. As opposed to vegetable fats and oils (other than olive oil), where only one oil is generally identified as originating from an oilseed (e.g., corn oil), a diversity of definitions and specifications is used in the identification of and trade in animal fat products. These often include statements of the allowed limits of any number of quality parameters. 

This is a review of synthetic efforts made at these laboratories in recent years. Stereoisomers of sex pheromones of various insect species were synthesized in order to facilitate identification and permit more thorough evaluation of their potential in insect control programs. Syntheses are described for pheromones of the stable fly, tsetse fly, southern and western corn rootworms, and the Mediterranean fruit fly attractant, trimed-lure. In each instance centers of asymmetry were generated that made use of diastereomer formation using readily available (R)- and (S)-a-methyl-benzylamine. Resolutions were achieved either by preparative HPLC, or fractional crystallization of amides. The latter technique was rendered synthetically useful for the preparation of configurationally pure acids by virtue of transformations wrought upon the amides that made them subject to cleavage under very mild conditions. 

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