Initial plant scale trials of the nitrosation of an amino acid revealed a number of issues: _ Much lower yield compared to
laboratory scale _ Considerable loss of mass balance _ Large excess of nitrosating agent required for complete reaction _
Highly reactive off-gases produced causing fires in the carbon absorber _ Reaction sensitive to agitation speed _ The by-product
produces an impurity in the next process stage which has high human toxicity A kinetic and mechanistic study of the nitrosation
reaction, using isothermal power compensation calorimetry and GC/mass spectrometry, has been undertaken in order to understand
the above observations and to produce an improved manufacturing process - more robust, higher yielding, reduced effluent volumes
Authors:F. J. Lona-Ramírez, R. Herrera-Muñoz, V. Rico-Ramírez, F. Louvier Hernández, G. Luna-Bárcenas, and G. González-Alatorre
provide diazonium ions that are directly responsible for the alkylation of DNA [ 9 – 11 ].
Studies on the kinetics of the nitrosation of amides have been widely reported [ 11 – 15 ]. Given the carcinogenic characteristics of the nitroso
Authors:M. R. Granados-Uribe, F. J. Lona-Ramírez, C. Pérez-Pérez, J. Barajas-Fernández, V. Rico Ramírez, and G. González-Alatorre
that more than 15 species of laboratory animals, including some primates, were susceptible to its carcinogenic action [ 6 ]. Some studies have been carried out to determine their formation mechanism with the aim of blocking the nitrosation in one of the
Authors:Madan Pandey, Subha Rastogi, and Ajay Rawat
Phenolic compounds are plant metabolites found widely spread throughout the plant kingdom. Phenolic acids, low-molecular-weight phenolic compounds, are precursors of a variety of antimicrobial compounds, and are important in plant defense responses. They are also involved in the plants’ physiological activity, which depends on their antioxidant activity, i.e. the ability to scavenge both active oxygen species and electrophiles, their ability to inhibit nitrosation and to chelate metal ions, their potential for autooxidation, and their capability to modulate the activity of some cellular enzymes. Because of their importance in the standardization of plant products, an attempt has been made to develop a simple, rapid, and precise HPTLC method for the separation and identification of different phenolic compounds in a single analysis. A TLC method which separates, identifies, and quantifies six different phenolic compounds-gallic acid, ferulic acid, syringic acid, catechin, protocatechuic acid, and vanillin-with a single mobile phase was established. It was then validated for selectivity, linearity, precision, accuracy and robustness. The method was found to enable rapid, precise, accurate, simple, and cost-effective analysis of these important phenolic compounds for standardization of different plant materials and herbal products.
Authors:K. Grant, G. Mong, R. Lucke, and J. Campbell
Considerable attention has been focused on chelators such as ethylenediaminetetraacetic acid (EDTA) and N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), which form water-soluble complexes with most heavy metals. Most radionuclides are included in this class of constituents. As a result, chelator complexes have become very important environmentally because of their tendency to enhance the mobility of heavy metals through the soil and potentially contaminate groundwater. In addition, there is a correlation between chelator concentration and crust formation/gas release. The chelators are a class of compounds whose low volatility and high polarity preclude analysis by gas chromatography/mass spectrometry (GC/MS) without prior derivatization. Waste samples from a double-shell storage tank at Hanford were derivatized with BF3/methanol and analyzed using GC/MS. Results indicate the presence of EDTA, HEDTA, nitrilotriacetic (NTA), and citric acid. Nitrosoiminodiacetic acid was identified and determined to be an artifact of the derivatization procedure; it is assumed to arise from nitrosation of iminodiacetic acid in the waste sample.