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Calibration, Verification, Quantification, Statistical Treatment of Analytical Data, Detection Limits, and Quality Assurance/Quality Control
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
To illustrate, consider the determination of N-methyl carbamates, which is usually accomplished with a direct aqueous injection into a reversed-phase high-performance liquid chromatograph with post-column derivatization and fluorescence detection (RP-HPLC-Der-FL). Carbamates are used chiefly in agriculture as insecticides, fungicides, herbicides, nematocides, and sprout inhibitors. Let us assume that surface water runoff from a particular agricultural field in the Midwest U.S. yields a mean concentration level for carbaryl (Sevin®) of 0.1 ppm, with a known standard deviation of 0.025 ppm. If we accept an error tolerance in the mean concentration of 20% (20% of 0.1 ppm carbaryl is 0.02 ppm) at a 95% confidence interval (z = 1.96), using the equation above, we find that it is necessary to run six samples. However, most environmental analyses are done on samples whose mean concentration levels are not known and whose standard deviation for a population is not known as well.40
Carbon Nanotubes Used for Renewable Energy Applications and Environmental Protection/Remediation
Published in Kaufui V. Wong, Nanotechnology and Energy, 2017
Kaufui V. Wong, Benoit Bachelier
The modification methods include a thermal treatment using an oven. Then the CNTs were dispersed into flasks containing the chemical agents. These solutions are polymers with many amine groups, which can react with CO2 to form carbamate in the absence of water; that is the reason for the amount of CO2 absorbed on CNTs to increase. Carbamates are organic compounds derived from carbamic acid (NH2COOH) [68]. The absorption depends on temperature; when temperature increases, the absorption decreases. When moisture increases, the absorption increases.
Introduction to Polyurethanes
Published in I.R. Clemitson, Castable Polyurethane Elastomers, 2015
Polymer chemistry developed a nomenclature (language) different from the classical organic chemistry. The group “-NHCO-” in polymer chemistry is known as nylon whereas in biochemistry it is known as a peptide and in pure organic chemistry as an amide group. The urethane group “-NHCOO-” is called a carbamate in organic chemistry.
Mg/Al/Zr hydrotalcite like compounds as catalysts for green synthesis of carbamates
Published in Inorganic and Nano-Metal Chemistry, 2022
Marwa Aloui, Rihem Dardouri, Salwa B. Ghorbel, Mayra G. Álvarez, Francisco Medina, Mongia S. Zina
Carbamates, which are precursors of polyurethanes, reformal esters resulting from the unstable carbamic acid[7] are worldwide used in various industrial fields including agrochemical chemistry (herbicides, fungicides and insecticides), synthesis of pharmaceuticals, and as intermediates in synthesis of fine and commodity chemicals.[8] However, the traditional route for producing organic carbamates, based on the use of toxic and corrosive phosgene (COCl2) as a C1 synthon. Although, the use of CO2 as a safe substitute for phosgene represents an important benefit for the development of more environmentally benign process because carbon dioxide is a nontoxic, cheap, non inflammable and abundant source of carbon.[2]
Non-carcinogenic health risk from carbamate pesticide exposure of toddlers living in agricultural areas of Thailand
Published in International Journal of Environmental Health Research, 2022
Satinee Siriwat, Parichat Ong-Artborirak, Chakrit Ponrachom, Wattasit Siriwong, Thitirat Nganchamung
Carbamates are pesticides used extensively in agriculture to control insects, resulting in environmental contamination and the poisoning of living species. In particular, aldicarb, carbofuran, carbaryl, and methomyl are common insecticides that result in toxic exposure (Bolognesi and Merlo 2011; Silberman and Taylor 2020). Carbamates can inhibit acetylcholinesterase, an enzyme responsible for the hydrolytic mechanism of the neurotransmitter acetylcholine into choline and acetate, causing increased acetylcholinesterase levels at the synapse and potentiating postsynaptic cholinergic activity within the central nervous system, autonomic ganglia, and neuromuscular junctions, resulting in adverse effects (Gupta 2014). Exposure to carbamates can cause short-term health effects (e.g. headaches, dizziness, fatigue, eye and skin irritation) and long-term health problems (e.g. cancer, cardiovascular complications, neurological and reproductive system disorders (Frazier 2007; Morais et al. 2012; Gupta et al. 2017; Kim et al. 2017; Chetty-Mhlanga et al. 2021; El-Nahhal and El-Nahhal 2021).
Advances in state-of-art valorization technologies for captured CO2 toward sustainable carbon cycle
Published in Critical Reviews in Environmental Science and Technology, 2018
Shu-Yuan Pan, Pen-Chi Chiang, Weibin Pan, Hyunook Kim
Carbamates (RNH−COOR) are being used for production of pesticides, germicides, pharmaceuticals, and other organic chemicals. Important carbamate compounds include aromatic carbamates such as methyl N-phenyl carbamate (MPC), as well as alkyl carbamates such as methyl carbamate (MC), ethyl carbamate (EC), and butyl carbamate (BC). From the green chemistry point of view, CO2 can be used to generate the carbamates from amines and alcohols, which is considered as an environmentally benign route. At an ambient temperature and pressure, CO2 can easily combine with amines to form the corresponding carbamic acids. If alcohols are used as the alkyl source, however, the subsequent dehydrative condensation to carbamates proceeds slowly (Ion et al., 2008). Thus, an excess amount of a dehydrant is often used to overcome the equilibrium limitation.