Reagent

About: Reagent is a research topic. Over the lifetime, 60091 publications have been published within this topic receiving 1234928 citations. The topic is also known as: reagens.

Effect of Sequence in Extraction of Trace Metals from Soils

Abstract: While many workers have utilized various reagents for sequential extraction of soil trace metals, few studies have examined the order of extraction for key steps in the sequential procedure In this study, several sequences involving both adsorbed and structural (occluded) metal extractants were evaluated to determine the most appropriate sequential methodology for extracting different forms of Cu, Fe, and Mn For "specifically adsorbed" metals, Pb(NO3)2 and CH3COOH were used The results showed that the former reagent extracted less Cu, Mn, and Fe and was probably more specific in replacing metals covalently bound to adsorption sites Lead nitrate was therefore placed before CH3COOH extraction in the sequence Chao's NH2OHHCl reagent and K4P2O7, used for Mn oxide and organic metal removal, respectively, were found to solubilize significantly different amounts of Cu and Mn depending on sequence, with K4P2O7 extracting more metal when used first As NH2OH • HCl has little effect on organic metals, it should be used before K4P2O7 Noncrystalline and crystalline Fe compounds are solubilized next, using a variety of reagents, and residual (silicate lattice) metals are dissolved in the final step A nine-step sequential method is proposed to characterize trace metals in agricultural, polluted, and wasteamended soils Additional Index Words: sequential extraction, trace metal fractionation, soil Cu, soil Mn, soil Fe View complete article To view this complete article, insert Disc 4 then click button8

Mechanistic Studies on the Rh(III)-Mediated Amido Transfer Process Leading to Robust C–H Amination with a New Type of Amidating Reagent

Abstract: Mechanistic investigations on the Cp*Rh(III)-catalyzed direct C–H amination reaction led us to reveal the new utility of 1,4,2-dioxazol-5-one and its derivatives as highly efficient amino sources. Stepwise analysis on the C–N bond-forming process showed that competitive binding of rhodium metal center to amidating reagent or substrate is closely related to the reaction efficiency. In this line, 1,4,2-dioxazol-5-ones were observed to have a strong affinity to the cationic Rh(III) giving rise to dramatically improved amidation efficiency when compared to azides. Kinetics and computational studies suggested that the high amidating reactivity of 1,4,2-dioxazol-5-one can also be attributed to the low activation energy of an imido-insertion process in addition to the high coordination ability. While the characterization of a cationic Cp*Rh(III) complex bearing an amidating reagent was achieved, its facile conversion to an amido-inserted rhodacycle allowed for a clear picture on the C–H amidation process. The ne...

Automatic chemical analyzer

Abstract: An automatic chemical analyzer suitable for chemically analyzing a number of analysis items is disclosed. Samples in sample containers are sequentially dispensed to an array of reaction vessels using a first pipetting tube. Reagent solutions selected in accordance with the analysis items are fed to the reaction vessels using a second conductive pipetting tube. The reaction solutions in the reaction vessels are measured by a photometer. When the reagent solutions are sucked into the second pipetting tube, the liquid levels of the reagent solutions in the reagent containers are detected by a liquid level sensor formed by the second pipetting tube and a conductive electrode. The amounts of the reagent solutions remaining in the reagent containers are determined based on the position of the liquid level sensor and the numbers of times of dispense allowed to the reagent solutions with respect to the analysis items are displayed on a cathode ray tube.