Oxidation of tertiary amine buffers by copper(II)

1989 ◽  
Vol 28 (2) ◽  
pp. 169-170 ◽  
Author(s):  
Fengjiang Wang ◽  
Lawrence M. Sayre
Keyword(s):  
2020 ◽  
Vol 16 ◽  
Author(s):  
Bathinapatla Ayyappa ◽  
Suvardhan Kanchi ◽  
Myalowenkosi I. Sabela ◽  
Krishna Bisetty

BACKGROUND: Sucralose is a high intensity artificial sweetener sucralose and chemically known as 1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside. It is used as a sweetener and flavour enhancer in foods and beverages. Due to its high stability at wider temperatures and pH, made its applicability in various food products throughout the world. As per Joint FAO/WHO Expert Group on Food Additives (JECFA) in 1990, the daily intake of sucralose is 0-15 mg/kg body weight. The literature reports suggest that sucralose has a possible health threat due to the presence of chlorine groups, thereby leading to the several illnesses. The growing interest on the use of SUC in the foods, makes it necessary in developing a fast, reliable, cost effective and reproducible analytical method to determine SUC in food samples. The detection of sucralose and other carbohydrates like fructose, glucose and sucrose is a challenging task owing to its: (i) unavailability of the charged functions and (ii) lack of absorption of strong chromophoric nature in the UV region. Therefore, separation of non-absorbing neutral molecules needs a careful procedure with the suitable electrolyte systems. METHODOLOGY: An indirect UV detection capillary electrophoretic method is described for the separation of sucralose in different food samples. It was achieved by nucleophile substitution (SN2) in the presence of amine as background electrolytes. The morpholine buffer showed good buffering capacity in terms of migration time (< 8.0 min) and baseline stability when compared to other amine buffers (ethylamine, piperidine, triethylamine). The analytical applications of proposed method showed by recovery percentages of sucralose in real and spiked samples on intra and inter-day basis at optimum experimental conditions of 0.2 M buffer concentration and pH 12.0 at 230 nm UV detection. RESULTS: The selection of BGE, UV detection wavelength, buffer concentration, buffer pH, cassette temperature and applied voltage were optimized to enhance the sensitivity and selectivity of the separation method. Recoveries obtained were ranging from 96.87 to 98.82 % for real samples and 94.45 to 98.06 % for spiked samples respectively. Linearity was studied in the range of 2-10 mM, and showed a correlation coefficients of 0.9942 with LOD and LOQ found to be 0.3804 mg L-1 and 1.5215 mg L-1 with % RSD (n = 5) ± 1.27 and 1.19 % with respect to migration time and peak area. Furthermore, to better understand the separation of sucralose with amine buffers were investigated computationally using HOMO-LUMO calculations. The obtained results showed that the band gap decreases in the presence of amine moiety irrespective of its nature. CONCLUSION: In the study, novel background electrolytic system was successfully applied to separate sucralose using indirect UV detector with capillary electrophoresis. The FT-IR results confirmed that the interaction of sucralose with different amine buffers to better understand the separation chemistry behind sucralose and amine complexes. Moreover, computational results indicate that the direction of charge transfer from the amine functionality to the glucofuranosyl ring in each amine derivative of sucralose confirms the strong interaction between sucralose and amines, which led in the baseline separation of sucralose in different food samples.


RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25477-25483
Author(s):  
Qianya Cheng ◽  
Tong Zhou ◽  
Qing Xia ◽  
Xiulian Lu ◽  
Heng Xu ◽  
...  

The tertiary amine in F4b facilitates the Fenton-like reaction to generate toxic ˙OH which induces apoptosis through CDK-2 inactivation.


Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1054
Author(s):  
Noor Ul Ain ◽  
Tian-Yu Wang ◽  
Xiao-Ning Wu ◽  
Tong-Hong Wei ◽  
Jing-Shuo Zhang ◽  
...  

A doped polymer nanoparticle (dPNP) of electrochemiluminescence (ECL) was prepared via doping the anionic polyelectrolyte polyacrylic acid (PAA) and the cationic polymer poly-ethyleneimine (PEI) into the polymer nanoparticle (PNP), which was self-assembled by Ru(bpy)32+ derivative-grafted PAA (PAA–Ru) with both cations and anions. The good electrical conductivity of the doped polyelectrolyte PAA enhanced the ECL intensity of PNP to 109.1%, and the involvement of a large number of tertiary amine groups of the doped PEI further enhanced that to 127.3%; meanwhile, doping low-molecular-weight PEI into PNP, while simultaneously doping high-molecular-weight PAA, avoided the precipitation of PAA and PEI, due to interaction of the two oppositely charged polymers; and these also made the self-assembly procedure more effective and the nanoparticle structure more stable than PNP and also led to the production of rich residual PAA chains on the surface of dPNP. The storage results showed that the average hydrated particle diameter kept almost constant (197.5–213.1 nm) during 15-day storage and that the nanoparticles have rich surface charge of −11.47 mV (zeta potential), well suspension stability and good dispersity without detectable aggregation in the solution during the storage. Therefore, the nanoparticle is quite suitable for the antibody labeling, immunoassay and the storage. As a result, a high-sensitive ECL immunoassay approach with good precision, accuracy and selectivity was established and an ultra-low detection limit of 0.049 pg mL−1 (S/N = 3) for magnetic bead-based detection of Hepatitis B surface antigen was observed.


2020 ◽  
Vol 11 (21) ◽  
pp. 5572-5576 ◽  
Author(s):  
Noboru Hayama ◽  
Yusuke Kobayashi ◽  
Eriko Sekimoto ◽  
Anna Miyazaki ◽  
Kiyofumi Inamoto ◽  
...  

An asymmetric thia-Michael addition of arylthiols to α,β-unsaturated carboxylic acids using a thiourea catalyst that bears arylboronic acid and tertiary amine moieties is reported.


ChemInform ◽  
2012 ◽  
Vol 43 (41) ◽  
pp. no-no
Author(s):  
Gaosheng Yang ◽  
Chongrong Luo ◽  
Xiaolong Mu ◽  
Tingting Wang ◽  
Xin-Yuan Liu

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