A spin-labeling fluorophore(NA-TEMPO ·), formed by labeling α-naphthalene with a paramagnetic nitroxide(4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy), was explored for biologically relevant carbon-centered ra...A spin-labeling fluorophore(NA-TEMPO ·), formed by labeling α-naphthalene with a paramagnetic nitroxide(4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy), was explored for biologically relevant carbon-centered radicals. The horseradish peroxidase (HPR)/H 2O 2 reaction was used to generate radicals in derivatives of tyrosine and phenylalanine, and the Fenton reaction was used to generate radicals in deoxyguanosine, guanosine, bovine serum albumin(BSA) and DNA. TEMPO ·-NA, a weak fluorescent compound, showed a dramatic increase in fluorescence intensity after scavenging carbon-centered radicals. The spin-labeling fluorophore with dual function groups, the radical recognizing group and fluorescent group, would be significantly useful in monitoring the formation and translocation of carbon-centered radicals in complex biological systems.展开更多
Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but n...Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but not with N, N disubstituted 1 aminonaphthalenes such as sodium 1 naphthylaminodiacetate(NADA) and 1 dimethylaminonaphthalene(DMAN). No change in absorption spectra of NA and NAA was observed in this pH region.It was proposed that the dual fluorescence observed with NA and NAA was due to the excited state dissociation of the primary and secondary amines at high pH. From the dual fluorescence intensity ratio pH titration curve, the p K * as of NA and NAA were estimated to be between 14 and 15 which are much lower than the ground state p K a. The novel approatch is such a simple, convenient and frequent analysis technique that it can be widely used in detecting the substitutional derivatives of aminonaphthalene.展开更多
A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide（HTMAB） as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic aci...A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide（HTMAB） as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic acid（HQS） coupled with on\|line fluorescence detection has been developed. The chromatographic behavior of metal\|HQS complexes in the proposed system was systematically investigated.When the C\-\{18\} column modified by HTMAB and the suitable mobile phase coupled with fluorescence detection（\%λ\%\-\{ex\}=388 nm; \%λ\%\-\{em\}=518 nm） were employed, the detection limit of cadmium is 7.72 ng/mL with an injection volume of 20 μL, and the linear range of calibration curve for cadmium is 50\800 ng/mL. It was successfully applied to determination of bio\|available cadmium in polluted soils of China. Moreover, the possible species of Cd\|HQS on the column has been investigated by log\|log plot analysis.展开更多
The concentrations of lead and cadmium in the tree bark from Sanming and Xiamen, Fujian province, China were determined by atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry. The results...The concentrations of lead and cadmium in the tree bark from Sanming and Xiamen, Fujian province, China were determined by atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry. The results obtained in the outer tree bark and tree bark pocket could reflect the degree of present and historical air pollution at different sampling locations. Tree bark and tree bark pocket should be expected to be as a useful biomonitor of present and historical condition of air pollution.展开更多
文摘A spin-labeling fluorophore(NA-TEMPO ·), formed by labeling α-naphthalene with a paramagnetic nitroxide(4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy), was explored for biologically relevant carbon-centered radicals. The horseradish peroxidase (HPR)/H 2O 2 reaction was used to generate radicals in derivatives of tyrosine and phenylalanine, and the Fenton reaction was used to generate radicals in deoxyguanosine, guanosine, bovine serum albumin(BSA) and DNA. TEMPO ·-NA, a weak fluorescent compound, showed a dramatic increase in fluorescence intensity after scavenging carbon-centered radicals. The spin-labeling fluorophore with dual function groups, the radical recognizing group and fluorescent group, would be significantly useful in monitoring the formation and translocation of carbon-centered radicals in complex biological systems.
文摘Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but not with N, N disubstituted 1 aminonaphthalenes such as sodium 1 naphthylaminodiacetate(NADA) and 1 dimethylaminonaphthalene(DMAN). No change in absorption spectra of NA and NAA was observed in this pH region.It was proposed that the dual fluorescence observed with NA and NAA was due to the excited state dissociation of the primary and secondary amines at high pH. From the dual fluorescence intensity ratio pH titration curve, the p K * as of NA and NAA were estimated to be between 14 and 15 which are much lower than the ground state p K a. The novel approatch is such a simple, convenient and frequent analysis technique that it can be widely used in detecting the substitutional derivatives of aminonaphthalene.
文摘A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide（HTMAB） as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic acid（HQS） coupled with on\|line fluorescence detection has been developed. The chromatographic behavior of metal\|HQS complexes in the proposed system was systematically investigated.When the C\-\{18\} column modified by HTMAB and the suitable mobile phase coupled with fluorescence detection（\%λ\%\-\{ex\}=388 nm; \%λ\%\-\{em\}=518 nm） were employed, the detection limit of cadmium is 7.72 ng/mL with an injection volume of 20 μL, and the linear range of calibration curve for cadmium is 50\800 ng/mL. It was successfully applied to determination of bio\|available cadmium in polluted soils of China. Moreover, the possible species of Cd\|HQS on the column has been investigated by log\|log plot analysis.
文摘The concentrations of lead and cadmium in the tree bark from Sanming and Xiamen, Fujian province, China were determined by atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry. The results obtained in the outer tree bark and tree bark pocket could reflect the degree of present and historical air pollution at different sampling locations. Tree bark and tree bark pocket should be expected to be as a useful biomonitor of present and historical condition of air pollution.
