Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-...Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0- 0.05 mol/L KClO 4) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100 mg/L) of FHA and pH (2-12) had significant effects. A red shift in the longer wavelength peak region was observed when the concentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH= 5.0. The protonation constants (lgK’ HL) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r (A/B) values range from 0.61 to 2.59. A strong linear relationship between r (A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.展开更多
Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor...Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC）. Three terrestrial humic-like components （C1, C2 and C3） and one protein-like component （C4） were identified. Based on spatial dis- tributions, as well as relationships with salinity, the following assignments were made. The three humic-like components （CI, C2 and C3） showed conservative mixing behavior and came mainly from riverine input. The protein-like component （C4） was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were -78.46% for salinity, and -21.54% for apparent oxygen utilization （AOU）; those on C2 were -76.43% for salinity, and -23.57% for AOU; those on C3 were -70.49% for salinity, 7.01% for Chl-a, and -22.50% for AOU; those on C4 were -55.54% for salinity, 14.6% for Chl-a, and -29.86% for AOU in middle layer; and those on C4 were -57.37% for salinity, 29.02% for Chl-a, and -13.61% for AOU in bottom layer. Results indicated that CDOM in tile East China Sea was mainly affected by terrestrial inputs, and microbial ac- tivities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model present- ed a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index （HIX） suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.展开更多
A rapid,green and highly sensitive excitation-emission matrix（EEM） fluorescence method was proposed for analysis of irinotecan（CPT-11） in biological fluids including human plasma and urine samples of uncalibrated ...A rapid,green and highly sensitive excitation-emission matrix（EEM） fluorescence method was proposed for analysis of irinotecan（CPT-11） in biological fluids including human plasma and urine samples of uncalibrated interferences with the aid of second-order advantage.Due to the serious spectral overlapping from biological matrices,the parallel factor analysis（PARAFAC） and the alternating normalization-weighted error（ANWE） have been recommended to perform directly calibration and overcome the problem which makes the traditional fluorospectrophotometer in trouble.Satisfactory results can be achieved.Furthermore, performance of the proposed method was evaluated based on figures of merit and some statistical parameters.The accuracy of both algorithms was validated by the elliptical joint confidence region（EJCR） test.The precision and repeatability were also investigated by the relative standard deviations（RSDs） of intra-day and inter-day.展开更多
Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of sa...Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter （DOM）. The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.展开更多
A novel approach is proposed for direct quantitative analysis of thiabendazole in the orange extract by using excitation-emission matrix fluorescence coupled with second-order calibration methods based on the alternat...A novel approach is proposed for direct quantitative analysis of thiabendazole in the orange extract by using excitation-emission matrix fluorescence coupled with second-order calibration methods based on the alternating trilinear decomposition(ATLD) and the alternating normalization-weighted error(ANWE) algorithms,respectively. The average recoveries of thiabendazole in the orange extract by using ATLD and ANWE with an estimated component number of two were 99.7 ± 3.3% and 103.5 ± 4.1%,respectively. Furthermore,the accuracy of the two algorithms was also evaluated through elliptical joint confidence region(EJCR) tests as well as figures of merit,such as sensitivity(SEN),selectivity(SEL) and limit of detection(LOD). The experimental results demonstrate that both algorithms have been satisfactorily applied to the determination of thiabendazole in orange extract,and the perform-ance of ANWE is slightly better than that of ATLD.展开更多
Nowadays,the abuse of illegal drugs has been an increasingly grim problem in the world.Excitation–emission matrix fluorescence combined with parallel factor analysis was used to make a quantitative analysis of the si...Nowadays,the abuse of illegal drugs has been an increasingly grim problem in the world.Excitation–emission matrix fluorescence combined with parallel factor analysis was used to make a quantitative analysis of the simulated amphetamine-type illegal drugs.Satisfactory results were achieved for simultaneous determination of methamphetamine(MAM)and 3,4-methylenedioxymethamphetamine(MDMA)in the presence of adulterants.The average recoveries were(99.8±0.6)%and(101.6±5.7)%for MAM and MDMA,respectively.Figures of merit including root-mean-square error of calibration and prediction,sensitivity and selectivity were investigated to evaluate the performance of the proposed method.The limits of detection were 0.054 and 0.0021 g/mL for MAM and MDMA,respectively.展开更多
We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases...We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.展开更多
文摘Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0- 0.05 mol/L KClO 4) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100 mg/L) of FHA and pH (2-12) had significant effects. A red shift in the longer wavelength peak region was observed when the concentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH= 5.0. The protonation constants (lgK’ HL) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r (A/B) values range from 0.61 to 2.59. A strong linear relationship between r (A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.
基金supported by the National Basic Research Program of China(973 program,2010CB428701)the National Natural Science Foundation of China(41176063)
文摘Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC）. Three terrestrial humic-like components （C1, C2 and C3） and one protein-like component （C4） were identified. Based on spatial dis- tributions, as well as relationships with salinity, the following assignments were made. The three humic-like components （CI, C2 and C3） showed conservative mixing behavior and came mainly from riverine input. The protein-like component （C4） was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were -78.46% for salinity, and -21.54% for apparent oxygen utilization （AOU）; those on C2 were -76.43% for salinity, and -23.57% for AOU; those on C3 were -70.49% for salinity, 7.01% for Chl-a, and -22.50% for AOU; those on C4 were -55.54% for salinity, 14.6% for Chl-a, and -29.86% for AOU in middle layer; and those on C4 were -57.37% for salinity, 29.02% for Chl-a, and -13.61% for AOU in bottom layer. Results indicated that CDOM in tile East China Sea was mainly affected by terrestrial inputs, and microbial ac- tivities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model present- ed a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index （HIX） suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.
基金supported by The National Natural Science Foundation of China(No.20775025)The National Basic Research Program(No.2007CB216404) as well as PCSIRT.
文摘A rapid,green and highly sensitive excitation-emission matrix（EEM） fluorescence method was proposed for analysis of irinotecan（CPT-11） in biological fluids including human plasma and urine samples of uncalibrated interferences with the aid of second-order advantage.Due to the serious spectral overlapping from biological matrices,the parallel factor analysis（PARAFAC） and the alternating normalization-weighted error（ANWE） have been recommended to perform directly calibration and overcome the problem which makes the traditional fluorospectrophotometer in trouble.Satisfactory results can be achieved.Furthermore, performance of the proposed method was evaluated based on figures of merit and some statistical parameters.The accuracy of both algorithms was validated by the elliptical joint confidence region（EJCR） test.The precision and repeatability were also investigated by the relative standard deviations（RSDs） of intra-day and inter-day.
基金supported by the National High-tech Research Project ("863" Project) of China under contract Nos 2003AA635180 and 2006AA09Z167the Public Welfare Project of Marine Science Research under contract No 200705011the open project of Key Laboratory of Integrated Marine Monitoring and Applied Technologies for Harmful Algal Blooms,SOA, China under contract No200811
文摘Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter （DOM）. The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20775025 and 20435010)973 Advanced Research Project (Grant No. 2007CB- 216404)
文摘A novel approach is proposed for direct quantitative analysis of thiabendazole in the orange extract by using excitation-emission matrix fluorescence coupled with second-order calibration methods based on the alternating trilinear decomposition(ATLD) and the alternating normalization-weighted error(ANWE) algorithms,respectively. The average recoveries of thiabendazole in the orange extract by using ATLD and ANWE with an estimated component number of two were 99.7 ± 3.3% and 103.5 ± 4.1%,respectively. Furthermore,the accuracy of the two algorithms was also evaluated through elliptical joint confidence region(EJCR) tests as well as figures of merit,such as sensitivity(SEN),selectivity(SEL) and limit of detection(LOD). The experimental results demonstrate that both algorithms have been satisfactorily applied to the determination of thiabendazole in orange extract,and the perform-ance of ANWE is slightly better than that of ATLD.
基金supported by National Natural Science Foundation of China[grant number 81373239].
文摘Nowadays,the abuse of illegal drugs has been an increasingly grim problem in the world.Excitation–emission matrix fluorescence combined with parallel factor analysis was used to make a quantitative analysis of the simulated amphetamine-type illegal drugs.Satisfactory results were achieved for simultaneous determination of methamphetamine(MAM)and 3,4-methylenedioxymethamphetamine(MDMA)in the presence of adulterants.The average recoveries were(99.8±0.6)%and(101.6±5.7)%for MAM and MDMA,respectively.Figures of merit including root-mean-square error of calibration and prediction,sensitivity and selectivity were investigated to evaluate the performance of the proposed method.The limits of detection were 0.054 and 0.0021 g/mL for MAM and MDMA,respectively.
基金Supported by the National Natural Science Foundation of China under Grant No 60378008.
文摘We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.
