Search

This paper quantitatively determined the migration level of benzo(a)pyrene (BaP) from paper cups into aqueous food simulants or fatty stimulants, under different conditions by second derivative constant-energy synchronous fluorescence spectrometry (DCESFS), which proved to be a method with high sensitivity and spectral resolution. The influences of food simulants, time and temperature on the relative migration percent(%) of benzo(a) pyrene were discussed. Results showed that the recoveries of this method ranged from 89.2% to 104.3%. The migration percent(%) of fatty stimulants was higher than that of aqueous simulants. Migration into hot water was also observed, while the migration into cool water was almost negligible. The relative migration percent(%) increased with the increase of time and temperature.

The interaction between nanomaterials and biological macromolecules (including protein) is the important basis of biological safety assessments of nanomaterials. In this paper, the fluorescence spectroscopy, synchronous fluorescence spectroscopy and circular dichroism spectroscopy) were used to analyze the interaction between four water-soluble carboxyl carbon nanotubes (long-SWCNTs-COOH, short-SWCNTs-COOH, DWCNTs-COOH and MWCNTs-COOH) and human serum albumin. Results showed that the four water-soluble carboxylated carbon nanotubes could quench the intrinsic fluorescence of human serum albumin at different extents. Under the same concentration, the quenching ability of four carboxylated carbon nanotubes were in the order of DWCNTs-COOH

As a kind of coenzyme of one-carbon enzymes in vivo, folic acid belongs to B vitamins, which can interact with other vitamins and has great significance for converting among amino acids, dividing growth of cells and protein synthesis reactions. Half-life, concentration and reaction rate constant of drugs are important parameters in pharmacokinetic study. In this paper, by utilizing fluorescence spectrophotometer and stopped-flow spectrum analyzer, reaction kinetic parameters between bovine serum albumin(BSA) and folic acid in a bionic system have been investigated, which provide references for parameters of drug metabolism related to folic acid. By using Stern-Volmer equation dealing with fluorescence quenching experiments data, we concluded that under 25, 30, and 37 degrees C, the static quenching constants of folic acid to intrinsic fluorescence from bovine serum albumin were 2.455 x 10(10), 4.900 x 10(10) and 6.427 x 10(10) L x mol(-1) x s(-1) respectively; The results of kinetic reaction rate have shown that the reaction rate of BSA and folic acid are greater than 100 mol x L(-1) x s(-1) at different temperatures, pH and buffering media, illustrating that the quenching mechanism between BSA and folic acid is to form composite static quenching process. Reaction concentration of bovine serum albumin and its initial concentration were equal to the secondary reaction formula, and the correlation coefficient was 0.998 7, while the half-life (t1/2) was 0.059 s at physiological temperature. With the increase of folic acid concentration, the apparent rate constant of this reaction had a linear increasing trend, the BSA fluorescence quenching rate constant catalyzed by folic acid was 3.174 x 10(5) mol x L(-1) x s(-1). Furthermore, with different buffer, the apparent rate constant and reaction rate constant of BSA interacting with folic acid were detected to explore the influence on the reaction under physiological medium, which is of great significance to determine the clinical regimen, forecast the efficacy and toxicity of drugs and rational drug.

This paper studied the fluorescence spectral characteristic of chlorin e6-C15-monomethyl ester in different solvents to develop a fluorescence spectrometry for determining the concentration of chlorin e6-C15-monomethyl ester in plasma. By comparing the fluorescence spectral characteristics of chlorin e6-C15-monomethyl ester in six different solvents including methanol, ethanol, acetone, acetonitrile, phosphate buffered saline and water, the influence of different solvents on the fluorescence spectral characteristic of chlorin e6-C15-monomethyl ester has been examined. The results indicated that methanol and acetonitrile are the ideal solvent system, and the effect of phosphate buffered saline is better than water. The effect of organic solvent content and solution pH value on emission wavelength and fluorescence intensity was further evaluated. It was found that the fluorescence intensity of chlorin e6-C15-monomethyl ester was strong and stable in pH 7.2 phosphate buffered saline -acetonitrile (3 : 7) solution and can be detected at the excitation wavelength of 498.00 nm and the emission wavelength of 664.05 nm. Based on this, we developed the fluorescence spectrometry for determining chlorin e6-C15-monomethyl ester. It is specific and sensitive with good linearity over the range of 0.5-50 microg x mL(-1). The intra-batch and inter-batch precisions (RSD) were less than 10%, the extraction recoveries were all over 90%. The established method in this paper was simple, fast, effective and could be successfully applied to study the pharmacokinetics of chlorine e6-C15-monomethyl ester in SD rats.

This paper made use of three-dimensional fluorescence and ultraviolet-absorption spectrum to analyze the spectral characteristics of etroleum ether extract from Guizhou flue-cured tobacco and the overall characteristic spectral information of tobacco chemical substances were obtained. The three dimensional fluorescence and ultraviolet-visible absorption spectrum of each petroleum ether extract of flue-cured tobacco from different areas are generally similar, but their intensity is different. There have three characteristic peaks in three dimensional fluorescence spectra: I: Ex/Em = 297/326 nm, II: Ex/Em = 250/330 nm, III: Ex/Em = 225/336 nm respectively and meanwhile the order of these peaks intensity is I > III > II. The ultraviolet-visible absorption spectrum in 300-300 nm range presents four characteristic absorption peaks, whose maximum absorption wavelength are 329, 419, 445 and 419 nm respectively. Meanwhile, in accord with the relative intensity of characteristic peaks, it is known that there exist differences in the relative contents of the total chemical substances obtained from different flavor styles of the flue-cured tobacco. The clustering analysis results of three-dimensional fluorescence intensity score (D) and intensity ratio (R) show that in a certain range of distance coefficient, the flue-cured tobacco from different regions in Guizhou can be clearly divided into two classes "mildly sweet "and "alcohol sweet ". The classification can be well achieved in the smaller distance coefficient according to the ratio cluster of fluorescence intensity instead of the score cluster of fluorescence intensity. The method of three-dimensional fluorescence was better than that of ultraviolet-visible spectrometry in the matter of the clustering characteristic.

Flow injection-hydride generation-atomic fluorescence spectrometry was a widely used method in the industries of health, environmental, geological and metallurgical fields for the merit of high sensitivity, wide measurement range and fast analytical speed. However, optimization of this method was too difficult as there exist so many parameters affecting the sensitivity and broadening. Generally, the optimal conditions were sought through several experiments. The present paper proposed a mathematical model between the parameters and sensitivity/broadening coefficients using the law of conservation of mass according to the characteristics of hydride chemical reaction and the composition of the system, which was proved to be accurate as comparing the theoretical simulation and experimental results through the test of arsanilic acid standard solution. Finally, this paper has put a relation map between the parameters and sensitivity/broadening coefficients, and summarized that GLS volume, carrier solution flow rate and sample loop volume were the most factors affecting sensitivity and broadening coefficients. Optimizing these three factors with this relation map, the relative sensitivity was advanced by 2.9 times and relative broadening was reduced by 0.76 times. This model can provide a theoretical guidance for the optimization of the experimental conditions.

The curative effect of Banlangen granule is directly affected by its quality, so it is very important to choose a kind of effective method for testing it. The chemical treatment is needed as a pre-treatment for the quality testing by using common method at present, which will change or destroy the sample. For dealing with this problem, in the present paper, a fluorescence spectrum imaging experimental system based on LCTF (liquid crystal tunable filter) is set up to detect the characteristics fluorescence spectrum of Banlangen granules. The characteristic fluorescence spectrum curve of Banlangen standard material provided by Chinese Food Drugs Examination Research Institute is used as a reference substance for a comparison with other Banlangen granules. By normalizing the corresponding characteristic fluorescence spectrum of Banlangen granules of different raw materials, different manufacturers and different batches, the relationship between the characteristic fluorescence spectrum curve and the quality of Banlangen granule is discussed by using the method of comparative and cluster analysis. The experimental results show that the qualities of Banlangen granules are quite different from different manufacturers, which are basically reflected by the change in the intensity of fluorescence and peak position. All of these indicate that fluorescence spectrum imaging technology is a simple, rapid and nondestructive detection method for the quality control of Banlangen granule.

Photophysical photochemical properties, in vitro photodynamic anticancer activity and interaction with albumin of a new axially modified silicon phthalocyanine, i. e. di (2-amino-6-trifluoromethyl-4-pyrimidinyloxy) silicon phthalocyanine (SiPcF), were studied in the present paper. The Q band maximum absorption of SiPcF located at 686 nm with the molar absorption coefficient of 2.3 x 10(5) mol(-1) * L * cm(-1). The fluorescence emission of SiPcF peaked at 694 nm with a fluorescence quantum yield of 0.46. Its singlet oxygen quantum yield produced by photosensitization is 0.38, suggesting that SiPcF is an effective 1O2 photosensitizer. There is strong interaction between SiPcF and bovine serum albumin (BSA). The binding constant is 4.33 x 10(5) mol X L(-1) and the number of binding sites is 1. In vitro experiments show that SiPcF had a high photodynamic anticancer activity against human hepatoma cells HepG2 with an IC50 value down to 5 x 10(-7) mol X L(-1).

Using the FLS920P spectrometer of Edinburgh Instruments the three-dimensional fluorescence spectra of the fresh orange juice and the three samples of 100% orange juice bought in the supermarket were studied and their characteristic parameters were obtained. The comparison of the spectra and the characteristic parameters shows that they are apparently different, especially at the emission wavelength of 683 nm. This might be caused by the food additives added into the orange juice bought. The three-dimensional spectrum of the fresh orange juice with carrageenan was obtained. The comparison of the samples bought and the one with carrageenan shows that they are with little difference. The characteristic parameters of them are almost of no difference. Thus the conclusion can be drawn that the samples bought all have carrageenan. The results of the paper can somewhat help quantitatively study carrageenan in the orange juice.

Online measurement of soil moisture is significant for agricultural production. The abundance and deficiency of leaf water shortage has been able to effect measured by fluorescence, but the research of correlation between soil moisture and laser-induced fluorescence spectroscopy has not been carried out yet. In this paper, the relationship between laser-induced plant chlorophyll fluorescence and soil moisture was studied. In the experiment with rice as the research object, the chlorophyll fluorescence induced by a 450 nm LED light source was measured by a Y-shaped fiber probe, and the soil moisture was obtained by TDR sensors. The changes in the peak intensity near 743 nm of chlorophyll fluorescence under continuous water stress and intermittent water stress were studied. The result showed that the intensity decreased with the soil moisture content. Finally, the model between the soil water content and the intensity of chlorophyll fluorescence under continuous water stress was created by using Lorentzian equation, and the coefficient of determination (R2) of the model was high. The result indicated that the method mentioned in paper can be applied to measure soil moisture in agricultural production.

The mixed whey protein isolate (WPI)-dextran was treated by dry-heating to prepare Maillard reaction products (MRPs), which was characterized by the browning. The free amino groups content significantly decreased by 35.77% and 30.53% in glycated protein samples, as the molecular weight of dextran increased from 67 to 150 kD, respectively. This suggested that it was more difficult to be linked with WPI molecule when the chain length of dextran was increased. The characteristic of WPI-dextran conjugate was studied by fluorescence spectra in the paper. The maximum fluorescence intensity at 405 nm was obviously enhanced and G67 showed high fluorescence intensity than G150 over the wavelength range form 350 to 500 nm. This result revealed that the flourescent substance, a feature in Maillard reaction model system, was generated. As showed in the fluorescence spectra, the maximum fluorescence intensity at 470 nm was significantly decreased and the fluorescence intensity in each solution was in the order as follows: WPI>G150>G67. Moreover, the measurement of surface hydrophobicity index further showed that the hydrophobicity of WPI could be suppressed due to these two kinds of different molecular weight dextran.

Late embryogenesis abundant protein (LEA) can enhance the tolerance of organisms under drought, low-temperature and other stress conditions. However, their protection mechanisms are still unclear. In the present paper, the peptides consisting of multi-copies of 11-amino acid motif, such as PM2D and PM2E are proved to protect the activity of the lactate dehydrogenase (LDH) from freeze-thaw by using ultroviolet spectrometry. Furthermore, the fluorescence spectroscopic results show that the peptide consisting of multi-copies of 11-amino acid can stabilize the structure of LDH through synergy and multi-sites binding. However, the peptides consisting of less copies of 11-amino acid, such as PM2F and PM2G bind to LDH through one site, and the binding is weak. They thus can not protect the activity of LDH. In addition, the peptides consisted of multi-copies of 11-amino acid protect LDH by acting with trehalose synergically, and the protection mechanisms of LEA and trehalose on LDH are different.

The analytical method for the determination of methylmercury in seabird excrements was established using atomic fluorescence spectrometry coupled with microwave-assisted extraction In general, temperature and hydrochloric amount are the most important influencing factors on the extraction of MeHg in the samples, and the present paper optimized these two parameters. The result showed that 120 degrees C and 200 microL 6 mol x L(-1) hydrochloric acid are the best extraction conditions. Under these experimental conditions, the relative standard deviation (RSD) values of reduplicative analyses on standard reference material (human hair powder) and the same seabird excrement sample were 0.74% and 6.61% respectively, and their percent recoveries were over 90%. The combination of microwave-assisted extraction and atomic fluorescence spectrometry has many advantages such as simple operation, high sensitivity, low detection limit and low cost, therefore, it is suitable for rapid separation and analysis of trace methylmercury composition in the biological guanos. Using this method, we analyzed the methylmercury contents in the ancient and fresh seabird droppings taken from Xisha Islands of South China Sea, and the result showed that the Xisha guanos were rich in methylmercury and the large input of seabird guanos will cause serious environmental contamination in the remote island ecosystem of Xisha Islands.

In the present paper, the authors studied Guoyuan and Yanghe which are the most representative types of Su liquor. The authors got the three-dimensional fluorescence spectra of the liquor and analyzed their unique characteristics. Guyuan has obvious characteristics of the fluorescence in the 280-400 nm excitation wavelength range, including a major peak of fluorescence. Yanghe contains five clear fluorescence peaks in the 200-450 nm range of excitation wavelength. The two series of liquor have clear fluorescent characteristics in the 310-350 nm range of excitation wavelength, The range includes some organic compounds which play a decisive role in taste and flavor of Su liquor. The result of research provides a scientific basis for improving the mixing process of Su liquor and enhancing the quality of liquor.

Aiming at spectral detection of apple fluorescence canopy, the present paper carried out spectral detection tests under different weather conditions, different detection times, and different detection heights and angles to apple canopy in the two years of 2008 and 2009, so as to analyze impacts of these factors on apple canopy spectral characteristics and explore standardized spectral detection methods for apple fluorescence canopy. The results indicated the regularity in spectral reflectance of apple fluorescence canopy to a certain degree under different conditions, especially in the 760-1 350 nm near-infrared bands. The authors found that canopy spectral reflectance declined along with the decrease in sunshine and it is appropriate to detect canopy spectrum in sunny days with few clouds. In addition, spectral reflectance tended to be stable when the wind scale was below grade 2. The discrepancy of canopy spectra is small during the time period from 10:00 to 15:00 of a day compared to that of other times. For maintaining stable spectral curves, the height of detector to apple canopy needed to be adjusted to cover the whole canopy within the field of view according to detection angle of the detector. The vertical or approximately vertical detection was the best for canopy spectral reflectance acquisition. The standardization of technical methods of spectral detection for apple fluorescence canopy was proposed accordingly, which provided theoretical references for spectral detection and information extraction of apple tree canopy.

In the present paper, the authors utilize the wavelet base function coiflet2 (coif2) to analyze the 3D fluorescence spectra of 37 phytoplankton species belonging to 30 genera of 7 divisions, and these phytoplankton species include common species frequently causing harmful algal blooms and most predominant algal species in the inshore area of China Sea. After the Rayleigh and Raman scattering peaks were removed by the Delaunay triangulation interpolation, the fluorescence spectra of those phytoplankton species were transformed with the coiflet2 wavelet, and the scale vectors and the wavelet vectors were candidate for the feature spectra. Based on the testing results by Bayesian analysis, the 3rd scale vectors were the best feature segments at the division level and picked out as the fluorescence division feature spectra of those phytoplankton species, and the group of the 3rd scale vectors, the 2nd and 3rd wavelet vectors were the best feature segments at the genus level and chosen as the fluorescent genus feature spectra of those phytoplankton species. The reference spectra of those phytoplankton species at the division level and that at the genus level were obtained from these feature spectra by cluster analysis, respectively. The reference spectra base for 37 phytoplankton species was composed of 107 reference spectra at the division level and 155 ones at the genus level. Based on this reference spectra base, a fluorometric discriminating method for phytoplankton populations was established by multiple linear regression resolved by the nonnegative least squares. For 1 776 samples of single phytoplankton species, a correct discriminating rate of 97.0% at genus level and 98.1% at division level can be obtained; The correct discriminating rates are more than 92.7% at the genus level and more than 94.8% at the division level for 384 mixed samples from two phytoplankton species.

In the present paper the interaction mechanism and mode of biologically active cysteine dipeptide (Cys-Cys) with DNA was studied by UV-Vis spectrophotometry and fluorescence spectroscopy using ethidium bromide as a fluorescence probe. The results showed that in the buffer solution of Tris-HCl (pH 7.20), at low concentration of Cys-Cys, the ultraviolet spectrum of DNA-Cys-Cys system produced hypochromic effect with increasing the concentration of Cys-Cys. When the concentration of Cys-Cys increased to some high extent, the ultraviolet spectrum of DNA-Cys-Cys system produced hyperchromic effect. Salt-effect experiment showed that the interaction is liable to be affected by the ionic strengths, suggesting the existence of electrostatic binding between Cys-Cys and DNA. The fluorescence of EB-DNA had quenching effect with increasing the concentration of Cys-Cys, and the Stern-Volmer equation indicated that the quenching process was a static one. According to the Lineweaver-Burk equation the binding constant was determined to be 1.640 x 10(4) L x mol(-1). From the above results it can be concluded that the interaction mode of Cys-Cys with DNA was mainly electrostatic binding. These findings could contribute to further investigation on the mechanism of oligopeptides interaction with DNA.

In the present paper, the authors measured the fluorescence spectra of water, alcohols and major microcrystalline substances of different distilled spirits and synthesized their three-dimensional fluorescence spectra. By comparing the fluorescence spectra of major monomers with those of many different kinds of distilled spirits, the authors found that ethanol and many other monomers can influence the fluorescence spectra of distilled spirits. Apart from ethanol, the major microcrystalline substances, such as alcohols, acids, aldehydes and esters influence the fluorescence spectra of distilled spirits respectively. In the meanwhile, their influences are different. The influences of different kinds of monomers differ from each other in the respects of wavelength and intensity. The order of the influences from low level to high level is: alcohols, aldehydes, acids and esters. But the same kind of monomers can bring about almost the same fluorescence spectra. So, the same kind of monomers influences the fluorescence spectra of distilled spirits similarly. To sum up, the authors come to a conclusion that apart from water, every kind of monomers can influence the fluorescence spectra of distilled spirits. And the order of the influences from low level to high level is: alcohols, aldehydes, acids and esters. In the meanwhile, they influence the fluorescence spectra in different spectral range respectively. The outcome of the study is very important for the further detailed research on the fluorescence spectra of distilled spirits in the future.

The fluorescence spectra of ponceau 4R induced by 220-400 nm light were studied in the present paper. The result shows that ponceau 4R has four obvious fluorescence spectral peaks respectively located at 420, 530, 635 and 687 nm, each of these fluorescence spectral peaks has different best induced light, and the corresponding fluorescence spectra were listed. It was considered that this fluorescence comes from the transition n --> pi* of n electrons in the -OH and pi* --> pi of pi electrons in the naphthalene. The fluorescence spectral peaks at 420 nm come from the transition n --> pi* and the other three fluorescence spectral peaks come from pi* --> pi. But the intensity of the four fluorescence spectral peaks changes differently with the excited wavelength This paper attempted to give the expression of the four fluorescence spectral peaks based on the microcosmic mechanism. The reason for that ponceau 4R has complex fluorescence characteristic is that ponceau 4R not only has big and conjugate structure such as naphthalene and provides electron group -OH which can intensify its ability to emit fluorescence, but also absorbs electron group such as N=N which can depress its ability to emit fluorescence. Investigation on the fluorescence spectra and its characteristics will contribute to the study on the fluorescence spectra of other azo pigment and help find a new way for checking food safety.

In the present paper, the fluorescence spectra of three common pesticides, isoprocarb, metolcarb and pirimicarb, were theoretically studied. The geometries of these compounds were fully optimized by density function theory (DFT) method at the B3LYP/6-31+G level. The three compounds under study were confirmed as true minima on the potential energy surface in the presence of only real frequencies by the vibrational analysis. The fluorescence spectra were calculated by configuration interaction (CI) method with PCM model, and the results match with the experimental values. The results of calculation suggest that the three compounds with planar structures are hyperconjugation systems. By the addition of the donor-electron groups, the wavelengths of the fluorescence spectra increased, and the frequencies underwent red-shift. In addition, the substitute alkyl has no more influence on the fluorescence spectra, but the addition of amido groups has more influence on the fluorescence spectra.

The present paper reports three new europium complexes, EuL3(H2O)6, EuL3Phen(H2O)4 and EuL3 (TPPO) (H2O)5, synthesized with Eu(NO3)3 x 6H2O, 2-(4-fluorobenzoyl) benzoic acid, Phen and TPPO(L = 2-(4-fluorobenzoyl) benzoic acid, Phen = 1, 10-phenanthroline, TPPO = triphenyl phosphine oxide). Their composition and chemical structures were characterized by elemental analysis, IR and 1H NMR spectroscopy. The IR spectra indicated that all complexes exhibited the characteristic peaks of carboxylate, asymmetric stretching vibration (vas (CO2(- and symmetric stretching vibration (vs (CO2(- peaks; the C = O stretching band at 1,692 cm(-1) of COOH and the O--H stretching band around 2,500-3,200 cm(-1) disappeared. All these complexes had a smaller Deltav(vas (CO2(-))-vs(CO2(- value than that of NaL, so the carboxylate groups coordinated with the europium ion in the form of bridging bidentate. In 1HNMR, the signals of hydrogen in 2-(4-fluorobenzoyl) benzoic acid became wide and shifted upfield, and those in Phen, TPPO shifted downfield. The excitation and emission spectra were recorded at room temperature. The excitation spectra showed that the optimum excitation peaks of these three complexes, EuL3 (H2O)6, EuL3Phen(H2O)5 and EuL3(TPPO)(H2O)5, were at 353.0, 355.0 and 357.0 nm, respectively. All these three complexes showed Eu3+ ion characteristic emission bands, the electron-dipole transition 5D0 --> 7F2 and magnetism dipole transition 5D0 --> 7F1; their emission peaks were at 596.0, 617.0; 596.0, 619.0; 595.0, 620.0 nm, and the relative intensities were 1.1, 8.6; 15.2, 100.0; 3.6, 23.2, respectively. The intensity of 5D0 --> 7F2 was stronger than that of 5D0 --> F1, which indicated that europium ions were at asymmetric center. The emission intensities of europium ions were greatly sensitized by Phen.

Two new stilbene derivatives, 4-methacryloxyl-4'-nitrostilbene (NS) and 4-(6-methacryloxyl)-hexyloxy-4'-nitrostilbene (HNS), were synthesized and characterized by FTIR, UV-Vis, HPLC and 1H NMR. The influence of structure, concentration and solvent polarity on the fluorescence of the two compounds was investigated in the present paper. Results showed that both NS and HNS have concentration quenching effect and the fluorescence spectrum exhibited a red shift with the increase in the polarity of solvents. Moreover, the donor-acceptor structure is formed in HNS due to the introduction of donor group hexyloxy, which leads to a 72 nm red shift of the maximum wavelength of fluorescence compared with NS, and the fluorescence generated from such composite in DMF solution would change from yellow to orange.

In the present paper, the liquors of Hai zhi lan, Tian zhi lan and Meng zhi lan were selected as the objects, and by using equipment of UV-240 ultra-violet spectrophotometer and Sp-2558 multifunctional spectrometer, their absorption and three-dimensional fluorescence spectra induced by UV light were studied respectively. The maximum absorption wavelengths for all of them were located at 212 and 275 nm, but each has different intensity at 212 nm. Moreover, their three-dimensional fluorescence spectra were detected when they were induced by suitable UV-light, The results show that each of the spirits can emit three strong fluorescence lines at 310, 420 and 610 nm respectively when excited by UV-light at 245 nm. Furthermore, we found each of them can emit another two strong fluorescence lines when they absorb the UV-light at 310 and 345 nm. The authors found that they all have five different fluorescence peaks, but each has different intensity. According to the experimental phenomenon, through a careful analysis, it is pointed out that the differences of the five fluorescence peaks basically reflect the aging process and different content of the liquor. The three different brand yanghe classical liquors were identified fast and accurately. The paper also offered a kind of way to determine the quality and brand of white spirit.

Some of traditional Chinese medicine (TCM) contain arsenide, such as realgar. The total amount of arsenic in the TCM exceeds the limits according to related regulations. But the roles of arsenic in TCM or its side-effects depend on its species existing in those therapies, not on the total amount of arsenic. Therefore, in recent years, the analysis of arsenic in TCM focuses on the species of arsenic. The present paper combines the method of extracting chemical composition from bunge pricklyash seed and analyzing the contents and the speciation of arsenic of bunge pricklyash seed (BPS) in different habitat by atomic fluorescence spectrometry (AFS-3100). By using 0.45 microm filter membrane and mixed solvent, two different species of the decoction of BPS were extracted, named the suspended and the soluble, and by using ion-exchange resin, the soluble arsenic could be separated as As(III), As(V), MMA and DMA. The authors established the segregation analysis methods for those species. The results shows that BPS in different habitat all contain arsenic, mostly as the species of inorganic arsenic, and the contents of As(V) are higher than As(III). The lixiviating rate of arsenic is highest with the solvent of methanol-water (4/1), reaching 53.7%-62.3%. The recovery of the method was 96.0%-101.3% and the relative standard deviation was less than 2.66%. The results show that the sensitivity and reproducibility of this method were excellent, and provided theoretical basis for further development of BPS

In the present paper the fluorescence spectra of the blood serum excited with different wavelength were measured with the fluorescence photometer RF5301 (SHIMADZU) made in Japan. The relationship between the fluorescence spectra of the serum and the wavelength of the excitation light was studied during the experiment. The experimental results show that the linetype and peak wavelength of the fluorescence spectra of serum excited by ultraviolet radiation with different wavelength are almost the same, and they do not depend on the excitation wavelength. But the fluorescence peak value changes with the excitation wavelength. There are two high intensity emission intervals in the fluorescence spectra. One of these is from about 300 nm to 410 nm, and the other is below 310 nmr The fluorescence spectra are mostly centralized in the first interval, and the wavelengths of fluorescence peaks were found around two locations: one is near 330 nm and the other is near 370 nm. At this time the strife phenomena occur. When the excitation wavelength is about 250 nm or higher, the fluorescence peak only occurs at 330 nm, and the optimal excitation wavelength is 300 nm. While the wavelength is greater than 320 nm, the fluorescence intensity of the first interval begins to fall, while that of the other augments. And at this time the peak of wavelength of fluorescence is 452 nm. This study provides the experimental foundations for advanced study and applications of the characteristics of fluorescence spectrum of blood serum, and also offers the references to the wavelength selection of excitation light in the application of the photo-induced fluorescence spectra diagnostic technology.

Chinese rice wine has a history of more than 5000 years, only in China, hich is called "Nation Wine", and Shao Xing Chinese rice wine is a representative of it. The fluorescence spectra of 3 kinds of Shao Xing Chinese rice wine with different storage age induced by suitable UV-light were obtained in the present paper through experiment. The authors compared and analyzed them comprehensively by using three dimensional contour and two dimensional fluorescence technique, and found that their best induced light was all in the vicinity of 370 nm. The peak wavelength of 3 year storage age wine was 504 nm, while 488 nm and 505 nm were for 5 and 8 year storage age wine respectively. The emitted fluorescence existed in 400 to 680 nm, which had wide peak. More over, the emitting mechanism of Shao Xing Chinese rice wine was discussed. The authors also have explained the similarity and difference of fluorescence spectra among the 3 kinds of wine. The reason for wide fluorescence peak was also analyzed. This investigation contributes to the study of the characteristic, year detection and food safety of Chinese rice wine.

A method of spectral analysis, which can simultaneously detect dissolved organic matter (DOM) and chlorophyll a (Chl-a) in natural water, was developed in the present paper with the intention of monitoring water quality fast and quantitatively. Firstly, the total luminescence spectra (TLS) of water sample from East Lake in Wuhan city were measured by the use of laser (532 nm) induced fluorescence (LIF). There were obvious peaks of relative intensity at the wavelength value of 580, 651 and 687 nm in the TLS of the sample, which correspond respectively to spectra of DOM, and the Raman scattering of water and Chl-a in the water. Then the spectral fluorescence signature (SFS) technique was adopted to analyze and distinguish spectral characteristics of DOM and Chl-a in natural water. The calibration curves and function expressions, which indicate the relation between the normalized fluorescence intensities of DOM and Chl-a in water and their concentrations, were obtained respectively under the condition of low concentration(< 40 mg x L(-1))by using normalization of Raman scattering spectrum of water. The curves have a high linearity. When the concentration of the solution with humic acid is large (> 40 mg x L(-1)), the Raman scattering signal is totally absorbed by the molecules of humic acid being on the ground state, so the normalization technique can not be adopted. However the function expression between the concentration of the solution with humic acid and its relative fluorescence peak intensity can be acquired directly with the aid of experiment of fluorescence spectrum. It is concluded that although the expression is non-linearity as a whole, there is a excellent linear relation between the fluorescence intensity and concentration of DOM when the concentration is less than 200 mg x L(-1). The method of measurement based on spectral fluorescence signature technique and the calibration curves gained will have prospects of broad application. It can recognize fast what pollutants are and detect quantitatively their contents in water. It is realizable to monitor the quality of natural water with real time, dynamics and inlarge area.

Studies on the binding mechanism between protein and small molecules could give us lots of useful information. For example, a detailed characterization of drug-protein binding properties was essential for understanding the function of delivery, hence, interest in the mechanism of the interaction between them has attracted much research using different methods. In the present paper, the interaction mechanism between meso-tetra-(3,5-dibromo-4-hydroxyphenyl) porphyrin [T(DBHP)P] and bovine serum albumin (BSA) was investigated using fluorescence method. Based on the mechanisms of fluorescence quenching of BSA caused by T(DBHP)P, the binding constants between T(DBHP)P and BSA were measured at different temperatures. The experiment showed that T(DBHP)P and BSA have strong interactions. The binding constants of the reaction at 27 and 48 degrees C were calculated by fluorescence method, respectively. The binding constants are K = 1.30 x 10(6) L x mol(-1) at 27 degrees C, and K = 6. 32 x 10(5) L x mol(-1) at 48 degrees C. Because the binding constants decreased with increasing the temperature, the sort of quenching between T(DBHP)P and BSA was determined as static quenching. By the theory of Forster non-radiation energy transfer, the binding distance and the energy transfer efficiency at 27 degrees C between T(DBHP)P (accepter of energy) and BSA (donor of energy) were obtained to be 2.39 nm and 0.91, respectively. The binding distance was less than 7 nm, therefore, the interaction was similar to the non-radiation energy transfer, and the static quenching was further proved. According to the thermodynamic parameters, the main sorts of binding force between T(DBHP)P and BSA could be judged as electrostatic force when deltaG <0, deltaH <0 and deltaS >0. Using the synchronous fluorescence spectra, the effect of T(DBHP)P on the conformation of BSA was studied. The results indicated that the conformation of BSA was changed when T(DBHP)P was added, and the hydrophobic properties of the environment of residues in BSA decreased. It was proved that fluorescence quenching of BSA was induced by static quenching and non-radiation energy transfer.

The interaction of sorbitol and bovine serum album (BSA) was studied by fluorescence and ultraviolet absorption spectra. As it is well known to us, the interactional analysis between small molecular drug and biology macromolecule (such as protein, DNA, etc) is one of the important interactional analyses, which can not only offer new biological view but also supply chance for chemist and biochemist to synthesize new drug capable of regulating the biology process effectively. In the present paper, fluorescence spectrophotometry was first employed to study the interaction between BSA and sorbitol. At the same time, the synchronous fluorescence spectroscopy was adopted to review the configuration of BSA influenced by sorbitol, which provides important significance for clinical medication. The results show that sorbitol has strongly quenched the fluorescence of bovine serum albumin in natural physiological condition, the quenching mechanism is a static quenching procedure at different temperatures and drug concentration, and the variational absorption spectra also proves this deduction. At the same time, this article has also examined the influences of sorbitol on the fluorescence quenching of bovine serum albumin at different temperatures and drug concentration. The binding constants and the number of binding sites between sorbitol and BSA were calculated at different temperatures. Furthermore, the enthalpy and entropy changes in the interaction of sorbitol and bovine serum album were also obtained by the equations of Stern-Volmer and Lineweaver-Burk. From the thermodynamic parameters, it can be judged that the primary binding power between sorbitol and BSA is electrostatic force. Moreover, the synchronous fluorescence spectroscopy was applied to examine the effect of sorbitol on the configuration of BSA. The alterative configuration of BSA may be induced by the hydrophobicity environment of tyrosine with the increase in drug concentration. In conclusion, the fluorescence method is highly sensitive and convenient in the study of intermolecular interaction. Further studies in this field will open up the way to applications of biology macromolecule in analytical chemistry and analytical biochemistry.

Recently, non-invasive optical methods to monitor transmembrane electrical potential using voltage sensitive dyes have been applied widely in the studies of normal and pathological heart rhythms and defibrillation. In the present paper, the authors measured the excitation and the emission spectra of the voltage-sensitive dyes di-4-ANEPPS bound to phospholipid bilayer membranes. And according to the spectral shift of di-4-ANEPPS, the authors presented an optical mapping system combining a DALSA CCD camera and a LED light source. Using this optical mapping system, the authors could record the action potential duration of the heart cells with high spatial and temporal resolutions. It can be a powerful tool in the study of cardiac arrhythmia mechanisms.

The fluorescence spectroscopy is widely used in the analysis of the interaction between serum albumin (SA) and micromolecule compound, in which SA is measured as the fluorescence source to provide interaction information. A modified method has been compared with the classical method in the present paper, where the micromolecule compounds were used as the interested analytes whose fluorescence spectra were measured. The binding constants obtained based on the classical and modified methods were found much different by studying the two systems, BSA-TX and BSA-SH. The result shows that the classical method has the drawback of taking the fluorescence source of tryptophan instead of all other amino acids groups in SA molecule. Two novel methods were then reported, namely the modified fluorescence spectrometry method and fluorescence background subtracting method. The former could reflect the whole information of the interaction system, while the latter effectively over-came the overlay of spectra in the system, where the fluorescence spectra of the two components interfere with each other terribly. The effectivity of the two novel methods has been proved by ultra-violet spectrometry.

Protoporphyrin IX is an important kind of organic compound for vital movement, and can be used as the sign of tumour blood. Human protoporphyrin IX content in serum is very low, and affected by various factors. The serum fluorescence spectrum analysis system based on wavelet transform was used to discriminated the protoporphyrin IX weak signals. The protoporphyrin IX fluorescence spectrum was obtained by a multi-function spectrum measuring system, and decomposed several times by wavelet transform to distinguish the noise and spectrum signals. The fluorescence spectrum can be divided into corresponding discrete approximations signals (a1-a6) and discrete details signals (d1-d6) by six times of decomposition, showing the signal frequency decreasing with decomposition times increasing and the protoporphyrin IX fluorescence character peak appears here. The weak signals were discriminated and the exactly component and quantity can be acquired for further analysis. So it can be analysed quantitatively. The researches in the present paper provide the potential application in the diagnosis of incipient tumous using the serum fluorescence spectrum

In the present paper the basic theory that organic molecules can emit fluorescence as they are excited by ultraviolet rays is described, the molecular structures of a few common pesticides, such as carbamate, benzoylurea and fungicide, are analyzed, and the mechanism of fluorescence generation is also ascertained. Consequently, the theoretic basis for further detection of pesticides by means of fluorescence methods is provided. Moreover a steady-state fluorescence spectrograph was applied to conduct fluorescence spectrum experiments with standard solutions of these pesticides, the fluorescence spectra were obtained, and their fluorescence characteristics were also analyzed. The results indicate that carbamate, benzoylurea and fungicide pesticides may emit strong fluorescence when excited by UV rays under the condition of a certain solvent, their fluorescence spectra are distinct, and the resolution is fine. As a result, it is feasible to carry out qualitative and the quantitative analysis of the concerned pesticides by fluorescence spectral analysis.

A theoretical study on fluorescence spectra of three common pesticide compounds, iprodione, acetamiprid and carbaryl, is reported in the present paper. Their geometric configurations were optimized by ab initio method at B3LYP/6-31G level. Vibrational analyses were performed, and there was no imaginary frequency in their vibrational spectra. On these bases, their electronic spectra were calculated by CIS method at B3LYP/6-31+G level. The calculated results are basically consistent with the experimental values. In addition, the results also indicate that the intramolecular hydrogen bonding in N-1 compound has formed and the bond length is about 0.234 8 nm.

The absorption and fluorescence spectra of ethylene glycol and glycerol solution induced by UV light were studied respectively in the present paper. The most intense absorption wavelength for both of them was located at 198 nm. Moreover, fluorescence was detected when induced by suitable UV light, and the corresponding fluorescence spectra were listed. But there is no obvious relationship found between the fluorescence intensity and the excited wavelength, and a further research should be done. From the first derivative fluorescence spectra of ethylene glycol, it was concluded that under the UV light of 210 nm, the variation speed for relative intensity proved to be the fastest. In contrast, when excited by 225 nm, the speed proved to be the slowest. In addition, based on the quantum calculation and the transition from HOMO to LUMO of electronics in one-dimensional quantum well, the authors attempted to give out the value of absorption wavelength. In consideration of the bond-length variety brought out by the chain processing, the error between the experimental and calculation values should be apprehensible, and the latter can serve as some reference value in theory.

In the present paper, p-octacarboxyphenylazocalix[8]arene (CPAC) was used as supramolecular probe according to a reported method. The interaction of CPAC with drug norfloxacin (NFLX) was studied by fluorescence spectrometry. The results show that CPAC can strongly quench the fluorescence of NFLX because of the complex interaction between host and guest molecules in exo-inclusion complex. The spectral changes indicated that the quenching can be considered as static quenching mode. The hydrophobic interaction between the cavity of CPAC and the quinoline ring was the main force to consolidate the exo-inclusive complex CPAC-NFLX stability. The complex constant (K) and binding ratio (n) were determined to be 6. 38 X 10(5) L x mol(-1) and 1, respectively. Further experiment found that the calf thymus DNA and CPAC can combine, leading to the release of NFLX and the enhancement of fluorescence of the reaction system. It is expected that CPAC will be used as drug carrier and releaser.

Glutathione transferases (GST; EC2. 5. 1. 18) is an important detoxification enzyme which catalyze the conjugation of glutathione to a large variety of endogenous and exogenous electrophilic compounds to protect the functions of body. In the present paper, three dimensional fluorescence spectra were obtained, through which the authors could identify the fluorescence spectra of peptide bond, Tyr and Trp residue. The authors compared aromatic amino-acid residue fluorescence spectra in GST with dissociative to know red or blue shift of the fluorescence peak. The authors also studied the peptide bond and Trp residue fluorescence spectra at various pH, which suggested the change in GST surface and surface hydrophobicity, and the microenviroment change of aromatic amino-acid residue in enzyme.

In the present paper, the interaction of Magdala red and bovine serum albumin(BSA) was studied by UV-absorption and fluorescence spectrometry. The results of UV-absorption spectrometry show that the way of the interaction of Magdala red and BSA should obey the Scatchard Model. In other words, Magdala should be combined to some certain regions of BSA. Meanwhile, taking advantage of fluorescence quenching, the reaction mechanism of Magdala with BSA was explored. Protein molecule conformation change is discussed by synchronous fluorescence spectrometry.

The analysis technique of fluorescence is adopted to study the intensity of excitation fluorescence of blood in the present paper. The theoretical analysis and differences of normal and abnormal blood (hyperglycemia, hyperlipemia) are presented. The theoretical analysis was proved by experiment results. It was discovered that blood sugar consistency has an effect on blood fluorescence. In other words, with the same excitation wavelength and with blood sugar consistency increasing, the fluorescence intensity increases gradually. It is obvious that blood sugar is also a kind of fluorescein, and its consistency has an effect on fluorescence intensity, which is identical with the theoretical analysis, indicating that the experiment is successful, and it is possible to distinguish blood sugar consistency by comparing the fluorescence intensity in blood. It was also discovered that the higher the cholesterin content, the more intense the fluorescence. When excitation wavelength is especially 435 nm, the phenomenon is very obvious. The study paves a new way for the blood quick check and diagnosis of diseases.

In the present paper the basic theory that an organic substance can emit fluorescence as it is excited by ultraviolet rays is described and the relationships between the molecular structures of organic substances and fluorescence generation are studied. According to this theory, the molecular structures of a few common carbamate pesticides such as carbaryl, carbofuran and propoxur etc.are analyzed, their fluorescence characteristics are shown, and the mechanism of fluorescence generation of carbamate pesticides is ascertained. It provides a theoretic basis for further detecting carbamate pesticides by means of a fluorescence analytical method. Moreover a steady-state fluorescence spectrograph is applied to conduct fluorescence spectrum experiments with standard carbaryl solution and carbofuran solution. The results indicate that carbamate pesticides may emit fluorescence as excited by UV under the condition of a certain solvent, and that their fluorescence spectra are distinct and have fine resolution and less interference. It is feasible to detect carbamate pesticides by fluorescence spectral analysis.

The synchronous fluorescence, first-order and second-order-derivative synchronous fluorescence spectra of BaP in cigarette mainstream smoke were studied. It was indicated that the second-order-derivative synchronous fluorescence spectrum could decrease the disturbances of BaP homologous compounds and background of sample. Hereby the present paper introduces a new method to determine BaP in cigarette mainstream smoke by solid-phase-extraction second-order-derivative synchronous fluorescence. The detection limit is 0.2 ng x mL(-1), the average recoveries of BaP are 80.2%-86.2%, and the RSD is 2.64%-3.02%.

Research of the mechanism for delayed fluorescence origin play an important role in the application of DF. Based onthe charge recombination theory, the mechanism for delayed fluorescence origin is theoretically analyzed in this paper. The decay kinetics of DF, depending on the backward transport electron and oxidized state P680+, can be well fitted by poly-exponent. The relative fast component of DF originates from the Z+ P680 Q(A)- states, generated during the previous period of the sample illumination. On the other hand, the slow component of DF is ascribed to the state Q(B)= --the next electron carrier of deoxidized side in PS II. Meanwhile, the experimental results confirmed the theoretical conclusion. Furthermore, the authors testified that the third component with lifetime much greater than the time of the registration period (which is presented as a constant), is corresponds to the recombination of P680+ and the backward transport electron from PSI.

In the past few years extensive attention has turned toward optical biopsy, because of its ability to perform noninvasive, real time and accurate diagnosis of tissue pathologies, especially precancer. Fluorescence spectroscopy is one of a series of techniques widely developed for optical biopsy, and can be generally divided into two categories: fluorescence spectroscopy and imaging. This paper reviews the applications of autofluorescence and exogenous fluorescence to optical biopsy, and the principle and advantages as well as the clinic applications of various steady-state and time-resolved fluorescence spectroscopy and imaging techniques. Furthermore, the development perspectives of optical biopsy by using fluorescence spectroscopy and imaging are also briefly discussed.

A method of hydride generation-atomic fluorescence spectrometry was proposed in the present paper for the determination of trace arsenic and selenium in jellyfish. The samples were treated by the combination of microwave digestion and lyophilization. The optimal conditions for treating and analyzing samples were established. The problem of the effect of the superfluous acid in the digesting solution on the results was solved, and the influence of coexisting foreign ions on the determination of arsenic and selenium was investigated. The accuracy of the method was confirmed by the method of standard additions. This method proved to be simple, rapid and repeatable, and is suitable for the analysis of biologic samples containing water.

This paper describes a new method, multiphoton excitation fluorescence detection combined with capillary electrophoresis separation. The excitation source was a self mode-locked femtosecond titanium-sapphire laser (Spectra-physics Inc.), producing a stream of pulses with a pulse duration of about 100 fs at 82 MHz repetition rate. Its average power was about 200 mW at 750 nm. The laser beam was focused into a thin wall flow cell of capillary electrophoresis. A high numerical aperture objective (100 x NA 1.25) was chosen to focus the laser beam and to collect the fluorescence emitted by detecting molecules. Then the fluorescence was detected by a fast response PMT. All data were acquired and processed by a microcomputer. For three biological molecules, 5HT, FAD and NADH, it was demonstrated that they can be separated and detected efficiently by this method with three-photon and two-photon excitation respectively using only one 750 nm laser beam. The detection limits were 1.0 x 10(-6) mol x L(-1) for 5HT, 7.4 x 10(-7) mol x L(-1) for FAD and 9.8 x 10(-7) mol x L(-1) for NADH using the criterion of three standard deviations above background. The results are much better than those with UV absorption detection by one or two magnitudes.

In this paper, the interaction of the antibacterial peptide MDL-1 of Musca domestica L and E. coli DNA was investigated by fluorescence spectra. The interaction mode was studied by using ethidium bromide (EB) as an extrinsic fluorescence probe. The result of fluorescence spectra and Scatchard plot indicate that the binding constant and the number of binding sites between DNA and EB decrease with increasing concentration of MDL-1. The change in binding constant and binding sites showed that the conformation of DNA transformed. When the EB molecule just fitted into the interval, the fluorescence intensity was maximum. When MDL-1 was present in the system, the EB molecules was excluded from DNA, then the fluorescence intensity decreased. The result showed that the style was eletrostatic binding, groove binding and intercalation in the interaction of MDL-1 and double helix DNA. The binding constant of MDL-1 complex with DNA was determined. Meanwhile, it helped to explain the molecule mechanism of antibacterial peptides from the interaction style and structure characteristic of antibacterial peptide and bacterial DNA.

Fluorescence spectroscopy has achieved great successes in the study on the interaction of drugs and DNA in both quantitative analysis and qualitative analysis. While the fluorescence probe technique can be used to measure the intensity of drugs-DNA interaction, because the injected drugs can change the fluorescence intensity of the probe. In this paper, the authors use berberine as a probe to measure the interaction intensity between some anticancer drugs and DNA, calculate the constant D and determine the effects of those drugs. In addition, the authors point out that this method can not be efficient for certain drug solution.

Nucleic acid analysis is one of the most important techniques for the study in biotic field. The spectrophotometry using inherent ultraviolet absorption spectrum of nucleic acids and the spectrofluorimetry based on the interaction of nucleic acids and fluorescence probes were usually used for nucleic acid analysis. However, the spectrophotometry was severely limited by its low sensitivity, and the spectrofluorimetry suffered from the disadvantages of high cost and toxic reagents. Recently, resonance light scattering has emerged as a new nucleic acid analysis technique. The resonance light scattering analysis is becoming increasingly important because high sensitivity can be obtained with a common spectrofluorimeter by using inexpensive and safe reagents. In this paper, the principle of resonance light scattering was briefly stated and the recent advances of the nucleic acid analysis by resonance light scattering were reviewed with 57 references. The resonance light scattering probes for nucleic acid analysis were divided into four groups: organic dyes; cation surfactants; metal ions and their complexes; and drugs. The light scattering analysis for nucleic acids based on the formation of large particles was also stated.

This paper describes optimal conditions for HBsAbIgG labeling with a new fluorescence probe, 4,7-bis-chorosulfophenyl-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) for the solid phase time-resolved fluorimmunoassay (TRFIA). The result of experiment under states clearly that BCPDA may react with protein under relative mild condition. The relative bioactivity of reacted protein was more than 80%. The labeling molar ratio of BCPDA for HBsAbIgG was 45-70. The recovery was higher than 80%. Protein-BCPDA-Eu3+ complex is stable. It can emit very high fluorescence intensity with very long fluorescence life times. The fluorescence of Protein-BCPDA-Eu3+ complex has a very large stokes shift (270 nm). The emission band at 611.2 nm is very narrow. The research provides the base for developing non-isotopic immunoassay technique and clinical medical diagnosis.

In this paper, the medium (pH, organic solvent and surfactant) effects on fluorescence of eosin-5-isothiocyanate (eosin-ITC) have been studied in detail. The results show that the pH and polarity of system studied are two great important influence factors on fluorescence of eosin-ITC. The fluorescence intensity of eosin-ITC in weak acidic medium is higher obviously than that of in weak basic medium, but it is sensitive to change of pH, be careful to use. The reaction between surfactant and eosin-ITC shows a good electric selectivity, and the effect of CTMAB on fluorescence of eosin-ITC can be classified as two stages: monomer quenching (below cmc) and micelle sensibilization (above cmc). In the presence of micelle of CTMAB, the fluorescence intensity of eosin-ITC in weak basic medium is even higher than that of in weak acidic medium. In the presence of high organic solvent content, the fluorescence intensity of eosin-ITC is also increased obviously. These properties are available for use.