同步荧光法同时测定水溶解态的蒽和芘

利用PAHs具有高的荧光量子产率,同步荧光法具有快速、灵敏、选择性较好的优点,建立了同时测定水溶液中溶解态蒽和芘的方法。所建方法测定蒽和芘的线性范围分别为1.0×10-8~2.0×10-7mol/L和5.0×10-9~3.5×10-7mol/L,检出限分别为1.69×10-9mol/L、8.42×10-10mol/L,相对标准偏差分别为2.90%、2.34%(n=5)。运用所建方法尝试了自来水样品的测定。     

Simultaneous determination of carvedilol and ampicillin sodium by synchronous fluorimetry

The carvedilol and ampicillin sodium were simultaneously determined by the synchronous fluorimetry. With excitation wavelength at 254 nm, the maximum emission wavelengths of carvedilol and ampicillin sodium were at 357 and 426 nm, respectively. Because the emission spectra of carvedilol and ampicillin sodium were overlapped partially, carvedilol and ampicillin sodium cannot be determined directly by normal fluorimetric method. However, the synchronous fluorimetry can be used for determining both drugs simultaneously without separation procedure. The (Delta)(lambda) = 80 nm was used. Iso-propanol was selected as sensing reagent. Effects of pH, organic solvents and foreign ions on the determination of both drugs were studied. The linear relationship was obtained between the relative fluorescence intensity and concentration of carvedilol and ampicillin sodium in the range of 0.005-0.1 and 5.0-70.0 microg ml(-1), respectively. The linear regression equation of calibration graph for carvedilol is C = 0.000151F - 0.00210, and for ampicillin sodium is C = 0.0770F - 2.62. The correlation coefficient of linear regression equation is 0.9995 for carvedilol and 0.9998 for ampicillin sodium, respectively. The detection limit is 1 ng ml(-1) for carvedilol and 1 microg ml(-1) for ampicillin sodium. The relative standard deviations of carvidelol and ampicillin sodium are 2.47 and 1.61%, respectively. The recovery is from 96.0 to 103.0% for carcvedilol and from 98.0 to 105.0% for ampicillin sodium. This method was rapid, simple and highly sensitive for the determination of carvedilol and ampicillin sodium without pre-separation. The results obtained by this method agreed with those by the official methods. This method can be used for the determination of carvedilol and ampicillin sodium in the medicine dosage.     

Pefloxacin determination in urine by synchronous fluorimetry

The feasibility of using synchronous fluorescence spectra for the determination of fluoroquinolone antibiotics in biological liquids is demonstrated. Pefloxacin chelating with metal ions in a micellar medium increases the determination sensitivity.     

Trace zinc determination by synchronous derivative fluorimetry

A sensitive and selective synchronous-scanning derivative spectrofluorimetric determination of zinc based on the formation of a fluorescent chelate with 2-furaldehyde 2-pyridylhydrazone (FAPH) is described, and its analytical performance compared with that of the ordinary fluorimetric method. The detection limits lie in the ng ml range and the coefficient of variation is below 2% in both cases. The methods have been applied to the trace determination of zinc in pig liver tissue and environmental fume samples.     

Simultaneous determination of samarium, europium and terbium with quinaldic acid and phenanthroline by synchronous derivative fluorimetry

Synchronous derivative fluorescence of samarium, europium and terbium complexes with quinaldic acid and phenanthroline was examined in aqueous solution. The composition of these complexes was determined. The maximum emission wavelengths are 645 nm, 617 nm and 545 nm for samarium, europium and terbium, respectively. Under the optimal experimental conditions, the fluorescence intensity was a linear function of concentration in the range of 10-250 ppm for samarium, 0.5-50 ppm for europium and 0.5-300 ppm for terbium. Simultaneous determination of samarium, europium and terbium was successfully carried out for samarium oxide and middle rare earth mixture. The precision of the method, expressed as relative standard deviation, is within 1.1-2.5%.     

Degradation of anthracene, pyrene and benzo[a]-anthracene in aqueous solution by chlorine dioxide

Polycyclic aromatic hydrocarbons (PAHs) constitute an important group of micropollutants, which are known to be mutagenic, carcinogenic and/or co-carcinogenic and relatively persistent in the environment. The effects of chlorine dioxide (ClO2) on the degradation of anthracene (ANTH), pyrene (PYR) and benzo[a]anthracene (BaA) in aqueous solution were investigated using high performance liquid chromatography (HPLC). In preliminary experiments, it was observed that ClO2 could remove these three PAHs effectively within a short time. Several factors including reaction time, the concentration of ClO2 and pH of the reaction mixture influencing the degradation ratio of PAHs have been studied by batch experiments. The results showed that the degradation ratio of PAHs was affected by reaction time and the concentration of ClO2 instead of pH. The degradation ratio of ANTH, PYR and BaA could reach their maximum as approximately 99.0%, 67.5% and 89.5%, respectively, under the condition as follows: reaction time 30, 60 and 120 min, the concentration of ClO2 0.1, 0.4 and 0.5 mmol·L-1, and pH 7.2. ANTH was selected as the representative to study the reaction mechanism with ClO2. The oxidation products formed in the reaction of ANTH with ClO2 were tentatively identified by gas chromatography-mass spectrometry (GC-MS), and the results showed that the main product was 9, 10-anthraquinone, which could be biodegraded more easily and quickly than ANTH. Through analyzing the reaction properties of ANTH and ClO2, the possible pathway for the ANTH-ClO2 reaction was proposed based on the theory of single electron transfer (SET).     

Direct determination of salicylamide in serum by matrix isopotential synchronous fluorimetry

A method for the determination of salicylamide at concentrations between 25 and 350 ng ml(-1) by use of matrix isopotential synchronous fluorescence spectrometry (MISF) in combination with derivative techniques is proposed. The method allows the determination of compounds in samples with unknown background fluorescence without the need for tedious pre-separation. Synchronous scans are performed along a trajectory that connects points of identical intensity in a three-dimensional fluorescence spectrum. The unknown analytical signal of the serum is suppressed from the MISF spectrum, by calculating its first derivative at lambda(exc)=324 nm and lambda(em)=392 nm. In order to ensure maximum sensitivity and adequate selectivity, the experimental variables affecting the fluorescence intensity of the salicylamide band at lambda(exc)=328 nm and lambda(em)=418 nm were studied. Based on the results, the determination was performed in an aqueous medium at pH 12 that was adjusted with a sodium phosphate/hydrogen phosphate buffer. Calibration graphs were subjected to a comprehensive statistical analysis. The error propagation has been considered in order to calculate the detection limit by the criterium of Clayton.     

Rapid determination of sulfonated naphthalenes and their formaldehyde condensates in aqueous environmental samples using synchronous excitation fluorimetry.

Sulfonated naphthalenes and their formaldehyde condensates (SNFC) were determined in aqueous environmental samples by spectrofluorimetry. A clean-up step using n-hexane to extract possibly interfering nonpolar compounds such as naphthalene is the only preparatory procedure. Synchronous excitation mode with a gammalambda of 105 nm allows the determination of SNFC in environmental samples without additional clean-up or analyte enrichment. Interferences by humic acids and nitrate occurred only at concentrations higher than 1 mg C L(-1) and 10 mg NO3- L(-1), respectively. The limit of detection was 0.2 microg L(-1), the average recovery was 104% and the confidence interval (95% certainty) was 24%. The response factor for the quantitative determination of total SNFC, depending on the distribution of the different SNFC components, was validated for groundwater from two field sites using an HPLC-FD (fluorescence detection) method as a reference method.     

Simultaneous determination of propranolol and pindolol by synchronous spectrofluorimetry

A completely automated method to determine the most common parameters in cured meat products is proposed. The approach to full automation is based on the coupling of a robotic station for development of preliminary operations (namely weighing of the sample, grinding, leaching, filtration and transport to the aspiration zone) and a continuous unsegmented manifold for derivatisation and spectrophotometric monitoring of the reaction coloured products. This assembly works in an unattended fashion thus eliminating the bottleneck produced by the determination of these parameters in routine laboratories. The good agreement between results obtained by the proposed method and those from conventional methods for target analytes confirms its excellent performance and usefulness.     

Determination of gentamycin by synchronous derivative fluorimetry

Use of synchronous first-derivative fluorimetry for determination of gentamycin is described. Gentamycin reacts with acetylacetone and formaldehyde in pH 5.6 HOAc/NaOAc buffer solution to form N-gentamyl-2,6-dimethyl-3,5-diacethyl-1,4-dihydropyridine[I] which is a fluorescent substance. Spectra of [I] and the reagent blank can be separated with synchronous derivative fluorimetry, and gentamycin can be determined directly. The synchronous spectral peaks of [I] and the reagent blank are at 434 and 411 nm, respectively. The first-derivative peak of [I] is at 425 nm. Effects of pH, foreign ions, buffer system, and heating time on the determination of gentamycin have been examined. The linear regression equation of the calibration graph is C=0.0513H-0.0416, with a correlation coefficient of linear regression of 0.9978. C means total potency of gentamycin: U ml(-1); H means peak height in the linear regression equation calibration graph. The linear range for the determination of gentamycin is from 0.00 to 3.00 U ml(-1). Recovery is from 95.06 to 112.0%, R.S.D. of 3.8%. The results determined by the fluorimetric method agreed roughly with those by the microbiological method. The method is simple and has low detection limit.     

Simultaneous determination of yohimbine and boldine by first-derivative synchronous spectrofluorimetry

A method for the simultaneous determination of yohimbine and boldine in mixtures by first-derivative synchronous spectrofluorimetry has been developed. The method is based on their native fluorescence in 0.1N sulphuric acid medium. The constant wavelength difference chosen to optimize the determination was =_em -_em=82 nm. Yohimbine was measured at _ex//_em= 285/367 nm, and boldine at _ex/_em=272/354 nm. The range of application is 10–500 g/l for yohimbine and 1–50 g/l for boldine. The method was applied to the determination of yohimbine and boldine in synthetic mixtures and pharmaceuticals, with errors generally 2%. Relative standard deviations were about 2%.Dedicated to Professor Fermin Capitán on his 72th birthday     

Simultaneous determination of two anti-inflammatory drugs in serum using isopotential fluorimetry

The simultaneous determination of 6-methoxy-2-naphthylacetic acid (6MNA) and diflunisal in serum samples using the combination of matrix isopotential synchronous fluorescence (MISF) and first derivative technique is proposed. 6MNA and diflunisal exhibit overlapped spectra and serum produces background fluorescence that precludes the direct determination of these anti-inflammatory drugs by conventional fluorimetry. This method provides good analytical results for determination of compounds in samples with unknown background fluorescence. The method was applied for the simultaneous determination of 6MNA and diflunisal in serum samples at concentrations between 20-200 and 100-1000 ng mL⁻¹, respectively, by means of absolute values of first derivative of synchronous scan at 247.9/364.0 and 262.6/392.4 nm for 6MNA and diflunisal, respectively. In order to obtain maximum sensitivity and adequate selectivity, factors affecting fluorescence intensity were studied. As a result, the analyses were performed in water at a pH of 7.2, adjusted by using sodium dihydrogen phosphate/hydrogen phosphate (0.1 M) as a buffer solution. Serum samples were diluted 200 times. Analytical parameters of the proposed method were calculated according to the error propagation theory. The limit of detection calculated according to Clayton was 15.8 and 63.0 ng mL⁻¹ for 6MNA and diflunisal, respectively. The sensitivity, repeatability and reproducibility achieved with the proposed method were adequate for the determination of these anti-inflammatory agents in serum samples.     

Application of the effects of solvent and dissolved oxygen on the determination of benzo[a]pyrene by constant-wavelength synchronous spectrofluorimetry in smoke-flavouring

This work studies the effects of solvent and of dissolved oxygen in the determination of benzo[a]pyrene (BaP) by constant-wavelength synchronous spectrofluorimetry in smoke-flavour agents, as confirmation and quantification techniques. The wavelength of the most intense peak at the optimum excitation-emission wavelength interval (20 or 110 nm in most of nine solvents) varied by up to 5 nm, and the detection and quantification limits by a factor of up to 30. The best quantification limit was obtained with DMSO (0.09 mug l(-1)). The deoxygenation of the analyte solution decreased detection and quantification limits, by a variable factor (8-1.13 in the case of n-hexane and DMSO, respectively).     

Simultaneous determination of carbaryl and azinphos-methyl in water by first-derivative synchronous spectrofluorimetry

A method is proposed for the simultaneous determination of the pesticides carbaryl (CBL) and azinphos-methyl (AZM) in water by first-derivative synchronous spectrofluorimetry. It is based on the alkaline hydrolysis of both pesticides to their metabolites 1-naphthol (from CBL) and anthranilic acid (from AZM). The constant wavelength difference chosen to optimize the determination is Δλ=λ_em?λ_ex=103 nm. CBL is measured at 302/405 nm and AZM at 333/436 nm. The calibration graphs are linear between 2.0 and 500.0 ng/ml for CBL and between 1.2 and 500.0 ng/ml for AZM with detection limits of 0.62 ng/ml and 0.35 ng/ml, respectively. The precision of the method (RSD) is 2.4% at the 80.0 ng/ml level for CBL and 2.5% at the 80.0 ng/ml level for AZM. The method is applied to the determination of both analytes in samples of natural waters.     

The state of dissolved benzene in aqueous solution

Henry's law constants for benzene in water have been measured by bringing water layers into equilibrium with solutions of benzene in carbon tetrachloride or in cyclohexane. The mole fraction of benzene in the aqueous layer was determined by ultraviolet absorption spectrophotometry, and its fugacity was taken as equal to that in the nonaqueous phase, reliable data for the C₆H₆–CCl₄ and C₆H₆–c–C₆H₁₂ systems being available in the literature. Measurements were made at 5^o intervals from 10 to 30°C inclusive, at mole fractions down to from 10% to 20% of saturation. In no case did Henry's law constant depart significantly from constancy, and it was in reasonable agreement with some representative literature values based on saturated solubility. The constancy and the magnitudes of our K_h values indicate that appreciable dimerization does not occur in the temperature range examined here. This conclusion contrasts with the suggestion of Reid, Quickenden, and Franks that their calorimetrically measured heat of solution of benzene in water is different enough from the van't Hoff heat to imply possible dimerization of the solute; it also contrasts with the hydrophobic-bond-forming tendency which Ben-Naim, Wilf, and Yaacobi ascribe to benzene on the basis of their studies of the solubilities of benzene and biphenyl. The results of the latter study, when combined with the known second virial coefficient of benzene vapor, predict that more than 20% of the benzene in saturated aqueous solution at 25°C should be present as dimer, in clear contradiction to the results of the present work.     

Simultaneous determination of histidine and histamine by second-derivative synchronous fluorescence spectrometry

Simultaneous direct determination of histidine and histamine in mixtures is described. The method is based on the formation of fluorescent condensation products with o-phthaldialdehyde in a basic medium in the presence of 2-mercaptoethanol. Both the conventional and synchronous fluorescence spectra of these condensation products completely overlap, making determination by either of these techniques impossible. However, the determination can be performed by second-derivative synchronous fluorescence spectrometry. The method is simple, rapid and inexpensive and the measurements are performed in a single scan. Calibration graphs are linear in the range 0.1-4.0 mug/ml for histidine and 0.06-5.0 mug/ml for histamine. Mixtures of histidine and histamine in ratios between 12:1 and 1:8 have been satisfactorily resolved.     

Simultaneous determination of some rare-earth elements by derivative fluorimetry and use of the Kalman filter

A procedure for the simultaneous determination of dysprosium, europium, samarium and terbium by laser-induced derivative fluorimetry is described. The method is based on the use of 1 x 10(-4)M hexafluoroacetylacetone (HFA) and 2 x 10(-4)M tri-n-octylphosphine oxide (TOPO) as ligands in aqueous solution at pH 3. The first-derivative and Kalman-filter techniques were used for background correction and reduction of interference. The effects of foreign ions were investigated. The procedure is satisfactory for the simultaneous determination of these four lanthanides.     

Simultaneous determination of aluminium and beryllium by first-derivative synchronous solid-phase spectrofluorimetry

A method for the simultaneous determination of aluminium and beryllium in mixtures by first-deravative synchronous solid-phase spectrofluorimetry has been developed. Aluminium and beryllium reacted with morin to give fluorescent complexes, which were fixed on a dextran-type resin. The fluoresnce of the resin, packed in a 1-mm silica cell, was measured directly with a solid-surface attachment. The constant wavelength difference chosen to optimize the determination was Deltalambda = lambda(em) = 75 nm. Aluminium was measured at lambda(em)lambda = 445/520 nm and beryllium at lambda(em)lambda(em) = 430/505 nm. The range of application is between 0.5 and 5.0 ng/ml for both aluminium and beryllium. The accuracy and precision of the method are reported. The method has been successfully applied to the determination of aluminium and beryllium in synthetic mixtures and natural waters.     

Simultaneous determination of warfarin and bromadiolone by derivative synchronous fluorescence spectrometry

By using second derivative synchronous fluorescence spectrometry the simple resolution of mixtures of the anticoagulant rodenticides warfarin and bromadiolone in the presence of beta-cyclodextrin is accomplished which causes a differential effect on the fluorescence intensity of these compounds. The determination method developed is simple, fast and inexpensive; in addition, measurements are performed in a single scan. Mixtures of warfarin and bromadiolone in ratios between 4:1 and 1:10 were satisfactorily resolved.     

Simultaneous determination of histamine and spermidine by second-derivative synchronous fluorescence spectrometry

The method is based on formation of the fluorescent condensation products with o-phthaldialdehyde; 0.5–2000 ng ml^?1 histamine and 3–700 ng ml^?1 spermidine can be quantified, with relative standard deviations of 2–3%. Histamine/spermidine ratios of 2.5:1–1:30 can be handled. A selectivity study is reported.