Synchronous Fluorescence Intensity Research Articles

Native and synchronous fluorescence spectroscopy for determination of avanafil in presence of its co-formulated drug (dapoxetine hydrochloride): Application to pharmaceutical product, biological fluid and content uniformity.

The native and synchronous fluorescence spectroscopy procedures have been established and validated for the simultaneous determination of a binary mixture of dapoxetine hydrochloride (DAP) and avanafil (AVA). The first procedure is based on measurement of native fluorescence intensity of both drugs at λEm 337nm and 370nm using λEx 290nm and 314nm for DAP and AVA in methanol respectively. The second procedure describes a measurement of synchronous fluorescence intensity of these drugs at 232nm for DAP, and 267nm for AVA, using Δλ of 90nm. In the first procedure the fluorescence concentration were 0.1-4.0μg/mL for DAP and 0.5-16μg/mL for AVA. For the second procedure fluorescence concentrations were 0.025-1.0μg/mL and 0.5-16μg/mL for DAP and AVA respectively, with lower detection limit and quantification limits. The processes were successfully used for the limitation of DAP and AVA in their drug product without pre-separation. Then, the techniques were utilized for the determination of DAP and AVA in biological fluids. There is a good agreement between these results and the results obtained using a reference method.

Derivative constant wavelength synchronous fluorescence spectrometry for the simultaneous detection of cefadrine and cefadroxil in water samples.

A sensitive accurate spectrofluorimetric technique was developed to detect cefadroxil and cefradine traces in water samples simultaneously, by applying a procedure based on the formation of hydrolysis products corresponding to these compounds by sodium hydroxide (1N NaOH) treatment. The conventional and the synchronous fluorescence spectra of these hydrolyzed products were totally overlapped making resolving of this mixture impossible. The second-derivative constant-wavelength synchronous fluorescence spectra allowed their detection simultaneously in a single scan after experimental conditions optimization, which was measured at 390nm and 379nm for cefadroxil and cefradine, respectively at Δλ=30.0. The calibration curves between derivative synchronous fluorescence intensity and drugs concentration showed suitable linear correlation in the range of 0.1 to 5μg.mL-1 for cefadroxil and 0.5-10μg.mL-1 for cefradine. The proposed fluorimetric method is superior in being simple, environmental friendly and cost effective in comparison to the previously published reported methods.

Second-derivative synchronous spectrofluorimetric assay of dapagliflozin: Application to stability study and pharmaceutical preparation.

A highly accurate, simple and sensitive spectrofluorimetric analytical method for dapagliflozin (DGF) quantitation was developed. The proposed method was successively applied to DGF analysis in both its pure and pharmaceutical dosage forms. This method was developed to investigate DGF stability in its degradation products, as laid out in International Council for Harmonisation (ICH) rules. Kinetics of alkaline degradation of DGF was also calculated. The half-life time (t1/2 ) of the reaction was 75.32min. An alkaline degradation pathway was described. The present study involved measurement of the second-derivative synchronous fluorescence intensity of DGF at Δλ=30nm. Peak amplitude was measured at 322nm. Linear range of the calibration curve was 0.1-1.0μgml-1 . Lower detection and quantitation limits were 0.023 and 0.071μgml-1 , respectively, and indicated good sensitivity of the proposed method. Mean per cent recovery was 99.78±1.78%. The proposed analytical approach was successfully applied to DGF in the quality control laboratory and would be suitable as a stability-indicating assay.

Exploiting steroid-cyclodextrin complexes for selective determination of Estradiol Valerate and Norethisterone Acetate by synchronous fluorescence spectrofluorimetry.

Inclusion complexes of β-cyclodextrin with Estradiol valerate (EST) or Norethisterone acetate (NOR) have been utilized for synchronous fluorescence spectrofluorimetry. β-cyclodextrin improves fluorescence intensity as well as water solubility of the studied drugs. Samples in aqueous medium adjusted with ammonia were used in synchronous fluorescence to resolve the overlapped emission spectra. The effects of β-cyclodextrin concentration and Δ λ have been optimized for sensitive and selective analysis of EST and NOR binary mixture. Synchronous fluorescence intensity of the two drugs is measured at Δ λ of 70 nm. EST and NOR can be simultaneously determined at 230 nm and 270 nm, respectively. Calibration curves were linear over the ranges of 0.5-6.0 μg mL-1 and 0.2-2.0 μg mL-1 for EST and NOR, respectively. Official guidelines were followed to estimate the validation parameters of the proposed method. The detection limits were 0.08 μg mL-1 for EST and 0.007 μg mL-1 for NOR. The proposed method was successfully used for the analysis of EST and NOR in their commercial preparations and the obtained results revealed statistical agreement with those obtained by application of the reported method for both drugs. The proposed method is compared favorably to previously published method in terms of simplicity and hazardous solvent consumption.

Indirect synchronous fluorescence spectroscopy and direct high‐performance thin‐layer chromatographic methods for enantioseperation of zopiclone and determination of chiral‐switching eszopiclone: Evaluation of thermodynamic quantities of chromatographic separation

Economic and enantioselective synchronous fluorescence spectroscopy and high-performance thin-layer chromatography methods have been developed and validated as per ICH guidelines for the separation of zopiclone enantiomers using L-(+)-tartaric acid as a chiral selector, followed by determination of the chiral-switching eszopiclone. Synchronous fluorescence spectroscopy was successfully applied for chiral recognition of R & S enantiomers of zopiclone at ∆λ=110nm based on creating of diastereomeric complexes with 0.06M tartaric acid in an aqueous medium containing 0.2M disodium hydrogen orthophosphate. Synchronous fluorescence intensities of eszopiclone were recorded at 296nm in concentration range 0.2- to 4-μg/mL eszopiclone. High-performance thin-layer chromatography method depends on resolution of zopiclone enantiomers on achiral HPTLC silica-gel plates using acetonitrile:methanol:water (8:2:0.25, v/v/v) containing L-(+)-tartaric acid as a chiral mobile-phase additive followed by densitometric measurements at 304nm in concentration range of 1 to 10μg/band of eszopiclone. The effect of chiral-selector concentration, pH, and temperature on the resolution have been studied and optimized for the proposed methods. The cited procedures were successfully applied to determine eszopiclone in commercial tablets of pure and racemic forms. Enantiomeric excess was evaluated using optical purity test and integrated peak area to describe the enantiomeric ratio. Thermodynamics of chromatographic separation, enthalpy, and entropy were evaluated using the Van't Hoff equation. The proposed methods were found to be selective for identification and determination of the eutomer in drug substances and products.

Comparison of antigenicity and conformational changes to β-lactoglobulin following kestose glycation reaction with and without dynamic high-pressure microfluidization treatment

Previous work indicated that conformational changes of β-lactoglobulin (β-LG) induced by dynamic high pressure microfluidization (DHPM) was related to the increase of antigenicity. In this study, β-LG glycated with 1-kestose and combined with DHPM decreased the antigenicity of β-LG. The antigenicity of control, β-LG-kestose (0.1 MPa) and β-LG-kestose (80 MPa) were 100, 79 and 42 μg/mL respectively. The molecular weight of β-LG conjugated to kestose increased from 18.4 to 19.6 kDa and its conformation scarcely changed. Conversely, combined with DHPM treatment (80 MPa), β-LG conjugated to kestose formed two conjugates with molecular weight of 18.8 and 19.8 kDa, respectively. Furthermore, the unfolding of β-LG as a result of the treatments is reflected by a decrease of intrinsic and synchronous fluorescence intensity and changes to the secondary structure. The conformational changes induced by DHPM and glycation treatments synergistically decrease the antigenicity of β-LG due to more masked or disrupted epitopes.

Determination of trace fluoroquinolones in water solutions and in medicinal preparations by conventional and synchronous fluorescence spectrometry

Abstract Simple, rapid and sensitive and synchronous fluorescence spectrometry (SFS) were developed for determination the fluoroquinolones of ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENR) separately in water solutions and in medicinal preparations. The optimized wavelength intervals between the emission and excitation wavelengths were 170 nm, 160 nm and 170 nm for CIP, NOR and ENR, respectively. The different experimental parameters affecting the synchronous fluorescence intensities of the three fluoroquinolones were carefully studied. Under the optimal conditions, good linearity was obtained over the range of 0.01 to 1.20 mg/L, 0.005 to 0.45 mg/L and 0.005 to 0.60 mg/L for the CIP, NOR and ENR, and with good relative standard deviations below 1.9% (n=9). In addition, the detection limits for CIP, NOR and ENR were 0.17 μg/L, 0.013 μg/L and 0.055 μg/L, respectively. What is more, compared with the conventional fluorescence spectrometry, the SFS could detect lower concentrations of each fluoroquinolone. Moreover, the proposed SFS were validated and successfully applied for the quantitative assay of each fluoroquinolone in medicinal preparations.

First Derivative Synchronous Spectrofluorimetric Determination of Cyproheptadine Hydrochloride in Presence of its Oxidative Degradation Product at Critical Micelle Concentration

Simple and sensitive first derivative synchronous spectrofluorimetric method was developed for the determination of cyproheptadine hydrochloride in presence of its oxidative degradation product. The method was based on measuring the synchronous fluorescence of the drug in water at Δλ of 120 nm in the presence of a sodium dodecyl sulphate as a micellar system. The peak amplitude of the first derivative spectra was measured at 418 nm for the drug. The different experimental parameters affecting the synchronous fluorescence intensity of CYP were studied and optimized. The peak amplitude–concentration plot was rectilinear over the range of 0.1–1.6 µ gmL

Detection of trace tetracycline in fish via synchronous fluorescence quenching with carbon quantum dots coated with molecularly imprinted silica

A novel fluorescence-based sensor combining synchronous fluorescence spectroscopy (SFS) with molecularly imprinted polymers (MIPs) was fabricated with reverse microemulsion method. Tetracycline (TC), (3-aminopropyl) triethoxysilane (APTES), tetraethyl orthosilicate (TEOS) and carbon quantum dots (CDs) were used as template, functional monomer, cross-linker and signal sources respectively in the probe preparation. A synchronous fluorescence emission (λem) at 355nm was observed for the prepared MIP-coated CDs (MIP@CDs) particles when the wavelength interval (Δλ) was set as 70nm, and the synchronous fluorescence intensity could be rapidly and efficiently quenched by TC based on inner filter effect (IFE). The quenching efficiencies of synchronous fluorescence intensity was linearly fitted with tetracycline (TC) concentrations ranging from 0.1 to 50μmolL−1 with a detection limit (DL) of 9nmolL−1 (3σ, n=9). The MIP@CDs was used as a probe to detect TC in fish samples with the recoveries ranging from 98.4% to 103.1% and the relative standard deviation less than 6.0%. The results illustrated that the as-prepared MIP@CDs could be applied to the detection of trace TC in fish samples with rapidity, high sensitivity and accuracy.

Application of normal fluorescence and stability-indicating derivative synchronous fluorescence spectroscopy for the determination of gliquidone in presence of its fluorescent alkaline degradation product

Simple, smart and sensitive normal fluorescence and stability-indicating derivative synchronous spectrofluorimetric methods have been developed and validated for the determination of gliquidone in the drug substance and drug product. Normal spectrofluorimetric method of gliquidone was established in methanol at λ excitation 225nm and λ emission 400nm in concentration range 0.2–3μg/ml with LOD equal 0.028. The fluorescence quantum yield of gliquidone was calculated using quinine sulfate as a reference and found to be 0.542. Stability-indicating first and third derivative synchronous fluorescence spectroscopy were successfully utilized to overcome the overlapped spectra in normal fluorescence of gliquidone and its alkaline degradation product. Derivative synchronous methods are based on using the synchronous fluorescence of gliquidone and its degradation product in methanol at Δ λ50nm. Peak amplitude in the first derivative of synchronous fluorescence spectra was measured at 309nm where degradation product showed zero-crossing without interference. The peak amplitudes in the third derivative of synchronous fluorescence spectra, peak to trough were measured at 316,329nm where degradation product showed zero-crossing. The different experimental parameters affecting the normal and synchronous fluorescence intensity of gliquidone were studied and optimized. Moreover, the cited methods have been validated as per ICH guidelines. The peak amplitude-concentration plots of the derivative synchronous fluorescence were linear over the concentration range 0.05–2μg/ml for gliquidone. Limits of detection were 0.020 and 0.022 in first and third derivative synchronous spectra, respectively. The adopted methods were successfully applied to commercial tablets and the results demonstrated that the derivative synchronous fluorescence spectroscopy is a powerful stability-indicating method, suitable for routine use with a short analysis time. Statistical comparison between the results obtained by normal fluorescence and derivative synchronous methods and the official one using student's t-test and F-ratio showed no significant difference regarding accuracy and precision.

Zero and second-derivative synchronous fluorescence spectroscopy for the quantification of two non-classical β-lactams in pharmaceutical vials: Application to stability studies.

The formation of metal chelates with various ligands may lead to the production of fluorescent chelates or enhance the fluorescence of the chelating agent. This paper describes two sensitive, selective and computer-solved methods, namely, zero order (SF) and second-derivative synchronous spectrofluorimetry (SDSFS) for nano-quantitation of two carbapenems; meropenem (MP) and ertapenem (EP). The methods are based on the chelation of MP with Tb3+ and EP with Zr4+ in buffered organic medium at pH4.0 to produce fluorescent chelates. In the zero order method, the relative synchronous fluorescence intensity is measured at 327.0nm at Δλ=70.0 and 100.0nm for MP and EP, respectively. The second method utilizes a second-derivative technique to enhance the method selectivity and emphasize a stability-indicating approach. The peak amplitudes (2 D) of the second-derivative synchronous spectra were estimated to be 333.06 and 330.06nm for MP and EP, respectively. The proposed synchronous spectrofluorimetric methods were validated according to the International Conference on Harmonization (ICH) guidelines and applied successfully for the analysis of MP and EP in pure forms, pharmaceutical vials and in synthetic mixtures with different degradants of both drugs. Under optimum conditions, the mole-ratio method was applied and the co-ordination ratios of MP-Tb3+ and EP-Zr4+ chelates were found to be 1:1 and 1:3. The formation constants for the chelation complexes were evaluated using the Benesi-Hildebrand's equation; the free energy change (ΔG) was also calculated. The results indicated that EP-Zr4+ was more stable than the MP-Tb3+ chelate. Moreover, the developed methods were found to be selective and inexpensive for quantitative determination of both drugs in quality control laboratories at nano-levels.

Validated Stability-Indicating Derivative Spectrophotometry and Synchronous Fluorescence Spectroscopy Methods for the Determination of Dapoxetine Hydrochloride in the Presence of its Degradation Product and Co-Formulated Drugs

The stability of dapoxetine hydrochloride (DP) was studied in the presence of its acidic degradation product namely, (+)-N, N-dimethyl-1-phenyl-3-propanolamine (Deg 1) and the co-formulated drugs Vardenafil (VR) and Tadalafil (TD) using derivative spectrophotometry and synchronous fluorescence spectroscopy methods. Method I, stability indicating derivative spectrophotometry 1D was developed for the determination of DP in the presence of its hydrolytic degradation product and the co-formulated drug VR. The amplitude of the first derivative spectra 1D at λmax of 240 nm and 227 nm was measured for DP and VR, respectively. Method IIA, stability indicating synchronous fluorescence spectroscopy (SFS) was described for the determination of DP in the presence of its hydrolytic degradation product and the co-formulated drug TD. In this method (SFS) was performed at Δλ of 70 nm in acetonitrile medium and the synchronous fluorescence intensities of TD were measured at 212 nm. Method IIB, The first derivative synchronous fluorescence spectra FDSFS were applied for measuring the amplitudes of FDSFS at 295 nm and 242 nm for analysis of DP and TD, respectively. The degradation products was obtained in acidic stress condition of 5 M hydrochloric acid, separated, and identified by IR and mass spectrometry to confirm its structure, and elucidate degradation pathway. The methods were applied for stability-indicating assay of DP (method I and II), VR (method I) and TD (method II) in bulk powders, laboratory prepared mixtures and co-formulated pharmaceutical preparations containing degradation product of DP. The results obtained were satisfactory compared with those obtained from the comparison methods and no significant differences were found. The two stability indicating methods were validated as per ICH guidelines.

Monitoring of Heart Ischemia in Blood Serum

Our aim was to study the selected cases of the patients with ischemic heart disease and to analyze the structure of blood serum of patients in comparison with control serum of healthy subjects by methods: synchronous fluorescence fingerprint and atomic force microscopy that are still not used in clinical practice. Our results of fluorescence analysis showed that blood serum of all patients with ischemic heart disease decreased intensity of fluorescence in comparison with control blood serum. Endogenous fluorescence of synchronous fluorescence fingerprint of blood serum of patients with unstable angina pectoris state after non ST elevation myocardial infarction; angina pectoris and arterial hypertension 3 was similar, but atomic force microscopy revealed differences in the structure of blood serum of patients with the angina pectoris. Blood serum of patients with angina pectoris exhibited disappearance of fluorescence peak with maximum fluorescence and showed lower fluorescence intensity than control blood serum and blood serum of patients with arterial hypertension 2. Profiles of synchronous fluorescence fingerprint of blood serum of patients with arterial hypertension stage 2 showed formation of the new fluorescent peak with maximum fluorescence, similar shape of synchronous fluorescence fingerprint and higher fluorescence intensity than blood serum of healthy subjects. Blood serum sensitively revealed changes in the body by using untraditional novel techniques which enable the analysis of the mixture of blood serum and might be a new possibility in study of heart ischemia diseases.

Second-derivative synchronous spectrofluorimetric determination of nebivolol hydrochloride and amlodipine besylate in their combined dosage form.

A rapid, simple, accurate and highly sensitive spectrofluorimetric method was developed for the simultaneous analysis of nebivolol hydrochloride (NEB) and amlodipine besylate (AML). The method was based on measuring the synchronous fluorescence intensity of the drugs at Δλ = 40 nm in methanol. Various experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully studied and optimized. The calibration plots were rectilinear over concentration ranges of 0.05-1.5 µg/mL and 0.5-10 µg/mL for NEB and AML with limits of detection (LOD) of 0.010 and 0.051 µg/mL and limits of quantitation (LOQ) of 0.031 and 0.156, respectively. The peak amplitudes ((2) D) of the second derivative synchronous fluorimetry (SDSF) were estimated at 282 nm for NEB and at 393 nm for AML. Good linearity was obtained over the concentration ranges. The proposed method was successfully applied to the determination of the studied compounds in laboratory-prepared mixtures, commercial single and laboratory-prepared tablets. The results were in good agreement with those obtained using the comparison method. The mean percent recoveries were found to be 100.12 ± 0.77 and 99.91 ± 0.77 for NEB and AML, respectively.

Fluorescence spectroscopy as a tool for determination of coumarins by multivariate calibration.

At present, it is necessary to check the quality of many food products in which the content of coumarins is limited. Since a rapid and simple method for the determination of coumarin (COU), 4-hydroxycoumarin (4HC) and dicoumarol (DC) in tea samples was needed, we developed an alternative option to chromatography, i.e., fluorescence spectroscopy with multivariate calibration. The synchronous fluorescence spectra were recorded at constant wavelength differences 70, 80 and 90 nm from 200 to 400 nm. The different experimental parameters affecting the synchronous fluorescence intensities of the analytes were carefully studied and optimized. Partial least squares (PLS) method and multi linear regression (MLR) were compared on determining the concentrations. The best results were obtained by the PLS method on synchronous fluorescence spectra at Δλ = 90 nm. The results from the analysis of herbal tea Melilotus officinalis by synchronous fluorescence spectroscopy with PLS model are equivalent with the results from HPLC. Fisher F-test and Student's t-test confirmed this finding.

BIOANALYTICAL METHOD DEVELOPMENT AND VALIDATION OF MEMANTINE HYDROCHLORIDE BY SPECTROFLUORIMETRIC METHOD USING OPA Β-MERCAPTOETHANOL AS DERIVATIZING AGENT

A new, simple, accurate, sensitive and specific bioanalytical spectrofluorimetric method was developed and validated for estimation of memantine hydrochloride (MEM) in human plasma. Estimation of MEM in human plasma was done by spiked human plasma studies. Extraction of MEM from human plasma was carried out using 5% trichloroacetic acid for protein precipitation followed by liquid-liquid extraction with 5% IPA in n-hexane. For spectrofluorimetric estimation delta value 65 applied in synchronous mode (medium sensitivity mode) and fluorescence intensity was measured at 420 nm. Developed method was found linear to be in the concentration range of 50-300 ng/mL with correlation coefficient (R2) 0.9951. Percentage recovery was found to be 77.85-83.68% for MEM. High recovery shows that the method is free from the interference from plasma constituents. Hence, proposed method can be used for estimation of MEM in routine quality control laboratories for quantitative determination of MEM in bulk as well as in human plasma. Further it can also be used to determine plasma MEM concentration in drug monitoring or in pharmacokinetic investigations.

Simultaneous determination of desloratadine and montelukast sodium using second-derivative synchronous fluorescence spectrometry enhanced by an organized medium with applications to tablets and human plasma.

A rapid, simple, and sensitive second-derivative synchronous fluorimetric method has been developed and validated for the simultaneous analysis of a binary mixture of desloratadine (DSL) and montelukast sodium (MKT) in their co-formulated tablets. The method is based on measurement of the synchronous fluorescence intensities of the two drugs in McIlvaine's buffer, pH 2.3, in the presence of carboxy methyl cellulose sodium (CMC) as a fluorescence enhancer at a constant wavelength difference (Δλ) of 160 nm. The presence of CMC enhanced the synchronous fluorescence intensity of DSL by 216% and that of MKT by 28%. A linear dependence of the concentration on the amplitude of the second derivative synchronous fluorescence spectra was achieved over the ranges of 0.10-2.00 and 0.20-2.00 µg/mL with limits of detection of 0.02 and 0.03, and limits of quantification of 0.05 and 0.10 µg/mL for DSL and MKT, respectively. The proposed method was successfully applied for the determination of the studied compounds in laboratory-prepared mixtures and tablets. The results were in good agreement with those obtained with the comparison method. The high sensitivity attained by the proposed method allowed the determination of MKT in spiked human plasma with average % recovery of 100.11 ± 2.44 (n = 3).

Photodegradation-based detection of fluorescent whitening agents in a mountain river

Fluorescent whitening agents (FWAs) are highly soluble and poorly biodegradable ingredients used in laundry detergents and in industries (paper, textile, plastic manufacturing). They are likely to pass through biological wastewater treatment systems. The presence of FWAs in a mountain river was detected by monitoring the decay of synchronous fluorescence intensity at λex=360nm after exposing samples to ultraviolet (UV) light (365nm), for mimicking sunlight, for 15min. The method was first validated on four commercial FWAs (DAS-1, FB28, DMA-X and CBS-X) in different water matrices (deionized water and pristine river water in the presence of humic acid and dyes). A 40% decay was observed after 15min for the least photosensitive FWA (CBS-X). A field application was then performed on samples collected along a mountain river in which impacts of FWAs from domestic sources (laundry greywater) and industrial sources (paper and textile mills) were suspected. Variations of fluorescence decay at λex=360nm could be explained by these potential sources of pollution. It is suggested that the fluorescence decay at λex=280nm also be considered as an indicator, as some FWAs can exhibit fluorescence at that excitation wavelength.

Simultaneous determination of diphenylamine and nitrosodiphenylamine by photochemically induced fluorescence and synchronous fluorimetry using double scans method

A new synchronous fluorimetry in the combination with the photochemically induced fluorescence (PIF) method for simultaneous determination of nitrosodiphenylamine (NDPhA) and diphenylamine (DPhA) in aqueous and methanolic solution has been proposed. DPhA has a variety of applications and NDPhA is carcinogenic product of its. The method is based on the use of UV irradiation to produce fluorescent derivatives from NDPhA as a non-fluorescent molecule. The PIF properties of these amines in three media (water, methanol and acetonitrile) are reported. Because of their similar features, the fluorescence emission spectra of NDPhA photoproducts and DPhA were found to severely overlap in the whole wavelength region. Overlapping of conventional fluorescence spectra of these molecules is resolved by synchronous fluorometry using double scans method (SF-DS), thus making the use of separation techniques unnecessary for simultaneous determination of NDPhA and DPhA. The synchronous fluorescence intensity of NDPhA was measured at Δλ of 127 nm and at Δλ=75 nm for DPhA in solution, which are independent of each other. The best sensitivity can be achieved in water. The linear ranges for determination of NDPhA and DPhA were 1 × 10(-8) to 6 × 10(-6)molL(-1) and 4 × 10(-8) to 9 × 10(-6)molL(-1), and the limits of detection (LOD) were 8×10(-9) and 1 × 10(-8)molL(-1), respectively. The relative standard deviations (R.S.D.) of method is<3% (n=5). The proposed method was successfully applied for the determination of the two compounds in synthetic solutions, well water samples and also in gunpowder samples. The results obtained were favorably compared to those obtained with HPLC analysis.

Discrimination of edible olive oils by means of synchronous fluorescence spectroscopy with multivariate data analysis

The potential of fluorescence spectroscopy for the classification of olive oils was investigated. Synchronous fluorescence spectra were collected in the region of 240-700 nm with the wavelength intervals of 10, 30, 60 and 80 nm. Successive projection algorithm (SPA) was applied for the determination of representative wavelengths while the linear discriminant analysis (LDA) method was used to classify olive oils. The classification error of the method was low (0,9-6,4%) for measurements collected at all wavelength intervals. The best classification accuracy was obtained for synchronous fluorescence intensities acquired at 10 selected wavelengths with the wavelength interval equal to 10 nm.