Second-derivative Synchronous Fluorescence Spectrometry Research Articles

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).

Analysis of binary mixtures of flufenamic, meclofenamic and mefenamic acids by derivative synchronous fluorescence spectrometry

Second-derivative synchronous fluorescence spectrometry was used to develop a simple, rapid and sensitive spectrofluorimetric method for the determination of binary mixtures of the nonsteroidal antiinflammatory drugs flufenamic (FFA), meclofenamic (MCFA) and mefenamic (MFA) acids in serum and pharmaceutical formulations. The method is based on the intrinsic fluorescence of these compounds in chloroform. A Δ λ=105 nm was used for the resolution of FFA–MFA and MFA–MCFA mixtures, whereas the FFA–MCFA mixture was determined at Δ λ=40 nm. Serum samples are treated with trichloroacetic acid to remove the proteins, and the analytes are extracted in chloroform prior to determination. Pharmaceutical preparations were analysed without prior separation steps.

Determination of norfloxacin in real samples by different spectrofluorimetric techniques.

Simple, rapid, accurate and sensitive spectrofluorimetric methods for the determination of norfloxacin are described. The methods are based on the reaction of this drug with aluminium(III) ion to form a strongly fluorescent complex. Fluorescence properties of the AlIII-norfloxacin complex were used for the determination of this drug in pharmaceutical preparations. First-derivative constant wavelength synchronous fluorescence spectrometry was used for the determination of norfloxacin in the presence of nalidixic acid. The determination of norfloxacin in urine without the need of tedious pre-separation was achieved by using zero-crossing second-derivative synchronous fluorescence spectrometry.

Second-derivative synchronous fluorescence spectroscopy for the simultaneous determination of naproxen and salicylic acid in human serum.

Second-derivative synchronous fluorescence spectrometry was used to develop a simple, rapid and sensitive spectrofluorimetric method for the simultaneous determination of naproxen and salicylic acid in human serum. The method is based on the intrinsic fluorescence of naproxen and salicylic acid in chloroform-1% acetic acid solution. A delta gamma of 130 nm was used for the direct measurement of salicylic acid in the binary mixture, whereas naproxen was determined from direct measurements at delta gamma = 60 nm and by means of a correction equation which incorporates the concentration of salicylic acid. The range of application is 0-14 mg l-1 for naproxen and 0-13 mg l-1 for salicylic acid. The detection limits for naproxen and salicylic acid are 0.003 and 0.01 mg l-1, respectively. Serum samples are extracted into chloroform-1% acetic acid solution prior to instrumental measurement. Analytical recoveries range from 97 to 105% (mean 102%) for naproxen and from 97 to 112% (mean 103%) for salicylic acid. The within-run precision (RSD) for the method for four naproxen-salicylic acid mixtures varied from 1.2 to 6.7% and the day-to-day precision for mixtures varied from 2.1 to 5.0%.

Simultaneous determination of naproxen and its desmethyl metabolite in human serum by second-derivative synchronous fluorescence spectrometry

A simple, rapid, sensitive and selective method for the simultaneous determination of the non-steroidal anti-inflammatory drug naproxen (NAP) and its main metabolite the 6-demethylated derivative (DNAP) in human serum is described. The method is based on the intrinsic fluorescence of both acids in alkaline aqueous solution. The broad-band overlapping conventional spectra of both compounds are resolved by means of second-derivative synchronous fluorescence spectrometry, thus obviating the need for pre-analysis sample separation techniques. NAP and DNAP are determined in serum supernatant solution after removal of proteins with acetonitrile at pH 11.7. Recoveries from sera spiked with NAP (5–70 μg ml −1) and DNAP (0.25–5 μg ml −1) ranged from 95 to 106% (mean 99.6%) and from 95 to 104% (mean 100.1%), respectively.

Simultaneous determination of acetylsalicylic acid and its major metabolites in human serum by second-derivative synchronous fluorescence spectrometry.

A method is described for the simultaneous determination of acetylsalicylic, salicylic, gentisic and salicyluric acids (ASA, SA, GA and SU, respectively) in serum, based on their native fluorescence. The ASA-SA-GA-SU-containing serum samples are extracted with chloroform-1% acetic acid solution; ASA and SA are determined in the organic phase, and GA and SU in the aqueous phase, after removal of protein with trichloroacetic acid, at pH 5.0 and 11.6, respectively. The ASA-SA and GA-SU-SA mixtures are resolved using second-derivative fluorescence spectrometry and the appropriate empirical equations involving the effect of each acid on the signal of the other. Recoveries from sera spiked with ASA (1.0-10 micrograms ml-1), SA (25-50 micrograms ml-1), GA (0.05-0.2 micrograms ml-1) and SU (1.0-5.0 micrograms ml-1) ranged from 100 to 104% (mean 101%), from 93 to 99% (mean 97%), from 94 to 104% (mean 99%) and from 94 to 107% (mean 98%), respectively.

Simultaneous determination of acetylsalicylic and salicylic acids in human serum and aspirin formulations by second-derivative synchronous fluorescence spectrometry

A second-derivative synchronous scanning spectrofluorimetric method for the simultaneous determination of acetylsalicylic acid (ASA) and salicylic acid (SA) is described. The method is based on the native fluorescence of both acids in a 1% acetic acid-chloroform solution. Both ASA and SA can be determined within the concentration ranges 0.2-70 and 0.03-10 micrograms ml-1, respectively. The effect of each acid on the signal of the other has been studied in detail. Empirical equations have been used to overcome this effect, thus allowing the accurate determination of both acids in binary mixtures, without a separation step. The method has been applied to the determination of ASA and SA in blood serum and to the determination of SA impurities in aspirin formulations. Recoveries from sera spiked with both ASA (2.5-50 micrograms ml-1) and SA (100-160 micrograms ml-1) varied from 99.5 to 106.7% (mean = 102.6%) and from 93.0 to 98.0% (mean = 95.8%), respectively. Recoveries of SA from spiked aspirin solutions (0.25-1.5 mg g-1 of aspirin) varied from 98.0 to 102.0% (mean = 100.3%).

Simultaneous determination of gallium and zinc in biological samples, wine, drinking water, and wastewater by derivative synchronous fluorescence spectrometry.

A simple, rapid, sensitive, and selective method for the simultaneous determination of gallium and zinc using derivative synchronous fluorescence spectrometry has been studied. This determination is based upon the formation of fluorescent complexes with salicylaldehyde thiocarbohydrazone (SATCH). The reaction is carried out at pH 4.7 in aqueous-ethanol medium (52% (v/v) ethanol). The use of second-derivative synchronous fluorescence spectrometry permits the simultaneous determination of gallium and zinc in the concentration intervals of 2-40 and 20-1500 ng/mL, respectively. The effect of interferences was studied. The method has been applied to the determination of gallium and zinc in biological samples (after destruction of the organic matter by using a HNO/sub 3/-H/sub 2/O/sub 2/ mixture), wine, drinking water, and wastewater.

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 μg/ml for histidine and 0.06–5.0 μg/ml for histamine. Mixtures of histidine and histamine in ratios between 12:1 and 1:8 have been 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.