ABSTRACT
This report presents a novel methodology based in the quickly acquisition of full UV-vis range spectra combined with the joint determination of kinetic parameters and chemiluminescence signals. Then this technique allows obtaining three-dimensional chemiluminescence spectra profiles containing kinetic and spectroscopic information. That is especially useful for resolving mixtures of luminophors because of more analytical information for each analyte is available increasing the selectivity relative to conventional chemiluminescence methods. To accomplish this, a conventional Back-Thinned CCD detector is used and the three-dimensional chemiluminescence spectra is subsequently processed so that two-dimensional spectra with different trajectories can be obtained by dedicated software CLTotal. The potential of the proposed analytical methodology was assessed for the simultaneous determination of two polycyclic aromatic hydrocarbons. The chemiluminescent reaction between DNPO and hydrogen peroxide induced by their presence was used to record 3D spectra and the software CLTotal to subsequently construct linear variable-angle trajectories in the spectra, in order to obtain more selective 2D spectra facilitating the simultaneous determination of the analytes. The results of the statistical analysis testify to the usefulness of the proposed method for the intended purpose.
ABSTRACT
INTRODUCTION: 1-Naphthylacetic and 2-naphthoxyacetic acids belong to the synthetic branch of auxins. Auxins have attracted considerable interest as a subject of study by virtue of their biological and physiological significance. Their broad use as plant growth regulators has raised the need for simple, rapid, sensitive and selective analytical methods for their determination in real samples. OBJECTIVE: The primary aim of this work was to develop an analytical method for the simultaneous determination of 1-naphthylacetic acid and 2-naphthoxyacetic acid in commercial technical formulations, tomato and various fruit types (apple, strawberry, orange and plum) by room temperature phosphorescence. METHODOLOGY: Filtrated solutions of aqueous slurries from ecological fruit and tomato samples are acidified and then extracted with dichloromethane. Once the solvent is evaporated, the dried residue is dissolved in sodium dodecyl sulphate (a micellar agent), and supplied with thallium (I) nitrate as an external heavy atom source and sodium sulphite as deoxygenation agent to enhance the ensuing phosphorescence. RESULTS: The broad-band overlapping spectra for the two analytes were resolved by first- and second-derivative phosphorescence spectrometry. Zero-crossing measurements at 488.5 nm in the first-derivative spectrum and 469.5 nm in the second derivative spectrum exhibited a linear dependence on the 2-naphthoxyacetic acid and 1-naphthylacetic acid concentration, respectively. The detection limits as determined in accordance with the error propagation theory were 11.5 ng/mL for 1-naphthylacetic acid and 15.6 ng/mL for 2-naphthoxyacetic acid. CONCLUSION: The proposed method affords the determination of 1-naphthylacetic acid and 2-naphthoxyacetic acid in real samples with near-quantitative recoveries from agricultural products.
Subject(s)
Fruit/chemistry , Glycolates/analysis , Luminescent Measurements/methods , Naphthaleneacetic Acids/analysis , Spectrum Analysis/methods , Vegetables/chemistry , Citrus sinensis/chemistry , Fragaria/chemistry , Luminescent Measurements/instrumentation , Solanum lycopersicum/chemistry , Malus/chemistry , Methylene Chloride/chemistry , Plant Extracts/analysis , Plant Extracts/chemistry , Plant Growth Regulators/analysis , Prunus/chemistry , Reproducibility of Results , Sodium Dodecyl Sulfate/chemistry , Sulfites/chemistry , Temperature , Thallium/chemistryABSTRACT
A rapid, simple, and inexpensive spectrofluorimetric method has been proposed for the simultaneous quantification of diflunisal, salicylic acid, fenoprofen, and 6-methoxy-2-naphthylacetic acid (6MNA). First-derivative nonlinear variable-angle synchronous fluorescence spectrometry has been developed to improve the selectivity of fluorescence measurements without loss of sensitivity. It allows the simultaneous determination of different substances in a mixture from a single spectrum based on a single scan. The analyses were performed in an ethanol-water (70%) medium at a pH of 9.2, adjusted by using ammonium/ammonia (0.5 M) as a buffer solution. The linear concentration ranges are 30.0-100.0, 100.0-600.0, 50.0-150.0, and 30.0-100.0 ng/mL for salicylic acid, fenoprofen, diflunisal, and 6-methoxy-2-naphthylacetic acid, respectively, at lambda(ex)/lambda(em) = 281.1/423.6, 241.2/301.2, 284.1/403.8, and 268.7/339.6 nm, respectively. Analytical parameters of the proposed method were calculated according to the error propagation theory. The sensitivity, repeatability, reproducibility, and limits of detection achieved with the proposed method are adequate for the determination of these anti-inflammatory drugs.
