Determination Of Caffeine Research Articles

Simultaneous Capillary Liquid Chromatography Determination of Drugs in Pharmaceutical Preparations Using Tunable Platforms of Polymethacrylate Monolithic Columns Modified with Octadecylamine

Nowadays, analytical techniques tend to develop cheap and green approaches to reduce the costs and minimize environmental impacts. In this study, poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths were prepared in capillary columns (0.25 mm i.d. × 20 cm length) as reactive and tunable platforms, and then simply functionalized based on a ring-opening reaction of epoxide with octadecylamine. The columns were successfully used as reversed-phase stationary phases for determination of ascorbic acid, paracetamol, caffeine, aspirin, and ibuprofen in pharmaceutical combinations. The synthesized monoliths have been estimated by FT-IR spectroscopy, SEM and specific surface area; also, the porous and hydrodynamic properties have verified the differences before and after modification. While the columns before modification were unable to separate the drugs, the columns after amination allowed for the complete separation of the five drugs in about 10 min at 23 µL min−1 flow rate with chromatographic resolution more than 2.12. The developed assay showed excellent suitability (RSDs < 2.6%), wide linear ranges (0.07–300 µg mL−1), sensitive detection limits (0.022–0.060 µg mL−1), good repeatability (RSDs < 4.76%) and acceptable columns reproducibility (RSDs < 18.58%). The method was successfully applied for commercial pharmaceutical preparations; the average recovery values were found to be in the range of 98.03–104.54% (RSDs < 5.51%). The satisfactory recovery percentages along with the perfect correlation between the retentions of standard compounds and the active ingredients extracted from the commercial tablets indicate the accuracy and selectivity of the developed method. The prepared columns and validated method were finally compared with previous reports, particularly commercial C18 stationary phases. This is a very useful comparison due to the structural similarity between the prepared polymeric materials and C18 particulate stationary phases. The prepared capillary columns exhibited various advantages such as the fast separation time, wide linear ranges, low analysis costs, and trivial environmental wastes.

Simultaneous Determination of Caffeine and Pyridoxine in Energy Drinks using Differential Pulse Voltammetry at Glassy Carbon Electrode Modified with Nafion®

AbstractA new voltammetric method for simultaneous determination of caffeine and pyridoxine present in different types of commercial energy drinks has been developed. This electroanalytical method is based on anodic oxidation of these biologically active nitrogen‐containing heterocycles at glassy carbon electrode covered with thin layer of sulfonated fluoropolymer Nafion® using differential pulse voltammetry in 0.1 M Britton‐Robinson buffer of pH 4.5 at potential step 5 mV, potential amplitude 70 mV, and scan rate 50 mV/s. Linear ranges for caffeine and pyridoxine determination were 63.1–600 μM and 7.5–200 μM with the detection limits of 18.9 and 2.2 μM, respectively. It was validated using high‐performance liquid chromatography with spectrophotometric detection. Obtained results have shown that voltammetric approach is very simple and low‐cost analytical method which can be used for routine determination of caffeine and pyridoxine in energy drinks.

Adsorptive stripping voltammetric method for the determination of caffeine at integrated three-electrode screen-printed sensor with carbon/carbon nanofibers working electrode

A commercially available screen-printed carbon electrode coated with carbon nanofibers (SPCE/CNFs) and differential-pulse adsorptive stripping voltammetry (DPAdSV) were used to determination of caffeine. The process of electrochemical oxidation of caffeine in 0.1 mol L−1 sulfuric acid at the SPCE/CNFs surface was investigated by cyclic voltammetry (CV). The effect of the supporting electrolyte type, pH and concentration, time and potential of accumulation, amplitude and scan rate were studied to select the optimum experimental conditions. Under the optimized conditions, the well-defined caffeine peak was observed at 1.25 V (vs. screen-printed silver reference electrode) in 0.1 mol L−1 sulfuric acid. The caffeine was accumulated at − 0.8 V for 60 s. The oxidation peak current was proportional to concentration of caffeine from 2.0 × 10−7 to 1.0 × 10−6 mol L−1 with detection limit of 5.6 × 10−8 mol L−1. The presented method has been successfully applied for the determination of caffeine in beverage samples.

Fabrication of SnS/TiO2@GO Composite Coated Glassy Carbon Electrode for Concomitant Determination of Paracetamol, Tryptophan, and Caffeine in Pharmaceutical Formulations.

Designing an electrochemical sensor which is simple, cheap, sensitive, fast, and accurate is inevitable, as it is important in drug quality control, point-of-care diagnosis, and other clinical studies. Sensors for simultaneous determination of paracetamol, tryptophan, and caffeine have not been reported so far, and we report an electrochemical sensor via incorporating tin sulfide (SnS) and titanium dioxide (TiO2) on graphene oxide (GO) sheets (SnS/TiO2@GO ternary composite) for their separate and simultaneous determination through cyclic voltammetry and differential pulse voltammetry techniques. The surface morphology and structural properties of the composite were characterized by analytical techniques. The electrochemical study of SnS/TiO2@GO composite modified glassy carbon electrode (GC-SnS/TiO2@GO) showed high activity toward the oxidation of paracetamol, tryptophan, and caffeine with significant decrease in overpotential due to large surfaceand high carrier mobility. The peak currents during separate determination of paracetamol, tryptophan, and caffeine increased linearly with the increase in concentration from 9.8 nM to 280 μM for paracetamol, from 13.3 nM to 157 μM for tryptophan, and from 16.6 nM to 333 μM for caffeine. The detection limit (3σ/ S) was 7.5, 7.8, and 4.4 nM for paracetamol, tryptophan, and caffeine, respectively. The electron transfer coefficient (α), surface coverage concentration (Γ), number of electrons transferred ( n), and diffusion coefficient ( D) were calculated and discussed. The fabricated electrode showed low detection limit, wide linear range, and excellent reproducibility, selectivity, and stability. The study was also extended to the analysis of commercial tablets, beverageand human blood serum.Therefore, the present electrode holds great promise for identification and quantification of drugs in combination.

A comprehensive structural comparison between cellulose and starch polymers functionalized cobalt nanoparticles sensors for the nanomolar detection of paracetamol

A novel and advanced sensor was fabricated by the electrodeposition of cobalt nanoparticles (Nano Co) on the surface of carbon paste electrode (CPE) modified with cellulose (C) (CPE/C//NanoCo) and starch (S) (CPE/S//NanoCo) polymers for the simultaneous determination of paracetamol (ACOP), warfarin (WA) and caffeine (CAF). Starch and cellulose are polysaccharides with very high molecular weights. The difference between the two polymer's behaviors is electrochemically investigated in this paper through voltammetric and Impedance spectroscopy measurements where the electroactive surface area of the two sensors were improved, displaying a remarkable increase in the peak current after the addition of Nano-Co. Experimental results specify a linear correlation between ACOP peak current and its concentration in the range from 2.0×10−8 to 1.5×10−4molL−1, leading to a detection limit of 9.9×10−10M. for (CPE/S//NanoCo) sensors. Finally, the sensor was successfully used to determine ACOP in commercialized tablets (panadol), with a recovery ranging from 99.4% to 101.8%.

Novel cork-graphite electrochemical sensor for voltammetric determination of caffeine

Cork powder and granules are the major sub-products of the cork industry, which is an important economic activity in Portugal and other Mediterranean countries. Currently, many applications have been envisaged for this natural material, therefore, in this communication, for first time, a novel electrochemical sensor has been successfully prepared and tested based on cork and graphite. The device construction was performed by using cork and graphite in a mass ratio of about 50 and 70%. Cork-graphite electrode was characterized in terms of its surface morphology and electrochemical properties. The electrochemical sensor was tested for the determination of caffeine in real samples. Caffeine oxidation peak appeared at +1.51V (vs. Ag/AgCl) in acidic solution at graphite and cork-graphite electrodes. However, cork-graphite electrode in a mass ratio of 70% showed the better sensibility for determining caffeine in aqueous solutions. A linearly relationship of current peak and caffeine concentration was achieved up to 1000μM, with a limit of detection (LOD) of about 2.94μM. Additionally, the caffeine concentrations estimated in drugs and soft drinks, using cork-graphite sensor at 70% of cork, were very similar to those obtained by HPLC; indicating that the proposed electroanalytical method has considerably sensitivity and precision. The results clearly indicated that, cork-graphite sensor represents a novel tool, offering a significant development over unmodified carbon materials.

Derivatization of Ions under the Conditions of Surface Assisted Laser Desorption/Ionization

A method for the chemical modification (derivatization) of ions obtained by surface assisted laser desorption/ionization (SALDI) is proposed. Derivatization is based on the interaction of desorbed ions with alcohol molecules. The method is simple, does not affect the duration of analysis and ensures the improvement of the analytical characteristics of the SALDI method, when analysis is carried out under the conditions of peak interference and strong fragmentation of analyte ions. The efficiency of the method is demonstrated in the determination of caffeine, pyrrolidine, and diphenhydramine under the conditions of atmospheric pressure sample application.

First- order Derivative and UV-spectrophotometric Methods for Simultaneous Determination of Paracetamol, Ibuprofen, and Caffeine in Bulk and Parmaceutical Formulatation

Aims: This work is to develop accurate and simple spectrophotometric methods with the first derivative for estimation of Ibuprofen (IBU), Caffeine (CAF) and Paracetamol (PAR) in bulk and pharmaceutical preparation. Method: The methods use ethanol 90%: 0.1 N sodium hydroxide (25:75) as a solvent for analysis. The wavelengths were determined for each drug in the range of 200-400 nm in spectrum mode. UV-spectrophotometer-equipment used to calculate the first derivatives through which IBU, CAF, and PAR were evaluated for simultaneous assay. The validity of the methods is established on the basis of linearity, accuracy and precision, limit of detection and limit of quantification. The methods applied to estimate the level of PAR, IBU, and CAF in a capsule dosage form. Results: The linearity of the methods was in the range of (1 - 15) µg /ml at λ max 220 nm for IBU, for CAF was (1-10) µg /ml at λ max 272 nm, and for PAR was (1-16.5) µg /ml at λ max 257 nm. In the second method, by application of first derivatives, IBU has an absorbance at 212 NM (in contrast CAF and PAR have zero value at is this wavelength) whereas, CAF absorbed at 272 nm (in contract IBU and PAR have zero value at this wavelength) whereas PAR has absorbance at 230 nm (in contrast IBU and CAF has zero value). Upon derivative assay, the amount was 98.58 %, 98.15% and 98.66% for PAR, IBU, and CAF, respectively. Conclusion: The suggested methods can be effectively applied for simultaneous determination of IBU, CAF and PAR in the bulk and capsule dosage form with good precision, recovery and less percentage of error.

Electrodeposition of 4-Benzenesulfonic Acid onto a Graphite-Epoxy Composite Electrode for the Enhanced Voltammetric Determination of Caffeine in Beverages.

Caffeine is widely present in food and drinks, such as teas and coffees, being also part of some currently commercialized medicines, but despite its enhancement on several functions of human body, its exceeding use can promote many health problems. In order to develop new fast approaches for the caffeine sensing, graphite-epoxy composite electrodes (GECE) were used as substrate, being modified by different diazonium salts, synthetized as their tetraflouroborate salts. An analytical method for caffeine quantification was developed, using sware wave voltammetry (SWV) in Britton–Robinson buffer pH 2.0. Detection limits for bare electrode and 4-benzenesulfonic modified electrode were observed circa 145 µmol·L−1 and 1.3 µmol·L−1, respectively. The results have shown that the modification shifts the oxidation peaks to lower potential. Kinetics of the reaction limited by diffusion was more expressive when caffeine was added to the solution, resulting in decreases of impedance, characterized by lower Rct. All results for caffeine determination were compared to a reference chromatographic procedure (HPLC), showing no statistical difference. Analytical parameters for validation were suitably determined according to local legislation, leading to a linear behaviour from 5 to 150 µmol·L−1; precision of 4.09% was evaluated based on the RDC 166/17, and accuracy was evaluated in comparison with the reference method, with recovery of 98.37 ± 2.58%.

Evaluating the processed beans of different cocoa (Theobroma cacao L.) accessions for quality parameters

The objective of this study was to evaluate the variability in quality parameters of different identified cocoa plus trees from Coimbatore district in Tamil Nadu. Thirty five (35) plus trees in two different farmers field were evaluated for their quality traits. The quality parameters like fat content (%), carbohydrate content (mg/g), protein content (mg/g), theobromine content (mg/g), caffeine content (mg/g), catechin content (mg/g) and caffeic acid content (mg/g). A rapid method like high performance liquid chromatography (HPLC) method is used for the determination of theobromine, caffeine, catechin and caffeic acid in cocoa beans. Among the 35 plus trees evaluated for bean quality, highest fat content was recorded in Tc (Vedapatti) 94, while highest carbohydrate content was recorded in Tc (Vedapatti) 64 and highest protein content was recorded in Tc (Vedapatti) 76. The highest theobromine was recorded in Tc (Vedapatti) 63, caffeine was recorded in Tc (Vedapatti) 91, while the amount of caffeic acid and catechin was the highest in Tc (Vedapatti) 76. This evaluation study showed wide variation for quality parameters. These variability may be used in further breeding program enhance the quality traits and improve flavours of the final product.

HPLC Determination of Benzoic Acid, Saccharin, and Caffeine in Carbonated Soft Drinks

HPLC Determination of Benzoic Acid, Saccharin, and Caffeine in Carbonated Soft Drinks

A fast and sensitive isocratic high performance liquid chromatography method for determination of guaraná (Paullinia cupana) flavan-3-ols

Most methods for quantification of catechins in guaraná and other food matrices rely on lengthy gradients to resolve all peaks, and the analysis time for one sample is around 45–135 min. The present method is a fast, sensitive and simple HPLC-UV method, with a 16-minute isocratic run that deliver the high throughput needed to process a large number of samples without compromising the analyte stability. This method is suitable for the determination of catechins, procyanidins (up to degree of polymerisation 2) and caffeine in guaraná extracts, in vitro digesta, and Caco-2 cell permeates. The higher sensitivity was achieved by detection at 210 nm, after checking for the absence of interfering substances in the matrices. The method was validated and LODs of 0.019, 0.030, 0.028, 0.030, and 0.043 nmol/mL were achieved for catechin, epicatechin, procyanidin B1, procyanidin B2 and caffeine, respectively. Standard recovery at three different concentrations were within 97–109%. Intra- and inter-day variabilities (RSD) were both under 4%.•This is an isocratic HPLC-UV method for the quantification of flavan-3-ols from guaraná (Paullinia cupana), which is 3–8 times faster and >80 times sensitive than previously published methods using UV or diode array detectors.•It is cost-effective as it uses the widely available and affordable UV detector and consumes less solvent due the short analysis time.•With low LODs, fast sample preparation and the short analytical run, this method can be used for the quantification of flavan-3-ols and caffeine in guaraná extracts as well as guaraná in vitro digesta and its Caco-2 permeates.

Determination of Theobromine and Caffeine in Theobroma cacao Husk from Ethanolic Extract by GC-MS after CC Separation

After CC separation of 21 samples from Theobroma cacao Husk was analyzed by GC-MS, from ethanolic extract at 90% was recovered a solid residue of 1 g after several days on the table of the Lab. This main residue (300 mg) was analyzed after successive separations with mixtures of CHCl3: MeOH (7:3) and CHCl3: MeOH (5:5) in CC using Silica Gel G 60-120 Mesh. All samples were analyzed by TLC on silica gel with fluorescent indicator 254 nm on aluminum cards (layer thickness 0.2 mm) (10 × 20 cm) using CHCl3: MeOH: n-propanol: water (5:6:1:4) as eluent (v/v/v). The presence of Caffeine (CF) and Theobromine (TB) was confirmed after several analyses of the samples by their characteristic fragmentation pattern but nevertheless was found the presence of Theophylline.

Electrochemical Sensor for Caffeine Based on a Glassy Carbon Electrode Modified with an Attapulgite/Nafion Film

AbstractIn the present work, a simple and economic analytical method based on attapulgite/nafion coated glassy carbon electrode (AT/Naf/GCE) has been developped for the electrochemical determination of caffeine. Prior to its use, the ionic exchange properties and conductivity of AT/Naf/GCE were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Caffeine gave an irreversible oxidation peak around +1.41 V (vs Ag/AgCl reference electrode) in 0.1 M H2SO4 at pH 1.5. The peak current varied linearly with the square root of the scan rate, showing that the transfer process is controlled by diffusion. The heterogeneous rate constant, the transfer coefficient and the number of electrons involved were calculated. Upon optimization of key analytical parameters involved in the electroanalysis of caffeine by DPV, the recorded oxidation peak current varied linearly with caffeine concentration in the range from 0.1 to 4 μm, leading to a detection limit of 4.57×10−8 M (S/N=3). The developed electrode exhibited good stability and was easily regenerated. The effect of some important potential interfering compounds (ascorbic acid, dopamine, uric acid, sulphite ions and glucose) on the signal of caffeine was also examined. The obtained electrode was successfully employed in the determination of caffeine content in a commercial drug.

Magnetic solid phase extraction of trace paracetamol and caffeine in synthetic urine and wastewater samples by a using core shell hybrid material consisting of graphene oxide/multiwalled carbon nanotube/Fe3O4/SiO2

A new hybrid material was synthesized including magnetic graphene oxide/multiwalled carbon nanotube core shell (GO/MWCNT/Fe3O4/SiO2) and used as magnetic solid phase extraction adsorbent for separation and pre-concentration of paracetamol and caffeine subsequent detection by high performance liquid chromatography. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry, Raman spectrometry, X-ray diffraction spectrometry, scanning electron microscopy, mapping photographs and BET surface area analysis. The experimental variables on the extraction efficiency were studied and optimized. The optimum conditions for quantitative extraction of paracetamol and caffeine were obtained as of adsorbent amount, 70 mg; pH, 8.0; and elution with 1 mL of methanol by vortex mixer for 60 s. Validation experiments showed that the developed method had good linear ranges 5–800 ng mL−1 for caffeine and 10–1000 ng mL−1 for paracetamol, respectively. The limits of detection were found as 1.48 and 3.32 ng mL−1 for caffeine and paracetamol, respectively. The accuracy of the developed magnetic solid phase extraction method was proved by addition-recovery tests by using model solutions and the developed method was successfully applied for the determination of paracetamol and caffeine in synthetically prepared urine and waste water samples.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF CAFFEINE IN GREEN COFFEE BEANS (COFFEA ARABICA L.) FROM THREE DISTRICTS OF WEST JAVA, INDONESIA BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Objective: To develop and validate a simple, accurate, and precise HPLC method for the determination of caffeine in green coffee beans (Coffea arabica L.) from three districts of West Java, Indonesia.Methods: The analytical method was conducted using Enduro C-18 (250 x 4.6 mm) column with methanol: water (37: 63) as a mobile phase, the flow rate was 1.0 ml/min, and the detector wavelength was set at 274 nm. The selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, and system suitability testing were evaluated as the parameters of validation.Results: The retention time of caffeine was 6.36 min. % RSD for precision was 0.192. The linearity of the method was obtained using a concentration range of 1-200 ppm with the correlation coefficient of 0.998. The limit of detection was 9 ppm and the limit of quantitation was 28 ppm. The accuracy was in between 90.723%-102.853%. Caffeine levels from Garut, Pangalengan, and Tasikmalaya were 1.454 ± 0.004%, 1.574 ± 0.082%, and 2.280 ± 0.004%.Conclusion: The proposed HPLC method meets the acceptance criteria of validation parameters and can be applied for routine analysis.

One-Step in Situ Preparation of Fe3O4/Carboxylated Multi-Walled Carbon Nanotube Hybrid for the Determination of Caffeine in Carbonated Beverages

Abstract Magnetic carboxylated multi-walled carbon nanotubes (Fe3O4-MWCNTs-COOH) have been prepared via in situ preparation. The Fe3O4-MWCNTs-COOH composite was characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer, and then was successfully applied for the determination of caffeine in carbonated beverages coupled with high performance liquid chromatography. Compared with cetyltrimethylammonium bromide modified magnetic nanoparticles (Fe3O4/CTAB), chitosan modified magnetic carboxylated multi-walled carbon nanotubes (Fe3O4-MWCNTs-COOH/Chitosan), magnetic hydroxylated multi-walled carbon nanotubes (Fe3O4 enclosure MWCNTs-OH) and a hybrid which was composed of magnetic carboxylated multi-walled carbon nanotubes and magnetic hydroxylated multi-walled carbon nanotubes (Fe3O4 enclosure MWCNTs-OH-MWCNTs-COOH), the Fe3O4-MWCNTs-COOH composite exhibited better extraction efficiency for caffeine. The main parameters affecting the extraction efficiency were optimized in detail. Under the optimal conditions, satisfactory performance was obtained. The calibration curve was linear over the concentration range of 7.0 to 600.0 ng mL−1 with correlation coefficients (r) between 0.9993 and 0.9995. The limit of detection was 2.0 ng mL−1. The recoveries were between 97.5% and 101.2% with relative standard deviations ranging from 1.8% to 3.7%. Overall, the proposed method was an effectual pretreatment and enrichment procedure and could be utilized for the analysis of caffeine in complex matrices.

Sustainable Eco-Friendly Ultra-High-Performance Liquid Chromatographic Method for Simultaneous Determination of Caffeine and Theobromine in Commercial Teas: Evaluation of Greenness Profile Using NEMI and Eco-Scale Assessment Tools.

Background: Green analytical chemistry (GAC) aims to eliminate or minimize the amount of hazardous solvents consumed and generated daily worldwide. Considering the environmental impact of all analytical procedures and replacing the polluting methodologies with clean ones is of a paramount interest. Objective: This work aims to develop and validate a sustainable, fast, and economic ultrahigh-performance liquid chromatography method for simultaneous determination of methylxanthines in commercial tea samples as well as to evaluate the greenness profile of the proposed method using two greenness assessment tools: National Environmental Methods Index (NEMI) and analytical Eco-scale. Methods: The method was designed based on applying GAC principles in method development. The green chromatography approach was applied by using benign mobile phases. The chromatographic separation was optimized to minimize sample preparation, achieve short analysis time with low solvent consumption, and minimize waste generation. Results: All the studied analytes were separated in only 1.7 min. The detection limits of the studied analytes ranged from 0.015 to 0.03 mg/L, while LOQs were in the range of 0.05 to 0.1 μg/L with UV detection. The proposed method neither uses nor generates harmful chemicals, it passes the four quadrants of the NEMI greenness profile, and it has a high Eco-scale score. Conclusions: Compared with the reported methods, the proposed method is greener, more economical, and faster; therefore, it can be used as a green alternative to the existing conventional methods for routine analysis of the studied analytes without harming the environment.

An automated homogeneous liquid-liquid microextraction based on deep eutectic solvent for the HPLC-UV determination of caffeine in beverages

This work presents an automated homogeneous liquid-liquid microextraction procedure for separation of caffeine from beverages. The microextraction procedure involved mixing sample and water-miscible deep eutectic solvent (DES, choline chloride with phenol at a 1:3 molar ratio) into a mixing chamber of a flow system resulting formation of homogeneous solution. Injection of aprotic solvent (tetrahydrofuran) into homogeneous sample solution promoted the fine DES droplets formation and caffeine extraction into DES phase separated. The automated homogeneous liquid-liquid microextraction procedure was coupled with a HPLC-UV system. The conditions of caffeine microextraction and its HPLC-UV determination in DES phase were studied and optimized. Under optimal experimental conditions the linear detection range and limit of detection, calculated from a blank test, based on 3σ were found to be 0.1–200 mg L−1 and 0.03 mg L−1, respectively. The application of the developed procedure was demonstrated in the determination of caffeine in commercial soft drinks samples.

Identification of novel natural inhibitors of snake venom nucleotidases using a structure-based molecular docking study

A new methodology for caffeine determination was developed based on the quenching effect on fluorescent emission of the molecule of Bovine Serum Albumin at λem = 338 nm (λex = 280). A flow injection disposition was designed improving significantly the sampling rate to 60 samples/h using potassium dihydrophosphate 5 · 10− 3 mol L− 1 buffer (pH 6.8) as carrier and flow rate of 1.5 mL min− 1. The experimental and instrumental conditions that influence on analytical quality parameters were systematically investigated, as consider: buffer nature and concentration, fluorophore nature and concentration, and carrier flow rate. The proposal is simple, fast, inexpensive and precise, with a linear range from 6.68 · 10− 6 to 4.0 · 10− 3 mol L− 1 and SD of 0.0668, under optimized conditions. Methodology sensibility and selectivity allowed a variety of sample analyses. It was successfully applied to caffeine quantification in energy drinks, dietary supplements and sliming infusion samples without previous treatment.