Simultaneous Determination Of Acetaminophen Research Articles

A Chemometric–Assisted Voltammetric Method for Simultaneous Determination of Acetaminophen and Diclofenac

AbstractDiclofenac (DCF) and Acetaminophen (ACT) are among the most important nonsteroidal anti–inflammatory drugs (NSAIDs) that sought after for their antipyretic, analgesic, and anti‐inflammatory properties. In addition, ACT and DCF show synergistic activity toward pain relief. Therefore, appropriate analytical strategies are required for the simultaneous quantification of these NSAIDs in prescription drugs. This study introduces a method for the direct and simultaneous determination of ACT and DCF using the voltammetric approach in conjunction with chemometric tools such as partial least squares (PLS) and genetic algorithm–multiple linear regressions (GA−MLR). The calibration set was established using differential pulse voltammetry for 25 distinct mixtures of ACT and DCF. The calibration curve exhibited linearity within the concentration ranges of 0.1–1000 μM for ACT and 0.1–100 and 100–1000 for DCF. The effectiveness of chemometric methods was evaluated by analyzing synthetic mixtures of ACT and DCF and applying these methods to real samples containing a commercial pharmaceutical preparation of the specified drugs. Both methods yielded favorable results.

Bio-synthesized copper nanoparticle decorated multiwall carbon nanotube-nanocellulose nanocomposite: An electrochemical sensor for the simultaneous detection of acetaminophen and diclofenac sodium

The present work reported the electrochemical detection of acetaminophen (ACOP) and diclofenac sodium (DS), using a nanocomposite of nanocellulose (NC), functionalized multiwall carbon nanotubes (fMWCNTs) and bio-synthesized copper nanoparticle (CuN) (NC-fMWCNT-CuN/GCE) prepared from ultrasonication and drop-casting methods. The bio-synthesized CuN was prepared for the first time using green tea leaves extract as the reducing and stabilizing agent. Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and Brunauer-Emmett-Teller (BET) analysis were used to characterize the morphological and structural properties of NC-fMWCNT-CuN nanocomposite. The simultaneous determination of ACOP and DS was performed using squarewave voltammetric (SWV) technique. The modified electrode revealed great potential with high selectivity, sensitivity, repeatability, reproducibility and stability with a broad linear range of 0.01–80 µM for ACOP and 0.05–80 µM for DS, and a detection limit of 0.00014 µM for ACOP and 0.00048 µM for DS. The developed sensor showed high sensitivity of 13.85 µA µM−1 cm−2 and 4.142 2 µA µM−1 cm−2 for the detection of ACOP and DS, respectively. The good recoveries and low RSDs demonstrated the possibility of application of the sensor for real sample detection. Therefore, NC-fMWCNT-CuN/GCE sensor showed excellent electrochemical performance in the simultaneous detection of ACOP and DS and a promising sensing platform for the detection of ACOP and DS in pharmaceutical formulation and human blood serum.

Design of NiCo2O4 nanoflowers decorated sulfurbridged covalent triazine frameworks nanocomposites for electrochemical simultaneous detection of acetaminophen and 4-aminophenol

Owing to the high toxicity of acetaminophen (ACOP) and 4-aminophenol (4-AP) when they are overused, the simultaneous determination of ACOP and 4-AP is crucial. In this present paper, an electrochemical sensor based on the nanocomposite of sulfurbridged covalent triazine frameworks (S-CTFs) and in situ formed nickel cobaltite (NiCo2O4) nanoflowers on S-CTFs, denoted as S-CTFs@NiCo2O4, was fabricated for the first time for sensitive detection of ACOP and 4-AP. S-CTFs@NiCo2O4 modified electrode exhibited the outstanding synergetic effects of S-CTFs (prominent enrichment ability and large surface area) and NiCo2O4 (excellent electrocatalytic activity). The developed electrode had the advantages of high reproducibility, repeatability, anti-interference and stability, and it exhibited a wide linear concentration range (2 ∼ 360 μM) and a low limit of detection (0.18 μM and 0.35 μM) for ACOP and 4-AP, respectively. In addition, the designed electrochemical sensor was evaluated towards the detecting ACOP and 4-AP in real samples with satisfactory recovery, illustrating that electrode has a broad prospect in the clinical application.

Rapid simultaneous spectrophotometric determination of acetaminophen, phenylephrine, and guaifenesin in a cold syrup formulation based on continuous wavelet transform and first derivative transform methods

In this study, simultaneous determination of acetaminophen (ACT), phenylephrine (PHE), and guaifenesin (GUA) in synthetic mixtures and syrup formulation was performed using spectrophotometry technique along with continuous wavelet transform (CWT) and derivative transform (DT). Among various wavelet families, Daubechies (Db2), Symlet (Sym4), and Coiflet (Coif2), were selected to analyze ACT, PHE, and GUA, respectively. Mean recovery and root mean square error (RMSE) of CWT method were found 100.19 %, 98.96 %, 95.35 % and 0.00023, 0.0026, 0.0031 for ACT, PHE, and GUA, respectively. For DT method, the first derivative absorption spectra were chosen for determining ACT, PHE, and GUA at 237, 224, and 219 nm, respectively. Mean recovery values were achieved between 97.15 % and 100.35 %. Also, limit of detection (LOD) and limit of quantification (LOQ) were obtained between 0.0138−0.1507, 0.0012−0.0123 μg ml−1 and 0.0695−0.7786, 0.0025−0.0767 μg ml−1 for CWT and DT methods, respectively. These proposed procedures were compared with the high-performance liquid chromatography (HPLC) as a reference technique via analysis of variance (ANOVA). The results did not show a significant difference between the methods. The suggested methods are simple and cost-effective for the quantitative assessment of three-component mixture.

Simultaneous determination of Acetaminophen and dopamine based on a water-soluble pillar[6]arene and ultrafine Pd nanoparticle-modified covalent organic framework nanocomposite

While numerous sensing strategies have been applied in the determination of Acetaminophen (AP), dopamine (DA), and ascorbic acid (AA), the selectivity is always a critical challenge based on their similar structure and function. Accordingly, the development of a highly selective sensing method is not only necessary but also crucial. In this study, a novel electrochemical sensing platform for the simultaneous determination of AP and DA has been successfully constructed based on a multifunctional nanocomposite (WP6-Pd-COF) of water-soluble pillar[6]arene (WP6), ultrafine Pd nanoparticles, and triethylene glycol-modified covalent organic framework (COF). Pd nanoparticles with an average size of 4.2 nm are prepared by reducing K2PdCl4 under the stabilization of oxygen-rich COF, which shows superior catalytic activity in electrochemical detection. A supramolecular host-guest recognition system introduced between WP6 and analytes (AP, DA, and AA) can effectively recognize AP and DA, implying the simultaneous determination of AP and DA by this approach. The electrode, best operated at a working potential range from -0.2 to 0.8 V (vs. Hg/Hg2Cl2), works in the concentration ranges of 0.2-8 μM for DA and 0.1-7.5 μM for AP, and has a detection limit of 0.06 μM for DA and 0.03 μM for AP (S/N = 3). Therefore, this study presents potential application values in sensing, catalysis, and other fields.

A flexible CVD graphene platform electrode modified with l-aspartic acid for the simultaneous determination of acetaminophen, epinephrine and tyrosine

A graphene platform electrode (GPE) was fabricated by transferring chemical vapor deposition (CVD) graphene films from copper foils to flexible polyethylene terephthalate substrates supported by polymethyl-methacrylate. l-Aspartic acid (l-Asp) was immobilized onto the surface of GPE by electrodeposition to form a poly-l-Asp/GPE, which was characterized by scanning electron microscopy, energy dispersive spectroscopy and Raman spectroscopy. Hence, a novel poly-l-Asp modified GPE was created for the simultaneous electrochemical determination of acetaminophen (AC), epinephrine (EP) and tyrosine (TY). Cyclic voltammetry was used for investigating the electrocatalytic activity of the poly-l-Asp/GPE sensor towards the detection of AC, EP and TY in comparison with that of GPE. The simultaneous determination of AC, EP and TY was realized by the differential pulse voltammetry technique at poly-l-Asp/GPE. The broad linear ranges to AC, EP and TY were obtained by chronoamperometry, which were from 0.05 to 108.25 μM for AC, 0.025 to 123.3 μM for EP and 0.1 to 93.9 μM for TY, with detection limits (S/N = 3) of 0.011 μM, 0.006 μM and 0.31 μM, respectively. Furthermore, the as-fabricated sensor showed extraordinary stability as well as high anti-interference ability, and was utilized successfully in detecting real samples.

Comparative dissolution studies on granules with acetaminophen and caffeine using the basket and paddle methods with simultaneous spectrophotometric determination of active substances

Abstract Acetaminophen and caffeine, popular therapeutic substances used to relieve pain or alleviate the symptoms of cold. The aims of the study were the comparison of granules, in terms of dissolution rate and moreover the development of spectrophotometric method to the simultaneous determination of both active pharmaceutical ingredients (APIs) in granules. The granules were tested by two pharmacopoeial methods of dissolution for solid dosage forms, and the dissolution profiles for each formulation were compared. A method of simultaneous determination of two medicinal substances by the double calibration method using derivative spectrophotometry was used. Considering the dissolution process carried out in the paddle apparatus, it was shown that more than 80% of acetaminophen and caffeine were released from each of the preparations in a clearly shorter time than 10 minutes. Carrying out the basket test, substances dissolved gradually, much slower than in the paddle method. The time required to release 80% of both active substances from majority of tested preparations was from 30 to 45 minutes. Application of the first derivative spectrophotometric method allows simultaneous determination of acetaminophen and caffeine in the mixture, without the need to separate them first.

Simultaneous Determination of Acetaminophen and Tyrosine Using Screen-printed Electrochemical Sensor Based on MWCNTs-doped Poly(glycine)/Poly(acrylic acid) Conducting Polymers

Simultaneous Determination of Acetaminophen and Tyrosine Using Screen-printed Electrochemical Sensor Based on MWCNTs-doped Poly(glycine)/Poly(acrylic acid) Conducting Polymers

Multi walled carbon nanotubes supported CuO-Au hybrid nanocomposite for the effective application towards the electrochemical determination of Acetaminophen and 4-Aminophenol

Herein, a newly developed CuO-Au composite was successfully decorated on multiwalled carbon nanotubes (MWCNTs) and employed as an electrochemical sensor. The developed nanocomposite (CuO-Au/MWCNTs) was dispersed on the surface of glassy carbon electrode (GCE) to produce CuO-Au/MWCNTs/GCE. The characterizations of nanocomposite was examined with the help of field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectrometry (EDX) and fourier transform infrared spectroscopy (FT-IR) techniques. The sensor showed promising electrocatalytic activity towards the individual and simultaneous determination of Acetaminophen (AC) and 4-Aminophenol (4-AP). The sensor showed good linear response for AC and 4-AP in the range from 0.2 μM to 6.0 μM and 0.5 μM to 1.6 μM with detection limits of 0.016 μM and 0.105 μM respectively. The sensor showed potential applications in evaluating kinetic parameters. The practical application of the developed electrochemical sensor was verified in pharmaceutical formulation and human serum sample successfully.

Low cost microfluidic device based on cotton threads for electroanalytical application.

Microfluidic devices are an interesting alternative for performing analytical assays, due to the speed of analyses, reduced sample, reagent and solvent consumption and less waste generation. However, the high manufacturing costs still prevent the massive use of these devices worldwide. Here, we present the construction of a low cost microfluidic thread-based electroanalytical device (μTED), employing extremely cheap materials and a manufacturing process free of equipment. The microfluidic channels were built with cotton threads and the estimated cost per device was only $0.39. The flow of solutions (1.12 μL s(-1)) is generated spontaneously due to the capillary forces, eliminating the use of any pumping system. To demonstrate the analytical performance of the μTED, a simultaneous determination of acetaminophen (ACT) and diclofenac (DCF) was performed by multiple pulse amperometry (MPA). A linear dynamic range (LDR) of 10 to 320 μmol L(-1) for both species, a limit of detection (LOD) and a limit of quantitation (LOQ) of 1.4 and 4.7 μmol L(-1) and 2.5 and 8.3 μmol L(-1) for ACT and DCF, respectively, as well as an analytical frequency of 45 injections per hour were reached. Thus, the proposed device has shown potential to extend the use of microfluidic analytical devices, due to its simplicity, low cost and good analytical performance.

Simultaneous determination of acetaminophen, theophylline and caffeine using a glassy carbon disk electrode modified with a composite consisting of poly(Alizarin Violet 3B), multiwalled carbon nanotubes and graphene

The authors describe a glassy carbon disk electrode which after modification with poly(Alizarin Violet 3B), multiwalled carbon nanotubes and graphene enables simultaneous determination of the drugs acetaminophen (AP), theophylline (TP) and caffeine (CF). The electrochemical response to AP, TP and CF at the modified electrode was studied by cyclic voltammetry, and the results revealed an excellent electrocatalytic activity towards the oxidation of the three analytes at potentials of typically 0.5, 1.15 and 1.4 V (vs. SCE) respectively. The anodic peaks are well defined and occur at lower oxidation potential and enhanced oxidation peak currents (compared to an unmodified electrode). Simultaneous differential pulse voltammetric measurements resulted in calibration plot for AP, TP and CF were obtained that cover range from 0.2 to 100 μM for AP, from 0.5 to 120 μM for TP, and from 1.0 to 120 μM for CF. The respective detection limits are 0.01, 0.02 and 0.10 μM. The method was applied to simultaneous determination of AP, TP and CF in spiked human serum and gave satisfactory results.

Simultaneous Determination of Acetaminophen and Tramadol Impurities in combination product of Acetaminophen and Tramadol Tablets by UPLC with Trifunctional Octadecyl Column

A Simple, Precise, Sensitive and time efficient stability indicating reverse phase Ultra Performance Liquid Chromatography (RP-UPLC) method was developed and validated for the simultaneous determination of Acetaminophen and Tramadol impurities present in fixed dose combination product. The components were separated in gradient elution mode using 0.1% Perchloric acid in water and acetonitrile as mobile phase. The column used was Acquity HSS T3 (100 mm x 2.1 mm, 1.8 µ) at a flow rate of 0.5 mL.min−1 with 30°C temperature. Quantification was achieved with detection wavelength of 215 nm. The developed method was validated for specificity, linearity, precision, accuracy, sensitivity (LOD & LOQ) and robustness in accordance with International Conference on Harmonisation (ICH) guidelines. The method is rapid, cost effective for the quantitative determination of Acetaminophen and Tramadol impurities in Acetaminophen and Tramadol tablets dosage forms.

Simultaneous determination of acetaminophen and dihydrocodeine in human plasma by UPLC-MS/MS: Its pharmacokinetic application.

An ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to determine acetaminophen (AAP) and dihydrocodeine (DHC) in human plasma simultaneously. Plasma samples were prepared using protein precipitation with acetonitrile, the two analytes and the internal standard midazolam were separated on an Acquity UPLC BEH C18 column and mass spectrometric analysis was performed using a QTrap5500 mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions of m/z 151.2→110.0 and m/z 302.3→199.2 were used to quantify for AAP and DHC, respectively. The linearity of this method was found to be within the concentration range of 50-10000ng/mL for AAP, and 1-100ng/mL for DHC in human plasma, respectively. The lower limit of quantification (LLOQ) was 50ng/mL and 1ng/mL for AAP and DHC in human plasma, respectively. The relative standard deviations (RSD) of intra and inter precision were less than 10% for both AAP and DHC. The analysis time of per sample was 1.0min. The developed and validated method was successfully applied to a pharmacokinetic study of AAP (500mg) with DHC (20mg) capsule in Chinese healthy volunteers (N=20).

Development and validation of a rapid derivative spectrophotometric method for simultaneous determination of acetaminophen, ibuprofen and caffeine

A zero-crossing derivative spectrophotometric method was used for the simultaneous determination of acetaminophen, ibuprofen and caffeine. The derivative spectra of standard solutions of each compound were obtained at different orders to find out the suitable zero-crossing points. Under the optimized conditions, determination of acetaminophen was performed at wavelengths of 311 and 270 nm using the third order (Δλ = 24.5) and fourth order (Δλ = 12.0) derivative spectra, respectively. Ibuprofen and caffeine were determined at wavelengths of 235 and 300 nm using the second order (Δλ = 21.0) and fourth order (Δλ = 27.0) derivative spectra. The method was found to be linear (r2 > 0.998) in the range of (μg/mL) 5–50 for acetaminophen, 5–30 for ibuprofen and 1–7 for caffeine in the presence of other compounds. The within-day and between-day precision and accuracy of the proposed method were acceptable (CV < 3% and error < 2%) for all three components and the proposed method was satisfactory for quality control purposes. The method was successfully applied to the simultaneous determination of acetaminophen, ibuprofen and caffeine in pharmaceutical dosage forms without any interference from excipients and there was no need to any prior separation before analysis.

A new electrochemical sensor for the simultaneous determination of acetaminophen and codeine based on porous silicon/palladium nanostructure

A porous silicon/palladium nanostructure was prepared and used as a new electrode material for the simultaneous determination of acetaminophen (ACT) and codeine (COD). Palladium nanoparticles were assembled on porous silicon (PSi) microparticles by a simple redox reaction between the Pd precursor and PSi in an aqueous solution of hydrofluoric acid. This novel nanostructure was characterized by different spectroscopic and electrochemical techniques including scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, fourier transform infrared spectroscopy and cyclic voltammetry. The high electrochemical activity, fast electron transfer rate, high surface area and good antifouling properties of this nanostructure enhanced the oxidation peak currents and reduced the peak potentials of ACT and COD at the surface of the proposed sensor. Simultaneous determination of ACT and COD was explored using differential pulse voltammetry. A linear range of 1.0–700.0µmolL−1 was achieved for ACT and COD with detection limits of 0.4 and 0.3µmolL−1, respectively. Finally, the proposed method was used for the determination of ACT and COD in blood serum, urine and pharmaceutical compounds.

Simultaneous Determination of Acetaminophen and Synthetic Color(s) by Derivative Spectroscopy in Syrup Formulations and Validation by HPLC: Exposure Risk of Colors to Children.

Color additives are used in pediatric syrup formulations as an excipient; though not pre-requisite, but pediatric syrup formulations are normally colored. An attempt has been made to measure simultaneously the single drug, acetaminophen (AT), along with the colors, carmoisine (CA), erythrosine (ET), and sunset yellow FCF (SSY) added in it by three derivative spectroscopy methods namely, 1st order, ratio, and differential derivative methods. Moreover, evaluation has been made for the exposure assessment of the colors added as excipient because some colors have been reported to cause allergic reactions and hypersensitivity in children. The present methods provide simple, accurate, and reproducible quantitative determination of the drug, AT, along with the color in synthetic mixtures and commercial drug formulations without any interference. The limit of detection varied from 0.0001-0.31 μg/ml while limit of quantification ranged from 0.002-1.04 μg/ml in all the three methods. The calibration curve of all the three derivative methods exhibited good linear relationship with excellent regression coefficients (0.9986-1.000). Both intra-day and inter-day precisions showed %RSD value less than 2% while the percentage recovery was found between 96.8-103.8%. The sensitivity of the proposed methods is almost comparable to HPLC and thus, can be used for determination of drug AT, and color simultaneously in pharmaceutical formulation on routine basis. The present methods also showed that colors like SSY and ET are saturating more than 50% of acceptable daily intake (ADI) value which is alarming and needs to be considered for modification by regulatory authorities to safeguard the health of children.

Simultaneous determination of five cold medicine ingredients in paracetamol triprolidine hydrochloride and pseudoephedrine hydrochloride tablets by pH/organic solvent double-gradient high performance liquid chromatography

A pH/organic solvent double-gradient mode in reversed-phase high performance liquid chromatography (HPLC) has been established as a new approach to the simultaneous determination of acetaminophen, caffeine, salicylamide, pseudoephedrine hydrochloride and triprolidine hydrochloride in paracetamol triprolidine hydrochloride and pseudoephedrine hydrochloride tablets. Through the optimization of the organic solvent gradient mode and pH/organic solvent double-gradient mode, the optimum double-gradient HPLC system of the five cold medicine ingredients has been built. The determination was carried out on a Diamonsiol C18 column (250 mm x 4.6 mm, 5 microm). The mobile phase consisted of methanol, 0.05 mol/L ammonium acetate solution and 0.08 mol/L acetic acid solution. The column temperature was set at 30 degrees C. The flow rate was 1.0 mL/min. The sample was measured at multiple wavelengths: 0-6 min, 280 nm; 6-7 min, 257 nm; 7-14 min, 280 nm; 14 min, 233 nm. The separation of the five cold medicine ingredients in the tablets was achieved in 25.5 min. The linear ranges of acetaminophen, pseudoephedrine hydrochloride, caffeine, salicylamide and triprolidine hydrochloride were 0.055 -0.998 g/L, 0.053-0.946 g/L, 0.007-0.129 g/L, 0.035-0.622 g/L and 0.002-0.039 g/L, respectively, with their correlation coefficients greater than 0.999 0. The detection limits (S/N = 3) were 0.09, 6, 0.02, 0.128 and 0.02 mg/L, respectively. Their mean recoveries were 97.9%-102.8%. The advantage of the method is the simultaneous determination of acidic, neutral and basic compounds. It also can improve the column efficiency of the analyte, compress the half-peak width and reduce the trailing. The optimized and validated method can be used for the simultaneous determination of the five cold medicine ingredients in the tablets.

Derivative Spectrophotometic Methods for Simultaneous Estimation of Acetaminophen and Guaiphenesin in their Combined Dosage Form

Derivative spectroscopy offers a useful approach for the analysis of drugs in mixtures. In this study First order derivative spectrophotometric method was developed for the simultaneous determination of Acetaminophen (ACET) and Guaiphenesin (GUAI) in bulk and combined tablet dosage form. The derivative spectrum for the method was obtained in methanol and the linearity was obtained in the concentration range of 2.0 - 10.0 µg/mL for Acetaminophen and 1.2 - 6.1 µg/mL for Guaiphenesin. The zero order spectrums are obtained at wavelengths 250nm for Acetaminophen and 274nm for Guaiphenesin. First order derivative spectrophotometric method was based on the determination of both the drugs at their respective zero crossing point (ZCP). The determinations were made at 209 nm (ZCP of Guaiphenesin) for Acetaminophen and 250 nm (ZCP of Acetaminophen) for Guaiphenesin. The mean % recovery was 100.4 and 99.8 % for Acetaminophen and Guaiphenesin respectively. The method was found to be simple, sensitive, accurate and precise and was applicable for the simultaneous determination of Acetaminophen and Guaiphenesin in pharmaceutical tablet dosage form. The results of analysis have been validated statistically and by recovery studies.

Simultaneous Determination of Some Analgesic Drugs Using Mixed Mode Stationary Phase

A new HPLC method based on a mixed mode stationary phase Hypersil Duet C18/SAX was developed and applied for the simultaneous determination of acetaminophen, acetylsalicylic acid and codeine. Parameters, such as the composition of the mobile phase, the nature of the organic modifier, the buffer type and the flow rate were investigated to optimize the separation. The results obtained show that the new HPLC method is rapid, highly efficient and selective. The studied compounds are separated in 10 min, by means of a mobile phase containing phosphate buffer (pH 7.50) and methanol (65:35 v v−1). The retention mechanisms of each analyte were investigated using both the linear solvent strength theory and stoichiometric displacement model. The method was fully validated and showed good linearity for each compound for a concentration ranging between 2.0 and 40 μg mL−1. The limits of detection and quantification were determined and they are lower than 0.1 μg mL−1. The precision (RSD) of the method does not exceed 2 % for all studied compounds. The method was successfully applied for the assay of acetaminophen, acetylsalicylic acid and codeine in pharmaceutical formulations.

Simultaneous Voltammetric Determination of Acetaminophen and Caffeine at a Graphite and Polyurethane Screen-Printed Composite Electrode

A selective electrochemical method was developed for the individual or simultaneous determination of acetaminophen and caffeine in phosphate buffer pH 6.0 on graphite and polyurethane screen-printed composite electrode (EIGPU) using Differential Pulse Voltammetry (DPV). The oxidation peaks of acetaminophen and the caffeine appeared at 0.3 V and 1.3 V(vs. pseudo-Ag/AgCl), respectively, showing the possibility of simultaneous determination of both analytes, at the EIGPU, besides the individual determination. Analytical curves for the simultaneous determination showed a linear response for both compounds. The acetaminophen presented a linear region in the concentration range 1.00 - 40.0 µmol L-1 with detection limit of 0.84 µmol L-1, and the caffeine presented a linear region, in the concentration range 4.00 - 200 µmol L-1 with detection limit of 1.6 µmol L-1. The proposed method was applied in the simultaneous determination of acetaminophen and caffeine in three pharmaceutical formulations, with results similar to those obtained using a HPLC method, at 95% confidence level (Student t-Test).