Separation Of Caffeine Research Articles

Determination of Pharmacologically Active Nitrogen-Containing Compounds on Silica Doubly Modified with 6,10-Ionene and Dextran Sulphate by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

An adsorbent for HPLC, silica doubly layer-by-layer modified with 6,10-ionene and dextran sulfate, is obtained. The adsorbent has both hydrophobic and hydrophilic and ion-exchange properties (because of the presence of hydrophobic anions and cations on the surface). A possibility of using the obtained adsorbent in HPLC with tandem mass spectrometric detection is shown. The conditions for the separation of caffeine, paracetamol, doxylamine, and chlorpheniramine in the isocratic mode are selected in elution with mixtures of acetonitrile and an acetate buffer solution. The most successful results are achieved by eluting the separated substances with the mobile phase acetonitrile–15 mM acetate buffer solution (glacial acetic acid/ammonium acetate with pH 5.55 in the ratio 10 : 90, vol). Gradient elution conditions are selected, a methodology is developed for determining traces of pharmaceuticals in human serum in the multiple reaction monitoring (MRM) mode using the internal standard method. The source and MRM transition parameters are selected individually for each compound. The linear range of the calibration curve for paracetamol and caffeine is 0.5–200 ng/mL and for doxylamine and chlorpheniramine, 0.05–50 ng/mL. The concentration of pharmacologically active compounds of caffeine, paracetamol, doxylamine, and chlorpheniramine in the blood serum of patients taking appropriate drugs is 165.2, 17.3, 10.2, and 35.3 ng/mL, respectively.

Green synthesis of caffeine based on methylating reagent dimethyl carbonate and environmental friendly separating method

AbstractIn this paper, a green process for the synthesis and separation of caffeine was reported. Theophylline sodium is used as the raw material, diazabicyclo[5.4.0]undec‐7‐ene as the catalyst, and Turkey red oil as the solvent, particularly, dimethyl carbonate was adopted in place of high toxic dimethyl sulfate to form a mixture of caffeine and by‐product sodium bicarbonate. After converting sodium bicarbonate to sodium carbonate, the solubility difference between caffeine and sodium carbonate at 40°C was for the first time utilized to achieve the purpose of separating caffeine with an excellent yield of 98.4% and a purity of greater than 99.0%. Furthermore, both the reaction mother liquor and separation mother liquor can be recycled and reused during the reaction and separation processes, respectively, with little caffeine loss. No industrial waste was discharged in the process of the improved synthesis and separation, which is therefore environmental friendly.

Sequential Green Extraction of Caffeine and Catechins from Green Tea

Separation of caffeine and catechins from tea extracts usually requires conventional liquid-liquid extraction employing chloroform. This work was planned to improve a green extraction technique to distunguish these important chemicals from green tea. Extraction of caffeine and catechins from Turkish green tea firstly employing MAE, and then to separate these compounds from each other using a SFE method were purpose of this study. Microwave assisted extraction was applied to extract tea components from green tea then i) conventional liquid-liquid extraction or ii) supercritical carbon dioxide fluid extraction (SFE) method was charged with the effective separation of caffeine and catechins. Initially, an ethanol: water mixture was used in a close microwave system under the particuler extraction situations of green tea samples (fresh, frozen or dried) picked up in three collection periods (first, second and third collection periods). MAE of tea samples was exerted under a controlled 600 W microwave power for 4 min irradiation time at 80 oC temperature. Then MAE crude aqueous extract was divided in to two portions. The first portion was fractionated first with chloroform to distunguish caffeine then ethyl acetate for catechins. Caffeine and catechins were successfully separated. Second portion was freeze-dried and obtained lyophilized solid was used for SFE. Caffeine (3.68% extract yield) was successfully separated from catechins with SFE at 250 bar and 60°C for 180 min. Constituents of the extracts were determined (caffeine and four catechins namely EGC, EC, C, EGCG) by HPLC to evaluate the effectiveness of the separation.

Simultaneous Determination of Caffeine, Taurine and Five Water-Soluble Vitamins in Tobacco Products by HPLC–MS/MS

The simultaneous determination of caffeine, taurine and five water-soluble vitamins (B1, B2, B3, B9, and B12) in tobacco products by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was established in this work. Tobacco powders of sampled tobacco products were extracted with water and then filtered. The filtrates were separated on an Agilent Eclipse XDB-C18 (2.1 mm i.d × 150 mm, 3.5 μm) column using methanol: ammonium acetate aqueous solution (10 mM) as the mobile phase at a flow rate of 0.3 mL min−1 using the gradient elution mode. These analytes were detected by electrospray ionization–tandem mass spectrometry (ESI–MS/MS) using a multiple reaction monitoring method. Under the optimized conditions, the separation of caffeine, taurine and five water soluble vitamins was achieved within 12 min. The linear ranges of caffeine, taurine and vitamins B1, B2, B3, B9, and B12 were 2.000–100.0, 0.3316–3316, 0.1248–249.6, 1.600–160.0, 0.5990–29.95, 0.3150–31.50, and 0.2246–2246 μg L−1, respectively, with linear correlation coefficient greater than 0.997. The detection limits (S/N = 3) of caffeine, taurine and vitamins B1, B2, B3, B9, and B12 were 0.445, 0.079, 0.031, 0.400, 0.179, 0.079, and 0.066 μg L−1, respectively. The precisions for intra-day (n = 11) and inter-day (n = 5) were 0.09–2.23% and 0.11–2.52%, respectively. The recoveries of these seven analytes in the spiked tobacco product samples were in the range of 95.1–102.8%. The proposed method has the merits of easy operation, fast analysis, high sensitivity and accuracy, which is applicable for batch determination and surveillance on caffeine, taurine and water-soluble vitamins in commercial tobacco products.

Extraction of caffeine and gallic acid from coffee by electrokinetic methods coupled with a hollow‐fiber membrane

AbstractIn this study the hollow fiber membrane coupled with electrokinetics was used, for the first time, for extraction and determination of caffeine and gallic acid from coffee prior to high performance liquid chromatography with photodiode array detection. Gallic acid (as an acid) and caffeine (as a base) were extracted from coffee at pH 5. In this work, several variables including applied voltage, coffee pH, acceptor phase pH, and extraction time were investigated. Our results showed that the extraction efficiency was increased when the applied voltage and extraction time were increased. The optimum conditions were pH 5 for the coffee, applied voltage of 20 V, and extraction time of 5 h. Gallic acid as an acid and caffeine as a base migrated to anode and cathode, respectively. Under the optimum conditions, gallic acid and caffeine were extracted with extraction efficiency of 21.3 and 23.4%, respectively. The intra‐day and inter‐day precisions (%) were found to be 7.6 and 4.8%, respectively. Therefore, this set‐up for electrokinetics was potentially considered as a selective and simple preparation method for simultaneous extraction and analysis of basic and acid compounds in various matrices.Practical applicationsThis study would benefit for extraction and separation of caffeine and gallic acid from coffee and other naturel samples. In this procedure, the new set‐up for EKE based on two hollow fibers were employed for simultaneous removal of basic and acidic compounds. The EKE is used for extraction of organic compounds from food/soils with low permeability. The practical applications of this procedure have become extensive in a variety of fields, including electrokinetic waste remediation, biomaterials, radionuclides, and organic materials.

Comparative Study for Selection of the Optimum Mobile Phase for Separation of Caffeine and Paracetamol by Using TLC Chromatographic Method

Objective. To investigate the best mobile phase for separation of Paracetamol (PAR) and Caffeine (CAF) using TLC method. Methods. Different mobile phases which were mentioned in literature review were tried and retention times for both PAR and CAF were recorded for each experiment separately. Results : It was found that retardation factors for solvent A Rf (PAR) =0,59 and Rf(CAF)=0,90 ; for solvent B Rf(PAR)=0,92 and Rf(CAF)=0,81; Rf(PAR)=0,22 and Rf (CAF)=0,16. Solvent A is composed of n-hexane-ethyl acetate-ethanol (2.5 + 1.5 + 0.4, v/v/v), solvent B is composed of chloroform,ethyl acetate and ammonia (15,0 + 4,3 + 0,3 v/v/v) and solvent C is composed of methanol,glacial acetic acid and water (25,0 +4,3+70,7 v/v/v ). Conclusion: It was found that the best solvent for separation of CAF and PAR in TLC chromatographic method was composed of n-hexane-ethyl acetate-ethanol (2.5 + 1.5 + 0.4, v/v/v).

Separation of polyphenol compounds and caffeine from green tea extract

The polyphenolic compounds in green tea extract i.e. tannins and polyphenols, especially catechins, attribute to organoleptic and heath promoting functions. For tea caffeine, although it is known to stimulate nervous system; however, overuse of caffeine may induce a number of detrimental effects including headaches and migraines. Therefore, this research is aimed at optimizing the separation of caffeine and the major tea polyphenols namely catechins from green tea extract using adsorption/desorption technique. In this study, Assam green tea extract was prepared by boiling 5%w/v tea leaves in 100 mL of acidified deionized water at 95°C for 10 mins. The pH of the tea-hot water mixture in the extractor was controlled at pH 4 using citric acid. This was done to minimize oxidative degradation of active ingredients. Total polyphenol content (TPC) of the fresh extract measured using a spectrophotometer was 8.8%w/v. Thereafter, the extract was evaporated until the final volume was 10 mL. Subsequently, the concentrate was separately flown in different resin columns i.e. polyamide 6, amberlite XAD-7, nylon 6/6 and polyamine at a constant flow rate of 2.7 mL/min. Water-ethanol mixtures (0 to 95%v/v of ethanol) were used as eluting agents in desorption process. It was found that, caffeine and catechins were clearly isolated from each other when the polyamide column was initially desorbed with water (to elute caffeine) followed by 50%v/v ethanol in water (to elute catechins). The recovery percentages of the isolation process for caffeine and individual catechins were 36.4% and in the rage of 28.5 to 98.7%, respectively. Therefore, the purified caffeine and catechins could be further used as ingredients in food, beverage and pharmaceutical industries.

Separation of Caffeine from Beverages and Analysis Using Thin-Layer Chromatography and Gas Chromatography–Mass Spectrometry

The Characterization and Analysis of a Product (CAP) project is used to introduce first-semester general chemistry students to chemical instrumentation through the analysis of caffeine-containing beverage products. Some examples of these products have included coffee, tea, and energy drinks. Students perform at least three instrumental experiments as a part of this five-part project to analyze different components of the beverage and its packaging. In this discussion, the first of these experiments is presented. Caffeine and other components, such as flavorings, are extracted from the product using dichloromethane. The extract is analyzed using thin-layer chromatography (TLC) and gas chromatography–mass spectrometry (GC–MS) to identify caffeine and other trace components. Students also calculate the percent abundance of the 35Cl and 37Cl isotopes from the dichloromethane mass spectrum. These exercises demonstrate several basic concepts introduced in the first-semester course, and are easily adaptable to using in several courses in the undergraduate curriculum.

Application of Surfactant Micellar Solutions as Extractants and Mobile Phases for TLC-Determination of Purine Bases and Doping Agents in Biological Liquids

Separation of caffeine and its metabolites (theophylline and theobromine) and doping agents (spironolactone, propranolol, and ephedrine) and determination of caffeine in serum sample and propranolol and ephedrine in urine were studied on normal-phase thin layers (“Sorbfil-UV-254”). Aqueous organic solvents and aqueous micellar surfactant solutions were compared as the mobile phases for separation. The acceptable separation of purine bases and doping agents was achieved by micellar Thin Layer Chromatography and normal-phase Thin Layer Chromatography. Anionic surfactant solution with added 1-propanol was the best eluent as for caffeine, theophylline, and theobromine separation, as for doping agents. The best characteristics of caffeine extraction from serum, and propranolol and ephedrine from urine were achieved when micellar eluent based on non-ionic Tween-80 surfactant was used. DOI: http://dx.doi.org/10.17807/orbital.v7i1.632

Separation of Caffeine and Tea Poly-phenols from Instant (Soluble) Tea Waste Liquor by Macro-porous Resins

Instant tea is presently manufactured by spraying and freeze drying the concentrated brew of processed tea leaves and dust. The purpose of this study was to develop a technique using macro-porous resins for separating Caffeine (Caf) and Tea Poly-phenols (TP) from the waste liquor generated by manufacturing instant tea. Optimum adsorption conditions were obtained using an initial concentration of Caf solution of 80 mg/L and a flow rate of 1.5 mL/min at 60°C; The optimal desorption conditions were determined using a flow rate of 1.0 mL/min, 80% aqueous ethanol of, eluent volume of 4 times of Bed Volume (BV). After column separation, the purity of Caf was enhanced from 6 to 23%, TP from 38 to 61% and with the final yield of 16.9% following the separation by D101 resin. This study demonstrated macro-porous resin can effectively separated Caf and TP from instant tea waste liquor.

Microemulsion Thin-layer Chromatographic Separation of Caffeine and Paracetamol and their Determination in Formulated Tablet and in Spiked Urine Sample by HPLC

A simple and accurate method was developed for the separation and simultaneous determination of Caffeine and Paracetamol. The separation was achieved on silica HPTLC plates with microemulsion (SDS: water: n-hexane: 1-butanol, 8 g: 8 ml: 160 ml: 25 ml) as a solvent system. The determination was achieved by HPLC after extraction of the solute from the spots. The determination was performed in isocratic elution mode with mobile phase acetonitrile-water (50 : 50, v/v) at a flow rate of 1.o mL/min in a C18 hypersil gold 150 mm x 4.6 mm, 5um particle size column. The detection was carried out at 272 by PDA detector. This method was validated for analytical parameters such as, linearity, specificity, precision, LOD and LOQ. The developed method was used for the identifiaction, separation and quantification of Caffeine and Paracetamol in formulted drug and in spiked urine sample. The % recoveries obtained in drug and in spiked urine samples are 99.2 and 98.9 (for Caffeine) and 99.8 and 99.7 (for Paracetamol), respectively.

Simultaneous and rapid determination of caffeine and taurine in energy drinks by MEKC in a short capillary with dual contactless conductivity/photometry detection

A method has been developed for the simultaneous determination of taurine and caffeine using a laboratory-made instrument enabling separation analysis in a short 10.5 cm capillary. The substances are detected using a contactless conductometry/ultraviolet (UV) photometry detector that enables recording both signals at one place in the capillary. The separation of caffeine and taurine was performed using the MEKC technique in a BGE with the composition 40 mM CHES, 15 mM NaOH, and 50 mM SDS, pH 9.36. Under these conditions, the migration time of caffeine is 43 s and of taurine 60 s; LOD for caffeine is 4 mg/L using photometric detection and LOD for taurine is 24 mg/L using contactless conductometric detection. The standard addition method was used for determination in Red Bull energy drink of caffeine 317 mg/L and taurine 3860 mg/L; the contents in Kamikaze drink were 468 mg/L caffeine and 4110 mg/L taurine. The determined values are in good agreement with the declared contents of these substances. RSD does not exceed 3%.

Application of a column classification method in a selectivity study involving caffeine and its related impurities

In this paper a comparative study of RP-LC column selectivity as obtained by the classification method of the Katholieke Universiteit Leuven (KUL method) and the selectivity obtained in real pharmaceutical analysis is reported. The separation of caffeine and its respective impurities was performed on 35 brands of stationary phases in accordance with the method prescribed in the European Pharmacopoeia (Ph. Eur.). Evaluation concerned the probability of appropriate column selection related to the selection of two different stationary phases for reference. The comparison was based on the traditional correlation of the F-values with the results of a system suitability test (SST) for the columns, as well as an application of a factor analysis (FA) for graphical visualisation of the differences and similarities between the stationary phases established against four test chromatographic parameters provided by the KUL method and the retention parameters of the compounds of interest describing the column performance test. The obtained results confirmed that the class of the stationary phases selected according to the chromatographic test parameters gave comparable separation for caffeine and its impurities.

An Efficient and Simultaneous Analysis of Caffeine and Paracetamol in Pharmaceutical Formulations Using TLC with a Fluorescence Plate Reader

A simple, rapid, and efficient method using TLC with a fluorescence plate reader has been described for simultaneous determination of caffeine and paracetamol. Determination was carried out using the fluorescence-quenching action of caffeine and paracetamol on a TLC plate with a fluorescent indicator at lambda ex = 254 nm in the linear ranges of 0.2-1.9 and 0.03-1.5 microg/L, respectively. Separation of caffeine and paracetamol were performed on the TLC plate, and the best results were obtained using the optimized mobile phase n-hexane-ethyl acetate-ethanol (2.5 + 1.5 + 0.4, v/v). Some important parameters, such as solvent type and ratio of the mobile phase, the presence of other components, and instrumental parameters, were studied. Caffeine and paracetamol detection limits were 0.025 and 0.032 microg/L, and RSD values for 0.6 microg/L caffeine and 0.06 microg/L paracetamol (n = 5) were 1.93 and 2.06%, respectively. Using this technique, some pharmaceuticals containing caffeine and paracetamol were analyzed with satisfactory results.

Special Selectivity of Molecularly Imprinted Monolithic Stationary Phase

A monolithic, molecularly imprinted column was prepared by an in situ therm‐initiated copolymerization process; the essential conditions of forming a non‐covalent molecular imprinting stationary phase are discussed and illustrated with caffeine and theophylline as examples from the angle of molecular construction, and examined by experiments. The results showed that the theophylline‐imprinted monolithic column has high selectivity to theophylline; baseline separation of caffeine and theophylline was achieved. However, only weak specific selectivity to the template molecule was observed for the caffeine imprinted monolithic column.

Separation of caffeine and theophylline in poly(dimethylsiloxane) microchannel electrophoresis with electrochemical detection

A method for the rapid separation and sensitive determination of caffeine and theophylline was presented in poly(dimethylsiloxane) (PDMS) microchannel electrophoresis integrated with electrochemical detection. By using methanol as an additive, the peak shape and resolution were essentially improved. The analytes were well separated within only 40 s in the running buffer of 5.0 mM borate solution (pH 9.2) containing 10% (v/v) methanol. The linear ranges were from 6 μM to 0.6 mM and the detection limits were 4 μM for caffeine and theophylline, respectively. The proposed method has been successfully applied to determine caffeine and theophylline in rat serum and urine.

Development of a New Preparative Spiral‐Coil Low‐Speed Rotary Countercurrent Chromatographic (Spiral‐Coil LSRCCC) Method

A new prototype, large‐scale countercurrent chromatograph was constructed. It was equipped with a three‐layer spiral column made from a continuous piece of convoluted Teflon tubing (8.5 mm I.D. and 9.7 m in length), which was accommodated in a spirally carved foam plastic holder. Two different types of two‐phase solvent systems were used to evaluate stationary phase retention and mixing effect between stationary and mobile phases, i.e., chloroform/water (1:1, v/v) for separation of caffeine and theophylline; and 1‐butanol/acetic acid/water (4:1:5, v/v/v) for separation of dipeptides, valyl‐tyrosine (val‐tyr), and tryptophyl‐tyrosine (trp‐tyr). A set of different elution modes (inside–outside and head–tail), and rotational speed (0–400 rpm) was assessed for stationary phase retention and separation efficiency. The elution mode of inside to outside of the spiral for the lower mobile phase or the opposite direction for the upper mobile phase, is rated the best for stationary phase retention due to observed spiral effect for liquid movement. Different operational parameters, such as rpm and flow rate of the mobile phase were evaluated for separation efficiency and speed. The obtained data revealed that the spiral effect and Archimedean screw force were two important contributing factors for yielding the enhanced speed and higher partition efficiency, compared to conventional low‐speed rotary countercurrent chromatography.

Ultrathin-layer chromatography.

The development of ultrathin-layer silica gel plates with a monolithic structure opens up a new dimension in thin-layer chromatography (TLC). The very small layer thickness of approximately 10 microm and the absence of any kind of binder in combination with the framework of this stationary phase lead to new and improved properties of these ultrathin-layer chromatographic (UTLC) silica-gel plates compared with conventional TLC and high-performance TLC (HPTLC) precoated layers. First of all, the advantages of the UTLC plates are the very short migration distances and, in combination with this, the short development times as well as the very low consumption of solvents as the mobile phase in connection with high sensitivity. The separations of amino acids, pesticides, pharmaceutically active ingredients, phenols, and plasticizers effectively demonstrate the possibilities of the new ultrathin-layer silica-gel plates. Furthermore, a comparison of UTLC, HPTLC, and TLC concerning retention behavior, efficiency, detection limits, migration times, and solvent consumption is performed effectively by the separation of caffeine and paracetamol.

Combination of flow injection with capillary electrophoresis. Part 6.: A bias-free sample introduction system based on electroosmotic-flow traction

A bias-free sample injection method based on electroosmotic-flow (EOF) traction was developed for the combined flow injection-capillary electrophoresis system. A Nafion joint implemented at a capillary fracture close to the capillary inlet was used for isolating the electric field during the split-flow sample injection, the sample solution being drawn into the capillary by EOF without bias effects. An electronic time relay system was adopted to control the switching of high voltage between the capillary inlet end and the joint. The peak area ratios of two model compounds, dimethyl sulfoxide and benzoic acid obtained using the proposed system were identical to those with gravity injection. Relative standard deviations of 0.5–2.5% ( n = 32) were achieved for peak height and peak area evaluation in the consecutive injections of a series of replicate sample solutions at a sampling frequency of 15 h −1 . Similar performance of the system was obtained with a reversed EOF background electrolyte after reversing the electrode polarity for a mixture of the anions, Cl −, SO 4 2−, NO 3 − and F − using indirect UV detection. The performance of the system for the analysis of real samples was demonstrated by bias-free sample injection in the separation of caffeine, theobromine and theophylline in beverage samples with satisfactory recoveries in the 92–107% range.

EXTRAÇÃO DOS ALCALÓIDES: CAFEÍNA E TRIGONELINA DOS GRÃOS DE CAFÉ COM C SUPERCRÍTICO

A descafeinação do café canephora é vantajosa tanto para a obtenção da cafeína quanto para valorização desta espécie. A cafeína, subproduto da descafeinação, atua como estimulante e diurético no organismo e é usado pelas indústrias de bebidas de refrigerante e farmacêutica. Existem patentes industriais aplicando CO2 supercrítico na extração da cafeína do café. Porém pouco é divulgado sobre a extração da trigonelina (alcalóide importante na formação da vitamina‘ niacina’), que atua no sistema nervoso central, na secreção da bile e no intestino. O objetivo deste trabalho foi levantar subsídios experimentais e teóricos para a extração de alcalóides dos grãos de café canephora, variedade robusta, usando CO2 supercrítico. Os dados foram obtidos num aparelho de extração a altas pressões onde as variáveis termodinâmicas são independentemente controladas. Os alcalóides foram analisados por Cromatografia Liquida de Alta Eficiência (CLAE). As solubilidades da cafeína pura e a obtida dos grãos de café no CO2 supercrítico foram determinadas a 313, 323 e 343 K, de 9,5 a 23,5 MPa. Os resultados revelam a existência de um comportamento retrógrado para a solubilidade da cafeína pura e a obtida dos grãos de café; também mostram a seletividade do CO2 supercrítico pela cafeína quando comparada a trigonelina. A modelagem termodinâmica do equilíbrio sólido-fluido usando uma equação de estado de quarta ordem correlacionou satisfatoriamente as solubilidades da cafeína pura no solvente supercrítico.