Recovery Of Caffeine Research Articles

Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry Measurement of Caffeine in Caffeine-Laced Pants and in Urine and Skin of a Pants User

A fast and sensitive ultra-performance liquid chromatography tandem mass spectrometry method was developed for the measurement of caffeine in caffeine-laced pants and in urine and skin of a pants user. The substance and its internal standard (N-ethylnorcotinine) were separated by reversed phase chromatography with 5 mM ammonium formate pH 3.0 and 0.3% formic acid in acetonitrile mobile phase (83:17 v/v) by isocratic elution and detected by tandem mass spectrometry operated in multiple reaction monitoring mode via positive electrospray ionization. Linearity was studied from 1.4 to100 ng/mL range for urine, from 5 to 100 ng/cotton swab for skin caffeine and from 1.3 to 100 µg/samples for 4 cm2 textile samples. Good determination coefficients (r2 = 0.99) were found in all cases. At three concentrations spanning the linear dynamic ranges of different samples mean recoveries of caffeine were always higher than 80% and intra-assay and inter-assay imprecision and inaccuracy were always better than 105%. For the first time, caffeine content in this cosmetotextile was determined together with the measurement of caffeine released on the user skin, the absorbed amount with resulting urinary concentrations.

Preparation, characterization and application of organic–inorganic hybrid caffeine imprinted monolith

The present work aims to synthesize an organic–inorganic hybrid caffeine imprinted monolith using one-step method. The synthesis conditions such as the type of inorganic precursor and porogenic solvent, the molar ratios of the monomer and cross-linker, the volume ratio of the inorganic alcoholysate and organic part were optimized. The morphology of the monolith was studied by scanning electron microscopy and Fourier transform infrared spectra. The imprinted factor of the monolith for caffeine reached 3.02. A simple, rapid and sensitive method for the determination of caffeine in children's milk using the organic–inorganic hybrid caffeine imprinted polymer monolith microextraction combined with high-performance liquid chromatography-photodiodes array detector was developed. Several parameters affecting the sample pretreatment were investigated, including the type, flow rate and volume of eluent, the flow rate and volume of sample solution. The assay exhibited a linear dynamic range of 8–500μgL−1 with the correlation coefficient above 0.9987. Lower limits of detection (LOD, at S/N=3) and quantification (LOQ, at S/N=10) in children's milk samples were 2.7 and 8μgL−1. Recoveries of caffeine from spiked children's milk ranged from 85 to 104% with relative standard deviations of less than 8.9%.

Extraction of caffeine from natural matter using a bio-renewable agrochemical solvent

This paper reports experimental data on the pressurized liquid extraction of caffeine from green coffee beans and green tea leaves using ethyl lactate (ethyl 2-hydroxy-propanoate). This solvent is a new bio-renewable agrochemical solvent, naturally produced by fermentation from corn derived feedstock, which has been recently considered as a very suitable and environmental benign solvent for food industrial applications.Static extraction assays (one step during 10min) were carried out in an Accelerated solvent extraction (ASE) system at three different extraction temperatures, namely 100, 150 and 200°C. Extraction yield and caffeine recovery were determined and compared with those obtained when using other liquid solvents, such as ethyl acetate or ethanol. High recovery of caffeine (≈60%) was found in the extracts produced using ethyl lactate, which demonstrates the potential use of this green solvent for the extraction of caffeine from different vegetable sources.

Dried Blood Spot Sampling with LC-MS Analysis for Routine Therapeutic Caffeine Monitoring in Neonates

A liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the determination of therapeutic levels of caffeine in dried blood spot (DBS) samples. Caffeine is used in the treatment of Apnoea of Prematurity (AoP) in newborn children. Calibration DBS samples were prepared by spotting 15 μL of whole blood spiked with the analyte onto specimen collection cards. 3 mm disks cut from the centre of the DBS were extracted in methanol containing the internal standard. The extract was separated using a Zorbax Eclipse Plus C18 column and the MS, operated in electrospray positive ion mode, used single ion monitoring atm/z195 for caffeine andm/z198 for the IS. The overall extraction recovery of caffeine from spiked blood spots was demonstrated to be 44–47%. Validation of the microanalytical method showed good precision (coefficient of variation) and accuracy (relative error) and specificity and was linear within the tested calibration range 500–25000 ng/mL for caffeine. Investigation of different specimen collection papers revealed different matrix effects with significant ion suppression from the FTA Elute paper itself. Requiring only a microvolume (15 μL) blood sample for analysis, the developed DBS based microanalytical method has the potential to facilitate the routine monitoring of caffeine in neonates.

Isolation of caffeine from aqueous media with solvents of homologous structure and its determination by spectrophotometry

The extraction of caffeine by hydrophilic and hydrophobic aliphatic alcohols of linear and branched structure is studied, also by water-soluble alkyl acetates. A correlation between the distribution ratios of caffeine (logD) and the molecular weight of alcohol (logM) is found. The concentration of caffeine in the aqueous phase is determined by UV spectrophotometry. The distribution ratios and recovery of caffeine are calculated.

Simple and Fast Methods Based on Solid-Phase Extraction Coupled to Liquid Chromatography with UV Detection for the Monitoring of Caffeine in Natural, and Wastewater as Marker of Anthropogenic Impact

Two concentration methods for fast and routine determination of caffeine (using HPLC-UV detection) in surface, and wastewater are evaluated. Both methods are based on solid-phase extraction (SPE) concentration with octadecyl silica sorbents. A common “offline” SPE procedure shows that quantitative recovery of caffeine is obtained with 2 mL of an elution mixture solvent methanol-water containing at least 60% methanol. The method detection limit is 0.1 μg L−1 when percolating 1 L samples through the cartridge. The development of an “online” SPE method based on a mini-SPE column, containing 100 mg of the same sorbent, directly connected to the HPLC system allows the method detection limit to be decreased to 10 ng L−1 with a sample volume of 100 mL. The “offline” SPE method is applied to the analysis of caffeine in wastewater samples, whereas the “on-line” method is used for analysis in natural waters from streams receiving significant water intakes from local wastewater treatment plants.

Fast chromatographic determination of caffeine in food using a capillary hexyl methacrylate monolithic column

Caffeine beverages are widely consumed in the world, so new analytical techniques providing fast and reliable data are essential for a rapid and accurate evaluation of food quality. A capillary hexyl methacrylate monolithic column was designed and prepared for simple, rapid, economical and sensitive high performance liquid chromatography method for the determination of caffeine in food, using a water/acetonitrile (90:10, v/v) mobile phase with ultraviolet (UV) detection. The method was validated over the range 0.16–250μg/mL of caffeine concentration and found to be linear (r>0.995, n=5) with relative standard deviation (RSD) less than 4.0%.Calibration curves prepared for tea, coffee and cocoa extracts were linear. The limits of detection and quantification were 0.05 and 0.16μg/mL, respectively. Recoveries of caffeine in food samples were found to be ranged from 89.0% to 116.6%, showing a good reliability of this method. Ruggedness and the case of external calibration versus standard addition for the analysis of real samples were also examined. The effect of temperature on the extraction was also investigated. This validated method was compared with the most commonly used conventional octadecylsilica packed column (C18), in terms of analysis time, reagents and solvents consumption, detection and linearity limits, porosity and permeability of each column.

Two new competitive ELISA methods for the determination of caffeine and cotinine in wastewater and river waters

Two enzyme-linked immunosorbent assays (ELISAs) for the determination of caffeine and cotinine in water samples were validated and evaluated for the analysis of river and wastewater samples. The caffeine ELISA shows an IC50 ranging from 2.21 to 2.73 ng ml−1, a limit of detection (LOD) of 0.135 ng ml−1 and cross-reacts with paraxanthine (CR% = 63), theophylline (CR% = 5.2), and theobromine (CR% = 2.8); while the cotinine ELISA shows an IC50 ranging from 0.38 to 0.45 ng ml−1, a LOD of 0.047 ng ml−1 and cross-reacts with 3′-hydroxycotinine (CR% = 32) and nicotine (CR% = 1.1). Calibration curves were constructed in buffer in the concentration range 0.175–5 ng ml−1 for the caffeine ELISA and 0.05–5 ng ml−1 for the cotinine ELISA. Precision and accuracy were also evaluated. For the two assays, repeatability and reproducibility, expressed as the relative standard deviation of the absorbance, were within 3% and 8%, respectively. From the spiking experiment, the recovery of caffeine found in river and wastewater was between 94–101% and 89–110%, respectively; while the recovery of cotinine found in river and wastewater was between 95–105% and 99–115%, respectively. Fifteen river water samples and four wastewater samples from different wastewater treatment plants (WWTPs) were analyzed by ELISA and confirmed by LC-MS/MS. Comparing the two methods a correlation coefficient of 0.935 was obtained, showing a small overestimation of the ELISAs with respect to LC-MS/MS.

Mathematical modeling for simultaneous extraction and fractionation process of coffee beans with supercritical CO2 and water

Mathematical modeling of extraction and fractionation of caffeine from coffee beans using SCCO2 and water was developed. Simulation of the extraction and fractionation process was conducted using a model based on mass transfer balances to estimate recovery of caffeine as non-polar compound both in CO2 and water phases. The model was developed regarding extraction and fractionation systems including batch and counter-current configurations in our previous work. Even though polar compound of chlorogenic acid from coffee beans was extracted in water phase, the simulation was focused on the extraction and fractionation of caffeine because chlorogenic acid was not fractionated but only extracted by water. Effective diffusivity of caffeine in water phase was used as fitting parameter to compare the simulation and experimental results. The value of effective diffusivity used for simulation in batch system was 3×10−12, 7×10−12 and 1×10−11m2/s; and the value used in counter-current system was 1×10−12m2/s. The simulation results were compared with the previous experimental results [3] at various temperatures, pressures, CO2 flow rates, non-polar recovery section heights and ratios of coffee and water mass. The simulation could describe experimental results almost for all extraction conditions. The model just had lack agreement with the experimental result for the ratio of coffee and water mass in water phase.

MULTI-SPE OF CAFFEINE AND CATECHIN COMPOUNDS FROM GREEN TEA BY CAFFEINE AND (+) CATECHIN MIPS

In this work, the caffeine and some catechin compounds (+) C, EC, and EGCG were extracted from green tea by using two molecular imprinted polymers (MIPs) as sorbent materials in a multi-solid-phase extraction (SPE) process known as MISPE (molecular imprinted solid-phase extraction). To obtain synthesis of MIP, (+) catechin (and caffeine) was employed as the template, AM (and MAA) as the monomer, EGDMA as the crosslinker, and AIBN as the initiator. A solution of (+) catechin (and caffeine) (0.2 mg/mL in methanol) was utilized in the solid extraction cartridges following loading, washing, and elution procedures with acetonitrile, methanol, and methanol/acetic acid (90/10, %v/v) as the solvents, respectively. This multi-solid-phase extraction protocol was applied for the extraction of caffeine and some catechin compounds from green tea. A comparison was made between the results obtained with the caffeine and (+) catechin MIP cartridges, blank polymer, and a traditional C18 reversed-phase cartridge. It was thereupon found that the recovery of caffeine by the caffeine-MIP-based sorbent used in this work was almost two and four times greater than that by a commercially available C18 material.

Dynamic microwave-assisted extraction coupled on-line with clean-up for determination of caffeine in tea

A rapid method based on dynamic microwave-assisted extraction (DMAE) coupled on-line with clean-up was developed for the determination of caffeine in tea samples. A TM 010 microwave resonance cavity was applied to concentrate the microwave energy. An extraction vessel was placed in microwave irradiation zone of the TM 010 microwave resonance cavity. A silica gel column connected with the extraction vessel was used to remove chlorophyll in tea. The extraction and clean-up procedures were carried out simultaneously in a single step. The DMAE parameters were optimized by the Box–Behnken design. The maximum extraction efficiency was achieved using 70 W of microwave power, 3.5 mL of extraction solvent and 1.0 mL min −1 of extraction solvent flow rate. The limit of detection obtained is 0.012 mg g −1. The RSDs of intra- and inter-day of eight kinds of tea samples are 2.7%–5.4% and 5.1%–7.3%, respectively. The recovery of caffeine in the tea samples is in the range of 88.2%–99.3%.The proposed method has selectivity and sensitivity and considerably less labor and time for determination of caffeine in tea compared with conventional extraction methods, such assoxhlet extractionand liquid–liquid extraction.

Simultaneous Extraction and Separation Process for Coffee Beans with Supercritical CO2 and Water

The aim of this work was to develop a new process for extraction and separation of polar and nonpolar compounds from natural materials using supercritical CO2 (SCCO2) in water. In this work, chlorogenic acid and caffeine from coffee beans were used as model compounds of polar and nonpolar compounds, respectively. Extraction and separation were conducted in three types of semicontinuous extractors with different sizes and flow types of CO2 and water. The effect of temperature and pressure in the separation mode using SCCO2 in flow and water in batch mode has been reported. Recovery of caffeine in the SCCO2 phase increased with decreasing temperature and increasing pressure. However, only the increasing pressure could promote the increasing recovery of caffeine and chlorogenic acid in water phases. The change of height of the nonpolar recovery section on the recovery of caffeine and chlorogenic acid in SCCO2 and water phases and on the separation factor has been studied using SCCO2 and water in co-current a...

Determination of Caffeine Content in Non-Alcoholic Beverages and Energy Drinks Using Hplc-Uv Method.

The purpose of this study was to determine the amount of caffeine in non-alcoholic energy drinks and prepared teas using reverse phase HPLC. Caffeine was extracted from 19 different types of non-alcoholic beverages and prepared teas sampled from supermarkets in Nairobi Central Business District, Kenya. These were analyzed alongside a caffeine standard of 99 % purity by use of HPLC-UV detector at the wavelength of 272nm, Supelco HS C18 column 25 cm x 4.6 cm x 5 μm, oven temperature of 40 oC, mobile phase 80:20 (v/v) of methanol: water and mobile phase flow rate of 1.5mL/min. For quantitation purposes, serial dilution of the caffeine standard gave correlation coefficient (r) of 0.9993 and the retention time of 2.11±0.03 minute. Percentage recovery of caffeine from the column ranged from 89.78 to 105.59%. Limits of detection and quantitation were found to be 0.279 and 0.931 μg/mL respectively. It was found that Burn®, XL energy drink® and Red Bull® had the highest amount of caffeine. It was however noted that though most of the non-alcoholic beverages had high caffeine content they had no label claim. Key Words: Reverse Phase High Performance Liquid chromatography (HPLC), Ultra violet visible (UV/VIS), caffeine, non-alcoholic beverages

A liquid chromatography method for quantifying caffeine dissolution from pharmaceutical formulations into colloidal, fat-rich media

A simple and rapid high-performance liquid-chromatography method is presented that permits quantification of caffeine in colloidal fat emulsions proposed as new ‘biorelevant’ dissolution media (Intralipid™ and various milks). Using a mobile phase of 0.1 M sodium acetate (pH 4.0) and acetonitrile (89.5:10.5, v/v) at 1 ml min −1, the drug and internal standard (7- β-hydroxyethyltheophylline) were eluted within 8 min. Caffeine extraction was undertaken by protein precipitation in ice-cold 12% (w/v) trichloroacetic acid and centrifugation at 10,000 rpm for 15 min. This simple extraction method generated caffeine recovery values (corrected for % fat content) of 75.4 ± 1.4–100.6 ± 5.5%. The limit of detection was within the range 0.25–0.4 μg ml −1 and linearity was demonstrated in each medium up to 125 μg ml −1. Precision was <11.5% RSD and intra- and inter-day accuracy was 93.4–109.3%. The validated method was applied to in vitro USP dissolution tests in milk which compared the kinetics of caffeine release from (i) extended release matrices containing hydroxypropyl methylcellulose (HPMC) and (ii) an immediate release commercial analgesic tablet. Good reproducibility was obtained in both extended and immediate release dissolution tests. The method provides high-throughput quantification of this common drug in fat emulsions used as biorelevant dissolution media.

Study of extraction and HPTLC - UV method for estimation of caffeine in marketed tea (Camellia sinensis) granules

A simple, precise and accurate high-performance thin-layer chromatographic (HPTLC) method has been established and validated for screening and quantitative estimation of caffeine in different extracts of tea samples (Camellia sinenesis). Separation was performed on silica gel 60 F254 HPTLC plates with ethyl acetate:methanol in the proportion of 27: 3 (v/v), as a mobile phase. The determination was carried out in the ultraviolet (UV) region using the densitometric remission-absorbance mode at 274 nm. Maximum recovery of caffeine was achieved when extracted with 5% diethyl amine in DM water (v/v). The maximum concentration of caffeine in tea samples was found to be 2.145%, dry weight basis. Caffeine response was found to be linear over the range of 2-14 μg per zone. Limits of detection and quantitation were found to be 40 and 120 ng/spot, respectively. The HPTLC method was validated in terms of precision, accuracy, sensitivity and robustness. Some rare parameters for the HPTLC method like calculation of flow constant (k) and plate efficiency (N) are included specially. Key words: Caffeine, Camellia sinensis, HPTLC - UV method, theaceae, tea granules

Supercritical CO2 recovery of caffeine from green coffee oil: new experimental solubility data and modeling

The caffeine solubility in supercritical CO2 was studied by assessing the effects of pressure and temperature on the extraction of green coffee oil (GCO). The Peng-Robinson¹ equation of state was used to correlate the solubility of caffeine with a thermodynamic model and two mixing rules were evaluated: the classical mixing rule of van der Waals with two adjustable parameters (PR-VDW) and a density dependent one, proposed by Mohamed and Holder² with two (PR-MH, two parameters adjusted to the attractive term) and three (PR-MH3 two parameters adjusted to the attractive and one to the repulsive term) adjustable parameters. The best results were obtained with the mixing rule of Mohamed and Holder² with three parameters.

Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry

A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 μL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 μg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6–101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

Solid-Phase Extraction of Caffeine and Catechin Compounds from Green Tea by Caffeine Molecular Imprinted Polymer

In this work, caffeine and some catechin compounds + C, EC, EGC, and EGCG were extracted from green tea by using molecular imprinted polymers (MIP) as sorbent materials in a solid-phase extraction (SPE) process known as MISPE (molecular imprinted solid-phase extraction). For synthesis of MIP, caffeine was employed as the template, MAA as the monomer, EGDMA as the crosslinker, and AIBN as the initiator. A solution of caffeine (0.2 mg/mL in methanol) was utilized in the solid extraction cartridges following loading, washing, and elution procedures with acetonitrile, methanol, and methanol-acetic acid (90/10, %v/v) as the solvents, respectively. This solid-phase extraction protocol was applied for the extraction of caffeine and some catechin compounds from green tea. A comparison was made between the results obtained with the MIP cartridges and a traditional C18 reversed-phase cartridge. It was thereupon found that the recovery of caffeine by the MIPbased sorbent used in this work was almost two and four times greater than that by a commercially available C18 material. A quantitative analysis was conducted by high performance liquid chromatography (HPLC) using a C18 column (5 μm, 250 × 4.6 mm) with methanol/water (40/60, %v/v) as the mobile phase at a flow rate of 0.5 mL/min.

Theobromine and Caffeine Recovery with Solvent Extraction

A chloroform extraction process was developed for recovery of theobromine and caffeine from the effluent of a theobromine synthesis plant. The product distributions in the extraction process were studied experimentally. In a chloroform–water system, the caffeine distribution ratio was about 15 and was not affected by pH in the 2 to 12 range, while the distribution ratio of theobromine was about 0.45 for pH<5 and was strongly affected by the pH of the aqueous phase. The distribution ratio of theobromine was near zero for pH>10. Therefore, theobromine and caffeine can be recovered separately by adjusting the pH in the aqueous phase. The crude products of theobromine and caffeine can been obtained in the recovery process by evaporation. The thermal stability of theobromine in aqueous solution was also studied. A reciprocating plate column (RPC) is suitable for this extraction process. Pilot tests were conducted with two columns having 38-mm I.D. Scale-up of the RPCs for an industrial system of 23 t/d capacity was based on the Karr correlation. A 400-mm diameter RPC with a 6-m high cartridge and a pair of 500-mm diameter RPCs with 12-m high cartridges were used for the recovery process. The operating results show that the theobromine recovery was 95% and the caffeine recovery was 99%.

Solid-phase extraction for the determination of caffeine in traditional Chinese medicinal prescriptions containing Theae folium by high performance liquid chromatography

A high performance liquid chromatographic method in combination with C-18 reverse phase solid-phase extraction (SPE) was developed for determination of caffeine (CA) in traditional Chinese medicinal prescriptions which contain Theae folium. The frequently used prescriptions include Shin-Yi-San, Chuan-Chyong-Char-Tyau-San, Tsang-Eel-San, San-Hwang-Shyr-Gau-Tang, Tzy-Shenn-Ming-Mu-Tang and Shiang-Chyong-San. The present HPLC system uses a Merck RP-select B column by isocratic elution with methanol and 1% (v/v) acetic acid (1:4) as the mobile phase and detected at UV 270 nm. 8-Chlorotheophylline was used as an internal standard. The extracts of prescriptions were treated by Supelclean LC-18 SPE tube for eliminating interferences. Blank decoctions of each prescription were also examined as a test for interferences. The recoveries of caffeine from the Chinese medicinal prescriptions ranged from 88.5 to 92.3%. The relative standard deviations of caffeine ranged between 0.86 and 1.97% (intraday) and 1.04 and 3.90% (interday). The contents of caffeine in standard decoctions ranged from 13.98 to 19.62 mg g −1.