Quantitative Analysis Of Caffeine Research Articles

Quantitative Analysis of Caffeine and Phosphoric Acid in Non-Alcoholic Beverages Marketed in Kosovo

Non-alcoholic beverages often contain various constituents and additives, influencing both their nutritional profiles and functional attributes. Given the ubiquity of these beverages and their potential health implications, rigorous quality checks are indispensable to ascertain compliance with health and safety standards. This research aimed to quantify caffeine and phosphoric acid levels in a diverse array of soft drinks from Kosovo’s market. To achieve this, 41 distinct non-alcoholic beverage samples from the local market were scrutinized. Caffeine concentrations were determined via UV-Vis spectrophotometry, while potentiometric titration was employed to assess phosphoric acid levels. As expected, energy drinks in Kosovo contained markedly higher caffeine concentrations compared to carbonated soft drinks and ice-tea variants. On the other hand, based on the results, analysed energy drinks showed somewhat greater caffeine contents than those reported in packaging of the beverage samples. Our study showed that a significant portion of the samples (21.95% for caffeine and 9.76% for phosphoric acid) did not conform to the standards set by EU 1169/2011 regulation or the EU 1333/2008 regulation. These findings underscore the urgency for relevant food safety authorities to implement rigorous oversight and enact appropriate protective measures. It is also imperative for the Kosovo National Food Safety Authority to craft specific regulations stipulating permissible additive concentrations, especially for caffeine and phosphoric acid, in non-alcoholic beverages.

A multiway spectral analysis model to monitor the kinetic chlorination reaction of caffeine and determine its content in commercial liquid and solid drinks.

A multiway data analysis model, namely parallel factor analysis (PARAFAC) was proposed to decompose a three-way array of second-order kinetic UV measurements, for the chlorination reaction of caffeine with NaOCl, into a set of the spectra, time, and concentration matrices. The multiway resolution provided the simultaneous estimation of spectral, kinetic, and quantitative analysis of caffeine. The ability of the PARAFAC tool was checked by analyzing the validation samples in the presence of interferences. The added recovery and relative standard deviations for caffeine in the spiked samples were calculated as 99.1%-99.5% and 0.52%-1.34% for Iced Coffee Black liquid coffee (ICB), 99.5%-103.0% and 0.42%-1.03% for Jacobs Monarch Gold 100% Instant Coffee (JMG) and 99.5%-101.4% and 0.11%-0.13% for Çaykur Black Filter (Süzen) Bag Tea (BTB). Caffeine in commercial drinks was analyzed using the concentration matrices of the PARAFAC application. The PARAFAC results were statistically compared to those obtained by the developed UPLC method.

Quantitative Analysis of Caffeine in different commercial kinds of coffee in Iraq

Caffeine is a widely consumed pharmacologically active substance around the world, Caffeine is a purine alkaloid derived from methylxanthine that is readily permeable through the blood-brain barrier and stimulates the adenosine receptors in the brain leading to its central nervous system stimulant activity. Most people regulate their caffeine consumption in accordance with the objective and subjective effects produced from the methylxanthine, However, individual response to caffeine varies greatly from person to person due to the variation in metabolism, age, sex, hormones, clearance, weight, genes, medicine intake and smoking behavior, therefore the amount of caffeine required to achieve the desired effect also varies greatlyand Since that the coffee beans are the world's primary sources of dietary caffeine this study was designed to determine the percent of the caffeine in different commercial coffee brands, the isolated caffeine was identified by different qualitative methods like TLC, and FTIR.

Quantitative Analysis of Caffeine in the Green Tea, Black Tea and Soft Drink Using UV-Visible Spectrophotometer

Objective -To determine the content of caffeine in the beverages like green tea, black tea, and soft drink which are commercially available in the local market of Hapur with the help of a UV Visible spectrophotometer. Method- To find out the content of caffeine, six different brands of green tea, black tea, and soft drink were purchased from the local market in Hapur. The caffeine was extracted from them using chloroform as an extractant and assessed qualitatively and quantitatively with the help of a UV Visible spectrophotometer. The maximum absorbance of caffeine in chloroform occurs at 273 nm. The standard solutions of caffeine from the range 2-30 ppm were prepared in the chloroform, show the linearity with the correlation coefficient of 0.99. From the calibration curve, the concentration of caffeine was determined in various brands. It is observed that black tea contains the maximum caffeine content followed by green tea and soft drinks. Findings- In this study the maximum caffeine content find out was (45.6 mg/g) in the Nice black tea sample and the minimum (0.161 mg/ml) in Pepsi soft drink sample. Novelty-The caffeine content reported here is higher than that of previous studies may be due to the modified approach [treatment temperature (90-1000C) and longer brewing time (05 minutes) in this study. The use of the UV-Visible spectrophotometer is also an alternative to the HPLC technique, thereby the working cost could be brought down. Keywords: Caffeine; brewing time; beverages; UV visible spectrophotometer; extraction

Rapid Qualitative and Quantitative Analysis of Caffeine and Sodium Benzoate in Annaca by Infrared Spectroscopy.

Objective To establish an infrared spectroscopic method for the rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples. Methods Qualitative and quantitative modeling samples were prepared by mixing high-purity caffeine and sodium benzoate. The characteristic absorption peaks of caffeine and sodium benzoate in Annaka samples were determined by analyzing the infrared spectra of the mixed samples. The quantitative model of infrared spectra was established by partial least squares （PLS）. Results By analyzing the infrared spectra of 17 mixed samples of caffeine and sodium benzoate （the purity of caffeine ranges from 10% to 80%）, the characteristic absorption peaks for caffeine were determined to be 1 698, 1 650, 1 237, 972, 743, and 609 cm-1. The characteristic absorption peaks for sodium benzoate were 1 596, 1 548, 1 406, 845, 708 and 679 cm-1. When the detection of all characteristic absorption peaks was the positive identification criteria, the positive detection rate of caffeine and sodium benzoate in 48 seized Annaka samples was 100%. The linear range of PLS quantitative model for caffeine was 10%-80%, the coefficient of determination （ R2） was 99.9%, the root mean square error of cross validation （RMSECV） was 0.68%, and the root mean square error of prediction （RMSEP） was 0.91%; the linear range of PLS quantitative model for sodium benzoate was 20%-90%, the R2 was 99.9%, the RMSECV was 0.91% and the RMSEP was 1.11%. The results of paired sample t test showed that the differences between the results of high performance liquid chromatography method and infrared spectroscopy method had no statistical significance. The established infrared quantitative method was used to analyze 48 seized Annaka samples, the purity of caffeine was 27.6%-63.1%, and that of sodium benzoate was 36.9%-72.3%. Conclusion The rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples by infrared spectroscopy method could improve identification efficiency and reduce determination cost.

Qualitative and Quantitative Analysis of Caffeine in Medicines by Terahertz Spectroscopy Using Machine Learning Method

Caffeine is an alkaloid and may be the most commonly ingested pharmacologically active substance in the world, but continuous abuse may lead to “caffeine poisoning”. In this study, we propose a method for the qualitative and quantitative analysis of caffeine in various medicines using terahertz spectroscopy combined with chemometrics. By comparing this terahertz (THz) spectroscopy technology (Fourier transform infrared instrument, FTIR) with high performance liquid chromatography (HPLC) and Raman spectroscopy, we prove that there is less than a 5% difference between the THz and HPLC results, which is far superior to the nondestructive testing results obtained using Raman spectroscopy. In addition, the quantitative analysis of caffeine in 86 medicines was conducted using the support vector regression (SVR) chemometric method, and the correlation coefficient R achieves 99.61%. Therefore, we have effectively proven that THz spectroscopy technology combined with chemometric can achieve nondestructive, fast, and efficient qualitative and quantitative detection of key ingredients in medicines.

Quantitative analysis of caffeine, ethoxybenzamide, chlorzoxazone, diazepam and indomethacine illegally adulterated in Chinese medical pills

Quantitative analysis of caffeine, ethoxybenzamide, chlorzoxazone, diazepam and indomethacine illegally adulterated in Chinese medical pills

Quantitative analysis of caffeine, ethoxybenzamide, chlorzoxazone, diazepam and indomethacine illegally adulterated in Chinese medical pills

A traditional Chinese medicine, which was brought by a consumer for treating heart disease and uricosuria, was obtained and tested the illegal adulteration with chemical drugs. In the qualitative analysis, two-dimensional TLC, with chloroform:ethanol (9:1,v/v) and ethyl acetate: methanol: ammonia water (8:1:1,v/v) as the solvent systems, established the presence of caffeine, indomethacin, ethoxybenzamide, chlorzoxazone and diazepam in the pills. For quantitative analysis, a reversed-phase HPLC method was established for simultaneous determination of the five chemical drugs. The analysis of the sample extract was performed on a Cosmosil 5C 18-AR column (4.6x150mm) by a linear gradient elution with the mobile phase of 0.05 M KH 2 PO 4-0.1% formic acid buffer and methanol, programmed from 60:40, v/v, to 40:60, v/v, for 30 min, with 30 mim hold and then 60:40, v/v, for the subsequent 15 min, at a flow rate of 0.7 ml/min and with propylparaben as an internal standard. The monitor wavelength was set at 230 nm. System suitability tests showed that the established method was quite suitable for the determination of the adulterants in the pills. By using this method, 30.8mg of caffeine, 71.4 mg of ethoxybenzamide, 35.7 mg of chlorzoxazone, 0.6 mg of diazepam and 9.3 mg of indomethacin, were found in each pill of the sample.

Exploration of Experimental Teaching for Rapid Separation and Quantitative Analysis by Ultra Performance Liquid Chromatography

Ultra high performance liquid chromatography (UPLC) is a novel technique in liquid chromatography. It is more efficient, rapid and sensitive than high performance liquid chromatography (HPLC), owing to using smaller particle size in analytical column. Because of these advantages, UPLC has been widely used in many fields. Experiments on rapid separation of caffeine, aspirin and phenacetin by UPLC and quantitative analysis of caffeine in compound aspirin tablets by external standard method were designed. In the experimental teaching, the basic principle, instrument composition and operation, the general methods of optimizing chromatographic conditions and the external standard method were introduced. Through this experiment, students not only better understood the theoretical knowledge, but also learned the operation of UPLC. More importantly, students’ experimental skills have been improved, their scientific thinking ability has been exercised.

Qualitative and quantitative analysis of caffeine in some commercial brands of tea consumed in India

Caffeine is a common organic molecule found in many beverages such as coffee, tea, energy drinks and cola, which make the drinks addictive. Caffeine has drawn more attention due to its physiological effects beyond its stimulatory effect on central nervous system, hence it is used both recreationally and medically to reduce physical fatigue and restore mental alertness when unusual weakness or drowsiness occurs. Caffeine content in various energy drinks and beverage varies from 10 to 50 mg of caffeine per serving; however the US Food and Drug Administration (FDA, 2006) limits the maximum amount in carbonated beverages to 6 mg/oz. Large amount of caffeine consumption can cause physiological and psychiatrically dependence. The aim of this study is to determine the concentration of caffeine in tea brands available in India to ensure whether the caffeine concentration in the follow tea as per FDA recommendation or not. There are few reputed brands like Taj, Red Label, Agni and other local brands like Mohini, and Krishna Gopal were studied, by using simple and fast standard UV-Visible spectrophotometric method. The minimum caffeine level was observed in the Mohini brand tea, while Taj tea brand sample showed the highest caffeine content.

女子大・生活科学実習の課題研究 : 嗜好飲料中のカフェインの定性・定量分析実験

女子大・生活科学実習の課題研究 : 嗜好飲料中のカフェインの定性・定量分析実験

Quantitative analysis of caffeine in some selected brands of energy drinks available in Kano State Nigeria

This research work was aimed to determine the pH and level of caffeine in some selected brands of energy drinks available in Kano state, Nigeria. Different brands of these products were purchased from different shops in Kano metropolis. Caffeine was carefully extracted from each product and analysed by ultraviolet/visible spectrophotometric methods. The results showed that the caffeine content of the energy drinks ranged from 34.65 to 40.88mg/100mL. Like-wise the mean pH of carbonated energy drinks were highly acidic ranging from 2.99±0.017 to 3.98±0.012, The reason behind the low pH values in carbonated drinks could be as a result of the presence of carbon (iv) oxide gas and other acids such as phosphoric acid, malic acid, ascorbic acid, citric acid and tartaric acid used as preservatives by the manufacturers of these product. Keywords: Energy drinks, Caffeine, pH, Kano- Nigeria

Theanine and Caffeine Content of Infusions Prepared from Commercial Tea Samples.

Background:Caffeine and L-theanine are pharmacologically important constituents of tea, especially due to their effects on the central nervous system. The effects of these two compounds are opposite: While caffeine is a well-known stimulant, theanine has a relaxing effect. Tea processing may influence the caffeine and theanine content of tea leaves.Objective:The aim of our work was to quantify these constituents from a set of commercial products to reveal the possible correlations of caffeine and theanine content and processing methods.Materials and Methods:Theanine and caffeine contents of 37 commercial white, green, oolong, black, and pu-erh tea samples were quantified by high-performance liquid chromatography-diode array detector.Results:The mean L-theanine content of white, green, oolong, and black teas were 6.26, 6.56, 6.09, and 5.13 mg/g, respectively. The same values for caffeine content were 16.79, 16.28, 19.31, and 17.73 mg/g.Conclusion:Though the effect of processing on theanine content was evident, quantification for these analytes does not seem to be a good criterion to discriminate the different types of tea. Caffeine content provided no information on the effect of processing, and the theanine content of the samples was rather variable, independently from the type of the tea. The quantitative analysis of caffeine and theanine is essential to assess the stimulating effect of the tea, however, for chemical profiling further secondary metabolites have to be determined.SUMMARY Thirty-seven commercial white, green, oolong, black, and pu-erh tea samples were analyzed for caffeine and theanine contentWhile the caffeine content was similar, the theanine contents of black teas were slightly lower and practically zero in pu-erhThe great variability of these two compound within the tea categories allows no discrimination of tea types based solely on theanine and caffeine quantificationContrary to the previous data, the way of processing has no determining effect on theanine content. FigureAbbreviations used: CZE: Capillary zone electrophoresis, DAD: Diode array detector, EEG: Electroencephalography, GC: Gas chromatography, HPLC: High-performance liquid chromatography, IR: Infrared spectroscopy, MEKC: Micellar electrokinetic capillary chromatography, MS: Mass spectrometry, RP: Reversed phase, RSD: Relative standard deviation, SD: Standard deviation, TLC: Tile liquid chromatography, UV: Ultraviolet

Potassium-based algorithm allows correction for the hematocrit bias in quantitative analysis of caffeine and its major metabolite in dried blood spots.

Although dried blood spot (DBS) sampling is increasingly receiving interest as a potential alternative to traditional blood sampling, the impact of hematocrit (Hct) on DBS results is limiting its final breakthrough in routine bioanalysis. To predict the Hct of a given DBS, potassium (K(+)) proved to be a reliable marker. The aim of this study was to evaluate whether application of an algorithm, based upon predicted Hct or K(+) concentrations as such, allowed correction for the Hct bias. Using validated LC-MS/MS methods, caffeine, chosen as a model compound, was determined in whole blood and corresponding DBS samples with a broad Hct range (0.18-0.47). A reference subset (n = 50) was used to generate an algorithm based on K(+) concentrations in DBS. Application of the developed algorithm on an independent test set (n = 50) alleviated the assay bias, especially at lower Hct values. Before correction, differences between DBS and whole blood concentrations ranged from -29.1 to 21.1%. The mean difference, as obtained by Bland-Altman comparison, was -6.6% (95% confidence interval (CI), -9.7 to -3.4%). After application of the algorithm, differences between corrected and whole blood concentrations lay between -19.9 and 13.9% with a mean difference of -2.1% (95% CI, -4.5 to 0.3%). The same algorithm was applied to a separate compound, paraxanthine, which was determined in 103 samples (Hct range, 0.17-0.47), yielding similar results. In conclusion, a K(+)-based algorithm allows correction for the Hct bias in the quantitative analysis of caffeine and its metabolite paraxanthine.

Simultaneous Determination of Caffeine and Water-Soluble Vitamins in Energy Drinks by HPLC with Photodiode Array and Fluorescence Detection

The high-performance liquid chromatography (HPLC) method with photodiode array (PDA) and fluorescence (FL) detection for the simultaneous separation and determination of caffeine and water-soluble vitamins is described. The method is relatively rapid: 13 compounds can be analyzed within 30 min: caffeine; ascorbic acid (vitamin C); thiamine (vitamin B1); riboflavin 5-phosphate (FMN, flavin mononucleotide) and riboflavin (vitamin B2); nicotinic acid and nicotinamide (vitamin B3); pantothenic acid (vitamin B5); pyridoxal, pyridoxamine, and pyridoxine (vitamin B6); folic acid (vitamin B9); and cyanocobalamin (vitamin B12). This HPLC method is designated for quantification of caffeine and water-soluble vitamins in liquid and tablet energy drinks as well as for determination of vitamins in vitamin supplements. The method was validated in terms of linearity, limit of detection (LOD) and quantification (LOQ), accuracy, and instrument precision. The LODs determined using HPLC-PDA ranged from 13 to 121 ng mL−1 and using HPLC-FL were between 8 and 61 ng mL−1. Intra- and interday instrument precisions for liquid energy drink, expressed as relative standard deviation (RSD), were less than 1.87 and 1.73 %, respectively, and less than 1.44 and 1.83 %, respectively, for tablet energy drink. The method could be useful in the quantitative analysis of caffeine and of water-soluble vitamins in energy drinks and vitamin supplements.

Ultra-violet Spectrophotometric Determination of Caffeine in Soft and Energy Drinks Available in Yenagoa, Nigeria

This study was carried out to determine the pH and levels of caffeine in eight brands of carbonated and energy drinks available in local market in Yenagoa, Nigeria. Quantitative analysis of caffeine was performed by a simple and fast standard UV spectrophotometric method, using carbon tetrachloride as the extracting solvent. Results showed that the pH of the beverages were slightly acidic ranging from 5.92-6.44. The minimum caffeine level was observed in the carbonated soft drink Coca Cola (43.71±0.55 ppm), while the energy drink, Red Bull sample showed the highest caffeine content (58.31±0.35 ppm). The carbonated soft drinks showed caffeine levels in the range of 43.71 and 45.83 ppm with average concentration of 44.52 ppm, whereas in the energy drinks it ranged from 47.56 to 58.31 ppm with a mean concentration of 52.24 ppm. The caffeine content in all the beverage samples analyzed in this study are well below the maximum allowable limits set by the US Food and Drugs Administration.

A Weak Cation-Exchange Monolithic SPE Column for Extraction and Analysis of Caffeine and Theophylline in Human Urine

A weak cation-exchange monolithic column has been prepared in stainless steel tubing and used as the solid-phase extraction material in quantitative analysis of caffeine and theophylline in urine. Column switching, with water as mobile phase, was used for on-line cleaning and screening of human urine samples. Reversed-phase high-performance liquid chromatography was then performed on a C18 column with methanol–water 30:70 (v/v) as mobile phase at a flow rate of 0.5 mL min−1. Ultraviolet detection was performed at 274 nm. Good linear relationships were obtained between response and concentrations of caffeine and theophylline in the range 0.1–50 μg mL−1. Absolute recovery ranged from 77.4 to 82.3% and inter-day and intra-day relative standard deviations were less than 5%. The method was suitable for analysis of caffeine and theophylline in human urine, because it eliminated tedious pretreatment and enabled rapid, economic, repeatable, and effective assay of traces of the drugs in biological samples.

Quantitative capillary electrophoresis and its application in analysis of alkaloids in tea, coffee, coca cola, and theophylline tablets

A quantitative CE (qCE) system with high precision has been developed, in which a 4-port nano-valve was isolated from the electric field and served as sample injector. The accurate amount of sample was introduced into the CE system with high reproducibility. Based on this system, consecutive injections and separations were performed without voltage interruption. Reproducibilities in terms of RSD lower than 0.8% for retention time and 1.7% for peak area were achieved. The effectiveness of the system was demonstrated by the quantitative analysis of caffeine, theobromine, and theophylline in real samples, such as tea leaf, roasted coffee, coca cola, and theophylline tablets.

Influence of agronomic variables on the composition of mate tea leaves (Ilex paraguariensis) extracts obtained from CO2 extraction at 30 degrees C and 175 bar.

The aim of this work is to assess the influence of light intensity (plants with direct sun exposure and in a controlled light intensity) and age of leaves (6-24 months) on the characteristics of the extracts of mate tea leaves obtained from carbon dioxide at high pressures. Samples of mate were collected in an experiment conducted under agronomic control at Industria e Comercio de Erva-Mate Barão LTDA, Brazil. The content of selected organic compounds of the extracts was evaluated by gas chromatography together with mass spectrometry. Quantitative analysis of caffeine, theobromine, phytol, vitamin E, squalene, and stigmasterol was performed, and the results showed that field variables exert a strong influence on the liquid yield and on the chemical distribution of the extracts.

Utility of caffeine analysis for forensic hair discrimination

Utility of caffeine analysis for the purpose of forensic hair discrimination was evaluated. Methanol extracts of each 5-cm strand of scalp hair, after its incubation at 37 degrees C for 15 h, was analyzed by gas chromatography-mass spectrometry (GC-MS). For quantitative analysis of caffeine, caffeine-d3 was added as internal standard to the methanol extract. Hair specimens were obtained from three victims and from twenty-two volunteers. The results showed that caffeine levels in hair varied according to each individual; caffeine was detected up to a maximum level of 4.19 ng/5-cm hair. The concentrations of caffeine in hair obtained from four different regions of the scalp in twenty-two volunteers showed a coefficient of variation not greater than 24.7% for each individual. Based on our data, it was concluded that caffeine levels give relatively high reliability for discriminating a victim's hair from others at a criminal or accidental scene, although it should be used in combination with morphological examination and ABO blood group determination.