• Archives of Pharmacal Research
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• v.13 no.3
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• pp.215-220
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• 1990

Two different, derivative spectrophotometric and gas-liquid chromatographic, procedures for direct quantitation of caffeine and some commonly dispensed antihistaminics in bulk forms, in their laboratory prepared mmixtures and in dosage formulations, have been investigated. The limit, sensitivity reproducibility and accuracy of each method were studied for each individual drug substance and in some usual pharmaceutical formulations.

• Korean Journal of Clinical Pharmacy
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• v.22 no.2
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• pp.167-175
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• 2012

Different studies have been conducted regarding caffeine as psychostimulant drugs and its effects as well as determination in various materials. Since, coffee and tea are most drinkable beverage in the world and their major constituent is caffeine. So, analysis of the effect of equal amount of caffeine in coffee and tea with respect to SD rats was studied. The present methodology was purposed to determine and validate caffeine amount in different brands of coffee and tea, and canvass locomotor and behavioral patterns of SD rats after administrating coffee and tea orally consisting of same amount of caffeine (10, 30 mg/kg). Determination of caffeine in different brands of coffee and tea and validation of caffeine were evaluated using HPLC. Depending upon different brands of tea and coffee, caffeine amount was altered. Meanwhile, amount of caffeine in tea was directly proportional to the temperature of liquid. Coffee and tea (Instant Maxim original coffee$^{(R)}$ and earl grey black tea$^{(R)}$) consisting 10, 30 mg/kg of caffeine were studied in SD rats for locomotor activity and behavioral patterns using Tru Scan 99. The locomotor activities of SD rats were increased after administration of coffee and tea consisting caffeine compared to water. The coffee consisted of higher amount of caffeine exhibited steep movement of SD rats. Similarly, rearing and scratching of SD rats as frequency and duration were increased in coffee and tea consisting caffeine compared with water. The study revealed that coffee and tea had effects in locomotor activity and behavioral patterns of SD rats.

• Analytical Science and Technology
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• v.26 no.6
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• pp.353-356
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• 2013

A method on the determination of caffeine in beverage with acridiene orange-${\beta}$-cyclodextrin (CD) inclusion complex was developed. The conditions such as pH of the sample solution and concentration of acridine orange and ${\beta}$-CD were optimized to 12.0(${\pm}0.5$), $1.9{\times}10^{-6}M$ and $1.25{\times}10^{-3}M$, respectively. Under these optimum conditions, the calibration curve of caffeine was obtained over concentration range of $5{\times}10^{-5}{\sim}1.1{\times}10^{-3}M$. The detection limit was $1.0{\times}10^{-5}M$. The relative errors(%) in beverage samples were less than 5.0%.

• Analytical Science and Technology
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• v.21 no.2
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• pp.84-92
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• 2008

A method for the determination of trace amount of caffeine in urine and various drink samples using hollow fiber-liquid phase microextraction (HF-LPME) and capillary gas chromatograph/nitrogen phosphorus detector (GC/NPD) has been established. HF-LPME method has been optimized with respect to several experimental parameters including the effects of the hollow fiber length, extraction solvent, stirring mode, pH and salt concentration for the determination of caffeine from aqueous samples. The correlation coefficient of calibration curve for caffeine was 0.9994. The average recovery was 102%(n=3). The established method is feasible for the determination of trace amounts of caffeine in several aqueous sample. The limit of detection (LOD) and the limit of quantitation (LOQ) have been found to be 2.5 and 10 ng/mL, respectively. The established HF-LPME method for the analysis of caffeine from aqueous sample can be used for the determination of biological, food and environmental samples.

• The Korean Journal of Zoology
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• v.19 no.4
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• pp.161-170
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• 1976

Since caffeine inhibits the active uptake of Ca by the sarcoplasmic reticulum, the action of caffeine on the fragmented sarcoplasmic reticulum of rabbit skeletal muscle was studied. Caffeine seemed not to bind tightly to the sarcoplasmic reticulum. The determination of sulfhydryl content of the fragmented sarcoplasmic reticulum, however, suggested that caffeine in some unknown manner influences the protein moiety and thereby increases the sulfhydryl content. The inhibition of Ca uptake by caffeine therefore might be considered as due to the result of this change in protein sulfhydryl content.

• Journal of Food Hygiene and Safety
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• v.5 no.4
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• pp.213-217
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• 1990

A simple and practical method for the determination of caffeine in coffee, black tea and green tea was studied. The analysis of caffeine was performed by reverse phase high perfomance liquid chromatography using a ${\mu}-Bondapak$ C18 column at isocratic condition with methanol-acetic acid-water (20: 1: 79) on UV detector at 280 nm. The extraction and clean-up of caffeine in sample is based on combing a simple pretreatment with the use of a Sep-Pak Alumina A cartridge. The average recoveries of caffeine from several samples were 95.2 -101.3%, the relative standard deviation for the whole procedure was 0.10 ~ 0.62%, and the detection limit of caffeine in sample solution was about $0.1\;\mu\textrm{g}\;per\;ml$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.224-232
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• 2008

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. The contents of catechins and caffeine in green tea are considered as a standard of quality evaluation of green tea. Therefor, the purpose of this study was to investigate the most suitable HPLC condition for simultaneous determination of catechins and caffeine in green tea extracts. The efficient HPLC analytical condition of catechins and caffeine contained green tea extracts was developed. The gradient elution employed a $250\;mm\;{\times}\;4.6\;mm$ i.d. YMC-pak ODS-AM 303 column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of 0.1% aqueous phosphoric acid, and mobile phase B, comprising 100% MeOH, and delivered at a flow rate of 1 mL/min as follows: $0{\sim}25\;min$, 80% A; $26{\sim}50\;min$, $80{\sim}70%$ A; 51 min, 80% A. $51{\sim}55\;min$, 80% A. The UV detection wavelength was set at 280 nm. The limit of detection (LOD) for catechins and caffeine standards were under 50 ng/mL.

• The Korean Journal of Community Living Science
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• v.24 no.1
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• pp.5-12
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• 2013

Caffeine is an alkaloid of the methylxanthine family known as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness in humans. There is a recommended upper limits of caffeine for health because a high dose can cause negative effects. Chlorogenic acid is a natural polyphenol compound known to have an antioxidant activity. In this study, the contents of caffeine and chlorogenic acid in coffee beans from different origins(Costa Rica, Indonesia, Vietnam) were determined by using liquid chromatography-tandem mass spectrometry(LC-MS/MS). The experiment offers more selectivity and sensitivity for those compounds compared with conventional methods such as UV/VIS spectrophotometry. The average concentrations of caffeine and chlorogenic acid in coffee beans origined in Costa Rica were 15.05 mg/g and 5.33 mg/g respectively. In the case of coffee beans origined in Indonesia, the average concentrations were 13.10 mg/g for caffeine and 3.75 mg/g for chlorogenic acid. Vietnamese coffee showed that the average concentrations were 17.79 mg/g for caffeine and 1.12 mg/g for chlorogenic acid. This study can contribute to a better understanding of the contents of caffeine and chlorogenic acid in various coffee beans in order to evaluate dietary intake.

• YAKHAK HOEJI
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• v.60 no.3
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• YAKHAK HOEJI
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• v.19 no.4
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• pp.240-245
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• 1975

The quantitative analysis of ethambutol.2HCl as well as commercial ehambutol preparations was undertaken by gas-liquid chromatography by finding optimum conditions, such as the use of internal standard, stability of an ethambutol-2HCl-caffeine standard solution, and the effect of column temperature, N, O-bis-(trimethylsily) acetamide [B.S.A.] concentrations and other substances present in the preparations. Under the chromatiographic conditions, an ethambutol-2HCl. caffeine standard, 9 min, 30sec. The relative molar response of ethambutol.2HCl and caffeine studied was 2.08. Ethambutol.2HCl could be quantitated up to 1$\times$10$^{-8}$ moles. the possible decomposition of B.S.A. due to the moisture when tested and the incoplete reaction for silylation could be minimized.