A fast and efficient method for the study of caffeine levels in energy drinks using micellar electrokinetic chromatography (MEKC)

Energy drinks are becoming popular in Brazil and in the world due to their stimulant properties. Caffeine is present in energy drinks with the aim of stimulating the central nervous system and intensifying brain activity. On the other hand, the ingestion of high doses of caffeine can cause undesirable symptoms such as anxiety and tachycardia. Therefore, it is necessary to monitor the caffeine content added to energy drinks to guarantee that the levels in the final product are in accordance with the labeling and within the legislation limits. The goal of this work was to validate a fast, efficient, and low-cost method for the determination of caffeine in energy drinks by micellar electrokinetic chromatography (MEKC). A total of seven brands were analyzed, each in three lots. The electrolyte was prepared with 50 mmol.L-1 of sodium dodecyl sulfate (SDS) and 10 mmol.L-1 of sodium carbonate (pH 11.0). The mean concentration of caffeine ranged from 122.8 to 318.6 mg.L-1. None of the brands had caffeine levels above the maximum limit. Considering the interval of confidence (95%), 72% of the samples had less caffeine than the amount informed on the product label.

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Analysis of Seven Biogenic Amines and Two Amino Acids in Wines Using Micellar Electrokinetic Chromatography

Applied Sciences ◽

10.3390/app9061193 ◽

2019 ◽

Vol 9 (6) ◽

pp. 1193 ◽

Cited By ~ 3

Author(s):

Chih-Ying Huang ◽

Yu-Xian Wang ◽

Xin-Zhi Wang ◽

Cho-Chun Hu ◽

Tai-Chia Chiu

Keyword(s):

Amino Acids ◽

Biogenic Amines ◽

Micellar Electrokinetic Chromatography ◽

Low Cost ◽

Background Electrolyte ◽

Sodium Dodecyl ◽

Fast Method ◽

Electrokinetic Chromatography ◽

Optimal Separation

A low-cost, simple, and fast method utilizing micellar electrokinetic chromatography for the simultaneous determination of seven biogenic amines and two amino acids was developed. A background electrolyte containing 5 mM phosphate buffer (pH 3.7) and 20 mM sodium dodecyl sulfate was used. The optimal separation of nine investigated analytes was achieved in 11 min, with limits of detection (S/N = 3) ranging from 0.11 to 0.61 µM. The linear ranges for all analytes were observed between 0.55 and 10.0 μM (R2 > 0.990). The developed approach was extended to the analysis of analytes in commercial wine and beer samples. The recoveries of the proposed method ranged from 98.8% to 115.6%.

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Determination of hydroxyanthraquinoids in Rhubarb by cyclodextrin-modified micellar electrokinetic chromatography using a mixed micellar system of sodium dodecyl sulfate and sodium cholate

Journal of Pharmaceutical and Biomedical Analysis ◽

10.1016/s0731-7085(02)00596-4 ◽

2003 ◽

Vol 31 (1) ◽

pp. 75-81 ◽

Cited By ~ 15

Author(s):

Xiaoyu Shang ◽

Zhuobin Yuan

Keyword(s):

Sodium Dodecyl Sulfate ◽

Micellar Electrokinetic Chromatography ◽

Sodium Dodecyl ◽

Sodium Cholate ◽

Electrokinetic Chromatography ◽

Micellar System ◽

Dodecyl Sulfate

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A sweeping-micellar electrokinetic chromatography method for the detection of three chlorophenols in cosmetic samples

Acta Chromatographica ◽

10.1556/1326.2020.00812 ◽

2020 ◽

Author(s):

Zhihan Zheng ◽

Xiaobin Li ◽

Fangfang Gao ◽

Huitao Liu ◽

Yuan Gao

Keyword(s):

Micellar Electrokinetic Chromatography ◽

Signal To Noise Ratio ◽

Sodium Dodecyl ◽

Electrokinetic Chromatography ◽

Chromatography Method ◽

Sample Matrix ◽

Pressure Injection ◽

Relative Standard ◽

On Line

AbstractA sweeping micellar electrokinetic chromatography (sweeping-MEKC) enrichment model was established for the determination of three chlorophenols (CPs) in cosmetics, namely, bithionol, pentachlorophenol (PCP), and 2,4,6-trichlorophenol (2,4,6-TCP). The optimum electrophoretic conditions were 20 mM NaH2PO4-80 mM sodium dodecyl sulfate (SDS) and 30% (v/v) acetonitrile (pH 2.3). The optimum on-line concentration conditions were as follows: sample matrix, 100 mM NaH2PO4; pressure injection at 20.67 kPa (3 psi) for 25 s. The linear range of bithionol, PCP, and 2,4,6-TCP are 0.20–4.00 μg mL−1, 0.10–2.00 μg mL−1, and 0.05–2.00 μg mL−1 respectively, with correlation coefficient (r) over 0.9972. The limits of detection (LOD) based on three times the signal-to-noise ratio (S/N = 3) are in the range of 0.0061–0.024 μg mL−1. Recoveries for the three CPs in powder and lotion samples are between 79.7 and 110.2% with relative standard deviation (RSD) of 1.38–5.54% and 92.2–121.3% with RSD of 0.72–6.09%, respectively. The proposed method can provide reference for the determination of trace CPs in different sample matrix.

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Determination of solute-micelle association constants for a group of benzene derivatives and polycyclic aromatic hydrocarbons with sodium dodecyl sulphate by micellar electrokinetic chromatography

Journal of Chromatography A ◽

10.1016/0021-9673(95)01331-8 ◽

1996 ◽

Vol 732 (2) ◽

pp. 345-359 ◽

Cited By ~ 25

Author(s):

M.A. García ◽

M.L. Marina ◽

J.C. Díez-Masa

Keyword(s):

Polycyclic Aromatic Hydrocarbons ◽

Aromatic Hydrocarbons ◽

Sodium Dodecyl Sulphate ◽

Micellar Electrokinetic Chromatography ◽

Sodium Dodecyl ◽

Association Constants ◽

Electrokinetic Chromatography ◽

Benzene Derivatives ◽

Polycyclic Aromatic

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Determination of four naphthalenediols in cosmetic samples by sweeping-micellar electrokinetic chromatography and a comparison with HPLC

Acta Chromatographica ◽

10.1556/1326.2021.00942 ◽

2021 ◽

Author(s):

Qian Wang ◽

Xiaobin Li ◽

Zhihan Zheng ◽

Huitao Liu ◽

Yuan Gao

Keyword(s):

Micellar Electrokinetic Chromatography ◽

Limit Of Detection ◽

Low Cost ◽

Hplc Method ◽

National Standards ◽

Sample Introduction ◽

Electrokinetic Chromatography ◽

Relative Standard ◽

Limit Of Quantitation

Abstract A sweeping micellar electrokinetic chromatography (sweeping-MEKC) method was developed for the determination of 1,7-naphthalenediol, 2,3-naphthalenediol, 1,5-naphthalenediol and 2,7-naphthalenediol in cosmetics. Several parameters affecting sweeping-MEKC method were studied systematically and the separation conditions were optimized as 20 mM NaH2PO4–110 mM SDS and 40% (v/v) MeOH (pH 2.4), with −22 kV applied voltage and UV detection at 230 nm. The sample matrix is 60 mmol L−1 NaH2PO4 and sample introduction was performed at 3 psi for 6 s. Separation of the four naphthalenediols was completed in less than 17 min. Limit of detection (LOD) and limit of quantitation (LOQ) are 0.0045∼0.0094 μg mL−1 and 0.015∼0.031 μg mL−1. Linear relationship (r 2 > 0.999) is satisfactory at the range of 0.1–10 μg mL−1. The developed method has been successfully applied to the determination of the four naphthalenediols in real cosmetic samples, with recoveries in foundation, sun cream and lotion in the range of 92.3%∼106.8% and relative standard deviation (RSD) less than 4.15%. A HPLC method described in the National Standards of the People’s Republic of China was carried out for the comparison with the proposed method. The results showed that the proposed sweeping-MEKC method has the advantages of fast, low cost with comparative sensitivity.

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Determination of 13-cis-Retinoic Acid and Its Metabolites in Plasma by Micellar Electrokinetic Chromatography Using Cyclodextrin-Assisted Sweeping for Sample Preconcentration

Molecules ◽

10.3390/molecules26195865 ◽

2021 ◽

Vol 26 (19) ◽

pp. 5865

Author(s):

Ying-Xuan Huang ◽

Yu-Ying Chao ◽

Yi-Hui Lin ◽

Jing-Ru Liou ◽

Hai-Chi Chan ◽

...

Keyword(s):

Retinoic Acid ◽

Micellar Electrokinetic Chromatography ◽

Sodium Dodecyl ◽

Internal Standard ◽

Electrokinetic Chromatography ◽

Experimental Conditions ◽

Sample Preconcentration ◽

All Trans Retinoic Acid ◽

Preconcentration Technique

The online preconcentration technique, cyclodextrin-assisted sweeping (CD-sweeping), coupled with micellar electrokinetic chromatography (MEKC) was established to determine 13-cis-retinoic acid (13-cis-RA), all-trans-retinoic acid (all-trans-RA) and 4-oxo-13-cis-retinoic acid (4-oxo-13-cis-RA) in human plasma. A CD-sweeping buffer (45 mM borate (pH 9.2), containing 80 mM sodium dodecyl sulfate (SDS) and 22 mM hydroxypropyl β-CD (HP-β-CD) was introduced into the capillary and, then, the sample dissolved in 70 mM borate (pH 9.2): methanol = 9:1 (v/v) was injected into capillary by pressure. The separation voltage was 23 kV. Compared to the conventional cyclodextrin-micellar electrokinetic chromatography (CD-MEKC) method, the new technique achieved 224–257-fold sensitivity enrichment of analytes. The limits of detection of 13-cis-RA, all-trans-RA were 1 ng/mL, whereas that of 4-oxo-13-cis-RA was 25 ng/mL in plasma. The linear ranges of 13-cis-RA, all-trans-RA were between 15 and 1000 ng/mL, whereas that of 4-oxo-13-cis-RA was between 75 and 1500 ng/mL. The coefficient of correlation between the concentration of analytes and peak area ratio of analytes and internal standard (2, 4-dihydroxy-benzophenone) for intra-day (n = 3) and inter-day (n = 5) analyses were both greater than 0.999. The optimized experimental conditions were successfully applied to determine 13-cis-retinoic acid and its metabolites in plasma samples from a patient during the administration of 13-cis-RA for treating acne.

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Determination of Nicotine in Tobacco by Chemometric Optimization and Cation-Selective Exhaustive Injection in Combination with Sweeping-Micellar Electrokinetic Chromatography

Journal of Analytical Methods in Chemistry ◽

10.1155/2015/869719 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Yi-Hui Lin ◽

Chia-Hsien Feng ◽

Shih-Wei Wang ◽

Po-Yun Ko ◽

Ming-Hsun Lee ◽

...

Keyword(s):

Micellar Electrokinetic Chromatography ◽

Direct Injection ◽

Sodium Dodecyl ◽

High Sensitivity ◽

Fold Increase ◽

Tobacco Product ◽

Detection Sensitivity ◽

Electrokinetic Chromatography ◽

Assay Performance ◽

The Central Nervous System

Nicotine is a potent chemical that excites the central nervous system and refreshes people. It is also physically addictive and causes dependence. To reduce the harm of tobacco products for smokers, a law was introduced that requires tobacco product containers to be marked with the amount of nicotine as well as tar. In this paper, an online stacking capillary electrophoresis (CE) method with cation-selective exhaustive injection sweeping-micellar electrokinetic chromatography (CSEI-sweeping-MEKC) is proposed for the optimized analysis of nicotine in tobacco. A higher conductivity buffer (160 mM phosphate buffer (pH 3)) zone was injected into the capillary, allowing for the analytes to be electrokinetically injected at a voltage of 15 kV for 15 min. Using 50 mM sodium dodecyl sulfate and 25% methanol in the sweeping buffer, nicotine was detected with high sensitivity. Thus, optimized conditions adapted from a chemometric approach provided a 6000-fold increase in the nicotine detection sensitivity using the CSEI-sweeping-MEKC method in comparison to normal CZE. The limits of detection were 0.5 nM for nicotine. The stacking method in combination with direct injection which matrix components would not interfere with assay performance was successfully applied to the detection of nicotine in tobacco samples.

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