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

Molecules ◽  
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.

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

2019 ◽  
Vol 9 (6) ◽  
pp. 1193 ◽  
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%.

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

2012 ◽  
Vol 32 (2) ◽  
pp. 401-404 ◽  
Author(s):  
Cristiano Augusto Ballus ◽  
Adriana Dillenburg Meinhart ◽  
Carolina Schaper Bizzotto ◽  
José Teixeira Filho ◽  
Helena Teixeira Godoy
Keyword(s):  
Micellar Electrokinetic Chromatography ◽  
Brain Activity ◽  
Low Cost ◽  
Sodium Dodecyl ◽  
Energy Drinks ◽  
Electrokinetic Chromatography ◽  
The Central Nervous System ◽  
The Mean ◽  
High Doses

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.

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

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.

Determination of Imipenem and Cilastatin in Medicinal Products by Micellar Electrokinetic Chromatography

2017 ◽  
Vol 13 (2) ◽  
pp. 158-166 ◽  
Author(s):  
Tyski Stefan ◽  
Gruba Ewa ◽  
Bukowska Bozena ◽  
Michalska Katarzyna ◽  
Karpiuk Izabela
Keyword(s):  
Micellar Electrokinetic Chromatography ◽  
Electrokinetic Chromatography ◽  
Medicinal Products

Determination of alcohols in mixtures by 19F NMR spectroscopy using hexefluoroacetone reagent

1982 ◽  
Vol 47 (7) ◽  
pp. 1973-1978 ◽  
Author(s):  
Jiří Karhan ◽  
Zbyněk Ksandr ◽  
Jiřina Vlková ◽  
Věra Špatná
Keyword(s):  
Standard Deviation ◽  
Nmr Spectroscopy ◽  
Standard Method ◽  
Internal Standard ◽  
Internal Standard Method ◽  
Concentration Region ◽  
Experimental Conditions ◽  
Curve Method ◽  
Sample Preparation Procedure

The determination of alcohols by 19F NMR spectroscopy making use of their reaction with hexafluoroacetone giving rise to hemiacetals was studied on butanols. The calibration curve method and the internal standard method were used and the results were mutually compared. The effects of some experimental conditions, viz. the sample preparation procedure, concentration, spectrometer setting, and electronic integration, were investigated; the conditions, particularly the concentrations, proved to have a statistically significant effect on the results of determination. For the internal standard method, the standard deviation was 0.061 in the concentration region 0.032-0.74 mol l-1. The method was applied to a determination of alcohols in the distillation residue from an oxo synthesis.

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