Determination of ephedrine alkaloids in Ephedra natural products using HPLC on a pentafluorophenylpropyl stationary phase

Ephedrae Herba: A Review of Its Phytochemistry, Pharmacology, Clinical Application, and Alkaloid Toxicity

Ephedrae Herba (Ephedra), known as "MaHuang" in China, is the dried straw stem that is associated with the lung and urinary bladder meridians. At present, more than 60 species of Ephedra plants have been identified, which contain more than 100 compounds, including alkaloids, flavonoids, tannins, sugars, and organic phenolic acids. This herb has long been used to treat asthma, liver disease, skin disease, and other diseases, and has shown unique efficacy in the treatment of COVID-19 infection. Because alkaloids are the main components causing toxicity, the safety of Ephedra must be considered. However, the nonalkaloid components of Ephedra can be effectively used to replace ephedrine extracts to treat some diseases, and reasonable use can ensure the safety of Ephedra. We reviewed the phytochemistry, pharmacology, clinical application, and alkaloid toxicity of Ephedra, and describe prospects for its future development to facilitate the development of Ephedra.

High-performance liquid chromatography quantitative analysis of ephedrine alkaloids in Ephedrae Herba on a perfluorooctyl stationary phase

Ephedrae Herba is one of the most commonly used herbal medicines, and it has been shown that most of the clinical efficacy for cold and asthma is exerted by its alkaloidal components. A simple and sensitive high-performance liquid chromatography method was developed using a perfluorooctyl column for the simultaneous determination of five alkaloids (norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, and methylephedrine) in Ephedrae Herba. The mobile phase comprising acetonitrile and 15 mM ammonium trifluoroacetate was used to elute the targets in isocratic elution mode. The method was validated for linearity (R²  > 0.999), repeatability, intraday and interday precision, recoveries with trueness (93.87-110.99%), limits of detection (5.35-5.76 µg/mL), and limits of quantification (20 µg/mL). The quantitative results revealed that the developed method was precise and accurate. Then it was successfully applied to determine the difference in the contents of three batches of Ephedrae Herba from three pharmaceutical companies.

A high throughput toolbox for comprehensive flavor compound mapping in mint

Essential oils of the genus Mentha are extensively used as flavor ingredients in the industry. To overcome the time consuming and laborious traditional flavor analysis, a new quick, high-throughput toolbox based on a bead-beater homogenization followed by a UHPLC-MS/MS analysis has been developed and validated. While terpenes could be directly detected using atmospheric pressure chemical ionization (APCI), carbonyl compounds and alcohols required derivatization by 3-nitrophenylhydrazine (3-NPH) and glycidyltrimethylammonium chloride (GTMA) to ensure sufficient sensitivity for analysis of a single leaf. Using this approach, in total, 59 flavor-active metabolites representing the characteristic flavor of mint were quantified in leaves as well as in distilled oils using fast and robust UHPLC-MS/MS methods. The application of this toolbox enables a mapping of key pathways of mint flavor biosynthesis and can therefore support extensive breeding studies and the monitoring of chemosensate changes, depending on factors such as growth stages and environmental conditions.

Calixarene based portable sensor for the direct assay of indiscriminate ephedrine content of weight loss herbal preparations

A novel potentiometric sensor was developed and optimized for the quantitative analysis of ephedrine in non-prescribed herbal supplements used as adjunctive therapy for weight loss. An initial optimization study aimed to reach the optimum membrane composition, sensor assembly, and experimental conditions. The study evaluated the effect of several factors on the sensor performance including different ion-exchangers, plasticizers, ionophores, membrane thicknesses, soaking solution concentrations, soaking time intervals, and pH. The optimized polyvinyl chloride membrane included tungstophosphoric acid hydrate as a cation exchanger, tricresyl phosphate as a plasticizer, and calix[8]arene as an ionophore to enhance the sensitivity and selectivity of the developed sensor. The polyvinyl chloride membrane was drop-casted over a polyaniline modified glassy carbon electrode surface to form a solid-state sensor. The proposed membrane succeeded to quantify ephedrine over a linear range of 6 × 10-6 to 1 × 10-2 M with a LOD of 3.60 × 10-6 M, acceptable selectivity, and fast response time. The IUPAC characterization of sensor response and International Conference on Harmonization validation parameters were calculated. The method successfully determined ephedrine concentration in spiked herbal mixtures and determined labeled and undeclared ephedrine content of weight loss herbal preparations.

HPLC-UV-QDa analysis of Citrus aurantium-labelled pre-workout supplements suggest only a minority contain the plant extract

Bitter orange (Citrus aurantium) is a common ingredient in pre-workout supplements with purported weight-loss and performance-enhancing effects. Supplements listing Citrus aurantium or p-synephrine have been associated with reports of adverse cardiovascular events attributed to the active biogenic amines, p-synephrine, p-octopamine or p-tyramine. Additionally, questions have been raised as to the authenticity of the plant-derived active components listed on the supplement labels. The aim of this study was to determine the quantities of these amines in a sample of pre-workout supplements which specifically listed Citrus aurantium, and assess the authenticity of plant material by comparing the ratios of amines found to that found in Citrus aurantium standardized reference materials (SRM). The quantities of amines in the supplements and SRMs were determined using a validated high-performance liquid chromatography-single quadrupole mass spectrometry (HPLC-UV-QDa) method. In the Citrus aurantium SRMs the quantities of trace amines found ranged from 5.30 to 38.00 mg/g (synephrine) 0.14-0.35 mg/g (octopamine) and 0.15-1.90 mg/g (tyramine) with an average ratio of 100:1:5 (synephrine: octopamine: tyramine). Only 42 % (5/12) of the supplements tested had ratios consistent with that found in the SRMs. The average trace amine ratio in those supplements was 100:1:3 while the quantities of trace amines found ranged from 0.35 to 31.31 mg/g (synephrine); 0.005 - 0.10 mg/g (octopamine) and 0.01-1.51 mg/g (tyramine). For the remaining supplements, some did not contain any detectable levels of trace amines or only synephrine was detected with concentrations ranging from 0.003 - 0.95 mg/g. These results suggest a role for authenticity/quality assurance testing of pre-workout supplements and more stringent regulation of pre-workout supplements.

Voltammetric Analysis of Ephedrine in Pharmaceutical Dosage Forms and Urine Using poly(Nile Blue A) Modified Glassy Carbon Electrode

OBJECTIVE

The electrochemical analysis of ephedrine which is a sympathometric drug has been studied using poly(Nile blue A) modified glassy carbon electrodes, cyclic voltammetry, differential pulse voltammetry and square wave voltammetry.

METHODS

The modified electrodes were prepared by potential cycling electropolymerization of Nile blue A in 0.1 M phosphate buffer solution at pH 6.0. The redox behavior of ephedrine was investigated in different buffer solutions at pH values between 5.5 and 9.0.

RESULTS

Scan rate studies showed that the electron transfer reaction of ephedrine was diffusion controlled. A linear response was obtained between the peak current and the ephedrine concentration in the range of 0.6 to 100 μM with a limit of detection of 2.91×10^-3 μM for differential pulse voltammetry in Britton-Robinson buffer solution at pH 9.0. The linearity range of ephedrine in human urine was between 1.0 and 100 μM with a detection limit of 8.16 nM.

CONCLUSION

The recovery studies in both pharmaceutical dosage forms and urine showed that the proposed method ensured good selectivity, precision and accuracy without any interference from inactive excipients.

A Review on Worldwide Ephedra History and Story: From Fossils to Natural Products Mass Spectroscopy Characterization and Biopharmacotherapy Potential

Growing worldwide, the genus Ephedra (family Ephedraceae) had a medicinal, ecological, and economic value. The extraordinary morphological diversity suggests that Ephedra was survivor of an ancient group, and its antiquity is also supported by fossil data. It has recently been suggested that Ephedra appeared 8–32 million years ago, and a few megafossils document its presence in the Early Cretaceous. Recently, the high analytical power provided by the new mass spectrometry (MS) instruments is making the characterization of Ephedra metabolites more feasible, such as ephedrine series. In this regard, the chemical compounds isolated from crude extracts, fractions, and few isolated compounds of Ephedra species were characterized by MS-based techniques (LC-MS, LC-ESI-MS, HPLC-PDA-ESI/MS, LC-DAD-ESI/MSn, LC/Orbitrap MS, etc.). Moreover, we carry out an exhaustive review of the scientific literature on biomedicine and pharmacotherapy (anticancer, antiproliferative, anti-inflammatory, antidiabetic, antihyperlipidemic, antiarthritic, and anti-influenza activities; proapoptotic and cytotoxic potential; and so on). Equally, antimicrobial and antioxidant activities were discussed. This review is focused on all these topics, along with current studies published in the last 5 years (2015–2019) providing in-depth information for readers.

Analytical strategies for the determination of amino acids: Past, present and future trends

This review describes the analytical methods that have been developed over the years to tackle the high polarity and non-chromophoric nature of amino acids (AAs). First, the historical methods are briefly presented, with a strong focus on the use of derivatization reagents to make AAs detectable with spectroscopic techniques (ultraviolet and fluorescence) and/or sufficiently retained in reversed phase liquid chromatography. Then, an overview of the current analytical strategies for achiral separation of AAs is provided, in which mass spectrometry (MS) becomes the most widely used detection mode in combination with innovative liquid chromatography or capillary electrophoresis conditions to detect AAs at very low concentration in complex matrixes. Finally, some future trends of AA analysis are provided in the last section of the review, including the use of supercritical fluid chromatography (SFC), multidimensional liquid chromatography and electrophoretic separations, hyphenation of ion exchange chromatography to mass spectrometry, and use of ion mobility spectrometry mass spectrometry (IM-MS). Various application examples will also be presented throughout the review to highlight the benefits and limitations of these different analytical approaches for AAs determination.

Leishmanicidal Activity of Plant Extracts from Sefrou, a Moroccan Focus of Leishmaniasis, against Various Leishmania Parasites in the Promastigote Stage

According to the World Health Organization, leishmaniasis remains a major worldwide public health problem. The province of Sefrou located in the center of Morocco is a focus of cutaneous leishmaniasis. The present study aims at evaluating the antileishmanial potential of Berberis sp.,Crataegus oxyacantha, Cistus salviifolius, Ephedra altissima and Lavandula dentatafrequently used by the local population. Methanolic extracts were tested against the promastigote form ofLeishmania tropica, Leishmania majorandLeishmania infantumusing tetrazolium-based colorimetric (MTT) assay. The total phenol and flavonoids content of all extracts were determined using the Folin–Ciocalteu reagent, aluminum chloride, and potassium acetate solutions respectively. The plant extracts exhibited antileishmanial activity with variability depending on the tested strain and the plant species compared to Glucantime® used as control (IC50 (the half maximal inhibitory concentration) > 1,000 μg/mL). The best inhibition was observed with Berberis sp., againstLeishmania major(IC50 = 394.40 ± 3.02 μg/ml), andEphedra altissima(reported for the first time) againstLeishmania infantum(IC50 = 490.84 ± 3.15 μg/mL).Leishmania tropicahas shown the same sensitivity behavior toward the five extracts (in average IC50 = 540 ± 11.20 μg/mL). The total phenolic content was higher forCrataegus oxyacanthaandCistus salviifolius(140.67 ± 3.17 μg eq Gallic Acid (GA)/ mg of Extract (E) and 133.83 ± 9.03 μg eq GA/mg of E respectively), while flavonoid was higher forCistus salviifoliusandLavandula dentata(57.92 ± 2.46 μg eq Quercetin (Que)/ mg of Extract (E) and 41.53 ± 1.74 μg eq Que/mg of E). All the tested extracts present some promising aspects that may cure cutaneous leishmaniasis in the center of Morocco; further bioguided assays are needed to isolate the fractions and the bioactive molecule.

Validation of a rapid and simple high-performance liquid chromatography-electrospray ionization-mass spectrometry method for simultaneous analysis of 15 key chemicals in slimming foods and herbal products

A rapid and simple high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed for simultaneous analysis of 15 key chemicals in slimming foods and herbal products. These chemicals were strictly restricted adulterants (phenolphthalein, sibutramine, fenfluramine, clopamide, ephedrine, norpseudoephedrine, caffeine and phenformin) and physiologically relevant active components (l-carnitine, nuciferine, aloe-emodin, rhein, emodin, chrysophanol and physcion). In multi-day validations, intra- (n = 5) and inter-day precision (n = 3), limits of detection and limits of quantification for all analytes were 0.60-7.22%, 0.75-9.45%, 0.09-10 μg/L and 0.30-33.3 μg/L, respectively. Mean recovery ranged from 71.4% to 116% for all analytes in three representative samples. The method was validated on 17 samples including 12 kinds of slimming foods and five kinds of herbal products, and was shown to be ideal for routine quantification of 15 key chemicals in slimming foods and herbal products, providing an efficient strategy for quality control and food safety evaluation of weight reducing supplements.

Network pharmacology-based prediction of the active ingredients and potential targets of Mahuang Fuzi Xixin decoction for application to allergic rhinitis

ETHNOPHARMACOLOGICAL RELEVANCE

Certain herbal formulae from Traditional Chinese Medicine (TCM) are effective for treating and preventing diseases in clinical practice. Mahuang fuzi Xixin Decoction (MFXD) is a TCM that is used to treat allergic rhinitis (AR); however, the active ingredients and potential targets of its action against AR remain unclear. Therefore, further investigation is required.

METHODS

A network pharmacology approach comprising drug-likeness evaluation, oral bioavailability prediction, multiple drug target prediction, and network analysis has been used in this study.

RESULTS

The comprehensive systematic approach was successfully to indentify 41 bioactive ingredients in MFXD, while 37 potential targets hit by these ingredients related to AR. Moreover, wherein four predicted ingredients possess anti-inflammatory effects were found by this technique.

CONCLUSIONS

Our works successfully predict the active ingredients and potential targets of MFXD for application to allergic rhinitis and helps to illustrate mechanism of action on a systematic level. This study not only provides new insights into the chemical basis and pharmacology of MFXD but also demonstrates a feasible method for discovering potential drugs from herbal medicine.

A beating heart cell model to predict cardiotoxicity: effects of the dietary supplement ingredients higenamine, phenylethylamine, ephedrine and caffeine

Some dietary supplements may contain cardiac stimulants and potential cardiotoxins. In vitro studies may identify ingredients of concern. A beating human cardiomyocyte cell line was used to evaluate cellular effects following phenylethylamine (PEA), higenamine, ephedrine or caffeine treatment. PEA and higenamine exposure levels simulated published blood levels in humans or animals after intravenous administration. Ephedrine and caffeine levels approximated published blood levels following human oral intake. At low or midrange levels, each chemical was examined plus or minus 50 µM caffeine, simulating human blood levels reported after consumption of caffeine-enriched dietary supplements. To measure beats per minute (BPM), peak width, etc., rhythmic rise and fall in intracellular calcium levels following 30 min of treatment was examined. Higenamine 31.3 ng/ml or 313 ng/ml significantly increased BPM in an escalating manner. PEA increased BPM at 0.8 and 8 µg/ml, while 80 µg/ml PEA reduced BPM and widened peaks. Ephedrine produced a significant BPM dose response from 0.5 to 5.0 µM. Caffeine increased BPM only at a toxic level of 250 µM. Adding caffeine to PEA or higenamine but not ephedrine further increased BPM. These in vitro results suggest that additional testing may be warranted in vivo to further evaluate these effects.

Chromatographic isolation of nanoparticles from Ma-Xing-Shi-Gan-Tang decoction and their characterization

ETHNOPHARMACOLOGICAL RELEVANCE

The herbal decoction is a complex dispersion system containing solutes, colloid, aggregates, emulsions and precipitates. In which phase bioactive phytochemicals are dispersed determines their delivery, action and metabolism. This study took ephedrine, a well-studied and widely used phytochemical, as an example to elucidate its exact distribution in the phases of Ma-Xing-Shi-Gan-Tang decoction (MXSGT), which is an Ephedra sinica Stapf. containing traditional Chinese medicinal formula, and the biological meaning of this distribution correspondingly. It may provide an important update to the safety and efficacy assessment of the herbal decoction and its active phytochemicals.

MATERIALS AND METHODS

In this study, the decoction was fractionated with size-exclusion chromatography coupled with multi-angle laser light scattering detector. The morphology of fractionated nanoparticles was observed with AFM and SEM. The bioactivities of the decoction, the ephedrine alkaloids loaded NPs (prepared by chromatography isolation) and the synthetic ephedrine were assessed by cell proliferation tests using five cell lines, namely Caco-2, L-02, Hep-G2, NR-8383, and Hela-229.

RESULTS

Nanoparticles with radii of gyration ranged from 50 to 150 nm were isolated, in spherical shape. Further analysis of nanoparticles on the subsequent reversed phase chromatography revealed that the majority of ephedrine (99.7%) and pseudoephedrine (95.5%) were associated with these nanoparticles, rather than dispersed freely in the real solution. The addition of both the herbal decoction and the separated ephedrine-loaded nanoparticles reserved higher cell viability/proliferation than that of the sole synthetic ephedrine among the Caco-2, L-02, Hep-G2, and NR-8383 cells. In contrast, the nanoparticles reduced the proliferating power of ephedrine on Hela-229 cells. In general, the ephedrine-loaded NPs conducted the intermediate influences on the cell viability, in either way.

CONCLUSIONS

The colloidal nanoparticles were separated from the decoction. The association of ephedrine alkaloids with nanoparticles was demonstrated and may have changed the bioactivity of the alkaloids. The naturally occurred colloidal nanoparticles may play an important role in the pharmacological properties of both the decoction and its active phytochemicals, therefore warrant further studies.

Deciphering the combination principles of Traditional Chinese Medicine from a systems pharmacology perspective based on Ma-huang Decoction

ETHNOPHARMACOLOGY RELEVANCE

The main therapeutic concept in Traditional Chinese Medicine (TCM) is herb formula, which treats various diseases via potential herb interactions to maximize the efficacy and minimize the adverse effects. However, the combination principle of herb formula still remains a mystery due to the lack of appropriate methods.

METHODS

A systems pharmacology method integrating the pharmacokinetic analysis, drug targeting, and drug-target-disease network is developed to dissect this rule embedded in the herbal formula. All these are exemplified by a representative TCM formula, Ma-huang decoction, made up of four botanic herbs.

RESULTS

Based on the deep investigation of the function and compatibility of each herb, in a molecular/systems level, we demonstrate the different pharmacological roles that each herb might play in the prescription. By the way of enhancing the bioavailability and/or making the pharmacological synergy among different herbs, the four herbs effectively combine together to be suitable for treating diseases.

CONCLUSIONS

The present work lays foundations for a more comprehensive understanding of the combination rule of TCM, which might also be beneficial to drug development and applications.

Extractive determination of ephedrine hydrochloride and bromhexine hydrochloride in pure solutions, pharmaceutical dosage form and urine samples

Simple, rapid, sensitive, precise and accurate spectrophotometeric methods for the determination of ephedrine hydrochloride (E-HCl) and bromhexine hydrochloride (Br-HCl) in bulk samples, dosage form and in spiked urine samples were investigated. The methods are based on the formation of a yellow colored ion-associates due to the interaction between the examined drugs with picric acid (PA), chlorophyllin coppered trisodium salt (CLPH), alizarin red (AR) and ammonium reineckate (Rk) reagents. A buffer solution had been used and the extraction was carried out using organic solvent, the ion associates exhibit absorption maxima at 410, 410, 430 and 530 nm of (Br-HCl)with PA, CLPH, AR and Rk respectively; 410, 410, 435 and 530 of (E-HCl) with PA, CLPH, AR and Rk respectively. (E-HCl) and (Br-HCl) could be determined up to 13, 121, 120 and 160; 25, 200, 92 and 206 μg mL(-1), using PA, CLPH, AR and Rk respectively. The optimum reaction conditions for quantitative analysis were investigated. In addition, the molar absorptivity, Sandell sensitivity were determined for the investigated drug. The correlation coefficient was ≥0.995 (n=6) with a relative standard deviation (RSD) ≤1.15 for five selected concentrations of the reagents. Therefore the concentration of Br-HCl and E-HCl drugs in their pharmaceutical formulations and spiked urine samples had been determined successfully.

New potentiometric sensors based on selective recognition sites for determination of ephedrine in some pharmaceuticals and biological fluids

New cost-effective potentiometric membrane sensors with cylindrical configuration responsive to ephedrine are described. The sensors setup is, based on the use of triacetyl-β-cyclodextrin [(triacetyl-β-CD)] as a neutral ionophore embedded in a plasticized poly (vinyl chloride) (PVC) matrix (sensor I) and carboxylated poly(vinyl chloride) [(PVC-COOH)] as a simultaneous plastic matrix and ion exchanger (sensor II). Both sensors showed significant enhancement of response towards ephedrinium cation (EPD(+)) over a concentration range of 3.0 × 10(-5)-8.0 × 10(-3) mol L(-1) at pH 4-9 and 3-8 with low detection limits of 5.7 × 10(-6) and 6.2 × 10(-6) mol L(-1) for sensors (I) and (II), respectively. The sensors displayed near-Nernstian cationic slope of 57.0 and 55.6 mV decade(-1) for EPD(+) and the effects of lipophilic salts and various foreign common ions were examined. The sensors were also satisfactorily used as tubular detectors in a double channel flow injection system. The intrinsic characteristics of the detectors in a low dispersion manifold under hydrodynamic mode of operation were determined and compared with data obtained under batch mode of operation. Validation of the method revealed good performance characteristics including long life span, good selectivity for EPD(+) over a wide variety of other organic compounds, long term stability, high reproducibility, fast response, low detection limit, wide measurement range, acceptable accuracy and precision. Applications of the sensors to the determination of EPD(+) in pharmaceutical formulations and spiked biological fluid samples were carried out and compared with standard techniques. Notably, the sensors introduced offer several advantages over many of those previously described that are amenable to quality control/quality assurance assessment of the homogeneity, stability and purity of ephedrine drug tablets.

Analysis of alkaloids from different chemical groups by different liquid chromatography methods

Alkaloids are biologically active compounds widely used as pharmaceuticals and synthesised as secondary methabolites in plants. Many of these compounds are strongly toxic. Therefore, they are often subject of scientific interests and analysis. Since alkaloids — basic compounds appear in aqueous solutions as ionized and unionized forms, they are difficult for chromatographic separation for peak tailing, poor systems efficiency, poor separation and poor column-to-column reproducibility. For this reason it is necessity searching of more suitable chromatographic systems for analysis of the compounds. In this article we present an overview on the separation of selected alkaloids from different chemical groups by liquid chromatography thus indicating the range of useful methods now available for alkaloid analysis. Different selectivity, system efficiency and peaks shape may be achieved in different LC methods separations by use of alternative stationary phases: silica, alumina, chemically bonded stationary phases, cation exchange phases, or by varying nonaqueous or aqueous mobile phase (containing different modifier, different buffers at different pH, ion-pairing or silanol blocker reagents). Developments in TLC (NP and RP systems), HPLC (NP, RP, HILIC, ion-exchange) are presented and the advantages of each method for alkaloids analysis are discussed.

Simple HPLC method for detection of trace ephedrine and pseudoephedrine in high-purity methamphetamine

A simple and sensitive HPLC technique was developed for the qualitative determination of ephedrine and pseudoephedrine (ephedrines), used as precursors of clandestine d-methamphetamine hydrochloride of high purity. Good separation of ephedrines from bulk d-methamphetamine was achieved, without any extraction or derivatization procedure on a CAPCELLPACK C18 MGII (250 × 4.6 mm) column. The mobile phase consisted of 50 mM KH2 PO4-acetonitrile (94:6 v/v %) using an isocratic pump system within 20 min for detecting two analytes. One run took about 50 min as it was necessary to wash out overloaded methamphetamine for column conditioning. The analytes were detected by UV absorbance measurement at 210 nm. A sample (20 mg) was simply dissolved in 1 mL of water, and a 50 μL aliquot of the solution was injected into the HPLC. The detection limits for ephedrine and pseudoephedrine in bulk d-methamphetamine were as low as 3 ppm each. This analytical separation technique made it possible to detect ephedrine and/or pseudoephedrine in seven samples of high-purity d-methamphetamine hydrochloride seized in Japan. The presence of trace ephedrines in illicit methamphetamine may strongly indicate a synthetic route via ephedrine in methamphetamine profiling. This method is simple and sensitive, requiring only commonly available equipment, and should be useful for high-purity methamphetamine profiling.

Separation of adrenergic amines in Citrus aurantium L. var. amara by capillary electrochromatography using a novel monolithic stationary phase

This manuscript reports on the use of capillary electrochromatography for the determination of tyramine, (±) synephrine, and (±) octopamine, the major alkaloids in bitter orange peel. A novel methacrylate-based monolithic stationary phase was prepared by UV-photopolymerization in 100 μm id fused-silica capillaries. It facilitated the quantitative assessment of alkaloids with a mobile phase comprising aqueous 10 mM ammonium acetate in ACN and isopropanol. Applied voltage and temperature were 25 kV and 25°C, and samples were injected in electrokinetic mode. The method reported herein revealed adequate sensitivity (LOD ≤0.6 μg/mL), repeatability (σrel ≤4.1%), accuracy (recovery rates between 95.2 and 102.2%), and precision (intra-day variation ≤5.7%, inter-day variation ≤4.1%). The application of the CEC assay on C. aurantium var. amara plant material and dietary supplements, which usually are advertised for slimming properties, indicated that synephrine (0.17-0.82%) is the dominant alkaloid.