Short-end Injection Research Articles

Magnetic solid-phase extraction based on restricted-access molecularly imprinted polymers for ultrarapid determination of ractopamine residues from food samples by capillary electrophoresis

An ultrafast, efficient, and eco-friendly method combining magnetic solid phase extraction and capillary electrophoresis with diode array detection have been developed to determine ractopamine residues in food samples. A restricted access material based on magnetic and mesoporous molecularly imprinted polymer has been properly synthesized and characterized, demonstrating excellent selectivity and high adsorbent capacity. Short-end injection capillary electrophoresis method was optimized: 75 mM triethylamine pH 7 as BGE, -20 kV, 50 mbar by hydrodynamic injection during 8 s, and capillary temperature at 25 °C; reaching ultrafast ractopamine analysis (∼0.6 min) with good peak asymmetry, and free from interfering and/or baseline noise. After sample preparation optimization, the conditions were: 1000 µL of sample at pH 6, 20 mg of adsorbent, stirring time of 120 s, 250 µL of ultrapure water as washing solvent, 1000 µL of methanol: acetic acid (7: 3, v/v) as eluent, and the adsorbent can be reused four times. In these conditions, the analytical method showed recoveries around to 100 %, linearity ranged from 9.74 to 974.0 µg kg−1, correlation coefficient (r) ≥ 0,99 in addition to adequate precision, accuracy, and robustness. After proper validation, the method was successfully applied in the analysis ractopamine residues in bovine milk and bovine and porcine muscle.

Rapid enantiomeric separation of indacaterol by electrokinetic chromatography

The first chiral methodology enabling the separation of indacaterol enantiomers was developed in this work by cyclodextrin-electrokinetic chromatography. Indacaterol (IND) is a chiral drug marketed as a pure enantiomer. Then, the separation and quantification of each enantiomer is of great importance for the quality control of pharmaceutical formulations. After selecting the most suitable chiral selector and background electrolyte, two Box-Behnken designs were achieved to optimize the electrophoretic conditions using two different approaches to shorten analysis times: i) decreasing the capillary length, or ii) performing a short-end injection. Indacaterol enantiomers were separated in less than 5 min with a resolution value of 3.6 under the optimal separation conditions: 0.7% (m/v) carboxymethyl-α-cyclodextrin in 50 mM sodium formate buffer (pH 4.0) and using a short-end injection. Then, the analytical characteristics of the method were evaluated and LODs of 0.05 mg/L for S-IND and 0.04 mg/L for R-IND were achieved. Also, the method allowed the detection of a 0.1% enantiomeric impurity (S-IND) in the R-IND-based pharmaceutical formulations. The developed method was applied to the analysis of two pharmaceutical formulations. Percentages of 97 ± 3% and 103 ± 6% of R-IND with respect to the labeled amounts were found.

Short-End Injection Capillary Electrophoresis and Multivariate Analysis for Simultaneous Determination of Heavy Metals in Passiflora incarnata Tea.

An ultra-fast method for the simultaneous determination of heavy metals in Passiflora incarnata tea by capillary electrophoresis (CE) using a short-end injection combined with multivariate analysis was proposed. Separation was conducted by hydrodynamic injection (5 s at 0.5 psi) using the short-end injection procedure in a fused uncoated silica capillary (50 cm total length, 10.2 cm effective length, 50 µm i.d.) with separation time less than 2 min. An indirect UV detection at 214 nm was employed by using imidazole as a chromophore. The buffer used was 6 mmol/L hydroxybutyric acid (HIBA). The optimum conditions by full factorial with a central point were achieved by 18-crown-6 concentration (23.3 mmol L−1), voltage (+11.4 kV), methanol concentration (3.8%), and temperature (20 °C). The method showed good linearity (R2 > 0.998) for both Cd and Pb, inter-day precision of less than 14.49%, and an adequate limit of quantification only for Cd (LOQ < 0.5 µg mL−1 for Cd) based on the US Pharmacopeial Convention limit requirements for elemental impurities. After method validation, the method was applied to Passiflora incarnata tea samples from a local market. Furthermore, the developed method showed great potential for the determination of metals in other samples with proper sample preparation procedures.

Identifiable universal fluorescent multiplex PCR equipped with capillary electrophoresis for genotyping of exons 1 to 5 in human red and green pigment genes.

Congenital red and green color blindness is the most X-linked recessive disorder in humans caused by deletions or gross structural rearrangements of the visual pigment gene array that lead to altered the functions of visual pigments in their retina differ from normal. The incidence is about 7-10% in male and close association of X-linked recessive disorders (such as: hemophilia A, hemophilia B, duchenne muscular dystrophy). However, the traditional genetic analysis methods are time-consuming and low-efficiencies. Therefore, the purpose of the study is to develop a rapid method for genotyping of red and green pigment genes. We describe herein the first method for simultaneous evaluation of ten exons in the red and green pigment genes for genetic analysis. A forward specific primers with identifiable universal fluorescent multiplex PCR (FSIUFM-PCR) method utilized one universal primer (containing two universal non-human sequences) and forward specific primers in the multiplex PCR reaction system for simultaneously fluorescent labeling of eleven gene fragments (ten exons in red and green pigment genes and one internal standard). All the PCR products were analyzed on capillary electrophoresis with short-end injection, which had the advantage of high resolution and rapid separation. Of all 80 detected individuals, 7 subjects with color vision deficiencies (including 3 subjects only had red exons 1-5, 4 subjects had a specific red-green or green-red hybrid gene and 73 subjects with normal color vision). All genotyping results showed good agreement with DNA sequencing data. This method provided a better potential technique for genotyping and identifying of red and green pigment genes. In addition, FSIUFM-PCR method will be useful in many fields, such as diagnosis of diseases, analysis of polymorphisms and quantitative assay.

A rapid electrokinetic chromatography method using short-end injection for the enantioselective separation of tryptophan

A rapid enantioselective methodology for the analysis of tryptophan was developed in this work by electrokinetic chromatography using short-end injection and an anionic cyclodextrin as chiral selector. No previous derivatization of tryptophan was necessary. The influence of different experimental variables on the enantiomeric separation was investigated. The use of a 100 mM formate buffer (pH 2.2) containing 1.25% sulfated-γ-cyclodextrin with an uncoated fused-silica capillary of 50 µm inner diameter with a total length of 48.5 cm (effective length of 8.5 cm), and an injection by applying a pressure of −50 mbar (short-end injection) for 4 s, enabled the enantiomeric separation of tryptophan within 2.5 min with a resolution of 7.4. As desirable, the enantiomeric impurity, D-tryptophan, was the first-migrating enantiomer. The analytical characteristics of the developed methodology were evaluated in terms of linearity, precision, accuracy, and limits of detection and quantification, showing its good performance to be applied to the analysis of tryptophan-based dietary supplements. A relative limit of detection of 0.1% was obtained for the enantiomeric impurity, D-tryptophan, in the presence of the L-enantiomer. Results showed that the developed methodology is an interesting alternative for the enantioselective analysis of tryptophan enabling the rapid quality control of dietary supplements.

Determination of 5-hydroxymethylfurfural in tomato-based products by MEKC method

5-Hydroxymethylfurfural (5-HMF) is a compound formed in carbohydrate-containing foods during thermal processing, especially under acidic conditions, and when in high levels it can cause damage to the health of the consumer. In this context, this work aimed to determine 5-HMF using green and validated method by capillary electrophoresis, as well as to analyze sugars (fructose, glucose, and sucrose), pH, and titratable acidity in tomato sauce, ketchup, and tomato paste. 5-HMF separation was performed with short-end injection (-50 mbar/3 s), separation voltage +30 kV, background electrolyte composed by 5 mmol L−1 sodium tetraborate and 120 mmol L−1 sodium dodecyl sulphate (pH 9.3), and direct detection at 284 nm. The results showed that the validation parameters evaluated (linearity, matrix effect, precision, and recovery) were satisfactory, and the method was characterized as excellent according to the green chemistry principles. The content of 5-HMF in the 23 tomato-based products analyzed ranged from 1.30 to 312 mg kg−1, which was positively and significantly correlated with sugars (fructose and glucose) levels and acidity. This study highlights the importance of monitoring of 5-HMF in tomato-based products, as well as the need for establishing maximum legal limits to offer a safe product to the consumer.

Capillary electrophoresis‐based enzyme assays for β‐lactamase enzymes

Generic in-capillary as well as offline CE-based enzyme assays were developed for serine-β-lactamases and metallo-β-lactamases. The hydrolysis of benzylpenicillin to benzylpenicilloic acid was analyzed using 100mM sodium phosphate solution, pH6.0, as a background electrolyte. In-capillary assays employed an uncoated as well as a polyethylene oxide-coated capillary, while the offline assays employing long end and short end injection were performed in an uncoated capillary. Using procaine hydrochloride or 4-hydroxybenzoic acid as internal standard, the respective assays were validated with regard to linearity, LOD and LOQ, repeatability, precision, and accuracy. The assays were applied to the determination of the Michaelis-Menten parameters Km and Vmax of Bacillus cereus penicillinase as well as New Delhi metallo-β-lactamase 1 and Verona integrin-encoded metallo-β-lactamase 2. Furthermore, the inhibition of the enzymes by irreversible and competitive inhibitors was evaluated. Comparable data were obtained with all assays. The use of a simple substrate ensured broad applicability to the various types of β-lactamases.

Chiral separation of rasagiline using sulfobutylether-β-cyclodextrin: capillary electrophoresis, NMR and molecular modeling study.

Pressure-assisted stereospecific capillary electrophoresis method was developed for the determination of enantiomeric purity of the antiparkinsonian agent (R)-rasagiline. The optimized method, 50mM glycine-HCl buffer pH 2, supplied with 30mM sulfobutylether-β-cyclodextrin, at 35°C, applying 12 kV in reversed polarity, and -8 mbar pressure (vacuum), short-end injection with -25 mbar × 2 s, was successful for baseline separation of rasagiline enantiomers (Rs = 3.5 ± 0.1) in a short analysis time. The method was validated according to current guidelines and proved to be reliable, linear, precise and accurate for determination of 0.15% S-enantiomer as chiral impurity in R-rasagiline sample, as well as quantification of the eutomer. Method application was tested on a commercial tablet formulation. Determination of spatial structure of diastereomeric associates was based on 1 H and 2D ROESY NMR, indicating that the aromatic moiety of the molecule can enter the cyclodextrin cavity. NMR titration and molecular modeling revealed that S-rasagiline formed a more stable inclusion complex with sulfobutylether-β-cyclodextrin, than its antipode, which is in agreement with electrophoretic results.

A Chiral Generic Strategy for Enantioseparation of Acidic and Basic Drugs Using Short End Injection Capillary Electrophoresis: Application to Design of Experiment.

The present work describes a capillary electrophoretic (CE) generic strategy used for chiral enantioseparation of Fluconazole (as an example of acidic drugs) and donepezil (as an example of basic drugs). Several modified cyclodextrins (CDs) were applied for enantioseparation of racemates such as highly sulfated α, γ CDs, hydroxyl propyl-β-CD, and sulfobutyl ether-β-CD. The starting screening conditions consist of 50mM phosphate-triethanolamine buffer at pH2.5, an applied voltage of 15kV, and a temperature of 25°C. The design of experiment (DOE) was based on a full factorial design of the crucial two factors (pH and %CD) at three levels, to make a total of nine (32) experiments with high, intermediate, and low values for both factors. Evaluation of the proposed strategy pointed out that best resolution was obtained at pH2.5 for the investigated racemates using low percentages of HS-γ-CD, while SBE-β-CD was the most successful chiral selector offering acceptable resolution, with best separation at low pH values and at higher %CD within 10min runtime. Regression study showed that the linear model shows a significant lack of fit for all chiral selectors, anticipating that higher orders of the factors are most likely to be present in the equation with possible interactions.

Rapid Separation of Organophosphate Pesticides using Micellar Electrokinetic Chromatography and Short-end Injection.

Organophosphate (OP) pesticides are highly toxic substances and are frequently represented as poisons. In order to qualify and quantify the selected OP pesticides (methyl paraoxon, ethyl paraoxon, methyl parathion, fenitrothion, and ethyl parathion), micellar electrokinetic chromatography and short-end injection were investigated. This is the first time that this combination has been used to separate OP pesticides. A capillary with 8.5cm effective length was used, and the analytes were separated within 2.1min. Separation conditions including buffer (type, pH, and concentration), sodium dodecyl sulfate concentration, and separation voltage were optimized. The limit of detection (LOD) was estimated in the range of 10-20μM. The OP pesticides spiked in artificial saliva and drinking water gave superior peak profiles, and good average recoveries 95.6% and 62.3%, respectively. Overall, a rapid method with excellent resolution and efficiency was developed and successfully applied in the analysis of potential sample matrixes.

Simultaneous elastase-, hyaluronidase- and collagenase-capillary electrophoresis based assay. Application to evaluate the bioactivity of the red alga Jania rubens

There have been many efforts to search for affordable and efficient cosmetic ingredients from natural sources and to evaluate their bioactivities using eco-responsible tools. Hyaluronidase, elastase and collagenase are responsible for the degradation of the main components of the extracellular matrix, namely the hyaluronic acid, elastin and collagen, respectively. The aim of this work was to develop a single capillary electrophoresis method to monitor simultaneously the activities of these three enzymes, without reactant immobilization or radioactivity use. The developed approach was used to evaluate the bioactivity of the red alga Jania rubens after microwave- or electrochemical-assisted extraction. For this purpose, the incubation time, the reactant concentrations, the separation buffer and the detection system were carefully chosen. CE with double detection system, LIF and HRMS connected in series, was used to ensure the simultaneous analysis of the substrates and products of the three enzymatic reactions. The optimized enzymatic conditions allowed the use of the same protocol to assess the 3 enzyme activities. These conditions consisted of 10 min pre-incubation of the enzyme (with alga extract) at 37 °C; 10 min incubation with the substrate at 37 °C and 10 min stop-time at 90 °C. 1.4 nL of each reaction mixture were co-injected into a 85 cm total length capillary using short-end injection. Ammonium acetate (50 mM, pH 9.0) was used for electrophoretic separation. All substrates and products were simultaneously detected in less than 10 min with good peak symmetry and efficiency, sufficient intra-day and inter-day repeatabilities (RSD < 4.5%; n = 3) and excellent LOQ (<5 nM). The results obtained using this multiple CE-based enzymatic assay showed the significant effect of Jania rubens ethanolic extracts on elastase, hyaluronidase and the metalloproteinase MMP-1.

A chiral enantioseparation generic strategy for anti-Alzheimer and antifungal drugs by short end injection capillary electrophoresis using an experimental design approach.

The present study describes a generic strategy using capillary electrophoretic (CE) method for chiral enantioseparation of anti-Alzheimer drugs, namely, donepezil (DON), rivastigmine (RIV), and antifungal drugs, namely, ketoconazole (KET), Itraconazole (ITR), fluconazole (FLU), and sertaconazole (SRT) in which these drugs have different basic and acidic properties. Several modified cyclodextrins (CDs) were applied for enantioseparation of racemates such as highly sulfated α, γ CDs, hydroxyl propyl-β-CD, and Sulfobutyl ether-β-CD. The starting screening conditions consist of 50-mM phosphate-triethanolamine buffer at pH2.5, an applied voltage of 15kV, and a temperature of 25°C. The CE strategy implemented in the separation starts by screening prior to the optimization stage in which an experimental design is applied. The design of experiment (DOE) was based on a full factorial design of the crucial two factors (pH and %CD) at three levels, to make a total of nine (32 ) experiments with high, intermediate, and low values for both factors. Evaluation of the proposed strategy pointed out that best resolution was obtained at pH2.5 for five racemates using low percentages of HS-γ-CD, while SBE-β-CD was the most successful chiral selector offering acceptable resolution for all the six racemates, with the best separation at low pH values and at higher %CD within 10-min runtime. Regression study showed that the linear model shows a significant lack of fit for all chiral selectors, anticipating that higher orders of the factors are most likely to be present in the equation with possible interactions.

Interinstrumental transfer of a fast short-end injection capillary electrophoresis method: Application to the separation of niobium, tantalum, and their substituted ions.

The interinstrumental transfer of a short-end CE method was studied. A model separation of the hexameric forms of niobium, tantalum, and their substituted ions (Nb6-x Tax with 0≤x≤6) was selected as test case. The method was first optimized on a Beckman instrument and in a second step transferred to an Agilent instrument. The transfer needed updated guidelines that tackled differences in effective capillary length, 8.5 (Agilent) versus 10 cm (Beckman), because of instrumental different capillary cartridges. Differences in effective length lead to migration time and separation efficiency inequalities, illustrated by a decrease in resolution between the substituted ions. The difference in effective length was overcome by adapting the lift offset parameter of the Agilent instrument. The lift offset default setting is 4 mm and by increasing this parameter both the inlet and outlet lifts are lowered and thus the detection window can be displaced and consequently the effective length was increased. The decrease in effective length difference and the effect on the separation efficiency was investigated and led finally to a restored separation of the substituted ions. The adaptation of the lift offset parameter during short-end injection methods was added to earlier developed guidelines to facilitate interinstrumental method transfer of CE methods.

Injections from sub-μL sample volumes in commercial capillary electrophoresis

A simple sample injection procedure compatible with commercial capillary electrophoresis (CE) instrumentation was developed, which enables handling sample volumes as little as 250nL for analytical applications where sample volume availability is of concern. Single-use micro-sampling inserts were prepared by thermal modification of polypropylene micropipette tips and the inserts were accommodated in standard CE vials in CE autosampler carousel. To ensure direct contact of separation capillary injection end with sample solution and to avoid possible damage to the capillary, a soft compression spring was placed at the bottom of the vial underneath the micro-sampling insert. Injections from sub-μL samples were carried out in conventional as well as in short-end injection mode, were compatible with standard i.d./o.d. (25–100μm/365μm) fused silica capillaries and with various background electrolyte solutions and detection modes. Excellent repeatability of replicate injections from 250nL to 3μL was achieved based on RSD values of quantitative analytical measures (peak heights ≤2.4% and peak areas ≤3.7%) for CE-UV–vis, CE-ESI–MS and CE-contactless conductivity detection of model basic drugs. The achieved RSD values were comparable with those for replicate injections of the drugs from standard CE vials. The reported concept of injections from micro-sampling inserts was further demonstrated useful in evaluation of micro-electromembrane extraction (μ-EME) of model basic drugs. Sub-μL volumes of operational solutions resulted in reduced lengths of μ-EME phases and improved extraction recoveries (66–91%) were achieved.

Validated capillary electrophoretic method for the enantiomeric quality control of R-praziquantel.

The enantiomers of praziquantel, the drug of choice in schistosomiasis, were separated by electrokinetic chromatography with cyclodextrins. Nine anionic cyclodextrins were screened for their ability to discriminate between the uncharged enantiomers. Seven investigated selectors presented chiral interactions with the enantiomers, these cases being interpreted in terms of stability constants and complex mobilities. The best results were delivered by sulfated-β-cyclodextrin, where quasi-equal stability constants were accompanied by extreme selectivity values and was explained on the basis of highly different mobilities of the transient diastereomeric complexes. Since the enantiomer migration order was unfavorable, a simple polarity switch was employed (detection end at anode), which apart from migration order reversal, also resulted in extreme resolution values (Rs > 35) and increased migration times. After optimization (50 mM phosphate buffer pH 2.0, supplied with 15 mM sulfated-β-cyclodextrin, 15 kV, capillary temperature 25°C, short-end injection with 50 mbar × 2s), analysis time under 10min were obtained, while still maintaining high resolution (Rs > 10). The method was validated according to the ICH guidelines and application of the method was tested on in-house synthetized R-praziquantel batches and on commercial, combination tablets containing racemic mixture of the drug.

Rapid Analysis of Alpinetin and Cardamonin in Alpinia katsumadai Hayata Using Short-End Injection Microemulsion Electrokinetic Capillary Chromatography Combined with Microwave-Assisted Extraction

A rapid and simple short-end injection microemulsion electrokinetic chromatography (MEEKC) method was developed for the routine analysis of alpinetin and cardamonin in Alpinia katsumadai Hayata in combination with microwave-assisted extraction (MAE). The key parameters affecting separation and extraction were investigated and optimized. The optimal MAE was performed at 800 W for 12 min with 100% ethanol as the extraction solvent, which gave a better extraction efficiency and required a significantly shorter time than conventional heat reflux extraction (HRE) and ultrasonic extraction (USE). When this detection system based on ethyl acetate oil-based MEEKC and short-end injection was applied, the analysis was completed in less than 1.5 min. In the method validation, the relative standard deviations of the migration times and peak areas of the two constituents were 0.74, 1.86% for alpinetin and 0.63, 2.05% for cardamonin, respectively. The recoveries ranged from 94.6 to 105.8%. Compared with previously reported methods, the present method offers a dramatic decrease in overall analysis time, and has the further advantages of easy operation and low running costs.

Development of a fast method for simultaneous determination of hippuric acid, mandelic acid, and creatinine in urine by capillary zone electrophoresis using polymer multilayer-coated capillary.

This paper reports the development of a fast separation method employing capillary zone electrophoresis for the simultaneous determination of hippuric acid, mandelic acid, and creatinine in samples of urine using a coated capillary. The background electrolyte was composed of 10mmolL-1 tris(hydroxymethyl)aminomethane and 30mmolL-1 2-hydroxy-isobutyric acid at pH3.6. The internal standard was 3,5-dihydroxybenzoic acid. Separations were performed in a fused silica capillary (32cm total length, 8.5cm effective length, and 50μm internal diameter) coated with crosslinked hydroxypropyltrimethyl ammonium chloride chitosan and κ-carrageenan. Direct UV detection was performed at a wavelength of 200nm. Samples and standards were injected hydrodynamically (-50mbar, 3s) using the short-end injection procedure. The electrophoretic system was operated under constant voltage of 30kV with positive polarity on the injection side. The separation time for hippuric acid, mandelic acid, and creatinine was less than 70s. The evaluation of some analytical parameters of the method for the three analytes showed good linearity (R 2 > 0.99), limit of detections of 0.21 to 0.63mgL-1, inter-day precision better than 3.0% (peak area), and recovery in the range of 98 to 106%. The method developed was applied in the analysis of the three analytes in urine samples. Graphical Abstract New method using capillary zone electrophoresis for analysis of creatinine, hippuric acid and mandelic acid in urine.

Screening of tyrosinase inhibitors by capillary electrophoresis with immobilized enzyme microreactor and molecular docking.

A new method for screening tyrosinase inhibitors from traditional Chinese medicines (TCMs) was successfully developed by capillary electrophoresis with reliable online immobilized enzyme microreactor (IMER). In addition, molecular docking study has been used for supporting inhibition interaction between enzyme and inhibitors. The IMER of tyrosinase was constructed at the outlet of the capillary by using glutaraldehyde as cross-linker. The parameters including enzyme reaction, separation of the substrate and product, and the performance of immobilized tyrosinase were investigated systematically. Because of using short-end injection procedure, the product and substrate were effectively separated within 2 min. The immobilized tyrosinase could remain 80% active for 30 days at 4°C. The Michaelis-Menten constant of tyrosinase was determined as 1.78 mM. Kojic acid, a known tyrosinase inhibitor, was used as a model compound for the validation of the inhibitors screening method. The half-maximal inhibitory concentration of kojic acid was 5.55 μM. The method was successfully applied for screening tyrosinase inhibitors from 15 compounds of TCM. Four compounds including quercetin, kaempferol, bavachinin, and bakuchiol were found having inhibitory potentials. The results obtained in this work were supported by molecular docking study.

Determination of Protamine and Insulin Using Short-End Injection Capillary Electrophoresis

A fast and inexpensive method for simultaneous determination of total protamine and insulin has been developed using capillary electrophoresis in the short-end injection setup with a bare-fused silica capillary. Optimized background electrolyte consists of 45 mM aqueous solution of phosphoric acid, pH 1.85. Separation is finished within 1 min; total analysis time including preconditioning is 4 min. The method exhibits excellent linearity within the concentration range 2.5–500 μg mL−1 for both analytes. Limits of detection are 1.0 and 0.7 μg mL−1 for protamine and insulin, respectively. Accuracy of the method has been successfully tested on a real sample of Neutral Protamine Hagedorn Insulin (NPH insulin) injection. The background electrolyte employed is inexpensive and experiments have shown that it does not need to be exchanged for at least 20 subsequent analyses.

Capillary electrophoresis method to determine siRNA complexation with cationic liposomes.

Small interfering RNA (siRNA) inducing gene silencing has great potential to treat many human diseases. To ensure effective siRNA delivery, it must be complexed with an appropriate vector, generally nanoparticles. The nanoparticulate complex requires an optimal physiochemical characterization and the complexation efficiency has to be precisely determined. The methods usually used to measure complexation in gel electrophoresis and RiboGreen® fluorescence-based assay. However, those approaches are not automated and present some drawbacks such as the low throughput and the use of carcinogenic reagents. The aim of this study is to develop a new simple and fast method to accurately quantify the complexation efficiency. In this study, capillary electrophoresis (CE) was used to determine the siRNA complexation with cationic liposomes. The short-end injection mode applied enabled siRNA detection in less than 5 min. Moreover, the CE technique offers many advantages compared with the other classical methods. It is automated, does not require sample preparation and expensive reagents. Moreover, no mutagenic risk is associated with the CE approach since no carcinogenic product is used. Finally, this methodology can also be extended for the characterization of other types of nanoparticles encapsulating siRNA, such as cationic polymeric nanoparticles.