Analysis of riboflavin in beer by capillary electrophoresis/blue light emitting diode (LED)-induced fluorescence detection combined with a dynamic pH junction technique

A simple, inexpensive and reliable method for the routine analysis of riboflavin in beer by capillary electrophoresis-light emitting diode (CE-LED) induced fluorescence detection is described. A simple and straightforward sample preparation is involved and the method is based on an inexpensive blue LED as the light source combined with an on-line sample concentration technique. For this detection system, using a normal micellar electrokinetic chromatography (MEKC), stacking-MEKC and dynamic pH junction techniques, the detection limits were found to be 480, 20 and 1 ng mL⁻¹, respectively. In addition, the number of theoretical plates for riboflavin was determined to be 3.8×10⁴ by means of a dynamic pH junction and this was improved to 3.2×10⁶ when the dynamic pH junction-sweeping mode was applied. The concentrations of riboflavin in 12 samples of different types of commercial beer were found to be in the range of 130-280 ng mL⁻¹.     

Analysis of parabens in cosmetics by low pressure liquid chromatography with monolithic column and chemiluminescent detection

This paper presents an application of chromatographic separation based on an ultra-short monolithic column and chemiluminescent detection in an FIA type instrument manifold for the determination of four paraben mixtures: methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP). The separation is achieved in 150 s using two consecutive carriers: first 12% ACN:water that changes 75 s after injection to 27% ACN:water. The detection is based on the oxidation of the hydrolysis product of parabens, p-hydroxybenzoic acid, with Ce(IV) in the presence of Rhodamine 6G which evokes chemiluminescence of sufficient intensity to enable a sensitive determination of these species. After optimization of the variables involved, the analytical method is characterized, displaying the following values for concentration ranges, detection limits and precision, as relative standard deviation at low concentration (0.15 mg l⁻¹)—MP: from 9.9 × 10⁻⁷ to 3.3 × 10⁻⁴ M; 1.9 × 10⁻⁸; 5.6%; EP: from 9.0 × 10⁻⁷ to 3.3 × 10⁻⁴ M; 2.8 × 10⁻⁸; 3.5%; PP: from 8.3 × 10⁻⁷ to 9.9 × 10⁻⁵ M; 2.3 × 10⁻⁸; 4.2%; and BP: from 7.7 × 10⁻⁷ to 9.9 × 10⁻⁵ M; 4.2 × 10⁻⁸ M; 6.2%. The method was applied and validated satisfactorily for the determination of these parabens in cosmetic samples, comparing the results against a liquid chromatography reference method.     

Determination of parabens in cosmetic products using multi-walled carbon nanotubes as solid phase extraction sorbent and corona-charged aerosol detection system

The potential of carbon nanotubes for the solid phase extraction of parabens in cosmetic products and the detection using a corona-charged aerosol detector (C-CAD) is presented in this work. The analytical procedure is based on a conventional solid phase extraction step for which 20 mg of multi-walled carbon nanotubes were packed in a 3-mL commercial SPE cartridge. Methylparaben, ethylparaben, propylparaben and butylparaben were thus isolated and preconcentrated from the pre-treated samples and subsequently separated on a RP-C18 column using acetonitrile:water, 50:50 (v/v) as mobile phase. The analytical signals for the individual parabens were obtained using C-CAD. The experimental variables affecting the extraction procedure and the instrumental detection have been deeply studied. Limits of detection were in the range of 0.5–2.1 mg L⁻¹, while the linear range was extended up to 400 mg L⁻¹. The average precision of the method varied between 3.3–3.8% (repeatability) and 4.3–7.6% (reproducibility). Finally, the optimized procedure was applied to the determination of the target preservatives in a variety of cosmetic products with satisfactory results.     

Validation of a micellar electrokinetic capillary chromatography method for the determination of imidurea, methyl and propylparabens in a pharmaceutical ointment

The quantitative aspects of a micellar electrokinetic chromatographic (MEKC) method for the determination of three preservatives (imidazolidinyl urea, methyl and propylparabens) in a pharmaceutical ointment are presented. Separation was carried out in a 31.2 cm long (21 cm to the detection window) × 50 μm i.d. fused silica capillary at an electric field of 960 V/cm and 25 °C. The electrolyte was 10 mM sodium dihydrogenophosphate containing 40 mM sodium dodecylsulfate (SDS) and adjusted to pH 6.1. Sample preparation consisted of a simple dispersion of the ointment in an internal standard solution (ethylparaben in the electrolyte). A 3.5 nl volume of the sample solution was introduced hydrodynamically into the capillary. The compounds detected at 200 nm were separated within 1.6 min. The method was validated with respect to specificity, linearity, accuracy, repeatability according to the International Conference on Harmonisation guidelines. Calibration curves were found to be linear for each compound (r²>0.999). Recovery studies performed by spiking an ointment placebo with the preservatives between 50 and 150% of their target concentration on 3 different days gave satisfactory results (mean recovery at each of the five concentrations ranging from 99.23 to 101.40%). The repeatability of sample preparation (n=6) was better than 2% for each of the preservatives.     

Determination of additives in cosmetics by supercritical fluid extraction on-line headspace solid-phase microextraction combined with gas chromatography-mass spectrometry

A new hyphenated technique couples supercritical fluid extraction in situ derivatization and on-line headspace solid-phase microextraction to gas chromatography-mass spectrometry (SFE in situ derivatization on-line HS-SPME-GC-MS) for the determination of paraben preservatives and polyphenolic antioxidants in cosmetics. The preservatives and antioxidants were extracted from the cosmetic matrices with supercritical carbon dioxide at a pressure of 13,840 kPa. The supercritical fluid extraction was performed at 55 °C for 10 min of static extraction then 15 min of dynamic extraction. The extractant subsequently was derivatized in situ with the silylation reagent N,O-bis(trimethylsilyl)trifluoroacetamide with 0.1% trimethylchlorosilane. The product was then adsorbed on a polyacrylate solid-phase microextraction (SPME) fiber in the headspace. Sea sand was used as a dispersive material in the SFE step. The analytical linear ranges for the preservatives and antioxidants were found to be from 10 to 1000 ng g⁻¹ with RSD values below 7.8%. The detection limits ranged from 0.5 to 8.3 ng g⁻¹. These results are better than those obtained by using only SPME or SFE for trace preservatives and antioxidants analysis in cosmetic matrices. The new method was successfully utilized to determine the amounts of preservatives and antioxidants in real cosmetics without the need for tedious pretreatments.     

Simultaneous determination of electroactive and non-electroactive food preservatives by novel capillary electrophoresis with amperometric detection

A novel capillary electrophoresis and amperometric detection method was achieved by adding an electroactive additive (3,4-dihydroxybenzylamine, 3,4-DHBA) to the running buffer, so that both electroactive and non-electroactive food preservatives were simultaneously determined. Under the selected optimum conditions, four electroactive preservatives (methylparaben, ethylparaben, propylparaben and butylparaben) and two non-electroactive preservatives (potassium sorbate and sodium lactate) were well separated and sensitively detected with detection limits (S/N = 3) ranging from 1.06 × 10⁻⁸ to 2.73 × 10⁻⁶ g mL⁻¹. This method has been successfully employed for the determination of both electroactive and non-electroactive preservatives in several food commodities.     

Improving the sensitivity of the determination of ceftiofur by capillary electrophoresis in environmental water samples: in-line solid phase extraction and sample stacking techniques

This paper describes two different approaches for increasing the sensitivity for the analysis of ceftiofur by capillary electrophoresis (CE). Two different techniques based on the introduction of an enlarged volume of sample, namely large volume sample stacking (LVSS) and in-line solid phase extraction (SPE) were studied and compared. LVSS allowed the on-column electrophoretic preconcentration of ceftiofur without modification of the separation capillary. In-line SPE-CE was developed by using a home-made microcartridge that was filled with a reversed-phase sorbent (C₁₈). The microcartridge was coupled in-line near the inlet of the separation capillary. LVSS and in-line SPE-CE allowed automated operation and improved sensitivity for the analysis of ceftiofur with respect to conventional CE. When environmental water samples were analyzed, an additional pretreatment step based on off-line SPE was necessary in both cases to further decrease the detection limits. In terms of sensitivity for the determination of ceftiofur in river water samples, the combination of off-line SPE with in-line SPE-CE was found the most sensitive with a detection limit of 10 ng L⁻¹, whereas the method based on the use of off-line SPE with LVSS presented a detection limit of 100 ng L⁻¹.     

Combination of off-line solid-phase extraction and on-column sample stacking for sensitive determination of parabens and p-hydroxybenzoic acid in waters by non-aqueous capillary electrophoresis

For the first time, a procedure based on solid-phase extraction (SPE) for the simultaneous extraction of a group of parabens (methyl, ethyl, propyl, butyl and benzyl p-hydroxybenzoates) and p-hydroxybenzoic acid (PHBA), from environmental water samples has been developed. Analysis of the extracts was performed by non-aqueous capillary electrophoresis (NACE) coupled with diode array detection (DAD), using large-volume sample stacking (LVSS) based on the electroosmotic flow pump as on-column preconcentration technique. Several water samples, such as tap, river, and wastewater samples, were analyzed using both SPE-NACE-DAD and SPE-LVSS-NACE-DAD methods. It has been observed that in addition to SPE parameters such as sorbent material, sample pH, breakthrough volume, addition of an organic solvent and elution solvent, also sample characteristics, such as organic matter content, have influence on SPE extraction yields, especially in the case of PHBA. The presence of PHBA and some parabens was detected at trace levels in surface water samples. Concentrations up to 8.4 ng mL⁻¹ were found in raw wastewater, with the highest levels corresponding to methylparaben, propylparaben, and their main degradation product, PHBA.     

Optimization of the separation of malachite green in water by capillary electrophoresis Raman spectroscopy (CE-RS) based on the stacking and sweeping modes

A capillary electrophoresis Raman spectroscopy (CE-RS) method based on the stacking and sweeping modes are described. A non-fluorescent compound (malachite green, MG; crystal violet, CV) and a doubled Nd:YAG laser (532 nm, 300 mW) were selected as the model compound and light source, respectively. In order to carry out a quantitative and analysis of MG, a monochromator was used to collect the specific Raman line at 1616 cm⁻¹ (the N-φ and C-C stretching, corresponding to 582 nm when the wavelength of the exciting source is 532 nm). The limit of detection (LOD) for MG was 1.6 × 10⁻⁵ and 1.1 × 10⁻⁵ M, respectively, based on the CZE and MEKC modes. This could be improved to 3.4 × 10⁻⁷ and 5.3 × 10⁻⁹ M, respectively, when the stacking and sweeping modes were applied. The method was also extended to the determination of MG in an actual sample.     

A novel stacking method of repetitive large volume sample injection and sweeping MEKC for determination of androgenic steroids in urine

In this research, a novel stacking capillary electrophoresis method, repetitive large volume sample injection and sweeping MEKC (rLVSI-sweeping MEKC) were developed to analyze the presence of three androgenic steroids considered as sport doping drugs, testosterone (T), epitestosterone (E) and epitestosterone glucuronide (EG) in urine. This method provides better sensitivity enhancement than the traditional large volume sample stacking-sweeping strategies due to sensitivity enhancement by repetitive injections. This multiple sampling method enhances sensitivity of monitoring of urine samples by UV detection (254 nm). Firstly, the phosphate buffer was filled into an uncoated fused silica capillary and the samples were injected into the capillary at 10 psi for 20 s, and then stacked at −10 kV for 1 min using phosphate buffer containing SDS. The above injecting and stacking steps were repeated five times. Finally, separation was performed at −20 kV, using phosphate buffer containing methanol, SDS and (2-hydroxypropyl)-β-cyclodextrin. Method validation showed that calibration plots were linear (r ≧ 0.997) over a range of 5-200 ng mL⁻¹ for T, 20-200 ng mL⁻¹ for E and 0.5-500 ng mL⁻¹ for EG. The limits of detection were 1.0 ng mL⁻¹ for T, 5.0 ng mL⁻¹ for E and 200.0 pg mL⁻¹ for EG. When evaluating precision and accuracy, values of RSD and RE in intra-day (n = 3) and inter-day (n = 5) analysis were found to be less than 10.0%. Compared with the simple LVSS-sweeping, which is also a stacking strategy, this method further improves sensitivity up to 25 folds (∼2500 folds with MEKC without preconcentration). This method was applied to monitor 10 athletes’ urine, and did not detect any analyte. The novel stacking method was feasible for monitoring of doping by sportsmen.     

Determination of parabens in shampoo using high performance liquid chromatography with amperometric detection on a boron-doped diamond electrode

Methylparaben (MePa), ethylparaben (EtPa) and propylparaben (PrPa) have been widely used, among others, as chemical preservatives in cosmetics, drugs and foods. As these compounds are linked with allergies, dermatitis and estrogenic properties, it is necessary to control the concentration of these substances in different matrices. The aim of this paper are: to evaluate the electrochemical behavior of parabens on the boron-doped diamond (BDD) electrode and the development of a chromatographic method, with electrochemical detection (HPLC-ED), for determination of parabens in shampoo. A BDD (8000 ppm) electrode was adapted in a thin layer mode analytical cell consisting of a stainless steel and a platinum wire as reference and auxiliary electrodes, respectively. Chromatographic separations were obtained with a reversed phase C8 analytical column and a mobile phase of 0.025 mol L⁻¹ disodium phosphate, pH 7.0, and acetonitrile (40:60, v/v), delivered at a flow rate of 1.0 mL min⁻¹. Sample preparation was performed by solid phase extraction using C18 cartridges and acetonitrile for elution. Benzylparaben was employed as internal standard. The HPLC-ED method developed, using the BDD electrode, was validated for the determination of parabens in shampoos and presented adequate linearity (>0.999), in the range of 0.0125-0.500% (w/w), detectability 0.01% (w/w), precision (RSD of 2.3-9.8%) and accuracy (93.1-104.4%) and could be applied for routine quality control of shampoos containing MePa, EtPa and PrPa.     

Determination of sildenafil citrate (viagra) and its metabolite (UK-103,320) by square-wave and adsorptive stripping square-wave voltammetry. Total determination in biological samples

The voltammetric behaviour of Sildenafil citrate (SC) and its main metabolite UK-103,320 (UK) was studied by square wave techniques, leading to two methods for its total determination in biological samples (urine and human serum). The application of the square wave (SW), without the adsorptive accumulation, shows a maximum response at −0.950 V. The effect of experimental parameters that affect this determination are discussed. The stripping technique, proved to be more sensitive, yielding signals three times larger than those obtained by applying a square wave scan without the previous accumulation. Two calibration graphs to determine total SC and UK concentration were established. Calibration graph in urine sample was linear in the range 4.4×10⁻⁸ to 4.8×10⁻⁷ M by the stripping mode with an accumulation time of 10 s. In the same conditions but in serum sample regression line was linear in the range 3.4×10⁻⁸ to 9.7×10⁻⁷ M. The two proposed methods (SW and square-wave adsorptive stripping voltammetry (SWAdSV)) were applied to the total concentration analysis in eight different biological samples by the standard addition method with satisfactory results in the four different serum samples by the SW and in the four urines by SWAdSV.     

Flow-injection chemiluminescence determination of aminomethylbenzoic acid and aminophylline based on N-bromosuccinimide-luminol reaction

A novel and sensitive chemiluminescence (CL) method for the determination of aminomethylbenzoic acid and aminophylline coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drugs on the chemiluminescence emission of N-bromosuccinimide-luminol (NBS-luminol) system. Under the optimum conditions, the decreased CL intensity is linear with the concentration of aminomethylbenzoic acid in the range of 2×10⁻⁸ to 1.0×10⁻⁶ g ml⁻¹ and with the concentration of aminophylline in the range of 1×10⁻⁷ to 7.0×10⁻⁶ g ml⁻¹, respectively. The detection limit is 7.0×10⁻⁹ g ml⁻¹ for aminomethylbenzoic acid (3σ) and 3.4×10⁻⁸ g ml⁻¹ for aminophylline (3σ). The relative standard deviations (R.S.D.) for 11 parallel measurements of 2.0×10⁻⁷ g ml⁻¹ aminomethylbenzoic acid and 1.0×10⁻⁶ g ml⁻¹ aminophylline are 2.6 and 3.0%, respectively. The proposed methods have been applied for the determination of the studied drugs in their pharmaceutical formulations with satisfactory results. The possible use of the proposed system for the determination of aminomethylbenzoic acid in plasma sample was also tested. The possible inhibition mechanism of aminomethylbenzoic acid and aminophylline on luminol-NBS system was discussed briefly.     

Stacking and separation of urinary porphyrins in capillary electrophoresis: optimization of concentration efficiency and resolution

We demonstrated that anionic porphyrins could be stacked and separated in micellar electrokinetic chromatography (MEKC) and microemulsion electrokinetic chromatography (MEEKC) by applying acetonitrile and high salt content in human urine sample matrix. The introduction of sample containing acetonitrile and sodium chloride into the CE capillary at more than 10% of the total capillary volume resulted in the improvement of peak resolution and the enhancement of detection sensitivity. The achieved acetonitrile stacking enrichment factors of six porphyrins ranged from 12 to 32 in MEKC and from 28 to 33 in MEEKC, respectively. The stacking technique was successfully applied for analyzing porphyrins present in urine samples that were deproteinized with acetonitrile. For the analysis of coproporphyrin isomers, addition of the sodium cholate (SC) into micelle and microemulsion solutions provided adequate resolution. Calibration curves obtained for the determination of coproporphyrin isomers were found linear between 30 and 400 nmol L⁻¹, and the limit of detection (LOD) was 20 nmol L⁻¹ in MEEKC. Intra- and interday precisions (n = 11) in the microemulsion separation system for the isomers at spiked concentrations of 40-400 nmol L⁻¹ in urine were in the range of 0.1-0.4% and 0.7-7.6% for migration time and peak area, respectively. Coproporphyrin III, coproporphyrin I and uroporphyrin were detected at levels of 80.7 nmol L⁻¹, 32.3 nmol L⁻¹ and 19.8 nmol L⁻¹, respectively, in the urine samples collected from healthy individuals. Different porphyrin profiles, however, were observed in urine samples from porphyria cutanea tarda (PCT) patients.     

Anodic voltammetric behavior and determination of cefixime in pharmaceutical dosage forms and biological fluids

The voltammetric behavior of cefixime was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. The oxidation of cefixime was irreversible and exhibited diffusion controlled process depending on pH. The oxidation mechanism was proposed and discussed. Different parameters were tested to optimize the conditions for the determination of cefixime. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was investigated. According to the linear relationship between the peak current and the concentration, differential pulse (DPV) and square wave (SWV) voltammetric methods for cefixime assay in pharmaceutical dosage forms and biological fluids were developed. For the determination of cefixime were proposed in acetate buffer at pH 4.5, which allows quantitation over the 6 × 10⁻⁶-2 × 10⁻⁴ M range in supporting electrolyte and spiked serum sample; 8 × 10⁻⁶-2 × 10⁻⁴ M range in urine sample; 6 × 10⁻⁶-1 × 10⁻⁴ M range in breast milk samples for both techniques. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and in the biological samples, respectively.     

Simultaneous spectrofluorimetric determination of levodopa and propranolol in urine using feed-forward neural networks assisted by principal component analysis

The simultaneous determination of levodopa (LD) and propranolol (PRO) using fluorescence spectrometric technique is described. The method involves measuring the natural fluorescence of these drugs in the micellar media of sodium dodecyl sulfate (SDS) using principal component analysis-feed-forward neural networks (PC-FFNNs). Experimental conditions such as effect of pH and SDS concentration were optimized. Under the optimum conditions, the linear determination ranges of LD and PRO are 2.0 × 10⁻⁸ to 1.0 × 10⁻⁵ mol L⁻¹ and 3.6 × 10⁻⁹ to 1.8 × 10⁻⁶ mol L⁻¹, respectively. A set of synthetic binary mixtures of LD and PRO was prepared and their concentrations were predicted by the proposed method. Satisfactory results were obtained by the combination of fluorescence technique with chemometrics methods. The method was successfully applied to the determination of LD and PRO in tap water and in urine samples.     

Cobalt phthalocyanine as a novel molecular recognition reagent for batch and flow injection potentiometric and spectrophotometric determination of anionic surfactants

Cobalt(II) phthalocyanine [Co(II)Pc] is used as both an ionophore and chromogen for batch and flow injection potentiometric and spectrophotometric determination of anionic surfactants (SDS), respectively. The potentiometric technique involves preparation of a polymeric membrane sensor by dispersing [Co(II)Pc] in a plasticized PVC membrane. Under batch mode of operation, the sensor displays a near-Nernstian slope of −56.5 mV decade⁻¹, wide response linear range of 7.8 × 10⁻⁴ to 8.0 × 10⁻⁷ mol L⁻¹, lower detection limit of 2.5 × 10⁻⁷ mol L⁻¹ and exhibits high selectivity for anionic surfactants in the presence of many common ions. Under hydrodynamic mode of operation (FIA), the slope of the calibration plot, limit of detection, and working linear range are −51.1 mV decade⁻¹, 5.6 × 10⁻⁷ and 1.0 × 10⁻³ to 1.0 × 10⁻⁶ mol L⁻¹, respectively. The spectrophotometric method is based on the use of [Co(II)Pc] solution in dimethylsulfoxide (DMSO) as a chromogenic reagent. The maximum absorption of the reagent at 658 nm linearly decreases with the increase of anionic surfactant over the concentration range 2-30 μg mL⁻¹. The lower limit of detection is 1 μg mL⁻¹ and high concentrations of many interfering ions are tolerated. Flow injection spectrophotometric measurements are carried out by injection of the surfactant test solution in a stream of the reagent in DMSO. The sample throughput, working range and lower detection limit are 25-30 samples h⁻¹, 4-60 and 2 μg mL⁻¹, respectively. The potentiometric and spectrophotometric techniques are applied to the batch and flow injection measurements of anionic surfactants in some commercial detergent products. The results agree fairly well with data obtained using the standard methylene blue spectrophotometric method.     

Flow injection potentiometric determination of clobutinol hydrochloride

New clobutinol (Clob) ion-selective polyvinyl chloride (PVC) membrane electrodes, based on the ion-associates of Clob with phosphotungstic acid or phosphomolybdic acid were prepared using dibutyl phthalate as plasticizing solvent. The electrodes were characterized in terms of membrane composition, temperature and pH. The sensors showed a near-Nernstian response over the concentration ranges (6.31 × 10⁻⁶)-(1.00 × 10⁻²) and (5.01 × 10⁻⁵)-(1.00 × 10⁻²) M in the case of clobutinol-phosphotungstate ((Clob)₃-PT) applying batch and flow injection (FI) analysis, respectively, and (1.58 × 10⁻⁵)-(1.00 × 10⁻²) and (5.01 × 10⁻⁵)-(1.00 × 10⁻²) M in case of clobutinol-phosphomolybdate ((Clob)₃-PM) for batch and FI analysis systems, respectively. The electrodes were successfully applied for the potentiometric determination of ClobCl in pharmaceutical preparation and urine in steady state and flow injection conditions. The electrodes exhibit good selectivity for Clob with respect to a large number of inorganic cations, sugars and amino acids.     

Selective and specific detection of sulfate-reducing bacteria using potentiometric stripping analysis

A fast, sensitive and reliable potentiometric stripping analysis (PSA) is described for the selective detection of the marine pathogenic sulfate-reducing bacterium (SRB), Desulforibrio caledoiensis. The chemical and electrochemical parameters that exert influence on the deposition and stripping of lead ion, such as deposition potential, deposition time and pH value were carefully studied. The concentration of SRB was determined in acetate buffer solution (pH 5.2) under the optimized condition (deposition potential of −1.3 V, deposition time of 250 s, ionic strength of 0.2 mol L⁻¹ and oxidant mercury (II) concentration of 40 mg L⁻¹). A linear relationship between the stripping response and the logarithm of the bacterial concentration was observed in the range of 2.3 × 10 to 2.3 × 10⁷ cfu mL⁻¹. In addition, the potentiometric stripping technique gave a distinct response to the SRB, but had no obvious response to Escherichia coli. The measurement system has a potential for further applications and provides a facile and sample method for detection of pathogenic bacteria.     

Micellar electrokinetic chromatography of organic and peroxide-based explosives

CE methods have been developed for the analysis of organic and peroxide-based explosives. These methods have been developed for deployment on portable, in-field instrumentation for rapid screening. Both classes of compounds are neutral and were separated using micellar electrokinetic chromatography (MEKC). The effects of sample composition, separation temperature, and background electrolyte composition were investigated. The optimised separation conditions (25 mM sodium tetraborate, 75 mM sodium dodecyl sulfate at 25 °C, detection at 200 nm) were applied to the separation of 25 organic explosives in 17 min, with very high efficiency (typically greater than 300,000 plates m⁻¹) and high sensitivity (LOD typically less than 0.5 mg L⁻¹; around 1–1.5 μM). A MEKC method was also developed for peroxide-based explosives (10 mM sodium tetraborate, 100 mM sodium dodecyl sulfate at 25 °C, detection at 200 nm). UV detection provided LODs between 5.5 and 45.0 mg L⁻¹ (or 31.2–304 μM), which is comparable to results achieved using liquid chromatography. Importantly, no sample pre-treatment or post-column reaction was necessary and the peroxide-based explosives were not decomposed to hydrogen peroxide. Both MEKC methods have been applied to pre-blast analysis and for the detection of post-blast residues recovered from controlled, small scale detonations of organic and peroxide-based explosive devices.