Rapid and cost‐effective method for the simultaneous quantification of seven alkaloids in Corydalis decumbens by microwave‐assisted extraction and capillary electrophoresis

A rapid and cost‐effective method based on microwave‐assisted extraction followed by capillary electrophoresis was developed for simultaneous quantification of seven alkaloids in Corydalis decumbens for the first time. The main parameters affecting microwave‐assisted extraction and capillary electrophoresis separation were investigated and optimized. The optimal microwave‐assisted extraction was performed at 40°C for 5 min using methanol/water (90:10, v/v) as the extracting solvent. Electrophoretic separation was achieved within 15 min using an uncoated fused‐silica capillary (50 μm internal diameter and 27.7 cm effective length) and a 500 mM Tris buffer containing 45% v/v methanol (titrated to pH^* 2.86 with H₃PO₄). The developed method was successfully applied to the quantification of seven alkaloids in Corydalis decumbens obtained from different regions of China. The combination of microwave‐assisted extraction with capillary electrophoresis was an effective method for the rapid analysis of the alkaloids in Corydalis decumbens .     

Efficient separation of tanshinones by polyvinylpyrrolidone‐stabilized graphene‐modified micellar electrokinetic chromatography

In this work, a PVP‐stabilized graphene was used in MEKC for the separation of tanshinones. Seven structurally similar tanshinones were studied, that is, tanshinone IIB, dihydrotanshinone I, tanshinone I, cryptotanshinone, 1,2‐dihydrotanshinone I, miltirone, and tanshinone IIA. To achieve optimal conditions, graphene concentration, sample solvent composition, SDS concentration, 2‐propanolconcentration, and buffer pH were investigated. At a separation voltage of 30 kV and a 41.5 cm effective length fused‐silica capillary, good resolution within 12 min was performed using 10 mM borate buffer (pH 9.3) containing 30 mM SDS, 10% v/v 2‐propanol and 6 μg/mL graphene. The method was validated in terms of linearity (r² > 0.9970), intra‐ and inter‐day precision were less than 3.56 and 4.83%, respectively. The proposed method was then successfully applied to Danshentong capsule, an herbal preparation from Salvia miltiorrhiza. Our results indicated the high separation efficiency of PVP‐stabilized graphene provided new opportunities for the analysis of complex samples.     

Development and validation of a chiral capillary electrophoresis method for assay and enantiomeric purity control of pramipexole

A rapid method for the enantioseparation of pramipexole and its R‐enantiomer has been developed by capillary electrophoresis. The influence of chemical and instrumental parameters was investigated including the type and concentration of chiral selectors, buffer composition and pH, co‐ions, applied voltage, capillary length and temperature. Optimal separation conditions were obtained using a 50 mM phosphate buffer (pH 2.8) containing 25 mM carboxymethyl‐β‐cyclodextrin on a fused‐silica capillary. Online UV detection was performed at 262 nm. A voltage of 25 kV was applied, and the capillary temperature was kept at 25°C. Hydrodynamic injection was performed at 3.45 kPa for 5.0 s. The separation of enantiomers was achieved in <6.5 min. The method was further validated in terms of stability of solutions, selectivity, linearity (both pramipexole and R‐enantiomer, R²>0.995), LOD and LOQ (0.91 and 2.94 μg/mL, respectively), repeatability (RSD<1.5%) and accuracy (pramipexole, 100.4%; R‐enantiomer, 100.5%). The proposed method was then applied to two kinds of pramipexole dihydrochloride monohydrate commercially available tablets, immediate release tablets (1.50 and 0.125 mg) and sustained release tablets (0.52 mg), to quantify the main component in the tablets. The amount of distomer could be quantified in bulk sample materials.     

Separation of chlorogenic acid and concentration of trace caffeic acid from natural products by pH‐zone‐refining countercurrent chromatography

Chlorogenic acid and caffeic acid were selected as test samples for separation by the pH‐zone‐refining countercurrent chromatography (CCC). The separation of these test samples was performed with a two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/water at a volume ratio of 4:1:5 v/v/v where trifluoroacetic acid (TFA; 8 mM) was added to the organic stationary phase as a retainer and NH₄OH (10 mM) to the aqueous mobile phase as an eluter. Chlorogenic acid was successfully separated from Flaveria bidentis (L.) Kuntze (F. bidentis) and Lonicerae Flos by pH‐zone‐refining CCC, a slightly polar two‐phase solvent system composed of methyl‐tert‐butyl‐ether/acetonitrile/n‐butanol/water at a volume ratio of 4:1:1:5 v/v/v/v was selected where TFA (3 mM) was added to the organic stationary phase as a retainer and NH₄OH (3 mM) to the aqueous mobile phase as an eluter. A 16.2 mg amount of chlorogenic acid with the purity of 92% from 1.4 g of F. bidentis, and 134 mg of chlorogenic acid at the purity of 99% from 1.3 g of crude extract of Lonicerae Flos have been obtained. These results suggest that pH‐zone‐refining CCC is suitable for the isolation of the chlorogenic acid from the crude extracts of F. bidentis and Lonicerae Flos.     

Development of an ultrasensitive stacking technique for 5‐nitroimidazole determination in untreated biological fluids by micellar electrokinetic chromatography

Cation‐selective exhaustive injection and sweeping followed by a MEKC separation is evaluated for the sensitive analysis of 5‐nitroimidazoles in untreated human serum and urine. Deproteinized serum and urine samples were diluted 76 and 143 times, respectively, in a low‐conductivity solvent (5.00 mM orthophosphoric acid containing 5.0% v/v methanol). Samples were electrokinetically injected at 9.8 kV for 632 s in a previously conditioned fused‐silica capillary (65.0 cm × 50 μm id). Separation was performed at –30 kV and 20°C using 44 mM phosphate buffer (pH 2.5), 123 mM SDS, and 8% v/v tetrahydrofurane as BGE. Signals were monitored at 276 nm and peak area was selected as analytical response. Good linearity (R² ≥ 0.988) and LODs lower than 1.5 and 1.8 μg/mL were achieved in serum and urine, respectively.     

Determination of malachite green in fish water samples by cloud‐point extraction coupled to cation‐selective exhaustive injection and sweeping‐MEKC

We have employed a high‐sensitivity off‐line coupled with on‐line preconcentration method, cloud‐point extraction (CPE)/cation‐selective exhaustive injection (CSEI) and sweeping‐MEKC, for the analysis of malachite green. The variables that affect CPE were investigated. The optimal conditions were 250 g/L of Triton X‐100, 10% of Na₂SO₄ (w/v), heat‐assisted at 60°C for 20 min. We monitored the effects of several of the CSEI‐sweeping‐MEKC parameters – including the type of BGE, the concentrations of SDS, the injection length of the high‐conductivity buffer, and the injection time of the sample – to optimize the separation process. The optimal BGE was 50 mM citric acid (pH 2.2) containing 100 mM SDS. In addition, electrokinetic injection of the sample at 15 kV for 800 s provided both high separation efficiency and enhanced sweeping sensitivity. The sensitivity enhancement for malachite green was 1.9×10⁴ relative to CZE; the coefficients of determination exceeded 0.9928. The LOD, based on an S/N of 3:1, of CSEI‐sweeping‐MEKC was 0.87 ng/mL; in contrast, when using off‐line CPE/CSEI‐sweeping‐MEKC the sensitivity increased to 69.6 pg/mL. This proposed method was successfully applied to determine trace amounts of malachite green in fish water samples.     

Simultaneous determination of atropine,scopolamine, and anisodamine in Flos daturae by capillary electrophoresis using a capillary coated by graphene oxide

A novel CE method was developed for the separation and determination of three main tropane alkaloids in Flos daturae with a capillary coated by graphene oxide (GO). The GO‐coated capillary was characterized by SEM, energy dispersive X‐ray spectroscopy, and Raman spectroscopy, and the results indicated that the inner surface of the capillary was partially coated by GO. A phosphate solution (40 mM, pH7.0) containing 20% v/v methanol and 30% v/v acetonitrile was used as the running buffer for the analysis of the atropine, scopolamine, and anisodamine. The linear ranges of atropine, scopolamine, and anisodamine was 0.5–200 μg/mL with satisfactory correlation coefficients (R²) > 0.9987, and this novel method provided an efficient separation for three tropane alkaloids as well as a good reproducibility and stability. Finally, the method was successfully applied for the determination of these three tropane alkaloids in plant extracts.     

Fast Determination of Clenbuterol and Salbutamol in Feed and Meat Products Based on Miniaturized Capillary Electrophoresis with Amperometric Detection

The fast separation capability of a novel miniaturized capillary electrophoresis with an amperometric detection (μCE‐AD) system was demonstrated by determining clenbuterol and salbutamol in real samples. The effects of several factors such as the acidity and concentration of the running buffer, the separation voltage, the applied potential and the injection time on CE‐AD were examined and optimized. Under the optimum conditions, the two β‐agonists could be baseline separated within 60 s at a separation voltage of 2 kV in a 90 mmol/L H₃BO₃‐Na₂B₄O₇ running buffer (pH 7.4), which was not interfered by ascorbic acid and uric acid. Highly linear response was obtained for above compounds over three orders of magnitude with detection limits ranging from 1.20×10^?7 to 6.50×10^?8 mol/L (S/N=3). This method was successfully used in the analysis of feed and meat products with relatively simple extraction procedures.     

Preparative separation of quaternary ammonium alkaloids from Corydalis yanhusuo W. T. Wang by pH-zone-refining counter-current chromatography

The optimal extraction condition for extracting quaternary ammonium alkaloid dehydrocorydaline from Corydalis yanhusuo W. T. Wang was investigated using orthogonal experimental design. pH‐zone‐refining counter‐current chromatography (CCC) with normal phase elution was successfully applied to preparative separation of alkaloids from the crude extract of Corydalis yanhusuo. The separation was performed with a biphasic solvent system composed of chloroform (CHCl₃)–methanol (MeOH)–water (2:1:1, v/v), in which the lower organic phase containing 10 mM of triethylamine was used as the mobile phase, while the upper aqueous phase containing 10 mM of hydrochloric acid was used as the stationary phase. The separation mechanism of quaternary ammonium alkaloids using pH‐zone‐refining CCC was discussed in comparison with standard high‐speed CCC. In the present study, the separation of 1.200 g of crude sample yielded 129 mg of dehydrocorydaline and 12 mg of palmatine at a high purity of 94 and 92%, respectively. Recovery for dehydrocorydaline and palmatine was 85 and 86%, respectively.     

Separation of catechins and methylxanthines in tea samples by capillary electrochromatography

In this paper, the simultaneous separation of several polyphenols such as (+)‐catechin, (–)‐epicatechin, (–)‐epigallocatechin, theophylline, caffeine in green and black teas by capillary electrochromatography (CEC) was developed. Several experimental parameters such as stationary phase type, mobile phase composition, buffer and pH, inner diameter of the columns, sample injection, were evaluated to obtain the complete separation of the analysed compounds. Baseline resolution of the studied polyphenols was achieved within 30 min by using a capillary column (id 100 μm) packed with bidentate C₁₈ particles for 24.5 cm and a mobile phase composed of 5 mM ammonium acetate buffer pH 4 with H₂O/ACN (80:20, v/v). The applied voltage and the temperature were set at 30 kV and 20°C. Precision, detection and quantification limits, linearity, and accuracy were investigated. A good linearity (R² > 0.9992) was achieved over a concentration working range of 2–100 μg/mL for all the analytes. LOD and LOQ were 1 and 2 μg/mL, respectively, for all studied compounds. The CEC method was applied to the analysis of those polyphenols in green and black tea samples after an extraction procedure. Good recovery data from accuracy studies ranged between 90% and 112% for all analytes.     

Determination of neonicotinoid insecticides in environmental samples by micellar electrokinetic chromatography using solid‐phase treatments

A sensitive and reliable method based on MEKC has been developed and validated for trace determination of neonicotinoid insecticides (thiamethoxam, acetamiprid, and imidacloprid) and the metabolite 6‐chloronicotinic acid in water and soil matrices. Optimum separation of the neonicotinoid insecticides was obtained on a 58 cm long capillary (75 μm id) using as the running electrolyte 40 mM SDS, 5 mM borate (pH 10.4), and 5% (v/v) methanol at a temperature of 25°C, a voltage of 25 kV and with hydrodynamic injection (10 s). The analysis time was less than 7 min. Prior to MEKC determination, the samples were purified and enriched by carrying out extraction‐preconcentration steps. For aqueous samples, off‐line SPE with a sorptive material such as Strata‐X (polymeric hydrophobic sorbent) and octadecylsilane (C₁₈) was carried out to clean up and preconcentrate the insecticides. However, for soil samples, matrix solid‐phase dispersion (MSPD) was applied with C₁₈ used as the dispersant. Good linearity, accuracy, and precision were obtained and the detection limits were in the range between 0.01 and 0.07 μg mL^?1 for river water and 0.17 and 0.37 μg g^?1 for soil samples. Recovery levels reached greater than 92% for all of the assayed neonicotinoids in river water samples with Strata‐X. In soil matrices, the best recoveries (63–99%) were obtained with MSPD.     

Rapid analysis of alkylphosphonate drugs by capillary zone electrophoresis using indirect ultraviolet detection

A rapid capillary electrophoretic method for the analysis of three alkylphosphonate drugs (i.e. fosfomycin disodium (FOS), clodronate disodium (CLO) and alendronate sodium (ALN)) was developed by using multiple probe BGE and indirect UV detection. BGE containing 30 mM benzoic acid, 5 mM salicylic acid and 0.5 mM CTAB (pH 3.8), temperature of 30°C, applied voltage of ?30 kV and detection at 220 nm provided baseline separation of all analytes (resolution (R)>2.2) in 3.2 min. EOF reversal by addition of CTAB and negative voltage polarity leading to the co‐EOF flow and short analysis time. Two probe BGE greatly improved peak symmetry. The method showed good linearity (r²>0.999 in ranges of 20–1000 μg/mL for FOS, 100–1000 μg/mL for CLO and 100–750 μg/mL for ALN) repeatablitiy (RSD<2.15%), recovery (99.3–101.1%) and sensitivity (LOD<50 μg/mL). Freshly prepared BGE and sample solutions are essential for the method precision and accuracy. This new method can be utilized for routine analysis of FOS, CLO and ALN in dosage forms because of its efficiency, reliability, speed and simplicity.     

Study of aldehyde oxidase by micellar electrokinetic chromatography separation of O6‐benzylguanine and 8‐oxo‐O6‐benzylguanine

A separation method for O⁶‐benzylguanine (O⁶‐BG) and 8‐oxo‐O⁶‐benzylguanine (8‐oxo‐O⁶‐BG) is developed by using MEKC. This study includes the optimization of separation and incubation parameters for both off‐line and on‐line procedures. The BGE consisted of 25 mM sodium phosphate buffer‐methanol (70:30, v/v), apparent pH 7.4, in which SDS and methyl‐β‐cyclodextrin were dissolved yielding final concentrations of 50 and 15 mM, respectively. Separations were performed at 15 kV using an untreated fused‐silica capillary (40 cm length, effective length is 30 cm) with the detection wavelength at 195 nm. The capillary was kept at 15°C. Good performances were demonstrated for the repeatability and linearity. The LOQ was determined to be 14 μM for 8‐oxo‐O⁶‐BG (S/N = 10). The accuracy values showed a bias of +7.9% for 50 μM and –7.0% for 100 μM. Premix and transverse diffusion of laminar flow profiles (TDLFP) methods were used for on‐line mixing and reaction of the substrate O⁶‐BG with aldehyde oxidase. Both procedures were successful in mixing as well as subsequent separation of the substrate and the metabolite, while the repeatability of TDLFP (14.7% (n = 3)) was much better than the premix technique.     

Polymer monolith microextraction online coupled to hydrophilic interaction chromatography/mass spectrometry for analysis of β2‐agonist in human urine

An analytical method based on online combination of polymer monolith microextraction (PMME) technique with hydrophilic interaction LC (HILIC)/MS is presented. The extraction was performed with a poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) monolithic column while the subsequent separation was carried out on a Luna silica column by HILIC. After 1:1 v/v dilution with 20 mM phosphate solution at pH 7.0 and centrifugation, urine sample was directly used for extraction. After optimization, 85% ACN (containing 0.3% formic acid v/v) was used for rapid online elution, which was also the mobile phase in HILIC to avoid band broadening during separation or carry‐over that was usually observed in PMME‐RP LC system. Online automation of extraction and separation procedures was realized under the control of a program in this study. The developed method was applied to rapid and sensitive monitoring of three β₂‐agonist traces in human urine. The LODs (S/N = 3) of the method were found to be 0.05–0.09 ng/mL of β₂‐agonists in urine. The recoveries of three β₂‐agonists spiked in five different urine samples ranged from 79.8 to 119.8%, with RSDs less than 18.0%.     

Capillary electrophoresis–electrochemiluminescence detection method for the analysis of ibandronate in drug formulations and human urine

A simple, rapid and sensitive CE method coupled with electrochemiluminescence (ECL) detection for direct analysis of ibandronate (IBAN) has been developed. Using a buffer solution of 20 mM sodium phosphate (pH 9.0) and a voltage of 13.5 kV, separation of IBAN in a 30‐cm length capillary was achieved in 3 min. ECL detection was performed with an indium tin oxide working electrode bias at 1.6 V (versus a Pt wire reference) in a 200‐mM sodium phosphate buffer (pH 8.0) containing 3.5 mM Ru(bpy)₃²⁺ (where bpy=2,2′‐bipyridyl). Derivatization of IBAN prior to CE‐ECL analysis was not needed. Linear correlation (r=0.9992, n=7) between ECL intensity and analyte concentration was obtained in the range of 0.25–50 μM IBAN. The LOD of IBAN in water was 0.08 μM. The developed method was applied to the analysis of IBAN in a drug formulation and human urine sample. SPE using magnetic Fe₃O₄@Al₂O₃ nanoparticles as the extraction phase was employed to pretreat the urine sample before CE‐ECL analysis. The linear range was 0.2–12.0 μM IBAN in human urine (r=0.9974, n=6). The LOD of IBAN in urine was 0.06 μM. Total analysis time including sample preparation was <1 h.     

Enantioseparation of rabeprazole and omeprazole by nonaqueous capillary electrophoresis with an ephedrine-based ionic liquid as the chiral selector

An ephedrine‐based chiral ionic liquid, (+)‐N,N‐dimethylephedrinium‐bis(trifluoromethanesulfon)imidate ([DMP]⁺[Tf₂N]^‐), served as both chiral selector and background electrolyte in nonaqueous capillary electrophoresis. The enantioseparation of rabeprazole and omeprazole was achieved in acetonitrile–methanol (60:40 v/v) containing 60 mm [DMP]⁺[Tf₂N]^‐. The influences of separation conditions, including the concentration of [DMP]⁺[Tf₂N]^‐, the electrophoretic media and the buffer, on enantioseparation were evaluated. The mechanism of enantioseparation was investigated and discussed. Ion‐pair interaction and hydrogen bonding may be responsible for the main separation mechanism. Copyright © 2010 John Wiley & Sons, Ltd.     

Capillary electrophoresis/mass spectrometry for the separation and characterization of bovine Cu,Zn‐superoxide dismutase

The native form of Cu,Zn‐superoxide dismutase (SOD‐1) is a homodimer that coordinates one Cu²⁺ and one Zn²⁺ per monomer. Cu²⁺ and Zn²⁺ ions play crucial roles in enzyme activity and structural stability, respectively. In addition, dimer formation is essential for SOD‐1 functionality, and in humans several SOD‐1 mutant isoforms have been associated with certain types of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disorder. In this paper we used capillary electrophoresis and mass spectrometry to study the different structures of bovine SOD‐1. The metal ions of the native enzyme (Cu₂,Zn₂‐dimer SOD‐1) were released in acidic medium in order to obtain apo‐SOD‐1, which is a monomer. Both substances were analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) and capillary electrophoresis with ultraviolet and electrospray ionization mass spectrometry detection (CE/UV and CE/ESI‐MS, respectively). With MALDI‐TOF‐MS, using matrices of sinapinic acid (SA) or 2,5‐dihydroxybenzoic acid (DHB) with or without trifluoroacetic acid (TFA), similar mass spectra were obtained for the metalated and non‐metalated samples. In both cases, an average molecular mass corresponding to the apo‐monomer SOD‐1 was calculated. This finding indicated that the metals were released from the Cu₂,Zn₂‐dimer SOD‐1 during sample preparation or ionization. For CE/UV and CE/ESI‐MS, two background electrolytes (BGEs) potentially compatible with ESI‐MS detection were used, namely 1 M of acetic acid (pH 2.3) and 10 mM of ammonium acetate (pH 7.3). Using a sheath liquid of 2‐propanol/water (60:40 v/v), with or without 0.1% v/v of formic acid, CE/ESI‐MS sensitivity was enhanced when the acidic BGE and the acidic sheath liquid were used. However, the electrophoretic profiles and the mass spectra obtained suggested that the metals of Cu₂,Zn₂‐dimer SOD‐1 were released, which generated the apo‐monomer during the electrophoretic separation. The neutral BGE provided enhanced conditions for the detection of the native enzyme. The differences between the mass spectra obtained for the Cu₂,Zn₂‐dimer and the apo‐monomer forms were significant and the presence of formic acid in the sheath liquid affected only sensitivity. Our results highlight the importance of selecting appropriate non‐denaturing separation and detection conditions to obtain reliable structural information about non‐covalent protein complexes by CE/ESI‐MS. Copyright © 2010 John Wiley & Sons, Ltd.     

Simple and fast analysis of iohexol in human serums using micro‐hydrophilic interaction liquid chromatography with monolithic column

A simple and rapid method based on micro‐liquid chromatography using a synthetic monolithic capillary column was developed for determination of iohexol in human serums, a marker to evaluate the glomerular filtration rate. A hydrophilic methacrylic acid‐ethylene dimethacrylate monolith provided excellent selectivity and efficiency for iohexol with separation time of 3 min using a mobile phase of 40:60 v/v 50 mM phosphate buffer pH 5/methanol. Four serum protein removal, methods using perchloric acid, 50% acetonitrile, 0.1 M zinc sulfate, and centrifuge membrane filter were examined. The method of zinc sulfate was chosen due to its simplicity, compatibility with the mobile phase system, nontoxicity, and low cost. Interday calibration curves were conducted over iohexol concentrations range of 2–500 mg/L (R² = 0.9997 ± 0.0001) with detection limit of 0.44 mg/L. Intra‐ and interday precisions for peak area and retention time were less than 2.8 and 1.4%, respectively. The method was successfully applied to serum samples with percent recoveries from 102 to 104. The method was applied to monitor released iohexol from healthy subject. Compared with the commercially available reversed‐phase high‐performance liquid chromatography method, the presented method provided simpler chromatogram, faster separation with higher separation efficiency and much lower sample and solvent consumption.     

Separation and determination of honokiol and magnolol in herbal medicines by flow injection-capillary electrophoresis

A simple, rapid, and accurate method for the separation and determination of honokiol and magnolol in Magnolia officinalis and related herbal medicines was developed by combination of flow injection (FI) and capillary zone electrophoresis (CZE). The analysis was carried out using an unmodified fused-silica capillary (50-μm I.D.; total length 7.5 cm; effective length 4.5 cm). A series of optimization steps afforded the following conditions: the sample solvent consisted of 150 mM NaOH and a running buffer composed of 10 mM sodium tetraborate/10 mM sodium dihydrogenphosphate (NaH₂PO₄) at pH 12 was applied for the separation of the analytes. The separation could be achieved within 5 min with a sample throughput rate of up to 28 h⁻¹. The repeatability (defined as the relative standard deviation, RSD) for honokiol and magnolol was 2.0% and 1.6% with peak area evaluation, 3.6% and 2.0% with peak height evaluation, and 2.0% and 1.4% with migration time evaluation, respectively. Regression equations revealed linear relationships (r = 0.9991–0.9998) between the peak area of each analyte and the concentration.     

CE method for analyzing Salmonella typhimurium in water samples

Salmonella typhimurium is commonly described as a food‐borne pathogen. However, natural and drinking water are known to be important sources for the transmission of this pathogen in developing and developed countries. The standard method to determine Salmonella is laborious and many false positives are detected. To solve this, the present work was focused on the development of a capillary zone electrophoresis method coupled to ultraviolet detection for determination of Salmonella typhimurium in water (mineral and tap water). Separations were performed in less than 11 minutes using 4.5 mM Tris (hydroxymethyl)‐aminomethane, 4.5 mM boric acid and 0.1 mM ethylene diamine tetraacetate (pH 8.4) with 0.1% v/v poly ethylene oxide as separation buffer. The precision of the method was evaluated in terms of repeatability obtaining a relative standard deviation of 10.5%. Using the proposed method Salmonella typhimurium could be separated from other bacteria that could be present in water such as Escherichia coli. Finally, the proposed methodology was applied to determine Salmonella typhimurium in tap and mineral water.