A rapid and reliable assay to determine flumequine, marbofloxacin, difloxacin, and sarafloxacin in commonly consumed meat by micellar liquid chromatography.

BACKGROUND: Micellar liquid chromatography - fluorescence detection was used to determine the antibiotics flumequine, marbofloxacin, difloxacin, and sarafloxacin in porcine, bovine, poultry, ovine, caprine, rabbit, and equine meat, to verify compliance with EU Regulation 37/2010 with regard to the occurrence of veterinary drugs in food. RESULTS: The analytes were isolated from the matrix by ultrasonication-assisted leaching in a micellar solution, and the supernatant was filtered and directly injected. The fluoroquinolones were resolved in < 19 min using a C18 column, with an isocratic mobile phase of 0.05 mol L-1 sodium dodecyl sulfate - 8% 1-butanol - 0.5% triethylamine buffered at pH 3. The limits of quantification (0.01-0.05 mg kg-1 ) were below the maximum residue limits (0.15-0.4 mg kg-1 ). The method was validated by EU Commission Decision 2002/657/EC guidelines. CONCLUSION: The method shows practical advantages such as simplicity, low cost, eco-friendliness, safety, and applicability for routine analysis, and is useful for surveillance programs. © 2018 Society of Chemical Industry.

Validation of a procedure to quantify oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin in selected meats by micellar liquid chromatography according to EU Commission Decision 2002/657/EC.

The suitability of an analytical method to determine oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin in edible tissues, based on micellar liquid chromatography coupled with fluorescence detection, to be applied in chicken, turkey, duck, lamb, goat, rabbit and horse muscle, is described. The method was fully matrix-matched in-lab revalidated, for each antimicrobial drug and meat, following the guidelines of the EU Commission Decision 2002/657/EC. The permitted limits were the maximum residue limits stated by the EU Commission Regulation 37/2010. The results obtained for the studied validation parameters were in agreement with the guidelines: selectivity (the antibiotics were resolved), linearity (r2  > 0.995), limit of detection (0.004-0.02 mg/kg), limits of quantification (0.01-0.05 mg/kg), calibration range (up to 0.5 mg/kg), recovery (89.5-105.0%), precision (<8.3%), decision limit, detection capability, ruggedness, stability and application to incurred samples. The method was found to be able to provide reliable concentrations with low uncertainty within a large interval, including the maximum residue limits, and then was useful to find out prohibited contaminated samples. The method did not require to be adapted for these matrices, and then it maintained its interesting advantages: short-time, eco-friendly, safe, inexpensive, easy-to-conduct, minimal manipulation and useful for routine analysis.

Determination of diuron, terbuthylazine, and terbutryn in wastewater and soil by micellar liquid chromatography.

An analytical method for the quantification of the herbicides and algaecides diuron, terbuthylazine, and terbutryn in wastewater and soil by micellar liquid chromatography was developed. The sample preparation was expedited to reduce the number of intermediate steps and the use of chemicals. The analytes in soils were recovered by ultrasonication in the mobile phase. The obtained supernatant and the water samples were directly injected, thus avoiding intermediate steps. The chromatographic behavior of the analytes, depending on the surfactant and alcohol was studied, in order to optimize the chromatographic run, by a chemometrical approach. The herbicides were resolved in <16 min using a C18 column and a mobile phase of 0.07 M sodium dodecyl sulfate/6% 1-pentanol phosphate buffered at pH 3, running under isocratic mode at 1 mL/min. The detection absorbance wavelength was set to 240 nm. The method was successfully validated in terms of selectivity, detection limit (0.06 mg/L in water and 0.3 mg/kg in soil), quantitation range (0.2-2 mg/L in water and 1-10 mg/kg in soil), trueness (-6.1 to +5.0%), precision (<9.4%), and ruggedness (<8.3%). The procedure was reliable, practical, easy-to-handle, available, short-time and ecofriendly and useful for routine analysis. Its applicability to real samples was evaluated by analyzing several wastewater, decorative reservoir, and soil samples from agricultural and urban sources.

Development and validation of a method to determine thiabendazole and o-phenylphenol in wastewater using micellar liquid chromatography-fluorescence detection.

A micellar liquid chromatographic method to determine thiabendazole (TBZ) and o-phenylphenol in wastewater is described here. The sample was directly injected without any additional treatment other filtration. The pesticides were resolved in <11 min, using a mobile phase of 0.10 M SDS-6% 1-pentanol buffered at pH 3 running through a C18 column at 1 mL/min. The detection was performed by fluorescence at 305/360 and 245/345 nm excitation/emission wavelengths for TBZ and o-phenylphenol, respectively. The method was validated following the directives of the Validation and Peer Review of U.S. Environmental Protection Agency Chemical Methods of Analysis guidelines in terms of selectivity, quantitation range (0.01-0.02 to 2 mg/L), detection limit (0.005-0.008 mg/L), trueness (92.1-104.2%), precision (<13.9%), robustness (<6.6%), and stability under storage conditions. The procedure was applied to the screening of TBZ and o-phenylphenol in wastewater samples from citrus packing plants, agricultural gutters, urban sewage, as well as in influent and effluent wastewater treatment plants.

Use of micellar liquid chromatography for rapid monitoring of fungicides post harvest applied to citrus wastewater.

A method based on micellar liquid chromatography has been developed to simultaneously monitor four pesticides largely post-harvest applied to citrus: thiabendazole, pyrimethanil, o-phenylphenol and imazalil. Water samples were filtered and directly injected without other treatment, thus avoiding extraction steps. The composition of the mobile phase was optimized using a chemometrical approach to achieve and excellent resolution to 0.07 mol/L SDS/5%, V/V 1-pentanol buffered at pH3. Mobile phase run through a C18 column at 1 mL/min at room temperature. The detection was performing by UV-Visible absorbance using a wavelength program: 0-10 min, 305 nm (for thiabendazole); 10-12; 265 nm (for pyrimethanil) and 12-18, 220 nm (o-phenylphenol and imazalil). The developed method was validated following the guidelines of the US Environmental Protection Agency in terms of: quantitation range, (0.5-4 to 15 µg/mL), linearity (r(2)>0.9995), sensitivity (LOD, 0.18-1.4 µg/mL), precision (<9.2%), trueness (93.9%-103.7%), and ruggedness (<9.9%). It was found that the fungicides remain up to eight days in surface water at outdoor conditions. The method was used to screen the presence of the analytes in several waste water samples, and was proved to be useful in routine analysis.

Analysis of thiabendazole, 4-tert-octylphenol and chlorpyrifos in waste and sewage water by direct injection ­ micellar liquid chromatography.

A micellar liquid chromatographic method has been developed for the simultaneous quantification of the pesticides thiabendazole and chlorpyrifos, as well as an alkylphenol, which is included in pesticide formulations, i.e., 4-tert-octylphenol, in water. A sample was filtered and directly injected, avoiding large extraction steps using toxic solvents, thus expediting the experimental procedure. The contaminants were eluted without interferences in <17 min, using a mobile phase of 0.15 M sodium dodecyl sulfate ­ 6% 1-pentanol buffered at pH 3, running through a C18 column at 1 mL min(-1) under the isocratic mode. This optimal mobile phase was selected using a statistical approach, which considers the retention factor, efficiency and peak shape of the analytes measured in only a few mobile phases. The detection was carried out by measuring absorbance at 220 nm. The method was successfully validated in terms of specificity, calibration range (0.5-10 mg L(-1)), linearity (r(2) > 0.994), limit of detection and quantification (0.2-0.3; and 0.5-0.8 mg L(-1), respectively), intra- and interday accuracy (95.2-102.9%), precision (<8.3%), and ruggedness (<9.3%). The stability in storage conditions (at least 14 days) was studied. The method was safe, inexpensive, produced little pollutant and has a short analysis time, thus it is useful for the routine analysis of samples. Finally, the method was applied to analyse wastewater from the fruit-processing industry, wastewater treatment plants, and in sewage water belonging to the Castelló area (Spain). The results were similar to those obtained by an already reliable method.

Analysis of epinephrine, norepinephrine, and dopamine in urine samples of hospital patients by micellar liquid chromatography.

An analytical method based on micellar liquid chromatography was developed to determine the concentration of three catecholamines (epinephrine, norepinephrine, and dopamine) in urine. The detection of these compounds in urine can be useful to diagnose several diseases, related to stress and sympathoadrenal system dysfunction, using a non-invasive collection procedure. The sample pretreatment was a simple dilution in a micellar solution, filtration, and direct injection, thus avoiding time-consuming and tedious extraction steps. Therefore, there is no need to use an internal standard. The three catecholamines were eluted using a C18 column and a mobile phase of 0.055 M sodium dodecyl sulfate-1.5% methanol buffered at pH 3.8 running at 1.5 mL/min under isocratic mode in less than 25 min. The detection was performed by amperometry applying a constant potential of +0.5 V. The procedure was validated following the guidelines of the European Medicines Agency in terms of the following: calibration range (0.09-5 µg/mL), linearity (r(2) > 0.9995), limit of detection (0.02 µg/mL), within- and between-run accuracy (-6.5 to +8.4%) and precision (<10.2%), dilution integrity, matrix effect, robustness (<8.4), and stability. The obtained values were below those required by the guide. The method was rapid, easy-to-handle, eco-friendly, and safe and provides reliable quantitative data, and is thus useful for routine analysis. The procedure was applied to the analysis of epinephrine, norepinephrine, and dopamine in urine samples from patients of a local hospital.

Use of micellar liquid chromatography to analyze darunavir, ritonavir, emtricitabine, and tenofovir in plasma.

Danuravir, ritonavir, emtricitabine, and tenofovir are together prescribed against AIDS as a highly active antiretroviral therapy regimen. Micellar liquid chromatography has been applied to determine these four antiretroviral drugs in plasma. The sample preparation is shortened to the dilution of the sample in a micellar solution, filtration, and injection. Clean-up steps are avoided, due to the solubilization of plasma matrix in micellar media. The drugs were analyzed in <20 min using a mobile phase of 0.06 M sodium dodecyl sulfate/2.5% 1-pentanol (pH 7) running under isocratic mode through a C18 column at 1 mL/min at room temperature. Absorbance wavelength detection was set at 214 nm. The method was successfully validated following the ICH Harmonized Tripartite Guideline in terms of selectivity, limit of detection (0.080-0.110 µg/mL), limit of quantification (0.240-0.270 µg/mL), linearity between 0.25 and 25 µg/mL (r(2) > 0.995), accuracy (89.3-103.2%), precision (<8.2%) and robustness (<7.5%). Real plasma sample from patients taking this therapy were analyzed. This is the first paper showing the simultaneous detection of this four drugs. Therefore, the methodology was proven useful for the routine analysis of these samples in a hospital laboratory for clinical purposes.

Quantification of melamine in drinking water and wastewater by micellar liquid chromatography.

Because of the large potential health impact caused by deliberate contamination with the synthetic chemical melamine of different products for human and animal consumption, the World Health Organization and the Food and Agriculture Organization of the United Nations provided a range of recommendations in order to facilitate obtaining needed data, among which was the determination of the background levels of melamine in drinking water and wastewater (December 4, 2008). A chromatographic procedure using a C18 column, a micellar mobile phase consisting of sodium dodecyl sulfate (0.1 M), and 1-propanol (7.5%) buffered at pH 3, and detection by absorbance at 210 nm is reported in this paper for the quantification of melamine in drinking water and wastewater. Samples were filtered and directly injected into the chromatographic system, thus avoiding an extraction procedure. The optimal mobile phase composition was obtained by a chemometrics approach that considered the retention factor, efficiency, and peak shape. Melamine was eluted in about 6.2 min without interferences. Validation was performed following U.S. Food and Drug Administration guidelines. The analytical parameters studied were linearity (0.03-5 microg/mL, R2 = 0.998), LOD (13 nglmL), intraday and interday accuracy (between 4.1 and 12.2%), intraday and interday precision (less than 14.8%), and robustness (RSD < 5.1% for retention time and <9.0% for area). The proposed methodology was successfully applied for analysis of local wastewater and drinking water, in which no melamine was found.

Use of micellar mobile phases for the chromatographic determination of melamine in dietetic supplements.

Melamine is a nitrogen-rich industrial chemical which is occasionally used to increase the apparent protein content of different products destined for human and animal consumption. In this work, a liquid chromatographic procedure that uses micellar mobile phases of sodium dodecyl sulfate (SDS) buffered at pH 3, a C18 column and UV detection is reported for the determination of melamine in dietetic supplements. Samples were reconstituted with a SDS solution and were directly injected, thus avoiding long extraction and experimental procedures. Melamine was eluted in less than 10 min with no interference by other compounds of the matrices. The optimum mobile phase composition was taken by a chemometrical approach that considers the retention factor, efficiency and peak shape. Validation was performed following the indications of the European Commission (Decision 2002/657/EC). The following parameters were considered: linearity (0.02-100 µg mL(-1); R(2) = 0.9996), intra- and inter-day precisions (<12.4%), accuracy (90.0-101.3%), and robustness (less than 9.8% and 5.1%, for retention time and peak area, respectively). The limits of detection and quantification were 9 and 20 ng mL(-1), respectively. Recoveries for several spiked samples were in the 85.8-114.3% range. These results indicate that the proposed methodology is useful for routine analysis of control quality of infant formula and adult dietetic supplements.

Development and validation of micellar liquid chromatographic methods for the determination of antibiotics in different matrixes.

Antibiotics are the most important bioactive and chemotherapeutic compounds to be produced by microbiological synthesis, and they have proved their worth in a variety of fields, such as medicinal chemistry, agriculture, and the food industry. Interest in antibiotics has grown in parallel with an increasingly high degree of productivity in the field of analytical applications. Therefore, it is necessary to develop chromatographic procedures capable of determining various drugs simultaneously in the shortest possible time. Micellar liquid chromatography (MLC) is an RP-HPLC technique that offers advantages over conventional HPLC as far as sample preparation, selectivity, and versatility are concerned. Its main advantage is that samples can be injected directly into the chromatographic system with no previous preparation step. This paper mainly focuses on the results of the authors' own recent research and reports the chromatographic conditions for determination of various antibiotics (penicillins, quinolones, and sulfonamides) in different matrixes (pharmaceuticals, biological fluids, and food). The work of other authors on MLC-based antibiotic determination has been included.

Determination of disulfiram by micellar liquid chromatography in illicit preparations.

Presently, disulfiram is used in aversion therapy for recovering alcoholics. It acts by inhibiting aldehyde dehydrogenase, leading to high blood levels of acetaldehyde. A simple direct injection micellar liquid chromatographic procedure was developed to determine disulfiram in illicit preparations (ayurvedic, herbal, divine ash, and traditional medicine), as well as in pharmaceuticals and biological samples (urine). After application of a predictive optimization strategy, the proposed method was developed using a 0.1 M sodium dodecyl sulfate-butanol 4% (v/v) buffered to pH 7 as the mobile phase at a flow rate of 1 mL/min, an octyl silyl (C8) 150 mm column, and diode array detection at 248 nm. Under the above conditions, the analysis time was below 8 min. Validation studies were based on U.S. Food and Drug Administration guidelines. The LOD (3 x SD criterion) was 15 ng/mL and LOQ (10 x SD criterion) was 70 ng/mL for disulfiram. The intraday and interday precisions were below 3.5%, recoveries were in the range of 97-102%, and robustness was below 3%. The optimized and validated micellar liquid chromatographic method was successfully applied to the determination of disulfiram in ayurvedic, herbal, divine ash, and other samples. The procedure developed could also be used in the fields of QC, routine analysis, and pharmacokinetic studies.

Monitoring disopyramide, lidocaine, and quinidine by micellar liquid chromatography.

A micellar liquid chromatography (MLC) method using a C18 column was developed to determine three antiarrhythmic drugs--disopyramide, lidocaine, and quinidine--that are most usually monitored in serum samples. After the application of an interpretative strategy for optimization of sodium dodecyl sulfate (SDS) and modifier concentrations in order to ensure the minimum analysis time, maximum sensitivity, and good resolution, the optimum chromatographic conditions for the determination of the three antiarrhythmics were flow rate, 1 mL/min; injection volume, 20 microL; separation temperature, 25 degrees C; mobile phase, 150 mmol/L SDS-7% (v/v) butanol-phosphate buffer, 10 mmol/L, pH 7-0.9% (w/v) NaCl; and detection at 214 nm. The calibration curves for the drugs were linear (r2 > 0.999). The intraday and interday precisions were lower than 3.9% (CV). Recoveries were 100 +/- 0.6% when the method was applied to both serum samples spiked with the antiarrhythmics (n = 10) and real serum samples. In all cases, the results were similar to those obtained using the reference method (fluorescence polarization immunoassay) usually used in the Spanish hospital. The proposed method is useful for hospital monitoring of the antiarrhythmics by direct injection into the chromatograph.

Tamoxifen monitoring studies in breast cancer patients by micellar liquid chromatography.

A simple micellar liquid chromatographic procedure is described to determine tamoxifen in plasma. To perform the analysis, tamoxifen solutions were diluted in water and UV-irradiated for 20 min to form the photocycled derivative with a phenanthrene core which shows intense fluorescence. Samples were then directly injected, thus avoiding long extraction and experimental procedures. The resolution from the matrix was performed with a mobile phase containing 0.15 M SDS-7% n-butanol at pH 3 running at 1.5 mL/min through a C18 column at 40 degrees C. Detection was carried out by fluorescence, and the excitation and emission wavelengths were 260 and 380 nm, respectively. The chromatographic analysis time was less than 15 min. The analytical methodology was validated following the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines. The response of the drug in plasma was linear and in the 0.5-15 microg/mL range, with r(2) > 0.999. Accuracy and precision were <9% in both cases. The limits of detection and quantification (in nanograms per millilitre) were 50 and 150 in plasma, respectively. The method developed herein shows no interferences by endogenous compounds. Finally, the analytical method was used to determine the amount of tamoxifen in the plasma of several breast cancer patients from a local hospital.

Use of Micellar Liquid Chromatography to Determine Mebendazole in Dairy Products and Breeding Waste from Bovine Animals.

Mebendazole is an anthelmintic drug used in cattle production. However, residues may occur in produced food and in excretions, jeopardizing population health. A method based on micellar liquid chromatography (MLC) was developed to determine mebendazole in dairy products (milk, cheese, butter, and curd) and nitrogenous waste (urine and dung) from bovine animals. Sample treatment was expedited to simple dilution or solid-to-liquid extraction, followed by filtration and direct injection of the obtained solution. The analyte was resolved from matrix compounds in less than 8 min, using a C18 column and a mobile phase made up of 0.15 M sodium dodecyl sulfate (SDS)-6% 1-pentanol phosphate buffered at pH 7, and running at 1 mL/min under isocratic mode. Detection was performed by absorbance at 292 nm. The procedure was validated according to the guidelines of the EU Commission Decision 2002/657/EC in terms of: specificity, method calibration range (from the limit of quantification to 25-50 ppm), sensitivity (limit of detection 0.1-0.2 ppm; limit of quantification, 0.3-0.6 ppm), trueness (92.5-102.3%), precision (<7.5%, expressed at RSD), robustness, and stability. The method is reliable, sensitive, easy-to-handle, eco-friendly, safe, inexpensive, and provides a high sample-throughput. Therefore, it is useful for routine analysis as a screening or quantification method in a laboratory for drug-residue control.

Determination of the insecticide imidacloprid in fruit juices using micellar high-performance liquid chromatography.

A simple and reliable HPLC method was developed to determine imidacloprid, a chloronicotinyl insecticide that has a highly specific affinity to the nicotinic acetylcholine receptor of insects, above its permissible limit of consumption in fruit juices (orange, apple, and a mixture of pineapple and pear). Samples were injected directly into a Kromasil C18 column, without any pretreatment step, using the micellar mobile phase 0.10 M sodium dodecyl sulfate and 2.5% (v/v) propanol buffered at pH 7 and UV detection at 210 nm. Under these conditions, imidacloprid was eluted in < 4 min with no interference by the endogenous compounds of the juice fruits. The analytical parameters' linearity (r > 0.9998) and intraday and interday precision (RSD 0.1-2.8 and 0.07-7%, respectively) were obtained in the method validation. LOD and LOQ were calculated to be 0.4 and 1.5 ng/mL, respectively. Recoveries were in the 98-103% range. The simplicity of the method makes it a good candidate for application in routine analysis in the area of food control and quality evaluation.

Micellar liquid chromatography determination of rivaroxaban in plasma and urine. Validation and theoretical aspects.

A Micellar Chromatographic method to determine rivaroxaban in plasma and urine has been developed. The samples were dissolved in the mobile phase (SDS 0.05 M - 1-propanol 12.5%, phosphate buffered at pH 7) and 20 µL directly injected, avoiding the extraction and purification steps. Using a C18 column and running under isocratic mode at 1 mL/min, analyte was eluted without interference from the matrix in <6.0 min. The detection absorbance wavelength was set to 250 nm. The procedure was validated by Food and Drug Administration guidelines in terms of: system suitability, calibration range (0.05-5 mg/L), linearity, sensitivity, robustness, carry-over effect, specificity, accuracy (-11.1 to 4.2%), precision (<19.9%), stability and analysis of incurred samples. The method was found reliable, practical, easy-to-conduct, rapid, relatively eco-friendly, safe, inexpensive, widely available and with a high sample throughput. The method was applied to the analysis of incurred samples, including incurred sample reanalysis, to verify that the instrumentation works correctly. In addition, the constants of the different partition equilibria occurring in the column were elucidated in order to have a better comprehension of the theoretical aspects of the retention mechanism. A moderately strong association between rivaroxaban and the stationary phase and the micelles was found, weakened by short chain alcohol.

Stability studies of rifampicin in plasma and urine of tuberculosis patients according to the European Medicines Agency Guidelines.

Aim: The macrolide antibiotic rifampicin is prescribed against several infections, like tuberculosis disease. This drug decays to rifampicin quinone. Results/methodology: The biological fluids were diluted in a micellar solution and directly injected. Using a C18 column and a mobile phase of 0.15 M SDS-6% 1-pentanol phosphate-buffered at pH 7, running at 1 ml/min, the analytes were resolved in less than 15 min. The detection was by absorbance at 337 nm. Method was validated by the guidelines of the European Medicines Agency. Decomposition of rifampicin to rifampicin quinone was also studied. Discussion/conclusion: Procedure is rapid, easy-to-handle, economic, eco-friendly and with a high sample throughput. It was successfully used to monitor rifampicin in the plasma and urine of tubercular patients.

Procedure for the Screening of Eggs and Egg Products to Detect Oxolonic Acid, Ciprofloxacin, Enrofloxacin, and Sarafloxacin Using Micellar Liquid Chromatography.

A method based on micellar liquid chromatography was developed to determine oxolinic acid, ciprofloxacin, enrofloxacin, and sarafloxacin in eggs and egg products. The antimicrobial drugs were obtained in a micellar solution which was directly injected. The analytes were resolved using a C18 column and a mobile phase of 0.05 M sodium dodecyl sulfate-7.5% 1-propanol-0.5% triethylamine, buffered at pH 3 with phosphate salt, running under the isocratic mode. The signal was monitored by fluorescence. Validation was successfully performed according to the EU Commission Decision 2002/657/EC in terms of specificity, calibration range (LOQ to 1 mg/kg), linearity (R2 > 0.9991), limit of detection and decision limit (0.01-0.05 mg/kg), limit of quantification (0.025-0.150 mg/kg), detection capability (<0.4 times decision limit), trueness (-14.2% to +9.8%), precision (<14.0%), robustness, and stability. The procedure was environmentally friendly, safe, easy-to-conduct, inexpensive, and had a high sample throughput, thus it is useful for routine analysis as a screening method in a laboratory for food residue control.

Anserine and carnosine determination in meat samples by pure micellar liquid chromatography.

Anserine and carnosine, which are both imidazole dipeptides, are natural antioxidants that are present in some types of meat. A pure micellar liquid chromatographic procedure was developed using a micellar mobile phase of 0.10 M sodium dodecyl sulphate buffered at pH 7, an amino column and UV detection. Three types of stationary phases (C18, phenyl and amino columns) were examined and the procedure was used to determine the two compounds in meat samples. They were completely resolved without any interference from the protein band. Total analysis time was 12 min. The limits of detection (ng/mL) were 71 and 53 for anserine and carnosine, respectively. Calibration curves were constructed on three different days (r>0.998). Repeatability and intermediate precision were evaluated at three different concentrations in meat matrices, the residual standard deviations being below 2.1%. Meat samples of poultry, pork and beef were injected directly into the chromatographic system after extraction in a sodium dodecyl sulphate solution and filtration. The possibility of direct injection using micellar liquid chromatography reduces the cost and time of analyses, and decreases error sources owing to minimised risks of losses and chemical changes in the analytes. Moreover, the selection of a pure mobile phase of sodium dodecyl sulphate allows this procedure to offer a number of advantages, such as non-toxicity, non-flammability, biodegradability and low cost, in comparison with aqueous-organic solvents. Its simplicity, then, makes it a good candidate for application in routine analysis in the area of food control and quality.