Biomedical subjects

Petr Solich

Publications and source records attributed to Petr Solich.

18 recordsLinked to original sources

PubMed2006

Determination of estradiol and its degradation products by liquid chromatography.

A novel HPLC method for simultaneous determination of estradiol and its seven degradation products in topical gel was developed. Zorbax SB-CN (150 mm x 4.6 mm, 5 microm) analytical column and mobile phase composed of acetonitrile, phosphoric acid 0.085%, and tetrahydrofurane (27:63:10, v/v/v) at flow-rate 1.0 ml min(-1) were used for the chromatographic separation using UV detection at 225 nm. The active substance estradiol was separated from all its known degradation products successfully. Two degradation products estrone and Delta(9(11))-estrone were not separated sufficiently, their peaks were evaluated as a sum of two components. The method was validated according to ICH guideline recommendations and thereafter it was successfully applied for stability tests of topical cream Estrogel HBF in the quality control laboratory. Limits of detection for degradation products ranged from 1.03 x 10(-5) to 1.14 x 10(-4) mg ml(-1), limits of quantitation for degradation products were in the range 3.43 x 10(-5) to 3.81 x 10(-4) mg ml(-1). The developed method is selective, precise, accurate and sensitive enough for determination of estradiol and its known degradation products.

Chromatography, High Pressure Liquid↗

PubMed2006

Advantages of ultra performance liquid chromatography over high-performance liquid chromatography: comparison of different analytical approaches during analysis of diclofenac gel.

Miniaturization embracing instrumentation, column particle size, and column dimensions is one of the major current trends in separation techniques. This leads to shortening of analysis time and great savings in solvent consumption. Ultra performance liquid chromatography (UPLC) is one of the new developments in liquid chromatography. An ultra-high pressure system allows using of small particle-packed columns with small diameter, which has a positive effect on both system efficiency and analysis time. An analytical method for determination of the active substance diclofenac, the degradation product 1-(2,6-dichlorphenyl)-2-indolinone, and the preservatives methylparaben and propylparaben was used for testing and comparing LC systems. Various octadecylsilica-based analytical columns were examined. Acquity UPLC BEH C18 (2.1 x 50 mm, 1.7 microm) and (2.1 x 100 mm, 1.7 microm) were tested for UPLC. The following analytical columns were used in a test for HPLC: Purospher RP 18e (125 x 4.0 mm, 5 microm), Zorbax Eclipse XDB C18 (75 x 4.6 mm, 3.5 microm), Zorbax Eclipse SB C18 (50 x 4.6 mm, 1.8 microm), as was a monolithic column (Chromolith Performance RP-18e (100 x 4.6 mm). Results of a System Suitability Test (SST) were calculated and compared for each chromatographic peak. System efficiency and analysis duration were compared with regard to solvent consumption and system maintenance

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2006

Development and validation of a liquid chromatography method for the simultaneous determination of alpha-tocopherol, retinol and retinyl esters in human serum using a monolithic column for the monitoring of anticancer therapy side effects.

Among other side effects, administration of anticancer agents is accompanied by manifestations of gastrointestinal toxicity and disturbances of antioxidant balance. The monitoring of these toxic effects in clinical practice is impeded by a dearth of reliable laboratory methods. Therefore, a simple and rapid reversed-phase high-performance liquid chromatography procedure for selective and sensitive determination of retinol, a-tocopherol, and retinyl esters (retinyl-palmitate and retinyl-stearate) in blood serum has been developed and presented in this study. A Series 200 LC HPLC instrument from Perkin Elmer (Norwalk, USA) with diode-array detector (DAD) was used for the analysis. Separations of retinol, alpha-tocopherol, retinyl-palmitate, and retinyl-stearate were performed using a Chromolith Performance RP-18e, 100 x 4.6 mm monolithic column from Merck (Darmstadt, Germany). Gradient elution was used at a flow rate of 3 mL/min; the mobile phase was methanol-water (95:5, v/v) for 0-2.1 min and methanol-2-propanol (60:40, v/v) for 2.1-4.9 min. The total time of analysis was 6 min. The injection volume was 20 microL and the analysis was performed at ambient temperature. Detection of retinol, alpha-tocopherol, and retinyl esters was carried out at 325, 295, and 330 nm, respectively. For practical assessment of the method, the vitamin A absorption test was performed on seven healthy controls as well as on six patients with non-small cell lung carcinoma or head and neck carcinoma previously treated by chemotherapy and/or radiotherapy, six patients with rectal carcinoma before chemoradiotherapy, four patients with gastrointestinal stromal tumor (GIST) before treatment with imatinib, and a breast cancer patient with chemotherapy-induced diarrhea. Present data demonstrate the feasibility of large scale HPLC determination of vitamin E, vitamin A, and retinyl esters in human serum using a silica monolithic column, and this method may represent a valuable aid in the laboratory monitoring of the toxicity of anticancer therapy.

Absorption↗

PubMed2006

Simple determination of betamethasone and chloramphenicol in a pharmaceutical preparation using a short monolithic column coupled to a sequential injection system.

This contribution describes the use of a new separation method based on a reversed-phase sequential injection chromatography (SIC) technique for simultaneous determination of chloramphenicol and betamethasone in pharmaceutical eye drops. A short monolithic column coupled with a sequential injection analysis (SIA) system enabled separation of two compounds in one step. A Chromolith Flash RP-18e, 25 x 4.6 mm column with a 5 mm precolumn (Merck, Germany) and a FIA1ab 3000 system (USA) with a 6-port selection valve and 5 mL syringe were used for sequential injection chromatographic separations in this study. The mobile phase used was acetonitrile-water (30:80, v/v), flow rate 0.48 mL/min; UV detection was at two wavelengths, i.e., 241 and 278 nm (absorption maxima of betamethasone and chloramphenicol, respectively). The basic validation parameters showed good results: linearity of determination for both compounds including internal standard (propylparaben) >0.999; repeatability of determination (RSD) in the range 0.8-1.7% at two different concentration levels, and detection limits in the range 0.5-1.0 mg/mL. The chromatographic resolution between compound peaks was greater than 2.1 and the analysis time was less than 8 min under optimal conditions. The developed sequential injection chromatography method was compared with the HPLC method and was found to be applicable for routine analysis of active compounds in pharmaceutical preparations.

Betamethasone↗

PubMed2005

Development and validation of a novel LC non-derivatization method for the determination of amikacin in pharmaceuticals based on evaporative light scattering detection.

A novel method for the direct determination of the aminoglycoside antibiotic amikacin and its precursor component kanamycin was developed and validated, based on reversed phase LC with evaporative light scattering detector (ELSD). ELSD response to amikacin was found to be enhanced by: (a) use of ion-pairing acidic reagents of increased molecular mass, (b) increase of mobile phase volatility and (c) decrease of peak width and asymmetry (obtained by controlling the mobile phase acidity and/or ratio of organic solvent to water). Utilizing a Thermo Hypersil BetaBasic C(18) column, the selected optimized mobile phase was water-methanol (60:40, v/v), containing 3.0 mll(-1) nonafluoropentanoic acid (18.2mM) (isocratic elution with flow rate of 1.0 mlmin(-1)). ELSD experimental parameters were: nitrogen pressure 3.5 bar, evaporation temperature 50 degrees C, and gain 11. Amikacin was eluted at 8.6 min and kanamycin at 10.4 min with a resolution of 1.5. Logarithmic calibration curves were obtained from 7 to 77 microgml(-1) (r>0.9995) for amikacin and 8 to 105 microgml(-1) (r>0.998) for kanamycin, with a LOD equal to 2.2 and 2.5 microgml(-1), respectively. In amikacin sulfate pharmaceutical raw materials, the simultaneous determination of sulfate (t(R)=2.3 min, LOD=1.8 microgml(-1), range 5-40 microgml(-1), %R.S.D.=1.1, r>0.9997), kanamycin and amikacin was feasible. No significant difference was found between the results of the developed LC-ELSD method and those of reference methods, while the mean recovery of kanamycin from spiked samples (0.5%, w/w) was 97.3% (%R.S.D.<or=2.0, n=6). Further, the developed method was applied for the determination of amikacin in pharmaceutical formulations (injection solutions) without any interference from the matrix (recovery from spiked samples ranged from 95.6 to 103.8%).

Algorithms↗

PubMed2005

A comparison of performance of various analytical columns in pharmaceutical analysis: conventional C18 and high throughput C18 zorbax columns.

New improved types of analytical columns Zorbax Eclipse XDB-C18 (75 mm x 4.6 mm i.d., 3.5 microm) and Zorbax Eclipse XDB-C18 (50 mm x 4.6 mm i.d., 1.8 microm) have been tested for determination of estradiol (active substance), methylparaben, propylparaben (preservatives) and estrone (degradation product) and compared with the conventional C18 columns (250 mm x 3.0 mm i.d., 5.0 microm). The Zorbax columns differ with their particle size, column length and ODS (octadecylsilica) type as well. Higher flow-rates (up to about 2.5 ml min(-1)) could be applied regardless to back-pressure. The analysis - previously done at 40 degrees C - could be performed even at ambient temperature. Analytical run was shortened to 3.5 min (from 12 min used for the conventional C18 column) with the same or better retention characteristics. System suitability data for all Zorbax columns show the advantages of these columns for the practical use in routine quality control of pharmaceuticals, particularly from the point of view of speed of analysis and solvent consumption.

Chromatography, Liquid↗

PubMed2005

Sequential injection extraction based on restricted access material for determination of furosemide in serum.

Restricted access material (RAM) column containing 25 microm C18 alkyl-diol support was integrated into the sequential injection analysis (SIA) manifold and the SIA-RAM system was tested for direct determination of furosemide in serum. LiChrospher ADS column based on restricted access material is proposed to direct injection of biofluids. The integration of RAM material into SIA enabled creation of a comprehensive on-line sample clean-up technique combined with fluorescence quantitation of analyte. Centrifuged and diluted serum sample was aspirated into the system and loaded onto the column using acetonitrile-water (2:98), pH 2.7. The analyte was retained on the column while proteins contained in the sample were removed to the waste without precipitation and clogging the column. Interfering substances complicating the detection were washed out by acetonitrile-water (15:85), pH 2.7 in the next step. The extracted analyte was eluted by means of acetonitrile-water (25:75), pH 2.3 to the fluorescence detector (emission filter 385 nm). The whole procedure comprising sample pre-treatment, analyte detection and column reconditioning took 20 min. The recoveries of furosemide from serum lay between 101.4 and 103.4% for three concentrations of analyte.

Adsorption↗

PubMed2005

Determination of ambroxol hydrochloride, methylparaben and benzoic acid in pharmaceutical preparations based on sequential injection technique coupled with monolithic column.

The porous monolithic columns show high performance at relatively low pressure. The coupling of short monoliths with sequential injection technique (SIA) results in a new approach to implementation of separation step to non-separation low-pressure method. In this contribution, a new separation method for simultaneous determination of ambroxol, methylparaben and benzoic acid was developed based on a novel reversed-phase sequential injection chromatography (SIC) technique with UV detection. A Chromolith SpeedROD RP-18e, 50-4.6 mm column with 10 mm precolumn and a FIAlab 3000 system with a six-port selection valve and 5 ml syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-tetrahydrofuran-0.05M acetic acid (10:10:90, v/v/v), pH 3.75 adjusted with triethylamine, flow rate 0.48 mlmin(-1), UV-detection was at 245 nm. The analysis time was <11 min. A new SIC method was validated and compared with HPLC. The method was found to be useful for the routine analysis of the active compounds ambroxol and preservatives (methylparaben or benzoic acid) in various pharmaceutical syrups and drops.

Ambroxol↗

PubMed2005

Separation and determination of clotrimazole, methylparaben and propylparaben in pharmaceutical preparation by micellar electrokinetic chromatography.

In this study, micellar electrokinetic chromatography (MEKC) method was developed for the determination of clotrimazole (CLO), methylparaben (MP) and propylparaben (PP) in a pharmaceutical preparation. Separation was carried out in a fused silica capillary (60 cm x 75 microm i.d.) at 25 kV with UV detection at 212 nm. Optimized background electrolyte (BGE) was 15 mM phosphate buffer (pH 7.2) containing 30 mM sodium dodecyl sulfate (SDS) as a surfactant. Rectilinear calibration ranges were 50-500 mg l(-1) for CLO, 10-100 mg l(-1) for MP and 2.5-25 mg l(-1) for PP. The total analysis time was < 12 min.

Anti-Infective Agents, Local↗

PubMed2005

Flow-through sol-gel optical biosensor for the colorimetric determination of acetazolamide.

An optical biosensor based on immobilised carbonic anhydrase and its application to the determination of the anti-glaucoma agent acetazolamide by enzyme inhibition measurements, is described. The enzyme and a pH indicator dye, cresol red, were physically immobilised in overlapped sol-gel thin films, in a dual-layer format. Carbonic anhydrase catalyses the dehydration of HCO3-, which in turn causes a change of pH in the microenvironment of the sensor. By following the colour transition of cresol red, the enzymatic reaction as well as its inhibition by acetazolamide can be monitored. The sensor was integrated in a flow cell and coupled to a continuous flow system operating on a multicommutation and binary sampling approach. Measurements were made at pH 6.0 at the wavelength of 570 nm. Linear response was obtained for acetazolamide concentrations between 1.0 and 10.0 mmol l(-1), with a sampling frequency of 22 samples h(-1) and a detection limit of 0.2 mmol l(-1). The results obtained in the analysis of real samples were in good agreement with those obtained by a reference method, showing no significant differences at a confidence level of 95%.

Acetazolamide↗

PubMed2004

Comparison of performance of C18 monolithic rod columns and conventional C18 particle-packed columns in liquid chromatographic determination of Estrogel and Ketoprofen gel.

The performance of monolithic HPLC columns Chromolith (made by Merck, Germany) and conventional C18 columns Discovery (Supelco, Sigma-Aldrich, Prague, Czech Republic) was tested and the comparison for two topical preparations Ketoprofen gel and Estrogel gel was made. The composition of mobile phases - for Ketoprofen analysis a mixture of acetonitrile, water and phosphate buffer adjusted to pH 3.5 (40:58:2) and for Estrogel analysis a mixture of acetonitrile, methanol, water (23:24:53) - was usually not optimal for analyses at all types of columns. Thus an adjustment of components ratio was necessary for sufficient resolution of the compounds analysed. Various flow rates (1.0-5.0 ml/min) and mobile phases (usually increasing ratio of water content) were applied. Determination of active substances, preservatives and impurities and comparison of retention times and system suitability test parameters was accomplished. For Estrogel gel, following chromatographic conditions were found: using Chromolith Flash RP-18e monolith column, mobile phase was acetonitrile, methanol, water (13:24:63, v/v/v) and flow-rate 3.0 ml/min. Using monolith column ChromolithSpeedROD RP-18e, the mobile phase was acetonitrile, methanol, water (18:24:58, v/v/v) and flow-rate 4.0 ml/min. For the monolith column Chromolith Performance RP-18e, the mobile phase was acetonitrile, methanol, water (23:24:53, v/v/v), flow-rate 3.0ml/min. Analysis of Ketoprofen gel gave the best results using following analytical conditions: for monolith column Chromolith Flash RP-18e, mobile phase as a mixture of acetonitrile, water, phosphate buffer pH 3.5 (30:68:2, v/v/v) was used, at flow-rate 2.0 ml/min. For ChromolithSpeedROD RP-18e monolith column, acetonitrile, water, phosphate buffer pH 3.5 (35:63:2, v/v/v) was used as a mobile phase at flow-rate 3.0 ml/min. Chromolith Performance RP-18e gave the best results using mobile phase acetonitrile, water, phosphate buffer pH 3.5 (30:68:2, v/v/v) at the flow-rate 5.0 ml/min. It was proved that monolith columns, due to their porosity and low back-pressure, can save analysis time by about a factor of three with sufficient separation efficiency. Thus, for example 11 min long analysis can be performed in 4 min with comparable results.

Chromatography, High Pressure Liquid↗

PubMed2004

Ion selective electrodes for penicillin-G based on Mn(III)TPP-Cl and their application in pharmaceutical formulations control by sequential injection analysis.

The work describes the construction, evaluation and analytical application of ion selective electrodes sensitive to penicillin-G antibiotics for pharmaceutical products analysis. Different types of polymeric membranes based on PVC (poly(vinyl chloride)) and EVA (ethyl-vinyl-acetate), without internal reference solution, were prepared using 5,10,15,20-tetraphenylporphyrinate (TPP) manganese(III) (Mn(III)TPP-Cl) as electroactive material. Different additives such as tetra-n-octylammoniumbromide (cationic additive) and sodium tetraphenylborate (anionic additive) were incorporated into the membranes to evaluate their influence on electrodes performance. The comparison of the developed detectors was based on general analytical characteristics, selectivity and lifetime. To accomplish the analysis of real samples, two selective membranes composed of 33.0% (w/w) of PVC, 66.0% (w/w) of o-NPOE and 1.0% (w/w) of Mn(III)TPP-Cl (type A) and 33.0% (w/w) of PVC, 66.0% (w/w) of o-NPOE, 1.0% (w/w) of Mn(III)TPP-Cl and 10% mol (relative to the molar concentration of Mn(III)TPP-Cl) of sodium tetraphenylborate (type B) were used. Type A electrode presented a linear response between 2 x 10(-5) and 10(-1) moll(-1) for penicillin-G, a slope of about -59 mVdec(-1) and a reproducibility of about +/-0.5 mVday(-1), while type B exhibited a linear response between 5 x 10(-5) and 10(-1) moll(-1) for penicillin-G, a slope of about -61 mVdec(-1) and a reproducibility of about +/-0.3 mV day(-1). The potentiometric analysis of penicillin-G in pharmaceutical products was carried out by direct potentiometry and the results obtained were compared with those provided by the HPLC reference method. These membranes (type A and type B) were used to prepare tubular electrodes that were coupled to a sequential injection system (SIA) and presented a linear range between 2 x 10(-4) and 1 x 10(-2) moll(-1) and slopes of -59.3 +/- 0.8 and -57.3 +/- 1.2 mVdec(-1), respectively. The tubular electrode constructed using type B membrane (type TB) was used to carry out the potentiometric analysis of penicillin-G in pharmaceutical formulations. The proposed procedure enabled relative errors between 0.1% and 1.2% (n = 4) and a sampling-rate of about 25 samples per h.

Chemistry, Pharmaceutical↗

PubMed2004

High-performance liquid chromatography determination of phenolic components in wine using off-line isotachophoretic pretreatment.

The off-line combination of isotachophoresis (ITP) and high-performance liquid chromatography (HPLC) to improve sample pretreatment and determination of phenolic compounds in wine was investigated. The ITP system provided an enhanced sample load capacity and served as a sample clean-up technique, HPLC performed a final separation of the analytes presented in samples. The phenolic components were separated by Discovery RP Amid C16 chromatography column using water-methanol-acetonitrile-orthophosphoric acid gradient. The identification of phenolic compounds was made by comparison of the retention data obtained for the standard mixture, pretreated sample and the sample spiked standard additions. Satisfactory recoveries for all components analysed were observed between 86.1 and 109.2%.

Chromatography, High Pressure Liquid↗

PubMed2004

HPLC determination of estradiol, its degradation product, and preservatives in new topical formulation Estrogel HBF.

This paper deals with the development of a novel method for simultaneous determination of estradiol, its degradation product estrone, and two preservatives, methylparaben and propylparaben, in the topical preparation Estradiol HBF. After optimization of the analytical conditions the method was validated and applied in studies of the stability of the topical preparation Estrogel HBF. Separation of all these compounds was performed on a Supelco Discovery C18 (250 mm x 3.0 mm, 5 microm) analytical column. A mixture of acetonitrile, methanol, and water (23:24:53 v/ v) was chosen as mobile phase. UV absorbance at 225 nm was used for detection and quantitation of analytes. The total analysis time was less than 12 min at a flow rate of 0.9 mL min(-1). All the compounds were isolated from the topical gel by simple extraction with an acetonitrile solution of hydrocortisone, as internal standard, and using sonication and centrifugation thereafter. The supernatant was injected directly on to the analytical column. The recovery of the procedure was from 96.9 to 100.4%. Validation of method according international guidelines was successfully performed.

Administration, Topical↗

PubMed2004

Sequential injection chromatographic determination of paracetamol, caffeine, and acetylsalicylic acid in pharmaceutical tablets.

In this contribution, a new separation method for simultaneous determination of paracetamol, caffeine, acetylsalicylic acid, and internal standard benzoic acid was developed based on a novel reversed-phase sequential injection chromatography (SIC) technique with UV detection. A Chromolith Flash RP-18e, 25-4.6mm column (Merck, Germany) and a FIAlab 3000 system (USA) with an 8-port selection valve and a 5 mL syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-(0.01 M) phosphate buffer (10:90, v/v) pH 4.05, flow rate 0.6 mL min(-1). UV detection was at 210 and 230 nm. The validation parameters showed good results: linearity (r >0.999) for all compounds, detection limits in the range 0.3-0.8 microg mL(-1), repeatability (RSD) of peak heights between runs in the range 1.10-4.30% at three concentration levels and intra-day repeatability of the retention times in the range 0.28-0.43%. The analysis time was <6 min. The method was found to be applicable for the routine analysis of the active compounds paracetamol, caffeine, and acetylsalicylic acid in pharmaceutical tablets.

Acetaminophen↗

PubMed2003

Determination of bopindolol using the flow injection technique coupled with solid phase extraction.

In the proposed procedure, the determination of bopindolol using a flow injection analysis (FIA) technique, with spectrophotometric detection at 635 nm, is described. The method is based on the production of a green, water-soluble complex with ferric ions in acid medium. The automated lab-made FIA system was used for the direct determination of bopindolol in tablets. Bopindolol was adsorbed onto the solid phase in a mini-column, which was integrated directly into the flow system. The positive feature of the use of solid phase extraction (SPE) was the pre-concentration of bopindolol (seven times). The sample throughput was 50 samples per hour. Using the SPE method, bopindolol was determined with a linear range from 125 to 1000 microg ml(-1) (Relative standard deviation (R.S.D.)=1.87%), with a detection limit (3sigma) of 70 microg ml(-1). The method was applied to the determination of bopindolol in Sandonorm tablets. The results obtained were compared with a conventional HPLC method, both analytical techniques were in good agreement.

Calibration↗

PubMed2003

Reversed-phase porous silica rods, an alternative approach to high-performance liquid chromatographic separation using the sequential injection chromatography technique.

A commercially available porous silica rod column was used as a separation tool for the sequential injection analysis (SIA). A porous solid monolithic column showed high performance at a low pressure, allowing sequential injection analysis to be used for the first time for separation in HPLC fashion. In this contribution, we tried to demonstrate a new separation concept with SIA manifold for the simultaneous determination of four different compounds (methylparaben (MP), propylparaben (PP), triamcinolone acetonide (TCA) and internal standard ketoprofen (KP)) in a pharmaceutical triamcinolon cream 0.1% formulation. A Chromolith Flash RP-18e, 25 mm x 4.6 mm column with a 10 mm pre-column (Merck, Germany) and a FIAlab 3000 system (USA) with an 8-port selection valve and 10 ml syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-methanol-water (35:5:65, v/v/v) + 0.05% nonylamine, pH 2.5, flow rate 0.6 ml min(-1). The analysis time was <6 min. A novel sequential injection chromatography (SIC) technique with UV spectrophotometric detection was optimised and validated.

Chromatography, High Pressure Liquid↗

PubMed2002

Automated simultaneous monitoring of nitrate and nitrite in surface water by sequential injection analysis.

A fully automated procedure based on Sequential Injection Analysis (SIA) methodology for simultaneous monitoring of nitrate and nitrite in surface water samples is described. Nitrite was determined directly using the Griess diazo-coupling reaction and the formed azo dye was measured at 540 nm in the flow cell of the fibre-optic spectrophotometer. Nitrate zone was passed through a reducing mini-column containing copperised-cadmium. After the reduction of nitrate into nitrite the sample was aspirated by flow reversal to the holding coil, treated with the reagent and finally passed through the flow cell. The calibration curve was linear over the range 0.05-1.00 mg N l(-1) of nitrite and 0.50-50.00 mg N l(-1) of nitrate; correlation coefficients were 0.9993 and 0.9988 for nitrite and nitrate, respectively. Detection limits were 0.015 and 0.10 mg N l(-1) for nitrite and nitrate, respectively. The relative standard deviation (RSD) values (n = 3) were 1.10% and 1.32% for nitrite and nitrate, respectively. The total time of one measuring cycle was 250 s, thus the sample throughput was about 14 h(-1). Nitrate and nitrite were determined in the real samples of surface water, and the results have been compared with those obtained by two other flow methods; flow injection analysis based on the same reactions and isotachophoretic determination used in a routine environmental control laboratory.

Automation↗