Separon SGX Research Articles

HPLC Determination of Trace Levels of Benzylchloride, Chlorobenzene, Naphthalene, and Biphenyl in Environmental Samples

A simple HPLC method with on-line preconcentration has been developed for the separation and the determination of trace levels of benzylchloride, chlorobenzene, naphthalene, and biphenyl in tap and surface water. The separation was achieved on the column 150 × 3.2 mm filled with Separon SGX C18, dp=5mUm with the spectrophotometric detection at 220 and 250 nm. To enhance the selectivity of separation a water - methanol gradient was used. The method permits the measurement of benzylchloride, chlorobenzene, naphthalene, and biphenyl in environmental samples, with the detection limits of 10 ppt of naphthalene, 55 ppt of biphenyl, 90 ppt of benzylchloride, and 185 ppt of chlorobenzene (sample volume was 100 ml of water samples). The assayed procedure has been applied for the quantitative determination of benzylchloride, chlorobenzene, naphthalene and biphenyl in tap water and river water.

HPLC of Platinum Metals and Gold Based on Their Bromo Complexes

PtII,IV, PdII, and AuIII can be separated and quantitated by HPLC in the form of ion-associates of their bromo complexes with the cetyltrimethylammonium (CTMA) cation, using the acetonitrile-water 60 : 40 system containing 0.002 mol l-1 CTMA and 0.05 mol l-1 NaBr (pH 3) as the mobile phase and detection at 240 nm. In such circumstances the detection limits for the injection of 20 μl sample are 6.7, 0.4, 0.9, and 4.3 ng for PtII, PtIV, PdII, and AuIII, respectively. Excess Fe3+, Al3+, Mg2+, Ca2+, NO3-, SO42-, and Cl- does not interfere. On-line preconcentration of the PtII,IV bromo complexes on Separon SGX RPS is recommended.

RPHPLC analysis of some nitrophenols

Problem of nitrophenols group analysis as well as separation to individuals is still attracting attention of research and practicing chemists, environmental chemists and the others. Chromatographic behaviour in RPHPLC systems expressed by such parameters as retention time, sorption capacity, selectivity and/or elution order was studied for group of 8 nitrophenols: 2,4,6-trinitrophenol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,5-dinitrophenol, 2,6-dinitrophenol and 4-nitro-3-cresol. Condition for baseline separation of almost all of these nitrophenols on Separon SGX C18 were chosen. Sorption capacities were tested for 4 different RP materials. The data will be used for devising of Solid Phase Extraction (SPE) and/or column switching schema in RPHPLC sample pretreatment.

Determination of nitrophenols in soil

A method has been developed for the determination of 2-nitrophenol, 4-nitrophenol, 4,6-dinitro-ocresol, and 2-sec.butyl-4,6-dinitrophenol in soils. The procedure includes the extraction using 5% aqueous NaOH, removal of the co-extracted humic acids from the extract. sorption of the nitrophenols on Separon SGX C18 followed by desorption with methyl tert-butyl ether, and determination by capillary gas chromatography.

Determination of some cardiovascular drugs in serum and urine by capillary isotachophoresis

The separation and determination of amiloride, metoprolol, deacetylmetipranolol, labetalol and furosemide in human serum and urine by capillary isotachophoresis were investigated. Amiloride and β-blockers were separated by cationic isotachophoresis in the electrolyte system sodium morpholinoethanesulfonate buffer (pH 5.5) ( c L = 10 m M)-glutamic acid. Furosemide was separated using the anionic electrolyte system histidine hydrochloride buffer (pH 6.2) ( c L = 10 m M)-morpholinopropanesulfonic acid. Endogenous and the possible exogenous compounds were almost totally removed from serum and urine by solid-phase extraction using a Separon SGX C 18 cartridge. The recovery of compounds varied from 98.2 to 103.2%. The linearity range for the compounds was 50–1000 ng/ml. The relative standard deviations varied from 0.1 to 5.6%. The overall limits of determination ranged from 32 to 46 ng/ml of urine and from 39 to 46 ng/ml of serum, depending of the type of drugs.

Ion-chromatographic separation of metal cations in the presence of alpha-hydroxyisobutyric acid.

Separations of metal cations on a column packed with the strongly acidic cation exchanger Separon SGX CX were investigated in the presence of alpha-hydroxyisobutyric acid (HIBA) in the mobile phase. A retention model based on the general theory of side equilibria was elaborated and relations describing dependences of capacity factors of analytes on the compositon of the mobile phase were derived. Effects of HIBA concentration and pH of the mobile phase on the analyte retention were studied in detail. Stability constants of divalent metal cations (Cd(2+), Co(2+), Mn(2+), Ni(2+) and Zn(2+)) with HIBA were calculated from the experimental dependences of the reciprocal values of capacity factors on the ligand concentration.

Reversed-phase high-performance liquid chromatographic method for the quantitative determination of alkylbis(2-benzothiazolylsulfen)amides

An isocratic, reversed-phase HPLC procedure was developed for the simultaneous determination of isopropyl-, tert.-butyl-, tert.-amyl-, cyclohexylbis(2-benzothiazolylsulfen)amides. Quantitation is performed on a C 18 bonded-phase column (Separon SGX C 18 5 μm) using N-dicyclohexyl-2-benzothiazolesulfenamide as internal standard followed by UV photodiode-array detection. The precision ( n = 7) for all derivatives of alkylbis(2-benzothiazolylsulfen)amides is within 1.5%. Identification of the compounds also in the mixtures was done by NMR spectroscopy.

Determination of benzoylurea insecticides in apples by high-performance liquid chromatography

A method for the simultaneous determination of the benzoylurea insecticides diflubenzuron, flufenoxuron, flucycloxuron chlorfluazuron and triflumuron in apples using reversed-phase HPLC is described. The separation of analytes was performed on a Separon SGX C 8 column (150 × 3 mm I.D., 5 μm) with methanol-water (55:45, v/v) as the mobile phase. Benzoylurea residues were extracted with acetone and then partitioned into dichloromethane. The final clean-up step was conducted by gel permeation chromatography on Bio- Beads SX-3 using cyclohexane-chloroform (3:2, v/v) as the mobile phase.

Normal-phase high-performance liquid chromatographic separation of halocyclophosphazenes

Lower members of the chlorocyclophosphazene homologous series (NPCl 2) n , n = 3–6, were separated using normal-phase HPLC. Very good separation was achieved using Separon SGX (7 μm) silica gel column (250 × 4 mm I.D.) and n-heptane as the mobile phase. An addition of a more polar solvent (2-propanol) depressed the retention dramatically. The separated substances can be detected by spectrophotometry at a wavelength of ca. 220 nm, the detection limits varying the range ca. 30–1500 ng. The bromo derivative (NPBr 2) 3 exhibits a similar behaviour to the chloro derivatives.

High-performance liquid chromatographic assay for ibuprofen in whole blood using solid-phase extraction

A precise, accurate, reproducible one-step method for the high-performance chromatographic determination of ibuprofen in whole blood is described. Samples were, after haemolysis, prepared by solid-phase extraction. Analyses were performed using reversed-phase chromatography on a Separon SGX C 18 column with a mobile phase of methanol—water (pH 3) and ultraviolet detection at 222 nm. The method was used for pharmacokinetic studies in rabbits.

Detection and assay of secondary metabolites of Penicillium vermiculatum DANG

Thin-layer chromatography on silica gel plates with detection at 254 and 365 nm, spraying with vanillin-sulphuric acid, ethanol ammonia, aqueous iron(III) chloride or ethanolic potassium hydroxide is suggested for rapid detection of (−)-vermiculin, (−)-vermiculinic and vermiculic acids, (−)-vermistatin, (−)-mitorubrinol, vermilutin, (±)-dehydroaltenusin, (+)-vermixocin A, (−)-vermixocin B, funiculosic acid and 2-methylsorbic acid, metabolites of Penicillium vermiculatum DANG. High-performance liquid chromatography on a Separon SGX C 18 compact glass column eluted with methanol-water (pH 3) mixtures with detection at various wavelengths was used for assaying these compounds in cultivation media and extracts during their processing.

Reverse-Phase High Performance Liquid Chromatography of Metal Chelates of 4-(2-Pyridylazo)resorcinol and 4-(2-Thiazolylazo)resorcinol. Simultaneous Determination of Low Concentrations of Co, Ni and Fe

The behaviour of stable and inert metal chelates of 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol in RP HPLC and in its ion-pair modification (IP RP HPLC) on Separon SGX RPS silica gel was studied. Good results were obtained by the ion-pair variant in water methanol solutions at pH 7 in the presence of cetyltrimethylammonium bromide. The technique proved to be convenient for the preconcentration, separation and quantitation of low concentrations of Fe, Co, and Ni in waters.

Determination of Lovastatin (mevinolin) and mevinolinic acid in fermentation liquids

A rapid and simple HPLC method for the determination of Lovastatin (mevinolin) and mevinolinic acid in fermentation fluids of Aspergillus terreus using a Separon SGX C 18 column and methanol-18 m M orthophosphoric acid (77.5:22.5, v/v) as mobile phase with detection at 238 nm is described. The detection limit of Lovastatin and mevinolinic acid was 20–30 ng/ml.

Determination of platinum in plants by emission spectrometry after preconcentration on modified silicagel

Silicagel Separon SGX C18 (particle size 7 μm) was suitable for the preconcentration of 2–20 μg of Pt from 0.1 M hydrochloric acid in the presence of cationic surfactants especially dimethyllaurylbenzylammonium bromide, with subsequent elution with 96% ethanol. The recovery was 86–110% for 2 μg of Pt. The sample matrix corresponding to 2.5 g of average plant ash does not interfere. The final emission spectrometry of platinum was carried out in 15 A dc-arc at Pt I 265.942 nm in the presence of Au as internal standard (Au I 267.595 nm). RSD was 6.3% in average.

Simultaneous high-performance liquid chromatographic determination of salicylates in whole blood, plasma and isolated erythrocytes

A method using liquid—liquid extraction has been developed for the isolation of acetylsalicylic acid and its metabolites, salicylic, gentisic or possibly salicyluric acids, from whole blood, isolated erythrocytes and plasma. Methylene chloride proved to be the best of the organic solvents tested. For whole blood and isolated erythrocytes it was necessary to carry out haemolysis prior to their extraction. The high-performance liquid chromatographic conditions for the quantitation of acetylsalicylic acid and its metabolites from samples of whole blood, erythrocytes and whole plasma were optimized. Separation was performed using reversed-phase chromatography on Separon SGX C 18 and ultraviolet detection at 236 nm. A mixture of methanol—water (80:100, v/v) was the mobile phase, acidified with perchloric acid to pH 2.5.

Determination of traces of lanthanides in cerium oxide by liquid chromatography with on-column preconcentration

Traces of lanthanides can be effectively separated from other lanthanides in major concentrations and other elements by liquid chromatography on a column of Separon SGX C18 silica gel modified by sorption of ammonium dodecylsulphate or ammonium octanesulphonate and determined spectrophotometrically with Arsenazo III. Isocratic or stepwise acidity gradient elution with 90 mmol/l of ammonium 2-hydroxy-2-methylpropionate (HIBA) or 60 mmol/l of ammonium citrate was used. Interferences by the elements up to 103–104 concentration ratio can be eliminated. Lanthanides at mg/g level can be determined in cerium oxide with a relative standard deviation sr<2.5% (n=5).

An ion-exchange separation of Cu 2+, Cd 2+, Pb 2+ and Tl + on silica gel with polarographic detection

The HPLC separation of heavy metal cations was studied with a column packed with Separon SGX silica gel. The retention of the cations is controlled by an ion-exchange mechanism. The ion-exchange capacity is primarily dependent on the mobile phase pH. The analyte retention is further affected by the type and concentration of the completing agent present and of the counterion. The effect of acetate, tartrate and α-hydroxyisobutyrate as complexing agents and that of methanol as the organic modifier were studied in detail and the results were compared with the theoretical model of ion-exchange separation. Simple mixtures of metals can be rapidly separated on a short column (30 × 3.3 mm i.d.), e.g., with a mobile phase containing 10 −2 M tartrate at pH 6.0. The metals separated can be detected by dc amperometry at a hanging mercury drop electrode. The limits of detection at an electrode potential of −0.95 V (Ag/AgCl) are in the units—tens of ng range with 20-μl samples with satisfactory precision (RSD values of 2–6%). The main advantages of the method are rapidly and simplicity because derivatization of the analytes is not required.

High-performance liquid chromatographic determination of cholesteryl esters in the blood of obese children

The serum of obese children and adolescents was analyzed for cholesteryl esters. The test substances were first separated from the sample matrix by solvent extraction and thin-layer chromatography and then resolved in a reversed-phase high-performance liquid chromatographic system involving a Separon SGX C 18 column and a mobile phase of 2-propanol—acetonitrile (40:60, v/v), with ultraviolet detection at 206 nm. Cholesterol and 10-cholesteryl esters could be separated and determined within ca. 25 min at a flow-rate of 1 ml/min. The method was applied to a study of the effect of external conditions (physical stress, diet) on the content of cholesteryl esters in a test group of obese boys and girls aged from 13 to 16 years. The analyses have demonstrated that the above conditions do not affect the concentrations of the individual cholesteryl esters, although the total cholesterol concentration decreased significantly after spa treatment.

Determination of uranium in technological waters by ion-pair liquid chromatography

U(VI) can be efficiently determined in the range 0.3–1Om M after its separation from Th(IV), Zr(IV), Al(III), Fe(III), lanthanides and other ions by ion-pair liquid chromatography on a 3 x 150 mm glass column packed with Separon SGX C18 modified with sorbed ammonium dodecyl sulphate. Traces of uranium can be preconcentrated directly on the analytical column from acidified water solutions and separated from Th, Zr, Al, Fe, lanthanides and other elements, with an enrichment factor of $ ̃ 100 and recovery of 98 ± 8%, by isocratic or pH or concentration gradient elution with ammonium 2-hydroxy-2-methylpropionate or ammonium citrate solution. Post-column derivatization with 25μ M Arsenazo III in 0.1 M formate buffer at pH 2.7 is used for detection and quantification.

High performance liquid chromatographic determination of alkaloids fromVinca minor L.

Fourteen alkaloids from Vinca minor L. were separated and their concentration determined by high performance liquid chromatography using Separon SGX C18 with a mobile phase of methanol:water (0.02 mol/L NH4Cl, pH 8.2 adjusted with Et3N). The major alkaloids of the leaves were vincamine (0.13%), 1,2-dehydroaspidospermidine (0.06%) and vincaminoreine (0.028%). The dominant alkaloid of the root was 1,2-dehydroaspidospermidine (0.28%). The bisindole alkaloid vincarubine was found only in the leaves (0.007%).