Gas chromatographic determination of guanidino compounds in uremic patients using glyoxal as derivatizing reagent.

The guanidino compounds guanidine, methylguanidine, guanidinoacetic acid, guanidinopropionic acid, guanidinobutyric acid and guanidinosuccinic acid were eluted and separated after pre-column derivatization with glyoxal from an HP-5 column (30 m × 0.32 mm i.d.) with film thickness 0.25 µm at an initial column temperature of 100 °C for 2 min, with ramping of 20°C/min up to 250 °C and a nitrogen flow rate of 3 mL/min. Detection was by flame ionization detection. Linear calibrations were observed within 0.1-20.0 µmol/L, with limit of detection within 0.024-0.034 µmol/L for each compound. The separation was repeatable with relative standard deviation (RSD) (n = 6) within 1.2-1.8 and 1.1-1.6% in terms of retention time and peak height/peak area, respectively. The method was applied for the determination of the guanidino compounds from serum of uremic patients (n = 7) and healthy volunteers (n = 8), and amounts were observed within 1.33-11.71 and 0.07-0.39 µmol/L with RSD 1.1-3.5 and 1.1-3.0%, respectively. The results were further supported by the standard addition method.

Bis(isovalerylacetone)ethylenediimine nickel(II) as mixed stationary phase for gas chromatography.

Bis(isovalerylacetone)ethylenediimine Nickel (II) (IVA(2)enNi) was examined as a mixed stationary phase with OV1 on Chromosorb G/NAW 60-80 mesh size for gas chromatography (GC) separation of aromatic hydrocarbons, heteroaromatics, alcohols, aldehydes, ketones, esters, nitro-, and amino compounds. Forty-six compounds were examined, and the GC results were compared with those obtained with 3% OV1 on Chromosorb G/NAW 60-80 mesh size under similar operating conditions. Improved resolutions, peak asymmetry, number of theoretical plates, and Kovats indices were obtained on the mixed stationary phase 3% OV1 + 5% IVA(2)enNi (w/w) compared to 3% OV1 column. The stability constant (K(m)), enthalpies (DeltaH), entropies (DeltaS), and Gibbs free energies (DeltaG) of the GC elution on column (2 m x 3 mm i.d.) packed with 3% OV1 + 5% IVA(2)enNi (w/w) on Chromosorb have been calculated. Donor-acceptor complexation in the gas phase indicated by the negative values of enthalpy (-DeltaH) were within 9.4-12.38 Kcal/mol, and Gibbs free energy (-DeltaG) ranged from 1.48 to 4.24 Kcal/mol. The retention time transformation on both the phases were calculated. The obtained ratios from the stationary phases 3% OV1 and 3% OV1 + 5% IVA(2)enNi (w/w) were plotted on the x-axis and y-axis, respectively. Two-dimensional chromatographic plots for alkanes, aromatics, heteroaromatics, ketones, alcohols, esters, and nitro compounds were obtained with coefficient of determination within 0.4934 and 0.9617, which is indicative of some different kinds of interaction of two stationary phases with the solutes.

Spectrophotometric determination of tranexamic acid using vanillin.

A new spectrophotometric method has been examined for the determination of the tranexamic acid (TA) by derivatization with vanillin (VAN). The molar absorptivity of TA was calculated 25,160 L x mol(-1) x cm(-1) at lambdamax 354 nm and obeyed the Beer's law within 0.5-2.5 microg x mL(-1). The color reaction was highly stable and did not show any change in absorbance up to 24 h. The method was applied for the analysis of TA from capsules, injections and tooth pastes. The amounts of TA found in capsules, injections and tooth pastes of various pharmaceutical companies were observed with 249.0-250.9 mg/capsule, 249.3-250.7 mg/injection and 0.048%-0.049% in tooth pastes with relative standard deviation (RSD) 0.2%-5.0% (n = 3).

Quantitative separation of oxytocin, norfloxacin and diclofenac sodium in milk samples using capillary electrophoresis.

A simple, sensitive and rapid method has been developed for simultaneous separation and quantification of three different drugs: oxytocin (OT), norfloxacin (NOR) and diclofenac (DIC) sodium in milk samples using capillary electrophoresis (CE) with UV detection at 220 nm. Factors affecting the separation were pH, concentration of buffer and applied voltage. Separation was obtained in less than 9 min with sodium tetraborate buffer of pH 10.0 and applied voltage 30 kV. The separation was carried out from uncoated fused silica capillary with effective length of 50 cm with 75 microm i.d. The carrier electrolyte gave reproducible separation with calibration plots linear over 0.15-4.0 microg/mL for OT, 5-1000 microg/mL for NOR and 3-125 microg/mL for DIC. The lower limits of detection (LOD) were found to be 50 ng/mL for OT, and 1 microg/mL for NOR and DIC. The method was validated for the analysis of drugs in milk samples and pharmaceutical preparations with recovery of drugs within the range 96-100% with RSD 0.9-2.8%.

Use of modified sorbent for the separation and preconcentration of chromium species from industrial waste water.

A simple and sensitive method based on solid phase extraction (SPE) on acetyl acetone modified XAD-16 has been established for separation of Cr (III) and Cr (VI) from and industrial water samples. Two forms of chromium showed different exchange capacities at different pH values, viz. Cr (III) selectively retained at pH 5-7 whereas Cr (VI) retained at pH 1. Hence complete separation of the two forms of chromium is possible. Retained species were eluted with 5 mL of 2 mol L(-1) HNO(3) and 2 mol L(-1) NaOH. The detection limit of 0.02 and 0.014 microg mL(-1) was achieved for Cr (III) and Cr (VI), respectively, with an enrichment factor of 100 and 140. Various kinetic and thermodynamic parameters were also determined. The metal ion concentration was measured by atomic Absorption Spectroscopy. The possible retention mechanism is also discussed. The method was successfully applied for the speciation of chromium in industrial water samples.

Capillary gas chromatographic determination of methylglyoxal from serum of diabetic patients by precolumn derivatization with 1,2-diamonopropane.

Capillary gas chromatographic (GC) determination of methylglyoxal (MGo) was developed on the basis of precolumn derivatization with 1,2-diaminopropane (DAP) at pH 3. The elution was carried out on an HP-5 (30 m x 0.32 mm i.d.) connected with FID. The linear calibration curve was obtained for MGo within 0.09-1.04 microg/ml with detection limit of 40 ng/ml. Dimethylglyoxal (DMGo) also formed derivative with DAP and eluted and separated from MGo at column temperature 100 degrees C for 1 min with heating rate 30 degrees C/min up to 200 degrees C with run time 4.6 min. The nitrogen flow rate was 1.5 ml/min with split ratio of 10:1, v/v. MGo was determined from serum and urine of diabetics and healthy volunteers. The amounts of MGo from serum and urine of diabetic patients were 0.180-0.260 microg/ml and 0.170-0.250 microg/ml with relative standard deviation (R.S.D.) within 1-4% and 1-3%, respectively. The amounts of MGo from serum of healthy volunteers were 0.032-0.054 microg/ml with an R.S.D. of 1.5-3%. DMGo was not detected from the biological fluids and was used as an internal standard.

Capillary gas chromatographic determination of methylglyoxal from serum of diabetic patients by precolumn derivatization using meso-stilbenediamine as derivatizing reagent.

Stilbenediamine is used as derivatizing reagent for methylglyoxal (MGo) and dimethylglyoxal for the gas chromatographic (GC) determination of MGo from the serum of diabetic patients and healthy volunteers. The derivatization is obtained at pH 3. GC elution and separation are carried out on an HP5 column (30 m x 0.32 mm i.d.) at column temperature 150 degrees C with a programmed heating rate of 50 degrees C/min up to 250 degrees C, and a total run time of 7 min. The nitrogen flow rate is 5 mL/min and detection is carried out by flame ionization detection. The linear calibration curves are obtained with a range of 0.076-0.760 microg/mL and the detection limit is 25 ng/mL MGo. The amounts of MGo found in the serum of healthy volunteers and diabetic patients are 0.025-0.065 microg/mL and 0.115-0.228 microg/mL, with coefficient of variation 1.3-3.1% and 1.4-3.3%.

Sawdust--a green and economical sorbent for the removal of cadmium (II) ions.

The ability of sawdust (treated and untreated) waste, a waste material derived from the commercial processing of cedrus deodar wood for furniture production, to remove/preconcentrate Cd(II) ions from aqueous solution was determined. Sorption was found to be rapid (approximately 97% within 8 min). The binding of metal ions was found to be pH dependent, optimal sorption accruing at around pH 4-8. Potentiometric titrations of sawdust revealed two distinct pK(a) values, the first having the value similar to carboxylic groups (3.3-4.8) and second comparable with that of amines (8.53-10.2) with the densities 1.99 x 10(-4) and 7.94 x 10(-5), respectively. Retained Cd(II) ions were eluted with 5 ml of 0.1 mol l(-1) HCl. Detection limit of 0.016 microg ml(-1) was achieved with enrichment factors of 120. Recovery was quantitative using sample volume of 600 ml. The Langmuir and D-R isotherm equations were used to describe partitioning behavior for the system at different temperatures. Kinetic and thermodynamic behavior of sawdust for Cd(II) ions removal was also studied.

The efficacy of nitrosonaphthol functionalized XAD-16 resin for the preconcentration/sorption of Ni(II) and Cu(II) ions.

Amberlite XAD-16 resin has been functionalized using nitrosonaphthol as a ligand and characterized employing elemental, thermogravimetric analysis and FT-IR spectroscopy. The sorption of Ni(II) and Cu(II) ions onto this functionalized resin is investigated and optimized with respect to the sorptive medium (pH), shaking speed and equilibration time between liquid and solid phases. The monitoring of the influence of diverse ions on the sorption of metal ions has revealed that phosphate, bicarbonate and citrate reduce the sorption up to 10-14%. The sorption data followed Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters computed are 1/n=0.56+/-0.03 and 0.49+/-0.05, A=9.54+/-1.5 and 6.0+/-0.5 mmol g(-1) for Ni(II) and Cu(II) ions, respectively. D-R isotherm yields the values of X(m)=0.87+/-0.07 and 0.35+/-0.05 mmol g(-1) and of E=9.5+/-0.23 and 12.3+/-0.6 kJ mol(-1) for Ni(II) and Cu(II) ions, respectively. Langmuir characteristic constants estimated are Q=0.082+/-0.005 and 0.063+/-0.003 mmol g(-1), b=(4.7+/-0.2)x10(4) and (7.31+/-0.11)x10(4)l mol(-1) for Ni(II) and Cu(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantities of DeltaH=-58.9+/-0.12 and -40.38+/-0.11 kJ mol(-1), DeltaS=-183+/-10 and -130+/-8 J mol(-1)K(-1) and DeltaG=-4.4+/-0.09 and -2.06+/-0.08 kJ mol(-1) at 298 K for Ni(II) and Cu(II) ions, respectively. Using kinetic equations, values of intraparticle transport and of first order rate constant have been computed for both the metal ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination in tea, vegetable oil, hydrogenated oil (ghee) and palm oil by atomic absorption spectrometry using direct and standard addition methods.

Spectrophotometric and liquid chromatographic determination of dopamine from pharmaceutical preparations using acetyl acetone as derivatizing reagent.

Dopamine (DA) has been determined by spectrophotometry and by liquid chromatography as derivatives of acetylacetone (AA). The liquid chromatography of DA was carried out in the presence of hydroxyproline (HP), octopamine (OP) and tyramine (TY). The separation was obtained from Phenomenex C-18 column 5 pm (150 x 4.6 mm id) by isocratic elution with methanol: acetonitrile: water (45: 6: 49 v/v/v), UV detection was at 320 nm. Linear calibration curves were obtained for each with 2.5-40.0 microgml(-1) with detection limits in the range 1.8-80 ng injection(-1) (10 microl). The dopamine was determined in pharmaceutical preparations with coefficient of variation (CV) within 0.7-1.5%.

Capillary gas chromatographic determination of phenylpropanolamine in pharmaceutical preparation.

Analytical procedure has been developed for the gas chromatographic determination of phenylpropanolamine (PPA) using trifluoroacetylacetone (FAA) as derivatizing reagent. Elution is carried out from the column HP-5 (30 mx0.32 mm i.d.) with film thickness 0.25 microm at initial column temperature 70 degrees C for 5 min, followed by heating rate 10 degrees C/min up to 120 degrees C. Injection port temperature was maintained at 270 degrees C. Nitrogen flow rate was 2 ml/min and detection was by FID. The linear calibration curve was obtained with 30-150 microg/ml PPA with detection limit of 6.0 microg/ml. The method was used for the determination of PPA from Sinutab and Tavegyl-D tablets. The relative standard deviation (R.S.D.) for the analysis of pharmaceutical preparation was obtained within 0.4-0.9%.

Liquid chromatographic determination of vanadium in petroleum oils and mineral ore samples using 2-acetylpyridne-4-phenyl-3-thiosemicarbazone as derivatizing reagent.

Liquid chromatographic method has been developed, based on precolumn derivatization of vanadium(V) with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone (APPT). The complex is extracted in chloroform together with palladium(II), tin(II) and iron(III) and eluted and separated completely from Kromasil 100 C-18, 10 microm (25 cm x 4.6 mm i.d.) column with methanol:water:acetonitrile (60:30:10, v/v/v) with a flow rate of 1 ml/min. UV detection was at 260 nm. Linear calibration curve was obtained with 1-12.5 microg/ml vanadium(V) with detection limit of 8 ng/injection (20 microl). A number of metal ions tested did not affect the determination of vanadium. The test mixtures were analyzed for vanadium(IV) and vanadium(V) contents and relative% error was obtained +/-1-8%. The method was applied for the determination of vanadium in petroleum oils and mineral ore samples with vanadium contents of 0.32-2.3 and 121.7-717.3 microg/g with R.S.D. of 1.5-4.5 and 0.38-4.7%, respectively. The results correlated with reported values and by atomic absorption spectrophotometry.

Preconcentration and separation of Cr(III) and Cr(VI) using sawdust as a sorbent.

A simple, inexpensive method based on solid-phase extraction (SPE) on sawdust from Cedrus deodera has been developed for speciation of Cr(III) and Cr(VI) in environmental water samples. Because different exchange capacities were observed for the two forms of chromium at different pH-Cr(III) was selectively retained at pH 3 to 4 whereas Cr(VI) was retained at pH 1-complete separation of the two forms of chromium is possible. Retained species were eluted with 2.5 mL 0.1 mol L(-1) HCl and 0.1 mol L(-1) NaOH. Detection limits of 0.05 and 0.04 microg mL(-1) were achieved for Cr(III) and Cr(VI), respectively, with enrichment factors of 100 and 80. Recovery was quantitative using 250 mL sample volume for Cr(III) and 200 mL for Cr(VI). Different kinetic and thermodynamic properties that affect sorption of the chromium species on the sawdust were also determined. Metal ion concentration was measured as the Cr(VI)-diphenylcarbazide complex by UV-visible spectroscopy. The method was successfully applied for speciation of chromium in environmental and industrial water samples.

Enrichment of Pb(II) ions using phthalic acid functionalized XAD-16 resin as a sorbent.

A simple and reliable method has been developed using polymeric material containing phthalic acid as a chelating agent to concentrate ultratrace amounts of lead ions in aqueous solutions. After characterization by CHN, IR, and thermal studies, the static and dynamic sorption behavior of Pb(II) ions onto new synthetic resin has been investigated. The sorption has been optimized with respect to pH, shaking speed, and contact time between the two phases. Maximum sorption is achieved from solution of pH 5-8 after 10 min agitation time. The lowest concentration for quantitative recovery is 5.8 ng cm(-3) with a preconcentration factor of approximately 850. The kinetics of sorption follows the first-order rate equation with the rate constant k=0.58+/-0.04 min(-1). The variation of the equilibrium constant K(c) with temperature between 10 and 50 degrees C yields values of DeltaH, 52.4+/-1.65 kJmol(-1), DeltaS, 186+/-5.21 Jmol(-1)K(-1), and DeltaG(303K), -4.15+/-0.002 kJmol(-1). The sorption data of Pb(II) ions in the concentration range from 2.41x10(-6) to 1.44x10(-4) molL(-1) follows the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms at all temperatures investigated. The sorption of Pb(II) ions onto synthesized resin in the presence of common anions and cations has also been measured. The possible sorption mechanism of Pb(II) ions onto phthalic acid modified XAD-16 is also discussed. The sorption procedure is utilized to preconcentrate Pb(II) ions prior to their determination in automobile exhaust particulates by atomic absorption spectrometry using direct and standard addition methods.

Liquid chromatographic determination of cis-platin as platinum(II) in pharmaceutical preparation, serum and urine samples of cancer patients.

Spectrophotometric and high performance liquid chromatographic (HPLC) methods have been developed for the determination of cis-platin and carboplatin based on the pre-column derivatization of platinum(II) with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone. The complex was extracted in chloroform with molar absorptivity of 2.2x10(4)Lmol(-1)cm(-1) at 380nm. The complex eluted from a Phenomenex C-18 (150mmx4.6mm i.d.) column with methanol:water:acetonitrile:tetrabutyl ammonium bromide (1mM) (44:30:25:1, v/v/v/v) with a flow rate of 1ml/min and UV detection at 260nm. Ruthenium(IV) and selenium(IV) also separated completely. The linear calibration curve was with 0.5-12.5microg/ml and detection limit of 10ng/ml platinum(II).The analysis of cis-platin and carboplatin injections by spectrophotometric and HPLC methods indicated relative standard deviation (R.S.D.) of 0.66-2.1%. The method was used for the determinations of cis-platin in serum and urine of cancer patients after chemotherapy and platinum contents were found 148-444 and 50-90ng/ml with R.S.D. of 0.3-3.0 and 0.6-2.4% for the serum and urine, respectively. The recovery of platinum(II) from serum was 97% with R.S.D. 2.2%.

Liquid chromatography of uranium complexes of tetradentate Schiff bases.

Dioxouranium together with copper(II), nickel(II) and iron(II) were extracted in chloroform as complexes of bis(salicylaldehyde)-dl-stilbenediimine (dl-H2SA2S) or bis(salicylaldehyde)-meso-stilbenediimine (meso-H2SA2S), and separated by liquid chromatography with UV detection. The linear calibration range and detection limits were 40 - 200 ng and 10 ng/injection for each metal ion. The method was applied to the determination of uranium from mineral ore samples at concentrations of 30 - 700 microg/g with coefficients of variation from 3.6 to 5.5%. The relative elution of dioxouranium complexes of different Schiff bases was examined from reversed-phase HPLC; the substitution of methyl and phenyl groups at the bridge position enhanced the column retention of uranyl complexes.

Liquid chromatographic determination of gamma-aminobutyric acid in cerebrospinal fluid using 2-hydroxynaphthaldehyde as derivatizing reagent.

gamma Aminobutyric acid (GABA) was determined by precolumn derivatization with 2-hydroxynaphthaldehyde and elution was made using Phenomenex C(18), 5 microm column with methanol: water (62:38 v/v) and UV detection at 330 nm. In a mixture containing glycine, l-lysine and tyramine GABA separated completely. A number of amines and amino acids tested did not affect the response of GABA. A linear calibration curve was obtained for GABA in the range of 1.2-28.0 microg/ml with detection limit of 2.8 ng/injection (5 microl). The method was used for the determination of GABA in cerebral spinal fluid (CSF) samples and gave results of 19.0 to 22.4 microg/m1 with coefficient of variation 2.4%

Gas and liquid chromatography of metal chelates of pentamethylene dithiocarbamate.

Capillary GC and HPLC of metal chelates of pentamethylene dithiocarbamate were examined. Copper(II), nickel(II), cobalt(III), iron(III), manganese(II) and chromium(III) chelates formed in slightly acidic media (pH 5) were extracted in methyl isobutyl ketone or chloroform. Capillary GC elution and separation was carried out on methylsilicone DB-1 column (25 m x 0.2 mm I.D.) with film thickness 0.25 microm. Electron-capture detection was used. Elution was carried at initial column temperature 200 degrees C with an increment at a rate of 5 degrees C/min up to 250 degrees C and maximum temperature was maintained for 10 min. Symmetrical peaks with baseline separation were obtained with the metal chelates investigated with linear calibration range between 5 and 25 microg/ml for each metal ion and detection limits in the range of 0.5-6.0 microg/ml corresponding to 27-333 pg of metal ion reaching to the detector. HPLC separation was carried out from LiChrosorb ODS, 5 microm column and complexes eluted with methanol-water-1 mM sodium acetate (70:28:2, v/v) with a flow-rate of 1.2 ml/ml. UV detection was at 260 nm. The detection limits obtained were in the range 2-6 microg/ml. The methods were applied to the determination of metal ions in canal water and coal samples with RSD values within 4.15%. The results when compared with a standard flame atomic absorption spectrophotometric method and revealed no significant difference.

Liquid chromatographic determination of isoniazid, pyrazinamide and rifampicin from pharmaceutical preparations and blood.

Isoniazid (IN), pyrazinamide (Pz) and rifampicin (Rf) are separated on YMC-ODS column. IN was derivatized with 2-fluorene-carboxaldehyde (FA). The separation was achieved using ethanol-chloroform-acetonitrile water by isocratic elution and detected at 337 nm. The detection limits were 0.11 ng, 0.2 ng and 13 ng/injection (5 microl) for IN, Pz and Rf, respectively. The method of analysis was applied to the pharmaceutical preparations and in the blood samples of the patients suffering from tuberculosis after undergoing chemotherapy with IN, Pz and Rf. The amounts quantitated in blood showed 0.97 to 1.58 microg/ml IN, 3.44 to 4.09 microg/ml Pz and 1.98 to 3.5 microg/ml Rf with coefficient of variations 0.8-1.8%, 0.9-1.3% and 0.8-2.1%, respectively.

HPLC determination of phenylpropanolamine in pharmaceutical preparations using 4-dimethylaminobenzaldehyde as a derivatizing reagent.

A method is described for the high performance liquid chromatographic (HPLC) determination of phenylpropanolamine (PPA) based on precolumn derivatization with 4-dimethylaminobenzaldehyde (DAB) and elution from phenomenex C-18 column with methanol-water and detection by spectrophotometry at 418 nm. Linear calibration was obtained with 9.4--46.9 microg ml(-1) with a detection limit of 4.7 ng ml(-1). Vitamin B(12) and rifampicin when present together with PPA separated completely and could be determined simultaneously. PPA was determined in pharmaceutical preparations with a relative standard deviation of 0.6--1.6%.