Muhammad Yar Khuhawar
University of Sindh
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Featured researches published by Muhammad Yar Khuhawar.
Journal of Chromatography B: Biomedical Sciences and Applications | 2001
Muhammad Yar Khuhawar; G.A Qureshi
Spermine, spermidine, putrescine and cadaverine are aliphatic amines widely spread in the human body. Their concentrations together with their acetyl conjugates increase significantly in the biological fluids and the affected tissues of cancer patients. Their concentrations decrease with the improvement in the patients condition on multiple therapy. Various chromatographic techniques are frequently used in monitoring concentrations of di- and polyamines in cancer. Among these techniques, thin-layer chromatography and liquid chromatography using pre- or postcolumn derivatization, separating on a reversed-phase or an ion-exchange column are the most commonly used. Besides, high-resolution capillary column gas chromatography (GC) is increasingly used over packed column GC, and in recent years, capillary zone electrophoresis has also gained some importance in polyamine determinations. The review examines the prospects and the limitations of polyamines as cancer markers using chromatographic and electrophoretic techniques.
Journal of Chromatography B: Biomedical Sciences and Applications | 1999
Muhammad Yar Khuhawar; Ashfaq A. Memon; P.D. Jaipal; M. I. Bhanger
Trifluoroacetylacetone (FAA) derivatives of 1,4-diaminobutane (putrescine) (Pu) and 1,5-diaminopentane (cadaverine) (CA) were prepared and characterized by elemental microanalysis, IR, and mass spectrometry. Diamine derivatives were eluted from capillary gas chromatographic (CGC) column BP1 (12 m x 0.22 mm I.D.) or BP5 (50 m x 0.22 mm) with layer thickness 0.25 microm, using nitrogen as a carrier gas and flame ionization detection (FID). A solvent extraction procedure was developed for the extraction of Pu and CA from aqueous solution with a linear calibration range 0-20 microg/0.2 ml of extract with a detection limit of 0.5-0.6 ng/injection. The method was applied for the determination of Pu and CA in the serum of five cancer patients before and after radiotherapy. The serum of two healthy persons was also analyzed for Pu and CA contents. Pu and CA concentrations were found within the range 1.16-3.96 microg/ml and 0.88-1.46 microg/ml in cancer patients as compared to 0.11-0.16 microg/ml and 0.06-0.075 microg/ml respectively in healthy persons with a coefficient of variation (CV) within 0.62-5.47%. Pu and CA concentrations decreased on radiotherapy in cancer patients, but were much higher than in healthy persons.
Talanta | 2005
Muhammad Yar Khuhawar; G.M. Arain
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%.
Talanta | 1996
Muhammad Yar Khuhawar; S.N. Lanjwani
A method is described for the simultaneous high performance liquid chromatographic (HPLC) determination of copper, iron, nickel and vanadium, based on complexation of analytes by bis(acetylpivalylmethane)ethylenediimine (H(2)APM(2)en) followed by solvent extraction and HPLC separation on a reversed-phase. C-18, 5 microm column with UV detection at 260 nm. The method has been applied to the determination of metals in crude petroleum oils collected from the South Indus Basin oil fields. The results obtained are compared with those obtained by flame atomic absorption spectrometry.
Chromatographia | 2001
Muhammad Yar Khuhawar; F. M. A. Rind
SummaryTranexamic acid (Tr) reacts with 2-hydroxynaphthaldehyde (HN) in aqueous ethanol at neutral pH in a 1∶1 molar ratio to form a tranexamic acid-2-hydroxynaphthaldehyde (Tr-HN) derivative, with enhancement of spectrophotometric sensitivity. Tr-HN was eluted from a YMC-ODS column (150×4.6 mm id) and separated completely from the derivatizing reagent HN. Tr-HN also was separated from paracetamol and mefanemic acid. Quantitation was at 317 nm. The method was used for the determination of Tr from pharmaceutical preparations and blood samples after 2–3 hrs of administration of the drug. A number of additives and amino acids did not affect the determination.
Talanta | 2007
Saima Q. Memon; M. Iqbal Bhanger; Syed Moosa Hasany; Muhammad Yar Khuhawar
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.
Talanta | 2006
Muhammad Yar Khuhawar; G.M. Arain
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.
Journal of Chromatography A | 2002
M.A Arain; Muhammad Yar Khuhawar; Muhammad Iqbal Bhanger
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.
Talanta | 1998
Muhammad Yar Khuhawar; S.N. Lanjwani
The complexing reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) was examined for high performance liquid chromatographic (HPLC) separations of cobalt(II), copper(II) and iron(II) or cobalt(II), nickel(II), iron(II), copper(II) and mercury(II) as metal chelates on a Microsorb C-18, 5-mum column (150x4.6 mm i.d.) (Rainin Instruments Woburn, MA, USA). The complexes were eluted isocratically with methanol:acetonitrile:water containing sodium acetate and tetrabutyl ammonium bromide (TBA). UV detection was at 254 nm. The solvent extraction procedure was developed for simultaneous determination of the metals, with detection limits within 0.5-2.5 mug ml(-1) in the final solution. The method was applied for the determination of copper, cobalt and iron in pharmaceutical preparation.
Talanta | 1995
Muhammad Yar Khuhawar; S.N. Lanjwani
The reagent bis(salicylaldehyde)tetramethylethylenediimine has been used for the determination of dioxouranium(VI), based on complexation in aqueous solution at pH 6, followed by extraction in chloroform and HPLC determination on a Hypersil ODS (3 mum) column. The complex was eluted with the ternary mixture methanol-acetonitrile-water (40:30:30, v/v/v), with UV detection at 260 nm. Oxovanadium(IV), iron(III), copper(II), cobalt(II), nickel(II) and palladium(II) were completely separated and did not interfere in the determination of uranium. The linear calibration range and detection limits have been obtained. The method has been applied to the determination of uranium together with copper, iron and nickel in mineral ore samples.