Simultaneous Determination Of Theophylline Research Articles

Real time detection of adenosine and theophylline in urine and blood samples using graphene modified electrode

Herein, we report the grafting of stable graphene layers on to glassy carbon (GC) electrode by a two-step diazotization strategy using melamine. The resulting graphene modified electrode is used for the selective determination of theophylline (TP) in the presence of inhibitor neurotransmitter antagonist, adenosine (AD). The modified electrode surfaces are characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). Bare GC electrode fails to show stable voltammetric signals for TP and AD due to the surface fouling caused by the oxidation products of the analytes. However, the graphene modified electrode showed stable voltammetric signals for the simultaneous detection of TP and AD than the bare GC electrode. Further, the graphene modified electrode is used for the selective determination of TP in the presence of 34-fold excess AD. A linear plot is noticed upon increasing the TP concentration from 3.0 × 10−8-1.0 × 10−4 M. The limit of detection is found to be 5.4 × 10−9 M (S/N = 3). The practical application of the proposed modified electrode is demonstrated by the simultaneous determination of TP and AD in human blood serum and urine samples.

Simultaneous determination of theophylline and caffeine on novel [Tetra-(5-chloroquinolin-8-yloxy) phthalocyanato] manganese(III)-Carbon nanotubes composite electrode

This work reports the synthesis of new symmetrically substituted manganese(III) phthalocyanine (2eOHMnPc) (2) containing tetra 5-chloroquinolin-8-yloxy group at the peripheral position for the first time. Manganese(III) phthalocyanine (2) was synthesized by cyclotetramerization of 4-(5-chloroquinolin-8-yloxy)phthalonitrile (1) in the presence of corresponding metal salt (manganese(II) chloride). This peripherally substituted phthalocyanine complex (2) was purified by column chromatography and characterized by several techniques such as IR, mass and UV–Visible spectral data. This novel synthesized phthalocyanine was mixed with multiwalled carbon nanotubes in order to prepare the novel catalytic surface on glassy carbon electrode for theophylline and caffeine detection in acidic medium. The novel composite electrode surfaces were characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Individual and simultaneous determination of theophylline and caffeine were studied by differential pulse voltammetry. The detection limits were individually calculated for theophylline and caffeine as 6.6 × 10−9 M and 5.0 × 10−8 M, respectively. In simultaneous determination, LODs were calculated for theophylline and caffeine as 8.1 × 10−9 M and 3.0 × 10−7 M, respectively. The practical applicability of the proposed modified electrode was tested for the determination of theophylline and caffeine in green tea, cola and theophylline serum.

Fabrication of aminotriazole grafted gold nanoparticles films on glassy carbon electrode and its application towards the simultaneous determination of theophylline and uric acid

This paper describes the potentiodynamic formation of AuNPs film on glassy carbon (GC) and indium tin oxide (ITO) electrodes using aminotriazole (AT) functionalized AuNPs (AT-AuNPs) and the utilization of the resulting AT-AuNPs film for the simultaneous determination of adenosine inhibitor drug, theophylline (TP) and uric acid (UA). The potentiodynamically prepared AT-AuNPs film modified electrodes were characterized by cyclic voltammetry (CV), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The prepared AT-AuNPs film modified electrode showed excellent electrocatalytic activity towards TP and UA. Therefore, it was successfully used for the simultaneous determination of them in a mixture. Further, the AT-AuNPs film modified electrode was effectively used for the selective determination of TP in the presence of 25-fold excess UA. Using amperometry, detection of 40nM TP was obtained. The current responses of TP was increased linearly while increasing their concentrations from 4.0×10−8M to 1.0×10−4M and the detection limit was found to be 8.5×10−9M (S/N=3). The practical application of the present modified electrode was demonstrated by simultaneously determining the concentrations of TP and UA in human blood serum and urine samples.

Simultaneous determination of theophylline, tolbutamide, mephenytoin, debrisoquin, and dapsone in human plasma using high‐speed gradient liquid chromatography/tandem mass spectrometry on a silica‐based monolithic column

AbstractTheophylline, tolbutamide, mephenytoin, debrisoquin, and dapsone are marker substrates for CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. A silica‐based monolithic column (Chromolith SpeedROD RP‐18e, 50×4.6 mm) was used to separate these five marker substrates of cytochrome P450 within only 84 s. Linear gradient elution was from acetonitrile‐water‐formic acid (10 : 90 : 1, v/v/v) to acetonitrile‐water‐formic acid (90 : 10 : 1, v/v/v) in 1.4 min. The flow rate was 2.5 mL/min. The retention time was 0.52 min for theophylline, 0.67 min for debrisoquin, 0.78 min for dapsone, 0.96 min for mephenytoin, and 1.13 min for tolbutamide. Detection was by tandem mass spectrometry using a PE Sciex API 3000 mass spectrometer with a Turbo‐Ionspray source in positive mode. A simple protein precipitation method was used. This method was validated over the concentration range of 5–2000 ng/mL based on the sample volume of 0.1 mL.

Simultaneous determination of theophylline and dyphylline by micellar electrokinetic chromatography and application in drug formulations

A simple micellar electrokinetic chromatography is described for well resolution of theophylline, dyphylline and caffeine. The separation was performed at 25 °C using a background electrolyte consisting of 10 mM borate buffer at pH 9 and 40 mM sodium dodecyl sulfate (SDS) as running buffer. Under this condition, good separation with high efficiency and short analyses time required is achieved. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the borate buffer and sodium dodecyl sulfate. Using caffeine as an internal standard (I.S.), the linear range of the method for the determination of theophylline and dyphylline was over 0.03–1 μmol ml −1; the detection limit (signal-to-noise ratio 3; injection 0.3 psi, 3 s) was 0.01 and 0.02 μmol ml −1, respectively.

ChemInform Abstract: Simultaneous Determination of Theophylline and Its Metabolites by HPLC

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Determination of theophylline and paraxanthine in urine samples by liquid chromatography using the H-point standard additions method

The simultaneous determination of theophylline and paraxanthine in urine samples by the H-point standard additions method (HPSAM) is described. Samples are extracted with C 18 solid-phase extraction cartridges and chromatographed using a Hypersil C 18-ODS column and a mobile phase consisting of acetonirile-phosphate buffer in the gradient elution mode. Under these conditions theophylline and paraxanthine are eluted with short retention times. Although their chromatographic peaks are overlapped and their spectra are very similar, the H-point standard additions method provides excellent results in the determination of both xanthines at therapeutic levels.

Simultaneous Determination of Theophylline and Caffeine by Reversed Phase Liquid Chromatography Using Phenyl Column

Abstract Phenyl, C-8, and C-18 columns were evaluated for the simultaneous analysis of theophylline (TH) and caffeine (CA). The phenyl column was chosen for its capability of resolving of 1,7-dimethylxanthine from theophylline. The procedure utilized protein precipitation of either 50 or 100 ul of serum with diluted trichloroacetic acid, followed by analysis with either a manual isocratic or automated gradient elution mode. Chromatographic conditions were: column = phenyl (4.5 × 150 mm with a 4.5 × 50 mm guard column), mobile phase = phosphate or acetate/ACN, and detection wavelength = 280 nm. Peak height or area ratios of TH or CA to the internal standard, beta-hydroxyethyl theophylline (βHET) were linearly correlated to concentratiozn ranges between 2.5 to 20 or 50 mg/L. Precision studies of “quality control” samples showed that the day-to-day coefficients of variation were leas than 9% for both TH and CA. TH plasma concentrations of patients quantitated by this procedure were compared to the clinically accepted assay by FPIA using either polyclonal or monoclonal antibodies. Results were closely correlated. CA concentrations of these “patients” ranged from 0.1 to 5 mg/L. The present study showed that the phenyl column exhibited long-term stability, suitable for clinical application of drug monitoring. Further, the small sample size of 50 ul would be useful for neonatal monitoring of TH and CA.

Simultaneous determination of theophylline and caffeine after extractive alkylation in small volumes of plasma by gas chromatography—mass spectrometry

Simultaneous determination of theophylline and caffeine after extractive alkylation in small volumes of plasma by gas chromatography—mass spectrometry

Simultaneous determination of theophylline and its major metabolites in urine by reversed-phase ion-pair high-performance liquid chromatography

A new, highly selective high-performance liquid-chromatographic (HPLC) assay for theophylline and its major metabolites in urine is described. The method utilizes an ion-pair extraction followed by separation and quantitation by reversed-phase ion-pair gradient-elution HPLC. Comparison with several other methods showed that interferences were present in too many blank urine samples to allow for the accurate quantitation of the metabolites of theophylline by direct injection-isocratic HPLC assays. Sample processing involving ion-pair complexing and extraction together with gradient-elution systems is recommended for accurate pharmacokinetic studies.

The simultaneous determination of theophylline, theobromine and caffeine in plasma by high performance liquid chromatography

A high performance liquid chromatographic procedure for the stimultaneous micro-scale determination of theophylline, theobromine and caffeine in plasma is described. After a single dichloromethane extraction of 0.5--0.2 ml of acidified plasma, the evaporated residue is chromatographed on a reverse-phase gC-18) column. With a mobile phase of acetate buffer (pH 4)--acetonitrile (88:12) at a flow-rate of 2.0 ml/min., the three methylxanthines are separated within six minutes. Detection at xanthines are separated within six minutes. Detection at 276-280 nm enables quantitation of 0.1 mg/1 of drug in a 0.1 ml sample. The method is reproducible, correlates well with EMIT for plasma theophylline, and is applicable to the routine monitoring of both paediatric and adult patients as well as to metabolic studies.

Simultaneous determination of theophylline and its metabolites in urine

SummaryA quantitative method for the simultaneous determination of theophylline (THP) and its metabolites, 1,3-dimethyluric acid (1,3-DMU), 1-methyluric acid (1-MU) and 3-methylxanthine (3-MX), in urine is described, using a preliminary extraction step with ‘Extreluf column and high pressure liquid chromatographic separation. Urinary excretion data of theophylline and its metabolites from 2 healthy male volunteers on a regular diet demonstrated high background values of 1-MU, to a lesser degree for 3-MXandTHP, and virtually none for 1,3-DMU, when the subjects were not receiving theophylline. Observed increments {above background values) following single-dose (375 mg) administrations of theophylline, orally and rectally, demonstrated 1,3-DMU as the predominant urinary excretory product together with 3-MX as an additional urinary metabolite, while the virtual absence of any increments in the 1-MU metabolite would indicate that biotransformation of theophylline to the 1-MU pathway is minimal or insignificant...