Shun-Jin Lin

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 degrees C using a background electrolyte consisting of 10mM 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 micromol ml(-1); the detection limit (signal-to-noise ratio 3; injection 0.3 psi, 3s) was 0.01 and 0.02 micromol ml(-1), respectively.

Rapid Simultaneous Determination of Three Methylxanthines in Human Plasma by Capillary Electrophoresis

Abstract A simple capillary electrophoresis method is described for simultaneous determination of three methylxanthines, theophylline, dyphylline, and caffeine in human plasma. Plasma proteins are precipitated by acetonitrile and the supernatant was performed in Tris buffer (20 mM; pH 9) with sodium dodecyl sulfate (SDS) (150 mM) as an anionic surfactant. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the Tris buffer and SDS. Application of the proposed method to the determination of theophylline and dyphylline in human plasma proved to be feasible. The practicability of the proposed method is demonstrated on a healthy volunteer.

TRACE ANALYSIS OF AMIKACIN IN COMMERCIAL PREPARATION BY DERIVATIZATION AND HPLC

A simple and sensitive liquid chromatographic method has been developed for the determination of amikacin by derivatization. The method is based on the derivatization of amikacin with derivatizing agent, 1-naphthoyl chloride, in pyridine at 30°C for 1 h. After derivatization reaction, a dimethylamine acetonitrile solution was added to the reaction mixture to eliminate the excess derivatizing agent. The derivative was analysed by HPLC on a Delta-Pak C4 column with water-acetonitrile (15:85, v/v) as the mobile phase and detection at 295 nm. The parameters affecting the derivatization of amikacin, including reaction temperature, reaction time, and the amount of derivatizing agent, were investigated. The linear range of the method for the determination of amikacin was over 17–170 nmol/mL; the detection limit (signal to noise ratio = 5; injection volume, 20 μL) was 5 nmol/mL. Application of the method to the analysis of amikacin in commercial injections has proved satisfactory.

Trace analysis of amikacin in human plasma by high-performance liquid chromatography

SummaryA simple and sensitive liquid chromatographic method is described for the determination of amikacin in human plasma. The amikacin is derivatized with 1-naphthyl isothiocyanate (NITC) at 70°C. After derivatization, a methylamine acetonitrile solution is added to the reaction mixture to eliminate excess derivatizing agent. The resulting derivative was analysed by HPLC on a LiChroCART RP-C18 column with water-acetonitrile (57:43,v/v) mobile phase and detection at 230 nm. Parameters affecting derivatization of amikacin, including reaction temperature, reaction time and amount of derivatizing agent, were investigated. The linear range for the determination of amikacin in spiked plasma was over 10–52 nmol mL−1; the detection limit (signal-to-noise ratio=3; injection volume, 10 μL) was ca. 1 nmol mL−1. The relative standard deviation was <2.37% for intra-day assay (n=6), 5.80% for inter-day assay (n=6) and relative recovery was >91%.

SIMULTANEOUS DETERMINATION OF DIGOXIN AND DIGITOXIN BY DERIVATIZATION AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

A simple and sensitive liquid chromatographic method has been developed for the determination of digoxin and digitoxin by derivatization. The method is based on the derivatization of digoxin and/or digitoxin with derivatizing agent, 1-naphthoyl chloride, in pyridine at 50?C. Under the mild condition, the digoxin and digitoxin were derivatized into their highly sensitive derivatives. After the derivatization reaction, a dimethylamine- acetonitrile solution was added to the reaction mixture to eliminate the interference from the excess derivatizing agent. The derivatives obtained were performed on a reversed-phase C8 column with 88% acetonitrile as the mobile phase. The parameters affecting the derivatization of digoxin and digitoxin, including reaction temperature, reaction time, and the amount of derivatizing agent, were investigated. The linear ranges of the method for the determination of digoxin and digitoxin were over 1–50 nmol/mL and 5–50 nmol/mL; the detection limit (signal to noise ratio = 5; injec...

Derivatization-High Performance Liquid Chromatographic Determination of Methanol in Human Plasma

Abstract A simple and sensitive high performance liquid chromatographic method is described for the determination of methanol in human plasma, as a highly sensitive derivative. The methanol, spiked in plasma, after simple ultrafiltration treatment, was derivatized with 3-bromomethyl-7-methoxy-1,4-benzoxazin-2-one in a heterogeneous system, using benzalkonium chloride as phase transfer catalyst. The resulting derivative was chromatographed on a LiChrospher diol column with n-hexane:dichloromethane (9:1, v/v) as the mobile phase and 1-nitronaphthalene as the internal standard. The HPLC system showed good selectivity for methanol determination. Several parameters affecting the derivatization of methanol extracted from spiked plasma were investigated. The linear range for the determination of methanol in spiked human plasma was over 1–10 μmol/mL; the detection limit (signal to noise = 5, sample size 10 μL) of methanol was about 0.06 ± 0.02 μmol/mL. The intraday relative standard deviation (n = 6) and the inte...

MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY OF CYCLOSPORIN A IN A COMMERCIAL PREPARATION

A simple micellar electrokinetic capillary chromatography is described for the determination of cyclosporin A in commercial preparation. The analysis of cyclosporin A was performed in a Tris buffer (10 mM; pH 7.1) with sodium dodecyl sulfate (SDS) (30 mM) as an anionic surfactant. Applied voltage was 20 kV and temperature was 25°C. Cefaclor was used as an internal standard and detection set at 200 nm. Several parameters affecting the separation of the drug were investigated, including the pH of the buffer, the concentrations of the buffer and SDS. The linear range of the method for the determination of cyclosporin A was over 30–500 μM. Application of the method to the determination of cyclosporin A in capsules from a commercial source proved to be satisfactory.

Trace Analysis of Amikacin by Derivatization and High Performance Liquid Chromatography

A simple and sensitive liquid chromatographic method was developed for the determination of amikacin. The method is based on the detection of amikacin derivatized at amino groups with 1-naphthyl isothiocyanate. This reaction was carried out in pyridine at 70°C for 1 h. After derivatization, methylamine acetonitrile solution was added to the reaction mixture to eliminate the excess detribalizing agent. The derivative was analysed by reverse-phase HPLC on a LiChroCART Rp C18 column with water-acetonitrile (57:43, v/v) as the mobile phase, and detected at 230 nm. Several parameters affecting the derivatization of amikacin, including the reaction solvent, reaction temperature, reaction time and the amount of derivatizing agent, were investigated. The linear range of the method for the determination of amikacin was over 20-500 nmol/mL; the detection lime it (signal to noise ratio = 3; injection volume, 10 μl) was 5 nmol/mL. Application of the method to the analysis of amikacin in commercial injections has proven to be satisfactory.