Postcolumn Degradation Research Articles

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

A sensitive, high-performance liquid chromatographic method involving postcolumn degradation with sodium hypochlorite and using a hollow-fibre membrane as a reactor is described for the determination of penicillins. Penicillins were separated on a C18 column followed by postcolumn reaction with sodium hypochlorite and sodium hydroxide using aminated and sulphonated hollow-fibre membrane reactors immersed in each solution, and detected at 270–280 nm based on the UV absorbances of the degradation products. At penicillin concentrations of 2 μg/ml, the precisions (relative standard deviation) were 2.28–4.78%. The detection limits of the proposed method were 2.5–25 ng for each penicillin at a signal-to-noise ratio of 3. Ampicillin and its metabolites [(5 R,6 R)-ampicilloic acid, the (5 S,6 R)-epimer and (2 R)-pierazine-2′,5′-dione] in human serum and urine were simultaneously determined by this method.

High-performance liquid chromatographic determination of ampicillin and its metabolites in rat plasma, bile and urine by post-column degradation with sodium hypochlorite

A high-performance liquid chromatographic method has been developed for the determination of ampicillin (1) and its metabolites [(5 R, 6 R)-ampicilloic acid (2), the (5 S, 6 R)-epimer (3) and the corresponding (2 R)-piperazine-2′, 5′-dione (4)] in rat plasma, bile and urine. The method involves the separation of 1–4 from the background components of the biological fluids on a reversed-phase C 18 column, using sodium heptanesulphonate as an ion-pairing agent and methanol in the mobile phase, followed by post-column degradation with 1.5 M sodium hydroxide-0.02% sodium hypochlorite solution at ambient temperature, and detection of the degradation product(s) of each compound at 270 nm. The detection limits were about 25 ng for each compound at a signal-to-noise ratio of 3. At concentrations of 2–5 μ/ml of each compound, the within- and between-run precisions (relative standard deviation) were 0.77–7.15% and 1.76–5.96%, respectively. The plasma, biliary and urinary levels of 1 and its metabolites were determined by the proposed method after intravenous administration of 1 to rats.

Liquid chromatographic determination of amoxicillin and its metabolites in human urine by postcolumn degradation with sodium hypochlorite

A high-performance liquid chromatographic method has been developed for the determination of amoxicillin (I) and its metabolites [(5 R,6 R)-amoxicilloic acid (II), the (5 S,6 R) epimer (III), and and (2 R)-piperazine-2′,5′-dione (IV)] in human urine. They were separated from the background components of urine on a reversed-phase C 18 column using sodium heptylsulphonate as an ion-pairing agent and methanol as an organic mobile phase modifier. The eluent was led to the postcolumn degradation with 1.5 M sodium hydroxide plus 0.02% sodium hypochlorite solution at ambient temperature. The degradation product(s) of each compound was detected at 270 nm. The proposed method permits detection of I, II, III, and IV down to 1 μg/ml in neat urine samples. At a concentration of 5 μg/ml of each compound, within-and between-run precisions (relative standard deviation) were 1.12–5.79 and 0.90–2.70%, respectively. The urinary levels of I and its metabolites were determined by the proposed method after administration of I to humans.

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite.

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite.

Gas-liquid chromatographic determination of serum ethylene and propylene glycols: D. Suria and L.A. Wright, Dept. of Clinical Biochemistry, The Wellesley Hospital, Toronto, Ontario M4Y 1J3

A high-performance liquid chromatographic method has been developed for the determination of amoxicillin (I) and its metabolites [(5R,6R)-amoxicilloic acid (II), the (5S,6R) epimer (III), and and (2R)-piperazine-2′,5′-dione (IV)] in human urine. They were separated from the background components of urine on a reversed-phase C18 column using sodium heptylsulphonate as an ion-pairing agent and methanol as an organic mobile phase modifier. The eluent was led to the postcolumn degradation with 1.5 M sodium hydroxide plus 0.02% sodium hypochlorite solution at ambient temperature. The degradation product(s) of each compound was detected at 270 nm. The proposed method permits detection of I, II, III, and IV down to 1 μg/ml in neat urine samples. At a concentration of 5 μg/ml of each compound, within-and between-run precisions (relative standard deviation) were 1.12–5.79 and 0.90–2.70%, respectively. The urinary levels of I and its metabolites were determined by the proposed method after administration of I to humans.