Akiko Shinoda

Determination of estrogens and their conjugates in water using solid-phase extraction followed by liquid chromatography–tandem mass spectrometry

An analytical procedure for the determination of steroid estrogens and their conjugates was developed and applied to aqueous environmental samples. The analytes of 15 compounds were solid-phase extracted and fractionated into two fractions: one containing unconjugated (free) steroids and the other containing conjugates (sulfates and glucuronides). Identification and quantification were carried out using liquid chromatography coupled with tandem mass spectrometry. The recoveries for each compound ranged from 57 to 116% and reproducibilities represented as RSD ranged from 2.9 to 17%. Some of the sulfates and free compounds were detected in environmental samples, whereas most of the conjugates were below the detection limits.

Gas chromatographic-mass spectrometric determination of hydrophilic compounds in environmental water by solid-phase extraction with activated carbon fiber felt.

Simple gas chromatographic-mass spectrometric determination of hydrophilic organic compounds in environmental water was developed. A cartridge containing activated carbon fiber felt was made by way of trial and was evaluated for solid-phase extraction of the compounds in water. The hydrophilic compounds investigated were acrylamide, N,N-dimethylacetamide, N,N-dimethylformamide, 1,4-dioxane, furfural, furfuryl alcohol, N-nitrosodiethylamine and N-nitrosodimethylamine. Overall recoveries were good (80-100%) from groundwater and river water. The relative standard deviations ranged from 4.5 to 16% for the target compounds. The minimum detectable concentrations were 0.02 to 0.03 microg/l. This method was successfully applied to several river water samples.

Simultaneous determination of uric acid and creatinine in biological fluids by column-switching liquid chromatography with ultraviolet detection

A column-switching liquid chromatographic method for the simultaneous determination of uric acid and creatinine in human serum and urine was developed. Creatinine and uric acid were separated by size-exclusion chromatography on a hydrophilic gel column (C1) and creatinine eluted from C1 was separated from proteins by filtration through a longer hydrophilic gel column (C2). The creatinine fraction eluted from C2 was transferred to a weakly acidic cation-exchange column (C3) and then to a strongly acidic cation-exchange column (C4). Uric acid eluted from C1 after creatinine was transferred to an anion-exchange column (C5) and then to a hydrophilic gel column (C6). The mobile phase was a mixed buffer of pH 5.1 (propionic acid-succinic acid-NaOH, 60:15:60 mmol/l in water). Diluted serum and urine could be injected onto C1, and C1 was backflushed after the transfer of uric acid from C1 to C5. Creatinine and uric acid in the eluate were determined by measuring their ultraviolet absorption at 234 and 290 nm, respectively. The recovery of uric acid and creatinine added to diluted serum (20-fold dilution, concentration 20 and 5 mumol/l, respectively) was 98.9 +/- 0.56% and 100.9 +/- 1.29%, respectively. The recovery of uric acid and creatinine added to diluted urine (100-fold dilution, concentration 50 and 100 mumol/l, respectively) was 99.4 +/- 0.72% and 98.7 +/- 1.45%, respectively (mean +/- R.S.D., n = 6).