Junkichi Miura

Automated precolumn derivatization system for analyzing physiological amino acids by liquid chromatography/mass spectrometry

An automated method for high-throughput amino acid analysis, using precolumn derivatization high-performance liquid chromatography/electrospray mass spectrometry (HPLC/ESI-MS), was developed and evaluated. The precolumn derivatization step was performed in the reaction port of a home-built auto-sampler system. Amino acids were derivatized with 3-aminopyridyl-N-hydroxysuccinimidyl carbamate, and a 3 microm Wakosil-II 3C8-100HG column (100 x 2.1 mm i.d.) was used for separation. To achieve a 13 min cycle for each sample, the derivatization and separation steps were performed in parallel. The results of the method evaluation, including the linearity, and the intra- and inter-precision, were sufficient to measure physiological amino acids in human plasma samples. The relative standard deviations of typical amino acids in actual human plasma samples were below 10%.

Analysis of plasma catecholamines by high-performance liquid chromatography with fluorescence detection: simple sample preparation for pre-column fluorescence derivatization.

Analysis of plasma catecholamines (norepinephrine, epinephrine and dopamine) by high-performance liquid chromatography using 1,2-diphenylethylenediamine as a fluorescent reagent is described. We have developed an automatic catecholamine analyser, based on pre-column fluorescence derivatization and column switching. The analysis time for one assay was 15 min. The correlation coefficients of the linear regression equations were greater than 0.9996 in the range 10-10,000 pg/ml. The detection limit, at a signal-to-noise ratio of 3, was 2 pg/ml for dopamine. A new method of sample preparation for the pre-column fluorescence derivatization of plasma catecholamines was used. In order to protect the catecholamines from decomposition, an ion-pair complex between boric acid and the diol group in the catecholamine was formed at a weakly alkaline pH. The stabilities of plasma catecholamines were evaluated at several temperatures. After complex formation, the catecholamines were very stable at 17 degrees C for 8 h, and the coefficients of variation for norepinephrine, epinephrine and dopamine were 1.2, 4.2 and 9.3%, respectively.

High-sensitivity micro ultraviolet absorption detector for high-performance liquid chromatography

Abstract A UV absorption detector with a 0.6-μl flow cell for high-performance liquid chromatography (HPLC) was developed. In order to improve the signal-to-n

Analysis of body functions using a clinical liquid chromatograph

A clinical liquid chromatograph, which consists of a completely automated liquid chromatograph combined with a microcomputer for diagnosis, and its application to body function analyses are described. The analytical rate for urinary ultraviolet-absorbing constituents using anion-exchange chromatography was 12 samples per day, and the reproducibilities for retention time and peak area were less than 3% and 4%, respectively. Diagnostic methods for kidney functions using the chromatograms are discussed.

Correlative retention time peak identification method for glycated haemoglobin in high-performance liquid chromatography.

A convenient peak identification method in stepwise elution was investigated and correlation among the retention times of peaks in ion-exchange chromatography of glycated haemoglobin was assessed. By using a correlation method, accuracy of peak identification among columns with degradation and product deviations can be maintained. The correlative retention time identification procedure is treated theoretically.

Enhancement of chromatographic performances of porous polymer packings by diminishing their particle diameter.

HPLC用ポリマー充てん剤である第4級アンモニウム基修飾型のスチレン-ジビニルベンゼン共重合体を対象とし,充てん剤の微粒化による性能改善を図った.その結果,市販のポリマー充てん剤に比較して理論段数を2倍に,耐圧性を30%向上させることができた.これにより,核酸塩基の分析時間を従来に比べて1/3に短縮させることができた.