Ji-Seon Jeong

A reversed-phase high-performance liquid chromatography method with pulsed amperometric detection for the determination of glycosides.

We have developed a reversed-phase high-performance liquid chromatography pulsed amperometric detection (RP-HPLC-PAD) method for the determination of glycosides. It is sensitive, repeatable, and selective without the pretreatment step. Ginsenosides were separated completely in 50 min using an water-acetonitrile gradient as the eluent and detected by PAD under NaOH alkaline conditions. The ginsenoside detection limit (S/N=3) was 0.02-0.07 ng and the quantification limit (S/N=10) was 0.1-0.2 ng. The coefficient of linear regression was 0.9984-0.9998 for concentrations between 1 and 50 microg/mL. The intra- and inter-day precision (RSD) was less than 6.35% in Ginseng Radix and Shy-jiun-tzyy-tang extracts. The average recoveries from Ginseng Radix and Shy-jiun-tzyy-tang extracts were 98.19-105.45% and 96.89-102.22%, respectively.

HPLC with pulsed amperometric detection for sorbitol as a biomarker for diabetic neuropathy.

This study describes the optimal analytical conditions for sorbitol analysis by a high-performance anion-exchange chromatography-pulsed amperometric detection method. Its clinical utility as a diagnostic tool was established by measuring sorbitol in the sciatic nerves or salivary glands of diabetes mellitus-induced mice. Sorbitol was completely separated from other monosaccharides on an anion-exchange column with 100mM NaOH as eluent. The limit of detection (S/N=3) and limit of quantification (S/N=10) were 0.03 ng (3 ng/g) and 0.10 ng (10 ng/g), respectively. The linear dynamic range was 0.01-50.0 microg/g (r(2)=0.9997 and 0.9989 for sciatic nerves and salivary glands, respectively), and the mean recoveries for intra- or inter-day assays were in the range of 98.5-103.9%. This method easily identified diabetic and normal groups, making it a practical procedure for the rapid screening of diabetic neuropathy.

A pulsed amperometric detection method of galactose 1-phosphate for galactosemia diagnosis

Galactose 1-phosphate uridyltransferase deficiency causes the accumulation of galactose and galactose 1-phosphate (Gal 1-P) in the blood. We describe a new pulsed amperometric detection method for determining Gal 1-P levels as a pathognomic marker for the diagnosis of galactosemia. The method uses high-performance anion-exchange chromatography with pulsed amperometric detection. In an anion-exchange column, the analytes were separated in 5 min by the eluent mixture of 40 mM NaOH and 40 mM Na(2)CO(3). The detection limit (signal to noise ratio of 3) to Gal 1-P was 30 microg/dL. The linear dynamic range was 3.0-50 mg/dL (r(2)=0.9999). The mean recoveries of Gal 1-P for intra- and interday assays were 97.55-103.78%. This method clearly separated the type I galactosemia patients from the normal group and is a practical procedure for the rapid diagnosis of galactosemia.

Simultaneous diagnostic method for phenylketonuria and galactosemia from dried blood spots using high-performance liquid chromatography-pulsed amperometric detection

We developed a simultaneous diagnostic method for phenylketonuria (PKU) and galactosemia through simultaneous determination of phenylalanine (Phe) and galactose (Gal) by high-performance liquid chromatography (HPLC) with pulsed amperometric detection (PAD). The intra- and inter-day precisions were <5.8%, with satisfactory mean recoveries (98.2-105%). For all PKU-positive samples, Phe levels were above the cut-off value (>30.0 mg/L), but Gal levels were nearly zero. For 77% of galactosemia-positive samples, Phe levels were above the cut-off value, but Gal levels were above the cut-off value (>80.0 mg/L) for all samples. Our HPLC-PAD method can reduce the false-positive rate of misdiagnosis for PKU and galactosemia.

Determination of phenylalanine in blood by high-performance anion-exchange chromatography―pulsed amperometric detection to diagnose phenylketonuria

We have developed a high-performance anion-exchange chromatography with pulsed amperometric detection method for the detection of phenylalanine (Phe) and diagnosis of phenylketonuria (PKU). Sample pretreatment steps were simplified without derivatization. The analyte was separated within 5 min. The detection limit (S/N=3) for Phe was 50 pg. Linear dynamic range was 1.23-14.43 mg/dL (r(2)=0.9999) for a dried blood spot. The mean recoveries of Phe for intra- and inter-day assays were found to be 96.87-104.16%. This method clearly differentiated PKU-positive groups from normal groups, and proved to be a practical procedure for rapid screening and follow-up monitoring of PKU.

Detection of albiflorin and paeoniflorin in Paeoniae Radix by reversed-phase high-performance liquid chromatography with pulsed amperometric detection

We have developed a reversed-phase high-performance liquid chromatography-pulsed amperometric detection (RP-HPLC-PAD) method for the detection of albiflorin and paeoniflorin in Paeoniae Radix and Wu-ji-san. Albiflorin and paeoniflorin were completely separated using 10% acetonitrile in 5mM sodium phosphate buffer (pH 3.0) as an eluent and detected by PAD under alkaline conditions after using a post-column delivery system. The limit of detection (S/N=3) and the limit of quantification (S/N=10) were 0.10 and 0.35 ng for albiflorin, and 0.20 and 0.50 ng for paeoniflorin, respectively. The coefficients of linear regression were 0.9995 and 0.9999 for concentrations between 0.035 and 100 microg/mL. The intra- and inter-day precision (RSDs) was less than 3.56% in Paeoniae Radix and Wu-ji-san. The average recoveries from Paeoniae Radix and Wu-ji-san were 99.01-100.94% and 99.46-100.64%. This method shows higher selectivity than HPLC-UV method for analyzing albiflorin and paeoniflorin in Chinese medicinal preparation.

Sensitive high-performance liquid chromatography method of non-polar ginsenosides by alkaline-enhanced pulsed amperometric detection.

We determined the minute amount of non-polar ginsenosides in red ginseng with a reversed-phase high-performance liquid chromatography-pulsed amperometric detection (RP-HPLC-PAD) method. Non-polar ginsenosides efficiently extracted by ethyl acetate were well separated in 40min using a water-acetonitrile gradient eluent and detected by PAD under NaOH alkaline conditions. The ginsenoside detection limits (S/N=3) were 0.03-0.10ng. The coefficients of linear regression were 0.9972-0.9990. Intra- and inter-day precision (RSDs) was less than 8.34% and average recovery was 98.06-102.73%. The total amount of non-polar ginsenosides in hairy root of red ginseng was slightly higher than in the main root.

Sphingosine 1-Phosphate and Sphingosine Kinase Activity during Chicken Embryonic Development

The chicken embryo has been well used in studies of the developmental process, and during development sphingosine and sphingosine 1-phosphate (So1P) are considered critical mediators of cell death and survival. In this study, we compared the sphingolipid contents of chicken embryos during the early embryonic development period from day 3 to day 6. HPLC analyses of sphingosine and So1P in chicken embryos revealed that sphingosine levels were greatly reduced on day 4 whereas So1P levels were not significantly changed. Sphingosine kinase (Sphk) activities, which require sphingosine as substrate to produce So1P, were also greatly reduced on day 4. Collectively, we found sphingosine levels and Sphk activities, but not So1 P levels are changed in early stage of chicken embryos development.

Chromatographic diagnosis of maple syrup urine disease by measuring the l-alloisoleucine/l-phenylalanine ratio in dried blood spots

A high-performance ligand-exchange chromatography with ultraviolet detection method for confirmation diagnosis of maple syrup urine disease (MSUD) was developed that relies on the determination of branched-chain amino acids (BCAAs) and Phe levels in blood. The dynamic ranges for the BCAAs and Phe were 50-1000 μM (r(2)=0.9982-0.9996) and 74-873 μM (r(2)=0.9992) from a dried blood spot, and the BCAA detection limits (S/N=3) were 0.43-1.91 μM. The mean recoveries of BCAA for intra- and inter-day assays were 92.1-103.0%. The ranges of alloisoleucine (Allo-Ile)/Phe ratio were ND-0.04 and 1.5-2.4 for PKU and MSUD patient samples, respectively. The lowest ratio (1.5) of the MSUD samples was 37.5 times higher than the highest ratio (0.04) of the PKU samples. Therefore, the Allo-Ile/Phe ratio was very useful biomarker for confirmation diagnosis of MSUD.

Sensitive high-performance anion-exchange chromatographic determination of paeoniflorin and albiflorin by pulsed amperometric detection after solid-phase extraction.

We developed a method to simultaneously determine paeoniflorin and albiflorin levels using high-performance anion-exchange liquid chromatography with pulsed amperometric detection (HPAEC-PAD). The main principle of our method includes solid-phase extraction step using Amberlite XAD-2 sorbent to remove sugars and to selectively determine glycosides by PAD. Under these conditions, the linear dynamic range was 0.01-100 microg/mL, and the albiflorin and paeoniflorin detection limits (S/N=3) were 5 and 10 pg, respectively. The intra- and inter-day precisions (RSDs) were <5.07%, and the average recoveries from Paeoniae Radix and Si-ni-san ranged from 97.12 to 101.15%. Our method showed high selectivity, high sensitivity, and good repeatability for analyzing albiflorin and paeoniflorin in oriental medicinal preparation.