TY - JOUR
T1 - Determination of daidzein and genistein in soybean foods by automated on-line in-tube solid-phase microextraction coupled to high-performance liquid chromatography
AU - Mitani, Kurie
AU - Narimatsu, Shizuo
AU - Kataoka, Hiroyuki
N1 - Funding Information:
The present study was financially supported by Shimadzu Science Foundation, Japan Food Industry Center, and Grant-in-Aids for Scientific Basic Research (B (2), no. 14370729) from the Japan Society for the Promotion of Science.
PY - 2003/2/7
Y1 - 2003/2/7
N2 - An automated on-line method for the determination of the isoflavones, daidzein and genistein, was developed using in-tube solid-phase microextraction coupled to high-performance liquid chromatography (in-tube SPME-HPLC). In-tube SPME is a new extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. Daidzein, genistein and their glucosides tested in this study were clearly separated within 8 min by HPLC using an XDB-C8 column with diode array detection. In order to optimize the extraction of these compounds, several in-tube SPME parameters were examined. The glucosides daidzin and genistin were analyzed as aglycones after hydrolysis because the glucosides were not concentrated by in-tube SPME. The optimum extraction conditions for daidzein and genistein were obtained with 20 draw/eject cycles of 40 μl of sample using a Supel-Q porous layer open tubular capillary column. The extracted compounds were easily desorbed from the capillary by mobile phase flow, and carryover was not observed. Using the in-tube SPME-HPLC method, the calibration curves of these compounds were linear in the range 5-200 ng/ml, with a correlation coefficient above 0.9999 (n=18), and the detection limits (S/N=3) were 0.4-0.5 ng/ml. This method was successfully applied to the analysis of soybean foods without interference peaks. The recoveries of aglycones and glucosides spiked into food samples were above 97%.
AB - An automated on-line method for the determination of the isoflavones, daidzein and genistein, was developed using in-tube solid-phase microextraction coupled to high-performance liquid chromatography (in-tube SPME-HPLC). In-tube SPME is a new extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. Daidzein, genistein and their glucosides tested in this study were clearly separated within 8 min by HPLC using an XDB-C8 column with diode array detection. In order to optimize the extraction of these compounds, several in-tube SPME parameters were examined. The glucosides daidzin and genistin were analyzed as aglycones after hydrolysis because the glucosides were not concentrated by in-tube SPME. The optimum extraction conditions for daidzein and genistein were obtained with 20 draw/eject cycles of 40 μl of sample using a Supel-Q porous layer open tubular capillary column. The extracted compounds were easily desorbed from the capillary by mobile phase flow, and carryover was not observed. Using the in-tube SPME-HPLC method, the calibration curves of these compounds were linear in the range 5-200 ng/ml, with a correlation coefficient above 0.9999 (n=18), and the detection limits (S/N=3) were 0.4-0.5 ng/ml. This method was successfully applied to the analysis of soybean foods without interference peaks. The recoveries of aglycones and glucosides spiked into food samples were above 97%.
KW - Aglycones
KW - Automation
KW - Daidzein
KW - Food analysis
KW - Genistein
KW - Isoflavones
KW - Solid-phase microextraction
KW - Soybean
UR - http://www.scopus.com/inward/record.url?scp=0037423070&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037423070&partnerID=8YFLogxK
U2 - 10.1016/S0021-9673(02)02014-9
DO - 10.1016/S0021-9673(02)02014-9
M3 - Article
C2 - 12597624
AN - SCOPUS:0037423070
VL - 986
SP - 169
EP - 177
JO - Journal of Chromatography A
JF - Journal of Chromatography A
SN - 0021-9673
IS - 2
ER -