This study aimed to investigate the validation and modify the analytical method to determine quercetin- 3-o-gentiobioside and isoquercitrin in Abelmoschus esculentus L. Moench for the standardization of ingredients in development of functional health products. The analytical method was validated based on the ICH (International Conference for Harmonization) guidelines to verify the reliability and validity there of on the specificity, linearity, accuracy, precision, detection limit and quantification limit. For the HPLC analysis method, the peak retention time of the index component of the standard solution and the peak retention time of the index component of A. esculentus L. Moench powder sample were consistent with the spectra thereof, confirming the specificity. The calibration curves of quercetin-3-o-gentiobioside and isoquercitrin showed a linearity with a near-one correlation coefficient (0.9999 and 0.9999), indicating the high suitability thereof for the analysis. A. esculentus L. Moench powder sample of a known concentration were prepared with low, medium, and high concentrations of standard substances and were calculated for the precision and accuracy. The precision of quercetin-3-o-gentiobioside and isoquercitrin was confirmed for intraday and daily. As a result, the intra-day precision was found to be 0.50-1.48% and 0.77-2.87%, and the daily precision to be 0.07-3.37% and 0.58-1.37%, implying an excellent precision at level below 5%. As a result of accuracy measurement, the intra-day accuracy of quercetin-3-o-gentiobioside and isoquercitrin was found to be 104.87-109.64% and the daily accuracy thereof was found to be 106.85-109.06%, reflecting high level of accuracy. The detection limits of quercetin-3-o-gentiobioside and isoquercitrin were 0.24 μg/mL and 0.16 μg/mL, respectively, whereas the quantitation limits were 0.71 μg/mL and 0.49 μg/mL, confirming that detection was valid at the low concentrations as well. From the analysis, the established analytical method was proven to be excellent with high level of results from the verification on the specificity, linearity, precision, accuracy, detection limit and quantitation limit thereof. In addition, as a result of analyzing the content of A. esculentus L. Moench powder samples using a validated analytical method, quercetin-3-o-gentiobioside was analyzed to contain 1.49±0.01 mg/dry weight g, while isoquercitrin contained 1.39±0.01 mg/dry weight g. The study was conducted to verify that the simultaneous analysis on quercetin-3-o-gentiobioside and isoquercitrin, the indicators of A. esculentus L. Moench, is a scientifically reliable and suitable analytical method.

ABSTRACT
Materials and Methods
    실험재료 및 시약
    Quercetin-3-o-gentiobioside 및 isoquercitrin 분석
    표준용액 및 시험용액의 조제
    지표성분 분석법 유효성 검증
    특이성
    직선성
    정밀성 및 정확성
    검출한계 및 정량한계
Results and Discussion
    Quercetin-3-o-gentiobioside 및 isoquercitrin의 크로마토그램
    특이성 확인
    검량선을 이용한 직선성 확인
    정밀성 및 정확성
    검출한계 및 정량한계
    오크라 분말의 quercetin-3-o-gentiobioside 및 isoquercitrin함량분석
Acknowledgement
국문요약
Conflict of interests
ORCID
References

• 한웅호(강원대학교 식품환경융합학과) | Xionggao Han (Department of Food Biotechnology and Environmental Science, Kangwon National University, Chuncheon, Korea)
• 최선일(강원대학교 식품환경융합학과) | Sun-Il Choi (Department of Food Biotechnology and Environmental Science, Kangwon National University, Chuncheon, Korea)
• 문효(강원대학교 식품환경융합학과) | Xiao Men (Department of Food Biotechnology and Environmental Science, Kangwon National University, Chuncheon, Korea)
• 이세정(강원대학교 식품환경융합학과) | Se-jeong Lee (Department of Food Biotechnology and Environmental Science, Kangwon National University, Chuncheon, Korea)
• 진희구(차의과학대학교 식품생명공학과) | Heegu Jin (Department of Food Science and Biotechnology, College of Life Science, CHA University, Seongnam, Korea)
• 오현지(차의과학대학교 식품생명공학과) | Hyun-Ji Oh (Department of Food Science and Biotechnology, College of Life Science, CHA University, Seongnam, Korea)
• 조세행(㈜씨스팡, 연세중앙내과의원) | Sehaeng Cho (Syspang Co. Ltd, Seoul, Korea, Yonsei Medical Clinic, Seoul, Korea)
• 이부용(차의과학대학교 식품생명공학과) | Boo-Yong Lee (Department of Food Science and Biotechnology, College of Life Science, CHA University, Seongnam, Korea)
• 이옥환(강원대학교 식품환경융합학과) | Ok-Hwan Lee (Department of Food Biotechnology and Environmental Science, Kangwon National University, Chuncheon, Korea) Corresponding author