• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.411-417
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• 2017

This study was conducted to establish the analysis method for the contents of choline in infant formulas and follow-up formulas by ion chromatograph (IC). To optimize the method, we compared several conditions for extraction, purification and instrumental measurement using spiked samples and certified reference material (CRM; NIST SRM 1849a) as test materials. IC method for choline was established using Ion Pac CG column and 18 mM $H_2SO_4$ mobile phase. The parameters of validation were specificity, linearity, LOD, LOQ, recovery, accuracy, precision and repeatability. The specificity was confirmed by the retention time and the linearity, $R_2$ was over 0.999 in range of 0.5~10 mg/L. The detection limit and quantification limit were 0.14, 0.43 mg/L. The accuracy and precision of this method using CRM were 95%, 2.1% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested products were acceptable contents of choline compared with component specification for nutrition labeling. The standard operating procedures were prepared for choline to provide experimental information and to strengthen the management of nutrient in infant formula and follow-up formula.

• Journal of Nutrition and Health
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• v.29 no.9
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• pp.1028-1034
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• 1996

This study examined within-and between-individual variation in nutrient intakes in order to estimate the degrees of precison in dietary assessment among 59 female volunteers aged 21-23 years. Self-recorded 7-day dietary recalls and records were collected by during a 3 month period. Between the recall and record methods, there were little difference of within-and between-individual variations. Within-to-between individual variation ratios were > 2.0 for most of the nutrients examined, and were higher for niacin, vitamin A and C (>2.5) in the recals and for calcium, iron, vitamin A and C(>3.0) in the records. With 7-day dietary data, observed nutrient intakes were estimated to within 26-107% of the subjects' true(usual) intakes, among those vitamin C and energy showed the highest and lowest values, respectively. Correlation coefficients between observed and true nutrient intakes were 0.73-0.81 for the recalls and 0.68-0.77 for the records. In order to estimate with 20% precision, 12-13 days of dietary study were required for energy, 46 for calcium, 71-72 for vitamin A, and 199-200 for vitamin C. Attenuation factor ranged 0.73-0.81 for the recalls and 0.68-0.77 for the records. This study implies that commonly used 1 or 3 day dietary studies may not be appropriate for assessing individuals' nutrient intakes. Further research focusing on the methodological issues in the assessment of Korean diet are needed for between understanding of the relationship between diet and health in Koreans.

• Korean Journal of Community Nutrition
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• v.3 no.3
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• pp.423-429
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• 1998

This study examined within- and between-person variation in nutrient intakes in order to estimate the degree of precision in dietary assessment among 37 males and 46females whose mean age was 70.4 years old. To collect dietary data, each subject was interviewed 5 or 6 times using a 24-hour recall method during a 3 month period. Within- person variation ranged from 23.5% to 101.2%. Lower values of within-person variation were observed in energy, carbohydrated, protein and phosphorous while higher value was observed in vitamin A. Between person variations of nutrient intakes ranged 12.6-23.5% in most nutrients. With 1 day dietary data, observed nutrient intakes were estimated to within 6-25% of the group's usual9true) intakes and 52-198% of the individuals' usual intakes. The values of these maximum percentage deviations became smaller when the number of dietary recalls increased. The results of this study suggest that the Korean elderly subjects appear to have a slightly less diverse diet compared to young Korean women. Within persons, intakes of nutrients largely from animal sources were more variable for the Korean elderly than for their counterparts in Western countries. This study also implies that commonly used 1 day dietary study may be appropriate for assessing group means of nutrient intakes, but clearly not appropriate for assessing individual's nutrient intakes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.4
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• pp.565-569
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• 2011

Validation of quercetin as a marker compound in the standardization of Changnyeong onion extract developed for functional health food was attempted by analytical method. The specificity was satisfied with retention time and photo diode array (PDA) spectrum by analysis of quercetin using HPLC and comparison with standard compound. It showed a high linearity in the calibration curve as coefficient of correlation ($R^2$) of 0.9986, and the limit of detection (LOD) and limit of quantitation (LOQ) were 0.2 mg/L and 0.5 mg/L, respectively. Recovery rate test with quercetin concentration of 0.05, 0.075 and 0.1 mg/mL was revealed in the high range of 82.36~95.26%, 82.70~98.24% and 87.91~95.11%, respectively. The intra-day and inter-day precision in quercetin for Changnyeong onion extracts was 0.10~3.28% and 0.96~5.79%, respectively. Therefore, application of quercetin was validated in analytical method as a marker compound in Changnyeong onion extracts.

• Journal of Food Hygiene and Safety
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• v.35 no.3
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• pp.213-218
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• 2020

This study was conducted to develop a method of analysis for 4-hydroxy-L-isoleucine in the seed extract of fenugreek (Trigonella foenum graecum), a health functional food that contains dietary fiber. The analytical method for 4-hydroxy-L-isoleucine was derived with O-phthaldialdehyde reagent (OPA) and determined by HPLC-PDA. The method was performed on a Capcell Pak C₁₈ UG 120 column (4.6×250 mm, 5 ㎛) in isocratic elution mode using disodium phosphate and acetonitrile. The validation of the developed analytical method was conducted by evaluating several parameters; selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and repeatability. Excellent linearity (R²=0.999) was observed for 4-hydroxy-L-isoleucine in the concentration range (5-100 ㎍/mL). Observed recoveries of these compounds were found to be between 91.7 and 96.4%. Precision was between 0.2 and 2.4% relative standard deviation (%RSD).

• Journal of Food Hygiene and Safety
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• v.35 no.3
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• pp.252-260
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• 2020

This study was conducted to improve the standard method for vitamin B₁₂ and biotin contained in foods for special dietary uses to ensure the specificity of the complex matrix properties of foods. For the food code, the test method was improved to determine vitamin B₁₂ and biotin by high-performance liquid chromatography (HPLC)-UV using column-switching after concentration using immunoaffinity column. The immunoaffinity columns contain a gel suspension of monoclonal antibody specific to the vitamin of interest so that it can be used to concentrate the vitamin B₁₂ and biotin and remove interferences from the food extracts. Moreover, validation of advanced new methods was carried out to support the suitability of the proposed analytical procedure (specificity, linearity, detection limits (LOD), quantitative limits (LOQ), accuracy, and precision). The improved analytical method is being used to monitor relevant food items on sale. The results of this study showed that the new analytical method is suitable and appropriate for managing food intended for special dietary uses.

• Korean Journal of Plant Resources
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• v.27 no.5
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• pp.401-414
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• 2014

In an attempt to evaluate licorice quality based on its biological activity, we grafted an on-line high-performance liquid chromatography (HPLC) bioassay method into the previously established HPLC analysis method. The common antioxidant peaks in licorices of various origin were observed through an on-line HPLC/DPPH system leading to a decrease in absorbance at 517 nm for 2,2-diphenyl-1-picrylhydrazyl (DPPH). Among them, the licorice from Youngju possessed the highest activity. Therefore, three active standard compounds from the dehydroglyasperin C, dehydroglyasperin D, and isoangustone A, were isolated and elucidated by medium pressure liquid chromatography (MPLC) and instrumental analysis such as nuclear magnetic resonance (NMR), respectively. On-line HPLC/ABTS analysis method with the simultaneous determination of three standard compounds and their radical scavenging activity was established for the quality evaluation of licorices. 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radicals (ABTS) which is stable and effective was used in replace of DPPH. The radical scavenging activity of three standards is compared with that of Trolox, known as antioxidant, showing a negative peak with a decrease in absorbance at 734 nm for ABTS. This on-line HPLC/ABTS analysis method was validated for specificity, linearity, precision and accuracy in compliance with international conference on harmonization (ICH) guideline.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.420-424
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• 2019

An HPLC analysis method was developed and standardized for the detection of dieckol as a functional food ingredient in Ecklonia cava extracts. HPLC was performed using a Capcell Pak C18 column ($250{\times}4.6mm$, $5{\mu}m$) with a gradient elution of water and acetonitrile, both containing 0.1% (v/v) trifluoroacetic acid, at a flow rate of 1.0 mL/min at $25^{\circ}C$. The eluate was detected at 230 nm. For validation, the specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ) of dieckol were measured. The calibration curve for the detection of dieckol had high linearity ($R^2=0.9994$), with LOD and LOQ values of 0.38 and $1.16{\mu}g/mL$, respectively. Recovery of the quantified compound ranged from 99.61 to 100.71%. The relative standard deviation values of the intra-day and inter-day precisions were less than 1.7 and 1.25%, respectively. These results indicate that the reported HPLC method is simple, reliable, and reproducible for the detection of dieckol in Ecklonia cava extracts.

• Natural Product Sciences
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• v.22 no.1
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• pp.1-12
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• 2016

Compositional differences in flavonoids are varied in the big family of Compositae. By summarizing our previous analytical studies and other scientific evidences, new strategy will be possible to further analyze flavonoids and utilize them for human health. The HPLC analytical method has been established in terms of linearity, sensitivity, accuracy, and precision. Herbs of the family of Compositae have considerable amounts of peroxynitrite ($ONOO^-$)-scavenging effects and their phenolic substances. These effects may contribute to the prevention of disease associated with excess production of $ONOO^-$, depending on the high content of flavonoid substances.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.327-334
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• 2016

This study was conducted to establish the standard method for the contents of biotin in milk formulas. To optimize the method, we compared several conditions for liquid extraction, purification and instrumental measurement using spiked samples and certified reference material (NIST SRM 1849a) as test materials. LC-MS/MS method for biotin was established using $C_{18}$ column and binary gradient 0.1% formic acid/acetonitrile, 0.1% formic acid/water mobile phase is applied for biotin. Product-ion traces at m/z 245.1 ${\rightarrow}$ 227.1, 166.1 are used for quantitative analysis of biotin. The linearity was over $R^2=0.999$ in range of $5{\sim}60{\mu}g/L$. For purification, chloroform was used as a solvent for eliminating lipids in milk formula. The linearity was over 0.999 in range of 5~60 ng/mL. The detection limit and quantification limit were 0.10, 0.31 ng/mL. The accuracy and precision of LC-MS/MS method using CRM were 103%, 2.5% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested milk formulas were acceptable contents of biotin compared with component specification and standards for nutrition labeling. The standard operating procedures were prepared for biotin to provide experimental information and to strengthen the management of nutrient in milk formula.