Background
Lutein is gaining attention as a strong antioxidant contained in foods. It accumulates in the human blood and retina, and is considered to play an important role in the body, especially in the eyes.
Objective
A method to determine the lutein content of raw spinach (Spinacia oleracea L.) was developed with the aim of its enactment as a Japanese agricultural standard (JAS) measurement method for components beneficial to human health.
Methods
An interlaboratory study was conducted to evaluate an analytical method for the determination of lutein in spinach. The detection limit and quantification limit of lutein for this method were 0.2 and 0.7 mg/kg, respectively. Twelve participating laboratories independently analyzed test samples (five pairs of blind duplicates) using high-performance liquid chromatography (HPLC).
Results
After removal of a few outliers, the repeatability relative standard deviation (RSDr), reproducibility (RSDR), and predicted RSDR of the evaluated method were 3.4–7.5, 4.6–13, and 7.5–8.5%, respectively, in a concentration range from 64.9–150 mg/kg.
Conclusions
The HorRat values (RSDR/predicted RSDR) of the lutein concentration were calculated to be 0.61–1.6.
Highlights
The study results indicate the acceptable precision of this method.
An analytical method for the determination of O-methylated catechin in >benifuuki' green tea (Camellia sinensis L.) was investigated and evaluated by an interlaboratory study. Epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3 Me) was well separated within ten minutes by high performance liquid chromatography (HPLC). The detection limit (S/N=3) of EGCG3 Me in this method was 0.005 % (w/w). Ten participating laboratories independently analyzed five test materials (five pairs of blind duplicates) in an interlaboratory study. The repeatability (RSD r ) and reproducibility (RSD R ) of the evaluated methods were 1.4∼2.0 % and 1.6∼5.7 %, respectively, in a concentration range from 1.1 to 1.9 % (w/w). The HorRat values of the EGCG3 Me concentration were 0.39 to 1.4. The present study showed that this method has acceptable precision.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.