Determination and quantification of arbutin in plants using stable isotope dilution liquid chromatography–mass spectrometry

Jae Kwang Kim,Tae Jin Kim,Young Jin Park,Sun-Hwa Ha,Sang Un Park

doi:10.1007/s13765-018-0385-1

Abstract

Arbutin is a very safe whitening agent for human skin. Since it is more expensive than other agents and has a challenging synthesis, novel methods to obtain this valuable agent are needed. In this study, we developed a precise and accurate method to detect and quantify arbutin using stable isotope dilution liquid chromatography–mass spectrometry (LC–MS). One challenge that needed to be overcome was the matrix effect occurring during the LC–MS analysis due to the analyte ionisation enhancement or suppression in the electrospray ionisation source by co-eluting compounds. Notably, arbutin had different matrix effects in the various sample matrices. A solution to this problem was the use of [d4]-arbutin as a stable isotope-labelled internal standard (SIL-IS), as it compensated the matrix effect of arbutin because it was affected by almost the same matrix effect. The validation of the developed method showed excellent linearity (r2 = 1.000), precision (relative standard deviation ≤ 2.5%), accuracy (recovery, 97.42–98.52%), limit of detection (0.03 μg/mL), and limit of quantification (0.1 μg/mL). Finally, the method of arbutin detection was applied to blueberry leaves to compare the precision and accuracy results obtained by performing stable isotope dilution using LC–MS and gas chromatography–mass spectrometry. The method was applied to strawberry leaves and pear peels, indicating that the SIL-IS method can be expected to find application in the arbutin analysis in other plants.

Highlights

Arbutin, a naturally occurring glycoside of hydroquinone, acts as an inhibitor of the enzyme tyrosinase, which converts tyrosine into melanin in the skin [1, 2]
Since each sample has a different matrix effect and the data from the liquid chromatography–mass spectrometry (LC–MS) analysis influenced by the respective matrix effect are less reliable, it is necessary to develop an analytical method which would limit the matrix effects of various samples [32]
The matrix effects of arbutin in the samples were found to be in the range of 53–78%, which indicated an ionisation suppression (Table S1)

Summary

Introduction

A naturally occurring glycoside of hydroquinone, acts as an inhibitor of the enzyme tyrosinase, which converts tyrosine into melanin in the skin [1, 2]. The compounds resulting from the derivatisation step are unstable over time and include multiple TMS derivatives such as 5TMS and 4TMS arbutin derivatives [17] To overcome these problems, previous studies employed the stable isotope dilution method with [d4]-arbutin as an internal standard (IS), which successfully eliminates the issues of multiple TMS derivatives with low stability [17]. Previous studies employed the stable isotope dilution method with [d4]-arbutin as an internal standard (IS), which successfully eliminates the issues of multiple TMS derivatives with low stability [17] Another method with high selectivity and sensitivity is the LC–MS analysis. We compared this novel isotope dilution LC–MS method to the previously reported isotope dilution GC–MS method which employs the same SIL-IS [17]

Materials and methods

Method validation for the arbutin assay

Results and discussion