Quantitative Analysis of Blended Asian Lacquers Using ToF-SIMS, Py-GC/MS and HPLC.

Hye Hyun Yu,Seung Wook Ham,Jung-Ah Lim,Yeonhee Lee,Kang-Bong Lee

doi:10.3390/polym13010097

Hye Hyun Yu, Seung Wook Ham + Show 3 more

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https://doi.org/10.3390/polym13010097

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Abstract

Asian lacquer is a special polymeric material tapped from lacquer trees. The tree’s sap is a complex mixture of compounds, such as catechol lipids, polysaccharides, glycoproteins, enzymes, and water. Researchers have not yet quantitatively analyzed blended lacquers. We evaluated the compositions of Japanese and Vietnamese lacquers, and blends of the two, using time-of-flight secondary ion mass spectrometry (ToF–SIMS), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), and high-performance liquid chromatography (HPLC). ToF–SIMS provided quantitative results for blended lacquers; provided structural information on polymeric lacquer films; and indicated the presence of dimers of urushiol–urushiol, urushiol–laccol, and laccol–laccol derivatives. We used Py–GC/MS and HPLC to obtain linear calibration curves. The specific peak intensity was a linear function of the ratio of Japanese to Vietnamese lacquer in the blends. For an unknown mixture, all three techniques gave essentially the same results. These quantitative methods will be useful for improving the physical properties of polymeric lacquer films, and evaluating the lacquer quality in industry and historic conservation.

Highlights

Natural Asian lacquers have been widely used as coating materials and binding media in Asia for thousands of years because they provide highly useful properties, such as brilliance, beauty, and durability [1–5]
The blended lacquer saps were coated on silicon wafers for ToF–SIMS
As one can expect from major urushiol derivatives of Japanese T. vernicifluum, we observed specific aromatic fragment ions from catechol compounds, such as C7H7O2+ (123.0), C8H9O2+ (137.0), and C10H13O2+ (165.0), in the high-mass range between m/z = 100 and 200

Summary

Introduction

Natural Asian lacquers have been widely used as coating materials and binding media in Asia for thousands of years because they provide highly useful properties, such as brilliance, beauty, and durability [1–5]. One collects Asian lacquer sap mainly from three types of trees from the Anacardiaceae family. Toxicodendron vernicifluum grows in Japan, Korea, and China; its main lipid component is urushiol. The catecholic lipid component in Toxicodendron succedaneum from Taiwan and Vietnam is laccol, whereas it is thitsiol in Gluta usitata from Thailand and Myanmar [12–16]. It is worth noting that some form of pretreatment is required in order to convert the raw tree saps to a material suitable for application. In the drying process of lacquer sap, the major lipid components such as urushiol, laccol, and thitsiol are catalyzed by laccase to generate catechol radicals for polymerization [4,13]

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