HPLC and ToF‒SIMS Analyses of Toxicodendron vernicifluum Tree Sap Mixed with Other Natural Lacquers

Abstract

Lacquer sap has been used by humans from antiquitywhen it was treated as a luxury item because of its desirable physical properties. In modern times, although access barriers are lower, lacquer is still considered to be rare and valuable. Thus, low quality, inexpensive Vietnamese and Myanmarese lacquers and cashew nutshell liquid are frequently added to the costly Toxicodendron vernicifluum lacquer sap from Korea, China, and Japan. However, these blended lacquers can diminish the quality of artisan works. The Toxicodendron vernicifluum lacquer saps mixed with other natural lacquers were characterized using time-of-flight secondary-ion mass spectrometry (ToF−SIMS) and high-performance liquid chromatography (HPLC). ToF-SIMS provided the chemical structure of the lacquer monomer, copolymerized dimers, trimers, etc. HPLC provided quantitative analysis of the components of a randomly mixed lacquer. These techniques can be used to control the quality of commercial lacquer sap for the Asian lacquer industry and the traditional conservation of ancient objects.

Quantitative Detection of Thitsiol and Urushiol as Markers from the Gluta usitata Lacquer Tree Using HPLC

“…Urushiol showed double peaks corresponding to 3-pentadecyl catechol with retention times of 11.29 and 11.77 min, using a 260 nm UV detector. As shown in the previous study, split peaks were observed [25]. The splitting of the peak might originate from the chemical structure of urushiol 15:2, including two double bonds and two phenol groups.…”

“…For thitsiol analysis, acetonitrile and 20 vol.% aqueous acetic acid were mixed at a ratio of 9:1 and analyzed for 40 min using the isocratic elution method and 0.5 mL/min as the flow rate [ 13 ]. For urushiol analysis, acetonitrile and 0.1 vol.% aqueous trifluoroacetic acid were mixed at a ratio of 9:1 and analyzed for 20 min using the isocratic elution method and 1 mL/min as the flow rate [ 25 ]. Detection was performed using a UV detector at 260 nm (for urushiol analysis) and 280 nm (for thitsiol analysis) to obtain chromatograms.…”

“…Previous studies have used various techniques to analyze lacquer sap and lacquered cultural heritage artifacts, such as pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) [ 18 , 19 , 20 ], surface analysis using time-of-flight secondary ion mass spectrometry (ToF-SIMS) [ 21 , 22 ], and X-ray photoelectron spectroscopy (XPS) [ 23 , 24 ] to understand the structural properties and composition of lacquer. However, few quantitative studies of mixed lacquer have been performed [ 20 , 25 ]. In our previous study, the chemical structures of Korean, Chinese, and Vietnamese lacquer films and CNSL films were characterized using ToF-SIMS for the first time.…”

Optimising the analysis of Anacardiaceae (Asian lacquer) polymers using pyrolysis-gas chromatography-mass spectrometry

“…The C-C and C-O-C nature of the cross-links also prohibits wet chemical pretreatments to degrade the lacquer polymer to its monomers, making analysis using state of the art NMR, or chromatographic techniques coupled to mass spectrometry extremely difficult. Even though structural analysis of the cross-linked polymer is problematic, broad identifications can still be obtained using direct surface analysis techniques like Fourier transform infrared spectroscopy (FT-IR) [24,25], time of flight-secondary ion mass spectrometry (ToF-SIMS) [26][27][28] and X-ray photoelectron spectroscopy [29,30]. Those techniques can be utilised to differentiate between the lacquer polymers, but they do not allow us to study oxidative cross-linking or detailed analysis of historical objects decorated with Anacardiaceae lacquer.…”