Newly Introduced/Updated Instruments at the Center for Conservation Science in FY2024

　In FY2024, the Conservation Science Center newly installed a Raman spectrometer, a 3D fluorescence spectrophotometer, and a high-performance liquid chromatography system, and updated the existing pyrolysis GC/MS and ion chromatograph. These instruments are introduced below. (Figure 1)

Raman spectrometer
　When a material is irradiated with laser light, the wavelength of Raman scattered light changes depending on the molecular structure of the material at the point of irradiation. Using this principle, it is possible to analyze the structure of a sample in a non-contact and non-destructive manner. For this purpose, we have introduced three types of instruments: a stationary Raman microspectroscope that can also be used for mapping, a portable Raman microspectroscope that can be carried around, and a hand-held Raman spectroscope that is compact and easy to carry around. Raman spectroscopy can be used to analyze any sample other than pure metals, whether inorganic or organic. It can be used for various applications such as identification of dyes and pigments, elucidation of the causes of corrosion, and analysis of adhering materials on cultural properties. (Figure 2)

Three-dimensional spectrofluorometer
　Since the wavelength and intensity of fluorescence emitted from a sample varies depending on its structure, fluorescence analysis can be used to estimate the structure of materials constituting cultural properties. It is a non-contact, non-destructive measurement method and can be used to analyze any sample that emits fluorescence. There are a surprisingly large number of samples that emit fluorescence (for example, fluorescence can be detected in cloth, paper, and wood in many cases), and many cultural properties can be analyzed using this method, but it is a particularly powerful analysis tool for dyes. (Figure 3)

High-performance liquid chromatography system
　Used for the determination of aldehydes in the air and dyes in textiles, this system is equipped with a PDA detector, which is more powerful than a typical UV detector for identifying unknown substances. Since extraction is required, this is basically a destructive analysis method.

Pyrolysis GC/MS (updated)
　This instrument is capable of analyzing in detail the structure of samples consisting of polymers, such as paper, fabric, lacquer, and wood. Although it is a destructive method, it is possible to analyze even a very small amount of sample (1 mg). Qualitative quantification of atmospheric odors and residual solvents is also possible.

Ion chromatograph (updated)
　This is used for the quantitative determination of ammonia and organic acids in the air, and chloride and nitrate ions in water. It employs a suppressor method and is extremely sensitive.

　We will continue to analyze cultural properties using these instruments.

It can be seen that the spectra obtained are different depending on the material colorant. A resolution of 1 µm enables identification of the colorant material. In particular, the ability to analyze inksticks nondestructively is a major feature. In addition to pigments, a wide variety of samples can be analyzed, including dyes, minerals, metal corrosion, and fibers.

Accelerated aging test causes an overall decrease in fluorescence intensity. In particular, there are marked decreases in fluorescence intensity around the excitation wavelength of 280 nm and fluorescence wavelength of 420 nm. Since the fluorescence pattern changes depending on the degree of deterioration and the material itself, it is useful for evaluating the degree of deterioration and for analyzing the differences between different materials.