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A greater understanding of moisture sorption behaviour of aged wooden structural components, which has a close relationship with dimensional stability, is required to effectively evaluate and preserve historical artefacts. This study focused on the effects of aging on Baotou beam samples from a Chinese historical wooden building. An analysis of the sorption isotherms and hysteresis loops of a naturally aged, decayed sample (AOS), an aged sound sample (AIS), and a reference sample (RS), using classical sorption isotherm models revealed that the moisture sorption behaviour of samples from the same growth ring in a Baotou beam can differ significantly. AOS showed higher hygroscopicity than AIS, and both these samples were more hygroscopic than RS. Furthermore, the mono/multilayer moisture contents of AOS were always higher than those of AIS and RS. In addition, Fourier transform infrared, second-derivative infrared, and two-dimensional correlation infrared spectroscopy were used to investigate chemical changes in the samples. The relative hemicellulose and lignin contents of the samples changed significantly with wood aging. Furthermore, AOS exhibited the highest calcium oxalate content, which may be associated with fungal infections. Overall, these results provide valuable insights into the effects of aging on wood samples and the dimensional stability of timber structures, which could inform future research on methods for the preservation or restoration of aging timber structures. [ABSTRACT FROM AUTHOR]

To better improve the effects of magnetization on the solution wettability, in this paper, the formation mechanism of magnetized water was investigated based on the combined method between the numerical simulation and experiments. The simulation results indicated that magnetization can reduce the first wave of the radial distribution function of water molecules; meanwhile, with the increase of magnetic field intensity, the diffusion coefficient of water molecules shows the four stages of changes, i.e. the slow change (0–200 mT), rapid increase (200–350 mT), stable period (350–450 mT) and reduce period (450–500 mT). In addition, the experimental results also show that as the magnetic field strength increases (0–350 mT), the K-M value of the solution gradually decreases, indicating that the hydrogen bond structures among the water molecules are reduced, which further verifies that the large molecular clusters break into smaller molecule groups under the magnetic field. The surface tension and contact angle of the magnetized water were reduced by 6.33%, 13.47% than that of the untreated water, respectively. It was concluded that the magnetization mainly destroys the hydrogen bond structures among the water molecules and reduces the solution cohesion to improve the solution wettability, which is of great significance for proposing the novel dust control technologies based on the magnetic method. [Display omitted] • The formation mechanism of magnetized water was investigated and revealed. • The molecule structure changes were studied based on infrared experiments. • The diffusion coefficient of water molecules was studied based on simulation. • The hydrogen bonds between water molecules were fractured by magnetization. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectroscopy is often used as a simple, fast, and green method for the adulteration screening of botanical materials for foods and herbs. However, the overlapping of absorption signals of various substances significantly decrease the sensitivity and specificity of IR spectroscopy in the detection of adulterated samples. In this research, a model-free approach is proposed for the sensitive and non-targeted screening of botanical materials adulterated by adding other plant materials. First, the spectra of the entities in the test sample are collected by near-infrared spectroscopic imaging and clustered by unsupervised pattern recognition methods. The sample may be adulterated if there are two or more clusters of the entities. Next, the entities of different clusters are characterized by mid-infrared spectroscopy to interpret the chemical compositions to determine the clustering is caused whether by adulteration or other reasons. Second derivative spectroscopy and two-dimensional correlation spectroscopy are often needed to resolve the overlapped bands mathematically or experimentally to find the characteristic signals to identify the authentic and adulterant entities. The feasibility of this approach was proved by the simulated adulterated sample of saffron. In conclusion, botanical materials adulterated by adding other plant materials can be detected by a simple, fast, sensitive, and green screening approach using IR spectroscopic imaging, two-dimensional correlation spectroscopy, and necessary chemometrics techniques. [ABSTRACT FROM AUTHOR]

In order to develop a fast and effective method to distinguish D. cochinchinensis from some easily confused species, FT-IR and 2DCOS-IR spectroscopy were used to study D. cochinchinensis, D. retusa, D. bariensis, and D. oliveri. Specific stable differences were found in the IR spectra helpful to distinguish D. cochinchinensis from the other three similar species. It was revealed that there was a peak at 738 cm present in all 17 available heartwood specimens of D. retusa, but it was not detected in the 19 samples of D. cochinchinensis. All 19 samples of D. cochinchinensis had two peaks at 755 and 701 cm which did not occur in all 10 specimens of D. bariensis and D. oliveri. Further study revealed that these peaks were attributed to their extractives, indicating that the chemical composition of their extractives had some differences. Calcium oxalate crystals with characteristic absorption peaks at 1618, 1318, and 782 cm only occurred in D. bariensis and D. oliveri, but were not found in D. cochinchinensis. In addition, as suggested by the 2DCOS-IR spectra of the benzene-alcohol extractives of these four Dalbergia species, the benzene-alcohol extractives of D. cochinchinensis were more stable to thermal perturbation than the others. In conclusion, IR technique can provide persuasive evidence to distinguish the heartwood of D. cochinchinensis from D. retusa, D. bariensis, and D. oliveri. [ABSTRACT FROM AUTHOR]

The nondestructive and label-free infrared (IR) spectroscopy is a direct tool to characterize the spatial distribution of organic and inorganic compounds in plant. Since plant samples are usually complex mixtures, signal-resolving methods are necessary to find the spectral features of compounds of interest in the signal-overlapped IR spectra. In this research, two approaches using existing data-driven signal-resolving methods are proposed to interpret the IR spectra of plant samples. If the number of spectra is small, 'tri-step identification' can enhance the spectral resolution to separate and identify the overlapped bands. First, the envelope bands of the original spectrum are interpreted according to the spectra-structure correlations. Then the spectrum is differentiated to resolve the underlying peaks in each envelope band. Finally, two-dimensional correlation spectroscopy is used to enhance the spectral resolution further. For a large number of spectra, 'tri-step decomposition' can resolve the spectra by multivariate methods to obtain the structural and semi-quantitative information about the chemical components. Principal component analysis is used first to explore the existing signal types without any prior knowledge. Then the spectra are decomposed by self-modeling curve resolution methods to estimate the spectra and contents of significant chemical components. At last, targeted methods such as partial least squares target can explore the content profiles of specific components sensitively. As an example, the macroscopic and microscopic distribution of eugenol and calcium oxalate in the bud of clove is studied. [ABSTRACT FROM AUTHOR]

Finished herbal products (FHPs) are preparations made from one or more herbs. The first stage in assuring the quality, safety, and efficacy of FHPs is to identify the herbs in the products. A new simple and quick method is developed in this research to detect the marker ingredients in FHPs. The inherent chemical heterogeneity of herbs and FHPs makes it possible to resolve different ingredients, without any additional separation or labeling, by infrared microspectroscopic imaging. Therefore, multiple marker ingredients in FHPs can be recognized directly and simultaneously by the infrared microspectroscopic identification method. As an example, all six kinds of herbs in Liuwei Dihuang Wan are identified through the following steps: (1) Each herb is characterized by infrared spectroscopic imaging, then the spectra of the main ingredients are calculated by the combination of principal component analysis, independent component analysis, and alternating least squares. (2) One marker ingredient is chosen for each herb. Ten typical pixels, the spectra of which best match the calculated spectrum of the marker ingredient, are selected by partial least squares target. The average spectrum of the typical pixels is taken as the marker spectrum. (3) Correlation coefficients between the typical pixel spectra and the marker spectrum are calculated. The acceptance correlation threshold is determined through the beta distribution function and then validated by positive and negative samples. (4) Using the above marker spectra and correlation criteria, herbs in the model mixture and the commercial product are identified. Good recognition results reveal the potential of the infrared microspectroscopic identification method in the quality control of herbs and FHPs. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

There is growing popularity in the use of herbal medicines around the world. Due to the presence of a complex mixture of compounds in such medicines, there are few techniques that can be readily used for their characterization. Two-dimensional correlation infrared (2D-IR) spectroscopy is a promising technique that has been applied successfully in the analysis of complex mixtures including herbal medicines. The counterfeit check, growing condition identification, geographic region identification and processing procedure monitoring of herbal medicines using 2D-IR spectroscopy are reviewed. [ABSTRACT FROM AUTHOR]

Abstract: Dalbergia odorifera T. Chen, Pterocarpus santalinus L.F. and Pterocarpus soyauxii are three kinds of the most valuable wood species, which are hard to distinguish. In this paper, differentiation of D. odorifera, P. santalinus and P. soyauxii was carried out by using Fourier transform infrared spectroscopy (FT-IR), second derivative IR spectra and two-dimensional correlation infrared (2D-IR) spectroscopy. The three woods have their characteristic peaks in conventional IR spectra. For example, D. odorifera has obvious absorption peaks at 1640 and 1612cm−1; P. santalinus has only one peak at 1614cm−1; and P. soyauxii has one peak at 1619cm−1 and one shoulder peak at 1597cm−1. To enhance spectrum resolution and amplify the differences between the IR spectra of different woods, the second derivative technology was adopted to examine the three wood samples. More differences could be observed in the region of 800–1700cm−1. Then, the thermal perturbation is applied to distinguish different wood samples in an easier way, because of the spectral resolution being enhanced by the 2D correlation spectroscopy. In the region of 1300–1800cm−1, D. odorifera has five auto-peaks at 1518, 1575, 1594, 1620 and 1667cm−1; P. santalinus has four auto-peaks at 1469, 1518, 1627 and 1639cm−1 and P. soyauxii has only two auto-peaks at 1627 and 1639cm−1. It is proved that the 2D correlation IR spectroscopy can be a new method to distinguish D. odorifera, P. santalinus and P. soyauxii. [Copyright &y& Elsevier]

Abstract: The herbal materials of Asian ginseng (the root of Panax ginseng), American ginseng (the root of Panax quinquefolius) and Notoginseng (the root of Panax notoginseng) were differentiated by conventional Fourier transform infrared spectroscopy (1D-FTIR) and two-dimensional (2D) correlation FTIR applying a thermal perturbation. Altogether 30 samples were collected and analyzed. Their entire 1D-FTIR spectra in the range of 4000–400cm−1 and 2D-FTIR spectra in the region of 850–1530cm−1 were generally similar based on the peaks position and intensities. This indicated the chemical constituents in these species of herbs were not distinctively different. However, variation in peak intensity were observed at about 1640cm−1, 1416cm−1, 1372cm−1 and 1048cm−1 in the 1D-FTIR spectra among these species for their ease differentiation. Clustering analysis of 1D-FTIR showed that these species located in different clusters. Much difference in their second derivative FTIR pattern among the three species also provided information for easy differentiation. These species of herbs were further identified based on the positions and intensities of relatively strong auto-peaks, positive or negative cross-peaks in their 2D-FTIR spectra. The findings provide a rapid and new operational procedure for the differentiation of these notable herbs. The visual and colorful 2D-FTIR spectra can provide dynamic structural information of chemical components in analyte and demonstrated as a powerful and useful approach for herbs identification. [Copyright &y& Elsevier]

Abstract: Use Fourier transform infrared spectroscopy (FT-IR) to analyze simultaneously the main chemical constituents in different solvent extracts of seven kinds of Chrysanthemum samples of different regions. The findings indicate that different Chrysanthemum samples have dissimilar fingerprint characters in FT-IR spectra. Such spectral technique can provide substance structural information of the complicated test samples. According to these spectral fingerprint features, we cannot only identify the main components of different extracts, but also distinguish the origins of the Chrysanthemum samples from different regions easily, which is a troublesome work by existing analytical methods. FT-IR, with the characters of speediness, good repeatability and easy operation, can be used as an effective analytical means to study the complicated system, in our research, the tradition Chinese medicines. [Copyright &y& Elsevier]

Abstract: Infrared (IR) spectroscopy and two-dimensional (2D) correlation IR spectroscopy are shown to offer some information about stability and shelf life of milk powders without separation and extraction of individual components in this paper. Temperature has been chosen as the perturbation to monitor the infrared behavior of various milk powders, namely, whole milk powder (WMP), sweet whole milk powder (Sweet WMP), low-fat milk powder (LFMP), and skim milk powder (SMP). The sequential order of changes in protein, fat and carbohydrates (mainly lactose) in milk powders is studied for the first time. The protein changes before the sucrose in WMP, whereas the sucrose changes before the protein in Sweet WMP under temperature perturbation. It is also found that in SMP, carbohydrate changes prior to protein whereas in LFMP and WMP protein changes first as the temperature is increased. The conclusion can provide some useful reference to understand the thermal stability of milk powders. [Copyright &y& Elsevier]

Wild and cultivated Paridis Rhizoma (PR) were analyzed and characterized systematically by integral analysis method and two dimensional correlation infrared spectroscopy, both of which have been successfully utilized in the analysis of complex mixtures. According to their infrared spectra, peaks clusters at around 1642 and 1022 cm −1 could be considered as the key factors to discriminate them. Besides, significant differences emerged in their second derivative spectra, particularly the peaks at 1619, 1317 and 781 cm −1 attributed to calcium oxalate. In addition, standard IR spectra of starch, calcium oxalate and oil were used as references to compare with wild and cultivated PR, indicating that the relative contents of oil in cultivated PR are higher than that in wild PR. While, the relative content of calcium oxalate is higher in wild PR than cultivated one. Moreover, synchronous two-dimensional correlation spectra present great difference in the range of 1750–1350 cm −1 . Furtherly, cluster analysis based on principle component analysis algorithm were conducted, obtaining a good classification result. [ABSTRACT FROM AUTHOR]

The characterization of structure of organic salts in complex mixtures has been a difficult problem in analytical chemistry. In the analysis of Scutellariae Radix (SR), the pharmacopoeia of many countries stipulates that the quality control component is baicalin (≥9% by high performance liquid chromatography (HPLC)). The component with highest response in SR was also baicalin detected by liquid chromatography-mass spectrometry (LC-MS). However, in the attenuated total reflection Fourier transform infrared spectroscopy, the carbonyl peak of glucuronic acid of baicalin did not appear in SR. The results of element analysis, time of flight secondary ion mass spectrometry, matrix assisted laser desorption ionization mass spectrometry and solid-state nuclear magnetic resonance all supported the existence of baicalin magnesium salt. Based on this, this study proposes an analysis strategy guided by infrared spectroscopy and combined with multi-spectroscopy techniques to analyze the structure of organic salt components in medicinal plant. It is meaningful for the research of mechanisms, development of new drugs, and quality control. [Display omitted] • Baicalin was verified to exist in the form of magnesium salt in Scutellaria Radix through multi-spectroscopic characterization. • Taken medicinal plant as an example, we propose an identification strategy for organic salts in complex mixture systems. • It is suggested that the structure elucidation can be comprehensively determined by FT-IR as a guide and combined with other techniques. • Nonseparation analysis methods are indispensable in the structural analysis of organic salts in medicinal plant. [ABSTRACT FROM AUTHOR]

Highlights: [•] The content of Ganoderma commercial products can be detected using FTIR and 2DIR. [•] NL is a product from Sabah and 87% of its contents correlated with raw Ganoderma fruiting body cultivated in Semenyih. [•] The ingredients of Ganoderma from Tanjung Sepat were similar to YKG product. [•] The analysis proved that LC product contained starch as an excipient. [•] This study demonstrated the possibility of developing a verification tool to validate the purity of commercial products. [ABSTRACT FROM AUTHOR]

Abstract: A three-step infrared (IR) macro-fingerprint method combining conventional IR spectra, and the secondary derivative spectra with two-dimensional infrared correlation spectroscopy (2D-IR), was developed to analyze Spirulina powder before and after gamma irradiation. In the IR spectra, most of the absorption peaks of samples irradiated at 1, 2.7, 6, and 10.4kGy had lower intensities than the non-irradiated ones, whereas peaks at 1152, 1078, and 1051cm−1 were slightly enhanced with irradiation at 2.7, 6, and 10.4kGy. Their second derivative spectra amplified the differences and revealed that irradiation affected the C=O band of carboxylic acid and esters, and the N–H band of proteins. The peaks at 1746 and 1741cm−1, and those at 1730 and 1725 cm−1 became two broad peaks. Meanwhile, the three sharp peaks at 1548cm−1, 1544cm−1 and 1536cm−1 changed to two broad peaks at around 1547 and 1534cm−1 after irradiation at doses higher than 1kGy. The characteristic IR bands from 1700cm−1 to 1600cm−1, which represent the C=O band in proteins, also have different shapes and intensities after irradiation. The finding indicated that irradiation affected the secondary structures of protein which was confirmed by curve fitting results. During the process of increasing the temperature from 50 to 210°C, the ratio of amide I to II in absorption intensities in the 2D-IR spectra of the irradiated samples varied with different response for different samples. Saccharides in Spirulina powder had a higher thermostability than proteins, but the autopeaks of irradiated samples did show differences from the non-irradiated sample. The intensity of autopeaks at 1012cm−1 increased dramatically in the irradiated samples while that of peaks at 1053, 1071, and 1083cm−1 decreased after irradiation. Based on the three-step IR macro-fingerprint method, irradiated Spirulina powder samples were successfully and fast identified and discriminated. [Copyright &y& Elsevier]

Abstract: In this paper, the feasibility and advantage of employing FTIR spectroscopy and the corresponding second-derivative spectroscopy combined with 2D-IR spectroscopy for the analysis of water extracts of Ganoderma lucidum with different storage durations were investigated and demonstrated for the first time. In order to compare the second-derivative microscopic fingerprint spectra from the four periods of storage, the range from 1200 to 500cm−1 has to be ignored due to the detection of starch in the samples and the standard as well. This is crucial because the main characteristic band of polysaccharide was assigned within this range. The addition of starch as outer constituent was considered spoilage of polysaccharide content investigation. In fact, polysaccharide content in G. lucidum plays a main role as anti-cancer properties. The ranges from 1480 to 1200cm−1 and from 1700 to 1480cm−1 were interpreted and directly compared. For the range (from 1800 to 400cm−1), the 22 months sample was closest to the control, followed by 38 months, 13 months and 6 months product. The matching of the extract spectra with the control was not consistent and depended on which range of spectra had been chosen. Many factors can be considered which may have possibly affected inferences of the composition of the extract from different storage durations. [Copyright &y& Elsevier]

The American ginsengs (Radix panacis Quinquefolii) of different geographical regions from Beijing (China), Toronto (Canada), Vancouver (Canada), Wisconsin (USA), and the wild American ginseng can be discriminated and identified by using Fourier transform-infrared spectroscopy (FT-IR) and two dimensional correlation infrared spectroscopy (2D-IR). The FT-IR spectra of the five kinds of American ginseng have small differences, and their secondary derivative spectra have obvious finger-print feature, especially in the range of 1750–400 cm-1. Using the difference of the position and intensity of the special (peculiar) bands, which include both the peak at 1317 cm-1 assigned to oxalate group, and other peaks near 1050, 1020, and 866 cm-1 assigned to the starch, we can identify and discriminate them from each others. Furthermore, using the pattern of 2D-IR correlation spectra under thermal perturbation, we can very directly identify and discriminate them. As a result, the macroscopic IR finger-print method, which combines three-steps: general IR spectra, secondary derivative spectra as well as 2D-IR correlation spectra, can discriminate different American ginsengs effectively, fast, and nondestructively. [Copyright &y& Elsevier]

Paeonia lactiflora , a commonly used herbal medicine (HM) in Traditional Chinese Medicine (TCM), mainly has two species, Radix Paeoniae Alba (RPA) and Radix Paeoniae Rubra (RPR), for different clinical applications in TCM. For expounding the chemical profile of RPA and RPR and ensuring the clinical efficacy and safety, an infrared macro-fingerprint analysis-through-separation method integrated with statistical pattern recognition was developed to analyze and discriminate the two Paeonia lactifloras. In IR spectra, the major difference between the two was in the range of 1200–900 cm −1 : the strongest peak of RPA was at 1024 cm −1 , while that of RPR was 1049 cm −1 . The difference was magnified in second derivative spectra. The findings were further verified by investigating the separation process of total glucosides, stepwisely monitored by both of IR and UPLC-MS/MS. Simultaneously, the aqueous extracts of RPA and RPR had been separated continuously to acquire the comprehensively hierarchical chemical characteristics for undoubtedly identification and subsequently discrimination of the two herbs. Moreover, 60 batches of the two HMs (30 for each) were objectively classified by principal component regression (PCR) model based on IR macro-fingerprints. [ABSTRACT FROM AUTHOR]

Highlights: [•] The vibrational microspectroscopic identification method is proposed first. [•] Chemical compositions of hyphae and clumps in dry Poria powder are characterized. [•] Three types of hyphae are classified according to the infrared spectral features. [•] A new kind of spherical particles in dry Poria powder are found and studied. [Copyright &y& Elsevier]

Highlights: [•] Five ‘Danggui’ herbs containing 26 samples were analyzed by FTIR techniques. [•] Characteristic peaks on 1D-FTIR spectra of these herbs were assigned. [•] 26 herbal samples were objectively classified by PCA based on 1D-FTIR spectra. [•] Sameness and difference of 1D-, 2D-FTIR spectra among the 26 samples were shown. [•] Tri-step IR method combined with classification rapidly differentiate these herbs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nine sponges from two classes and six orders were discriminated by Tri-step IR. [•] Sponges of the same genus were definitely discriminated. [•] 2DCOS-IR was applied to identify sponges with similar chemical profile distinctly. [ABSTRACT FROM AUTHOR]

Highlights: [•] A multi-step IR macro-fingerprint method was developed to quickly discriminate three Uighur drugs of Eremurus. [•] Calcium oxalate and anthraquinones contents of the three Eremurus were estimated effectively by spectra. [•] 2D-IR spectroscopy indicated Eremurus samples varied with response to temperature. [ABSTRACT FROM AUTHOR]

Highlights: [•] MW2DCOS and PCA were combined for the first time to interpret time serial spectra. [•] Three stages of the curing process of a paint sample were found by MW2DCOS and PCA. [•] Time-resolved spectral changes are shown in AP-MW2D correlation spectra. [•] The time-resolved relationship of spectral peaks is revealed by PP- and PL-MW2DCOS. [ABSTRACT FROM AUTHOR]

Highlights: [•] The chemical constituents of the four species of Herba Cistanche were analyzed by IR spectroscopy comprehensively. [•] Multi-step IR macro-fingerprinting combined with statistical classification was developed to discriminate the four species. [•] 179 batches of the four Herba Cistanches were objectively classified by SIMCA based on IR macro-fingerprints. [ABSTRACT FROM AUTHOR]

Abstract: Although herbal medicine (HM) behaves as a complex system having high-potential for treating chronic/life-threatening diseases, compatible characterization metrics with hierarchical approaches to integrate molecular-level information into the whole system are lacking. Herein, we report a high-throughput methodology (holographic infrared (IR) spectroscopy) harmonizing with the character of HM, providing hierarchical infrared fingerprints (entirety, parts and single ingredients), and working as a “GPS” to navigate a comprehensive chemical characterization of HM circularly from system to molecular level by step-by-step HM analysis-through-separation of IR spectra indicative and vice versa by reconstitution-through-combination of adducting spectrum without a complete understanding of the chemical constituents, and demonstrate holographic chemical charaterization of a Chinese herb Danshen. Global chemical fingerprints of species at each hierarchical level and ingredient profile variations among multilevel species of Danshen are integratively interpreted with fast estimation of their relative contents of active compounds. Finally, integral dynamic information of Danshen separation process is disclosed straightforward by spectral retrieving technique. [Copyright &y& Elsevier]

Abstract: How to apply rapid and effective method to research medicinal herbs, the representative of complicated mixture system, is the current study focus for analysts. The functions of non-processed and processed medicinal herbs are greatly different, so controlling the processing procedure is highly important for guarantee of the curative effect. Almost, the conventional criteria of processing are based on personal sensory experience. There is no scientific and impersonal benchmark. In this article, we take Rehmannia for example, conducting a systematic study on the process of braising Rehmannia with yellow wine by using the multi-steps infrared (IR) macro-fingerprint method. The method combines three steps: conventional Fourier transform infrared spectroscopy (FT-IR), second derivative spectroscopy, and two-dimensional infrared (2D-IR) correlation spectroscopy. Based on the changes in different types of IR spectra during the process, we can infer the optimal end-point of processing Rehmannia and the main transformations during the process. The result provides a scientific explanation to the traditional sensory experience based recipe: the end-point product is “dark as night and sweet as malt sugar”. In conclusion, the multi-steps IR macro-fingerprint method, which is rapid and reasonable, can play an important role in controlling the processing of medicinal herbs. [Copyright &y& Elsevier]

Based on the systematic analysis of heartwood and alcohol extractives of D. ebenum , D. philippinensis and D. celebica by the three-step infrared spectroscopy (FT-IR, SD-IR and 2DCOS-IR), the three similar Diospyros wood are successful distinguished. In FT-IR spectra, the principal chemical components of heartwood are characterized for cellulose (the bands at around ∼1370, ∼1158, ∼1034 and ∼895 cm−1), lignin (the bands around ∼2935, ∼1510, ∼1462 and ∼1426 cm−1) and calcium oxalate (peaks at ∼1615, ∼1318 and ∼781 cm−1). The correlation coefficient among samples and standard material give the result that D. ebenum is lignin-rich and D. celebica is resin-rich, while D. philippinensis contains more calcium oxalate. In SD-IR spectra, D. philippinensis and D. celebica have peaks at 1731 cm−1 mean they contain more resin. Besides, the alcohol extracts of D. ebenum possesses stronger peak at 1651, 1632, 1584 and 1388 cm−1 which can be characterized for naphthalene derivatives component. Through the 2DCOS-IR synchronous spectra, the C–H of lignin (the auto peaks at ∼1450 and ∼1460 cm−1) of three heartwoods show strong intensity. Lignin shows high thermal sensitivity in D. ebenum , while it is similar sensitive with cellulose in D. philippinensis, but it is slightly lower thermal perturbation than cellulose in D. celebica. Meanwhile, the thermal sensitivity of Si–O and Si–C of alcohol extractives are different in the range of 935–1255 cm−1. In addition, the difference in thermal perturbation of C O and C N of resin and naphthalene derivatives could also be considered as the key factors to discriminate them. This research demonstrated that the FT-IR and 2DCOS-IR could analyze and discriminate confused ebony wood comprehensively. Image 1 • D. ebenum is lignin-rich and D. philippinensis contains more calcium oxalate. • The C–H of lignin of three heartwoods show dominant intensity in 2DCOS-IR spectra. • There are naphthalene derivatives component in alcohol extractives. • The thermal sensitivity of C O and C N of naphthalene derivatives is different. [ABSTRACT FROM AUTHOR]

It is difficult to distinguish the Pterocarpus santalinus in the furniture wood market, since it is similar to other tree species such as Dalbergia louuelii and Pterocarpus tinctorius. Moreover, the features of the wood are usually covered with the beeswax on the surface, making it even harder to be identified the tree species. Extractive is important components of wood and plays a significant role in the color of wood. Benzene-alcohol extractives contain specific chemical components of wood, which is an important part to distinguish tree species. Color parameters show that the color is obviously deepened when the sample is covered with beeswax. As shown in the SEM examination, beeswax appears on the wood surface in a large area and is immersed in the vessels of wood. In this paper, with the infrared spectrum three-step identification, the differences of the chemical composition of benzene-alcohol extractive are analyzed to distinguish tree species. The results show that the functional groups of the compounds contained in beeswax are mainly composed of long-chain methyl -CH3, methylene –CH2- and ester carbonyl C O, carboxyl C–O stretching at 2956, 2917, 2850, 1740, 1468, 1378 and 721cm-1. The absorption peaks of beeswax are so strong that they weaken the peaks of benzene-alcohol extractives from three tree species. In the FT-IR and SD-IR spectra, P. santalinus and P. tinctorius have strong peaks at 1736 cm−1, 1590 cm−1, 1151 cm−1 (1149 cm−1), 1067 cm−1 (1064 cm−1), 1033 cm−1, 958 cm−1 (959 cm−1), and 835 cm-1 (833 cm-1), while D. louvelii has a weak broad peak at 1630 cm-1 and 1602 cm-1, and there is no absorption peak at other wave numbers. At 754 cm-1 and 700 cm-1, no absorption peaks are found in the other two tree species. In the Synchronous 2DCOS-IR spectra in the ranges of 900–1200cm-1,1200-1425 cm-1, and 1480-1700cm-1, the sensitivity of some functional groups in P. santalinus and D. louvelii for the temperature perturbation tends to be the same. The main difference between them is that more functional groups of P. santalinus are sensitive to temperature disturbance. For P. tinctorius , it is sensitive to temperature perturbation, in which, the ester groups C–O stretching vibration at 1151, 1168, 1202 cm-1 and aromatic ring skeleton stretching belongs to flavonoids and lignin at 1511 and 1594 cm-1. The above results indicate that the three-step identification by the infrared spectroscopy can accurately and quickly distinguish tree species. • In this manuscript, based on Pterocarpus santalinus as the starting point, two confusing species were selected as the research object (Dalbergia louuelii and Pterocarpus tinctorius). In order to achieve accurate discrimination of three kinds of hardwood between blank and covered with beeswax, chromaticity test were used to determinate color differences; SEM were used to determinate microstructure; FTIR, SD-IR and 2DCOS-IR were used to discriminate the chemical characteristics. • When the wood surfaces of three tree species were covered with beeswax, the visual differences were small in color parameters. The SEM micro-topography showed that the beeswax appeared on the wood surface in a large area and was immersed in the vessels of wood. • The functional groups of the compounds contained in beeswax were mainly composed of long-chain methyl -CH3, methylene –CH2- and ester carbonyl C O, carboxyl C–O stretching at 2956, 2917, 2850, 1740, 1468, 1378 and 721cm-1. These absorption peaks were identical simultaneously in the spectrum of three tree species. Meanwhile, the characteristic peak intensity of them was significantly reduced, which increased the difficulty of differentiation, but the three species can still be distinguished at the characteristic peaks with strong intensity. [ABSTRACT FROM AUTHOR]