**2. Fourier transform infrared spectrum and 2DIR correlation spectroscopy for pure compound analysis**

This is the conventional and most widely used spectroscopy in functional group determination. For a known pure compound, each peak of spectrum will identify the main functional group within the specific range of wave number. The matching of peaks in spectrum of unknown and known compound is commonly used as a complimentary analytical method besides LCMS and NMR. Hence, such evidences of compound structure configuration are reliable. Software library incorporated into the system plays a main role in authentication of the compounds. **Figure 1** showed the one dimensional Fourier transform infrared spectrum of delphinidin-3-*O*-sambubioside in the range of 4000–400 cm−1.

The 2DIR correlation spectroscopy on pure compound needs to be presented in the form of synchronous and asynchronous spectra [2]. Synchronous spectrum is developed by combination and accumulation of two spectra of the same substance scanned under perturbation. The most commonly used perturbation is the thermal perturbation which supplies the heat at a range of temperature such as 50–120°C, and this supposedly provokes the vibration mode of the relevant bonds. The 2DIR spectra of pure compound, which represents the active sites of different bonding in the molecule, reacts to the heat simultaneously. The region of peak detected on the diagonal positively formed is named as autopeak. It is possible for the autopeak to increase or decrease during the thermal supply phase. The abundance part of 2DIR spectrum is the crosspeaks that are not scattered on the diagonal. They are either positive or negative, depending on the combination of increased or decreased spectral peak from both axes. In term of correlation, the correlation square

Fourier Transform Infrared and Two-Dimensional Correlation Spectroscopy for Substance Analysis http://dx.doi.org/10.5772/66584 177

FTIR is advantageous compared with dispersive spectrometer. FTIR also simplifies the com-

The development of numerous sampling accessories, such as attenuated total reflection (ATR), sample cell with different window material for liquid sample, 2DIR sample cell etc., widens the utility of FTIR for multi-sample type analysis. Therefore, the origin of the sample material has no barrier for FTIR, albeit the different objectives of the investigation. In fact, FTIR has been recognised as a rapid, direct and non-destructive analytical method. The challenge confronting FTIR is the interpretation of the qualitative or quantitative spectral data from different direction

Factors that influence the frequency vibration mode of a polyatoms molecule included concentration, thermal, time and chemical reaction. This so-called perturbation is an additional input manipulating the vibration mode of the functional group. Typically dominating the motion of the molecules in the normal mode are only one or few groups which vibrate relatively. The establishment of two dimensional correlation spectroscopy via appropriate perturbation on mid-infrared could be used to enhance the detail of infrared spectrum

**2. Fourier transform infrared spectrum and 2DIR correlation spectroscopy** 

This is the conventional and most widely used spectroscopy in functional group determination. For a known pure compound, each peak of spectrum will identify the main functional group within the specific range of wave number. The matching of peaks in spectrum of unknown and known compound is commonly used as a complimentary analytical method besides LCMS and NMR. Hence, such evidences of compound structure configuration are reliable. Software library incorporated into the system plays a main role in authentication of the compounds. **Figure 1** showed the one dimensional Fourier transform infrared spectrum

The 2DIR correlation spectroscopy on pure compound needs to be presented in the form of synchronous and asynchronous spectra [2]. Synchronous spectrum is developed by combination and accumulation of two spectra of the same substance scanned under perturbation. The most commonly used perturbation is the thermal perturbation which supplies the heat at a range of temperature such as 50–120°C, and this supposedly provokes the vibration mode of the relevant bonds. The 2DIR spectra of pure compound, which represents the active sites of different bonding in the molecule, reacts to the heat simultaneously. The region of peak detected on the diagonal positively formed is named as autopeak. It is possible for the autopeak to increase or decrease during the thermal supply phase. The abundance part of 2DIR spectrum is the crosspeaks that are not scattered on the diagonal. They are either positive or negative, depending on the combination of increased or decreased spectral peak from both axes. In term of correlation, the correlation square

of delphinidin-3-*O*-sambubioside in the range of 4000–400 cm−1.

plex algorithm into presentable data and is user-friendly.

176 Fourier Transforms - High-tech Application and Current Trends

of view.

interpretation.

**for pure compound analysis**

**Figure 1.** The 1D FTIR spectrum of the pure compound delphinidin-3-O-sambubioside in the range of 4000–400 cm−1. The appearance of Absorbance is transferred from 51.2% of transmission with the threshold of one. Most of the peaks are sharp and in various intensities depending on the absorption of each functional group under the wave number in the range of mid-infrared. The peak at 3412 cm−1 is assigned to –OH group. Methyl group could be determined by peak 2928 cm−1. These two peaks are common and normally appear in all the organic material. The range from 1700 cm−1 downward is the specific and important range for different characteristic of each compound., e.g. peak 1641 cm−1 refers to amide I for bonding C-O, etc.

existing on certain autopeaks and crosspeaks is the best way to interpret the correlation circumstances during the perturbation. The asynchronous spectrum was created on region not related to synchronous spectrum. The Noda's rules [3] are abided during the interpretation data process.

**Figure 2** showed the synchronous and asynchronous spectra of delphinidin-3-*O*-sambubioside in the range of 1700–700 cm−1.

### **2.1. Important usage of FTIR and 2DIR correlation spectroscopy in pure compound**

### *2.1.1. Qualification analysis for special functional group in the compound*

Pure compound has the capacity to show the whole corresponded bond taking part in the infrared transmission. The vibration mode of the whole molecule will be determined under the specific assignment. Pure compound normally shows many sharp peaks compared to compound with low purity. This concept is ideal for qualification and the respective peaks are used to identify each component in the molecule itself. In some way, the selective range of particular peak could be used in quantification under the Beer's Law using the spectrum Quant software [4].

**Figure 2.** The 2DIR spectra of delphinidin-3-O-sambubioside in the range of 1700–700 cm−1. (a) Synchronous spectrum. The correlation square is created from negative crosspeak at (1177, 1650), autopeak 1650 cm−1, negative crosspeak (1650, 1177) and autopeak 1177 cm−1. There is another bigger correlation square which is created from negative crosspeak (1019, 1650), autopeak 1649 cm−1, negative crosspeak (1650, 1019) and autopeak 1019 cm−1. A smaller correlation square is created from four red areas. They are positive crosspeak (1019, 1177), autopeak 1177 cm−1, positive crosspeak (1177, 1019) and autopeak 1019 cm−1. (b) Asynchronous spectrum. The positive crosspeak at (1177, 1650) determines the sequence action against perturbation of the area at 1650 cm−1 first reacted than area at 1177 cm−1. The similar scenario for the bigger correlation square where the peak area at 1650 cm−1 reacted first than area at 1019 cm−1. When compared with the area at 1019 cm−1 and 1177 cm−1, 1019 cm−1 is reacted first than 1177 cm−1. The sequence of decrease reacted to the thermal perturbation in The series is 1650 cm-1, 1019 cm-1, 1177 cm-1. (c) The autopeak spectrum of the 2DIR.

### *2.1.2. Identification of the functional groups present in unknown pure compound*

In identification of new compound by micro-fingerprinting via spectroscopy, this robust technique can be used to obtain useful information in chemical analysis.

### *2.1.3. Correlation of main functioning group*

Determination of correlation of main functioning group under autopeaks at diagonal line indicates another important interpretation that the bondings in the molecule react positively with mid-infrared. In addition, creating the correlation square among the autopeaks and the crosspeaks for pure compound is advantageous using 2DIR correlation spectroscopy interpretation of inter-molecule.

### *2.1.4. Quantification study for the sample*

The innovative Quant software specific for quantification under mid-infrared is another scope of investigation. The standard compound with different concentration is the conventional method for plotting the standard graph. The new version of Quant software has either the single peak or the range of wave number chosen for the quantification compatible under the standard graph. The single peak is chosen for crude extract spectrum as the way to eliminate the interruption of enormous overlapping vibration mode from uncertain components, while the range of wave number is the best tool for purified compound.
