**4. Fourier transform infrared spectrum and 2DIR correlation spectroscopy for raw material analysis**

Application of the new method of FTIR and 2DIR on raw material is still raising doubt due to the severely overlapping of peak making interpretation difficult. The detected peak could be due to more than one compound with similar assignment. Methods must be developed to ensure the assignment is interpreted correctly. In real life, raw material can be analysed using FTIR and 2DIR which will indirectly reduce the time for sample preparation. It is convenient in term of preparation and conserves the majority of the raw content.

Traditional Chinese medicines are the primer study model as raw material in the dried form using FTIR and 2DIR [5]. The difficulties, besides the problem of overlapping assignment, also include searching the main compounds which may coincide with the raw material spectrum. This kind of matching is reliable if the sufficient literature background on the raw material exists. Despite interruption of the 1D FTIR spectrum on raw material by mixture of compounds, the spectrum can be confirmed when 60% or more transmission is achieved with KBr. The second derivative is mandatory for the raw material spectrum. Modification on the derivative of spectrum shows that second derivative is the most appropriate for exploring the spectrum since the diagram is easily interpreted. In addition, the 2DIR correlation spectroscopy is another step to enhance the detail of the spectrum for detailed interpretation. Therefore, the tri-step analysis combine method, which involves stepwise progression from the superficial to high level of analysis, is advantageous for raw material using the mid-infrared spectroscopy analysis.

### **4.1. The advantages of FTIR and 2DIR for raw material**

### *4.1.1. Reduction in sample preparation steps*

Raw material from natural product has to be dried completely and pulverised before making disc with KBr. In FTIR and 2DIR analysis, the sample preparation process is simple. Since the presence of moisture in the environment affects the FTIR processing method, it is necessary to use dehumidifier to maintain the dryness of the environment.

### *4.1.2. Rapid*

**Figure 5.** Comparison of bovine gelatin and halal gelatin using 2DIR. (a) Synchronous spectrum of bovine gelatin in the range of 1800–600 cm−1. The higher intensity in the area of 1100–1000 cm−1 compared to spectrum of halal gelatin. (b) Synchronous spectrum of halal gelatin in the range of 1800–600 cm−1. (c) Asynchronous spectrum of bovine gelatin in the range 1800–1400 cm−1. The differences with halal spectrum are the intensity of the crosspeaks at (1480, 1625), (1572, 1733) and (1620, 1733) is more intense. (d) Asynchronous spectrum of halal gelatin in the range of 1800–1400 cm−1. (e) The autopeak spectrum of bovine gelatin in the range of 1800–600 cm−1. (f) The autopeak spectrum of halal gelatin in the range of 1800–600 cm−1.

182 Fourier Transforms - High-tech Application and Current Trends

By simplifying complicated preparation steps, analysis of raw material is rapid and direct. The analysis of the spectrum with air as background could be performed immediately after the infrared scanning. The pattern of each raw material will possess footage for the identification. Each raw material will be able to show the first image of its content under the scanning. The fingerprint of the original raw material will further confirm the material profile.

### *4.1.3. No-destructive method and conserve the material information*

A raw material conserves most of the natural contents except when contaminated with pollutants. The vulnerable step in the raw material processing is grinding, sufficiently drying and sieving with at least 200 mesh of sieve. However, these are considered less destructive when compared with further extraction on the raw material. In fact, the raw material can be tested under ATR which does not require a disc. The interferon beam has a glimpse of refection on the sample with diamond platform and produce spectrum in the range of 4000–650 cm−1. Comparison of the *H. sabdariffa* raw material spectrum performed with KBr and ATR, respectively, is shown in **Figure 6**.

### *4.1.4. Interpretation of poly-nutrient in crude*

When the whole profile of the raw material is presented with spectra especially in 2DIR, the correlation square generated under the perturbation is based on the active compounds responding concurrently. Such response is associated with a variety of compounds found in the raw extract. Information derived from such interpretation is vital as it provides a holistic picture of the reaction. **Figure 7** showed the correlation square formed between flavonoids peak and carbohydrate peak in *H. sabdariffa* raw material 2DIR synchronous spectrum.

**Figure 6.** 1D FTIR spectra of *H. sabdariffa* raw material scanned by two analysis methods. First spectrum is produced by mixing the Kbr powder with *H. sabdariffa* raw power dried sample in the ratio 200:1. The range of the spectrum is maximised from 4000 to 400 cm−1. Second spectrum is background with air and the raw material was placed on a diamond platform under ATR method. The range of spectrum is achieved till 650 cm−1, while the spectrum from 650 cm−1 to 400 cm−1 is lost. More number of peaks is observed under KBr method. However, ATR method is simpler since no disc is needed.

Fourier Transform Infrared and Two-Dimensional Correlation Spectroscopy for Substance Analysis http://dx.doi.org/10.5772/66584 185

tion. Each raw material will be able to show the first image of its content under the scanning.

A raw material conserves most of the natural contents except when contaminated with pollutants. The vulnerable step in the raw material processing is grinding, sufficiently drying and sieving with at least 200 mesh of sieve. However, these are considered less destructive when compared with further extraction on the raw material. In fact, the raw material can be tested under ATR which does not require a disc. The interferon beam has a glimpse of refection on the sample with diamond platform and produce spectrum in the range of 4000–650 cm−1. Comparison of the *H. sabdariffa* raw material spectrum performed with KBr and ATR,

When the whole profile of the raw material is presented with spectra especially in 2DIR, the correlation square generated under the perturbation is based on the active compounds responding concurrently. Such response is associated with a variety of compounds found in the raw extract. Information derived from such interpretation is vital as it provides a holistic picture of the reaction. **Figure 7** showed the correlation square formed between flavonoids peak and carbohydrate peak in *H. sabdariffa* raw material 2DIR synchronous spectrum.

**Figure 6.** 1D FTIR spectra of *H. sabdariffa* raw material scanned by two analysis methods. First spectrum is produced by mixing the Kbr powder with *H. sabdariffa* raw power dried sample in the ratio 200:1. The range of the spectrum is maximised from 4000 to 400 cm−1. Second spectrum is background with air and the raw material was placed on a diamond platform under ATR method. The range of spectrum is achieved till 650 cm−1, while the spectrum from 650 cm−1 to 400 cm−1 is lost. More number of peaks is observed under KBr method. However, ATR method is simpler since no disc is needed.

The fingerprint of the original raw material will further confirm the material profile.

*4.1.3. No-destructive method and conserve the material information*

respectively, is shown in **Figure 6**.

*4.1.4. Interpretation of poly-nutrient in crude*

184 Fourier Transforms - High-tech Application and Current Trends

**Figure 7.** 2DIR spectra of *H. sabdariffa* water extract with Trifluoroacetic acid (TFA) in the range of 1900–400 cm−1 from Selangor, Malaysia. (a) Synchronous spectrum. Three correlation squares are formed which are correlated with the C-O bond from ester group with carbohydrate group. They are negative crosspeak (720, 1771), 1771 cm−1, negative crosspeak (1771, 720) and 720 cm−1; positive crosspeak (1168, 1771), 1771 cm−1, positive crosspeak (1771, 1168) and 1168 cm−1; negative crosspeak (720, 1168), 1168 cm−1, negative crosspeak (1168, 720) and 720 cm−1. The spectrum indicates the holistic view of perturbation reaction of the different types of compound in the water crude extract. (b) Asynchronous spectrum. The sequence of reacted decrease as determined by Noda's rules under the thermal perturbation between 30 and 120°C with 10°C interval degree, i.e. 1171 cm−1, 1168 cm−1, 720 cm−1. (c) Autopeak graph. (d) 3D spectrum. The colour in dark blue illustrates the negative peak facing downward from plane.

### *4.1.5. Standardised method for authentication of a raw material derived from natural product*

The origin of the raw material in certain commercial medicinal products is difficult to be authenticated especially when they are presented as powder. Such products could be a portion of plant or other types of organism. Screening of the powder using KBr or ATR method will elucidate its chemical profile as the spectrum will confirm the origin as well as the purity. The compendium and monograph of herbal plants should include the spectrum as one of the methods in the authentication of medicinal products.
