5. Optimization of chitosan extraction by IR

4.3 Formula 3

niques such as NMR.

Table 4.

Figure 2.

114

FTIR spectrum of chitin and the baseline [73].

will be presented using IR.

In our study, a ratio had been already proposed [68, 71, 72]. However, choosing an appropriate calculation procedure was not an easy task since the choice of the baseline on FTIR spectra, reference, and the probe bands was difficult. In our work,

> A3450

where A1655 is the absorbance at 1655 cm�<sup>1</sup> of the amide I band as a measure of

The baseline problem for reference peaks has been studied and summarized in Table 4 and Figure 2. Table 4 shows that there are other formulas for calculating chitosan DD by FTIR and that these formulas have been approved by other tech-

A synthesis of the study on the effect of the operating conditions to know temperature concentration of the base and the time on the reaction of deacetylation

DA calibration curve Method for DA standard Ref. 1. DA = (A1655/A3450) � 155 Titration [66] 2. (A1320/A1420) = 0.3822 + 0.03133 � DA 1H NMR, 13C NMR [67] 3. (A1320/A3450) = 0.03146 + 0.00226 � DA 1H NMR, 13C NMR [67] 4. (A1560/A2875) = 0.2 + 0.0125 � DA Elemental analysis [71]

<sup>∗</sup> <sup>100</sup> 1:33

(4)

DD% <sup>¼</sup> <sup>100</sup> � A1655

the N-acetyl group content and A3430 is the absorbance at 3430 cm�<sup>1</sup> due to hydroxyl group as an internal standard. The value 1.33 represents the ratio of this absorbance for a fully acetylated compound. An appropriate baseline in each spec-

the average DD was determined by the following formula:

Calibration curves from absorption ratios versus standard DA values [73].

trum was determined by using origin software.

Modern Spectroscopic Techniques and Applications
