Page 235 - Natural Antioxidants, Applications in Foods of Animal Origin

214 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir where A is absorbance at a specified wavelength,

λ l is path length of light (transverse axis of cuvette) in cm,
∈ is extinction coefficient,
C is concentration.

The Beers Lambert law, illustrated in Figure 6.5, states the absorbance
(A) of light at a given wavelength (λ) is related to the concentration of a
chemical compound.

Solution
Wavelength Detector Color version of
selector
figure 5.

The difference between the incident and transmitted light
indicates the absorb;mcc

Black and w hite
version of
figure 5.

Wavelength Selector
The difference between the incident light and transmitted light indicates abosrbance
FIGURE 6.5 Beer’s law relates the concentration of the analyte of interest to the degree
of absorbance at a specified wavelength. The underlying principles for the components in
Equation 6.7 are presented in Table 6.2 and Figure 6.6.

TABLE 6.2 The Principle for Quantitative Spectroscopy is Based on the Relationships of
Absorbance (A), Path Length of Plane Polarized Light (l), and a Compound’s Extinction
Coefficient (ϵ). Modified from Data in Food Analysis: Theory and Practice, pp. 63–71.
Principle Dependent Independent R 2 Slope Y
variable y variable x m Intercept
Strong absorbing analyte A (ϵ) Absorbance Analyte A 100% 0.25 0
Weak absorbing analyte B (ε) Absorbance Analyte B 100% 0.06 0
Path length v. absorbance (l) Absorbance Path length 100% 1.24 0
(dimension of
cuvette)
Absorbance v. concentration (C) Absorbance [analyte] 100% 0.25 0