fitFTIRc: Relative Crystallinity Calculation of FTIR Spectrum of Starch...

In cryst: Calculate the Relative Crystallinity of Starch by XRD and FTIR

Description

Allow to calculate the relative crystallinity of starch by FTIR. The basic concept of SUN approach involves obtaining a gaussian holocrystalline-peak in the 800-1300 cm-1 region of FTIR spectrum of starch which is divided into amorphous region and crystalline region.

Usage

fitFTIRc(spectrum, mu = 1180, sigma = 60, k = 1, lim = c(1190, 1160,
  985, 950))

Arguments

spectrum	matrix. The matrix of FTIR spectrum baseline-corrected by drawing a tangentline in the 800-1300 cm-1 region. The first row corresponds to wavelength; the second row corresponds to intensity.
mu	numeric. Gaussian mean of holocrystalline-peak. Defaults to 1180.
sigma	numeric. Standard deviation of holocrystalline-peak. Defaults to 60.
k	numeric. Arbitrary scaling parameter. Defaults to 1.
lim	vector. Fitting points of holocrystalline-peak. Defaults to c(1190, 1160, 985, 950).

Details

Calculate the relative starch crystallinity of FTIR spectrum by SUN method.

Value

An object of class fitFTIRc, which is a list with the following components:

original	Original matrix of FTIR spectrum.
gauss	Gaussian curve fit.
fit	Summary of Non-Linear Least-Squares Model Fits.
summary	Summary calculation of crystallinity. Total area under the curve of the diffraction spectrum (A.U.); Amorphous area (A.U.); Crystalline area (A.U.); Relative crystallinity (%).

Author(s)

Claudio Pozo Valenzuela [aut, cre] and Saddys Rodriguez-llamazares [aut]

References

Sun, Y., et al. (2014). "A new method for determining the relative crystallinity of chickpea starch by Fourier-transform infrared spectroscopy." Carbohydrate Polymers 108: 153-158.

Examples

# Convert data frame to matrix, select A-type starch
spectrum <- as.matrix(t(FTIR[, c('wavelength','A')]))
# List of crystallinity components
crs <- fitFTIRc(spectrum = spectrum, mu = 1180, sigma = 60, k = 1, lim = c(1190, 1160, 985, 955))
# Original matrix
original <- crs$original
# Gaussian curve fit
gauss <- crs$gauss
# Summary of Non-Linear Least-Squares Model Fits
fit <- crs$fit
# Summary calculation of crystallinity
summary <- crs$summary

Example output

Loading required package: flux
Loading required package: caTools
This is flux 0.3-0
Loading required package: pracma

Attaching package: 'pracma'

The following objects are masked from 'package:caTools':

    combs, trapz

cryst documentation built on May 1, 2019, 8:10 p.m.