Extended Multiplicative Signal Correction as a Tool for Aquaphotomics

Gowen, Aoife; Stark, Edward; Tsuchisaka, Yutaro; Tsenkova, Roumiana

doi:10.1255/nirn.1270

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…The principal variations in these spectra were obtained by applying PCA and extracting the 1st PC loading as an "interferent spectrum". Extended multiplicative scatter correction (EMSC) could then be applied to the spectra of salt solutions, to correct the data for this interferent spectrum [15]. This would diminish the influence of ambient conditions on the spectra of salt solutions.…”

Section: Water Absorbance Patternmentioning

confidence: 99%

On the feasibility of near infrared spectroscopy to detect contaminants in water using single salt solutions as model systems

Gowen

Marini

Tsuchisaka

et al. 2015

Talanta

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Section: Water Absorbance Patternmentioning

confidence: 99%

On the feasibility of near infrared spectroscopy to detect contaminants in water using single salt solutions as model systems

Gowen

Marini

Tsuchisaka

et al. 2015

Talanta

Self Cite

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“…This was EMSC of the RAW spectra, as described by the equation where X is the RAW observed spectra, Xtrue¯ is the reference spectrum (the mean of spectra of calibration data), I is an interferent spectrum (to be determined), b o , b 1 and b 2 are fitting constants and e is the residual. 18 Rearranging equation (2) leads to …”

Section: Methodsmentioning

confidence: 99%

“…15 It has been used to observe the effect of various perturbations – chemical or physical – on water structure due to variation in temperature, solute concentration and/or the environment. 12,16–18 The aquaphotomics water absorption bands in the first overtone region of water, called the water matrix coordinates (WAMACS), were experimentally discovered and later theoretically confirmed, and correspond to specific water molecular species that are used to describe typical water states in an aqueous system. For instance, when the temperature of pure water is increased from 28 to 45°C, an increase in free water molecule states raises the absorbance at 1412 nm.…”

Section: Introductionmentioning

confidence: 99%

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Investigating aquaphotomics for temperature-independent prediction of soluble solids content of pure apple juice

Kaur

Künnemeyer

McGlone

2020

Journal of Near Infrared Spectroscopy

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The methods of aquaphotomics were explored as an aid to improve near infrared spectroscopic predictive modelling of the soluble solids content of pure apple juice at different temperatures. The study focussed on the first overtone region of the O–H stretching vibration of water (1300–1600 nm). A transmission-based FT-NIR (Fourier transform near infrared) spectrometer was used to acquire 103 spectra of freshly expressed juice samples from individual ‘Braeburn’ apples over the wavelength range of 870–1800 nm with a 1 mm cuvette at three temperatures, 20, 25 and 30°C. The aquagram of the first overtone water region showed a trend of increasing bound water absorption with rising soluble solids content, from 7.3 to 13.7°Brix, and increasing free water absorption with rising temperature from 20 to 30°C. Predictive models for apple juice soluble solids content at 25°C were developed using partial least squares regression with spectral pre-processing by standard normal variate (SNV) followed by second derivative transformation (SNV + 2D) or no pre-processing on absorbance spectra at all. The best result, with lowest standard error of prediction of 0.38°Brix, was obtained using the first overtone water region with partial least squares regression on the SNV + 2D spectra. The method of extended multiplicative scatter correction was used, as an additional pre-processing step, to improve apple juice soluble solids content prediction at different temperatures. The interference component selected for the extended multiplicative scatter correction method was the first principal component loading measured using pure water samples taken at the same three temperatures (20, 25 and 30°C). Such extended multiplicative scatter correction pre-processing greatly reduced the soluble solids content prediction bias, when applying the partial least squares regression model developed at 20°C to samples measured at 25 and 30°C, from 0.23 to 0.08 and 0.36 to 0.13°Brix, respectively. Model precision (in terms of standard error of prediction) was also slightly improved by 0.02°Brix in each case, from 0.40 to 0.38 and 0.46 to 0.44°Brix at 25 and 30°C respectively.

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“…In this sense, EMSC is really a spectroscopic modeling method, as shown by the first sentence of [ 5 ]: “Knowledge-driven versus data driven modelling”. EMSC is, therefore, a tool of choice for aquaphotomics [ 24 ].…”

Section: Most Usual Preprocessingmentioning

confidence: 99%

Preprocessing NIR Spectra for Aquaphotomics

Roger

Mallet²,

Marini

2022

Molecules

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Even though NIR spectroscopy is based on the Beer–Lambert law, which clearly relates the concentration of the absorbing elements with the absorbance, the measured spectra are subject to spurious signals, such as additive and multiplicative effects. The use of NIR spectra, therefore, requires a preprocessing step. This article reviews the main preprocessing methods in the light of aquaphotomics. Simple methods for visualizing the spectra are proposed in order to guide the user in the choice of the best preprocessing. The most common chemometrics preprocessing are presented and illustrated by three real datasets. Some preprocessing aims to produce a spectrum as close as possible to the absorbance that would have been measured under ideal conditions and is very useful for the establishment of an aquagram. Others, dedicated to the improvement of the resolution of the spectra, are very useful for the identification of the peaks. Finally, special attention is given to the problem of reducing multiplicative effects and to the potential pitfalls of some very popular methods in chemometrics. Alternatives proposed in recent papers are presented.

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Extended Multiplicative Signal Correction as a Tool for Aquaphotomics

Cited by 5 publications

References 6 publications

On the feasibility of near infrared spectroscopy to detect contaminants in water using single salt solutions as model systems

On the feasibility of near infrared spectroscopy to detect contaminants in water using single salt solutions as model systems

Investigating aquaphotomics for temperature-independent prediction of soluble solids content of pure apple juice

Preprocessing NIR Spectra for Aquaphotomics

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