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C. W. Huck
8.3.1 Example of an Application Where Differences Between
Performances of Portable Instruments (Based
on Different Designs) and a Benchtop Spectrometer
Were Demonstrated
Validation of the performance of handheld NIR spectrometers in relation to a
benchtop instrument in analyzing polyphenols in medicinal plant was conducted by
Kirchler et al [10]. In that case, portable NIR sensors demonstrated high feasibility
to predict concentrations of anti-oxidative active ingredients (rosmarinic acid and
similar polyphenols) in Rosmarinus officinalis, folium. The operating characteristics of two handled spectrometers, microPHAZIR and MicroNIR 1700, were closely
compared. These two devices differ significantly in the employed technology, i.e.,
wavelength selectors and detectors. The evaluation of the analytical performance
of miniaturized devices was conducted through the comparison with a reference
benchtop NIR spectrometer Büchi NIRFlex N-500. Sophisticated data analytical
tools were employed to obtain exhaustive comparison, e.g., hetero-correlated 2D
plots visualized the differences in the relative sensitivity toward different NIR absorption bands measured on the three spectrometers. In that study, the benchtop spectrometer yielded the best prediction of the rosmarinic acid content in the plant extracts. The
moderate analyte concentration in the sample (less than 7%) and complex matrix, as
well as several NIR wavenumber regions in which the molecule absorbs significantly,
could have contributed toward the inferior capability of portable spectrometers,
because of their limited spectral windows and resolutions.
8.3.2 Example of an Application Where
an Ultra-miniaturized and Affordable NIR
Spectrometer Performed Semi-comparably
with a Benchtop Instrument
Wiedemair et al. have tested the performance of SCiO in comparison with Büchi
NIRFlex N-500 for the analysis of protein content in millet samples [18] and the
fat content in cheese samples [19]. As can be deduced from Tables 8.2 and 8.3,
they found that the analytical performance of portable devices may considerably
vary between different scenarios. Although clearly inferior in the former analytical
problem (Table 8.2), in the determination of fat content in cheese (Table 8.3), the
inexpensive SCiO sensor delivered the performance, evaluated by statistical values,
comparable to the high-performing benchtop instrument. In this case, the analysis of
major nutrient was more successful; presumably, because it was a more significant
chemical constituent in the sample.
These examples demonstrate somewhat uneven performance profiles of miniaturized spectrometers, strongly depending on the particular analytical scenario.
C. W. Huck
8.3.1 Example of an Application Where Differences Between
Performances of Portable Instruments (Based
on Different Designs) and a Benchtop Spectrometer
Were Demonstrated
Validation of the performance of handheld NIR spectrometers in relation to a
benchtop instrument in analyzing polyphenols in medicinal plant was conducted by
Kirchler et al [10]. In that case, portable NIR sensors demonstrated high feasibility
to predict concentrations of anti-oxidative active ingredients (rosmarinic acid and
similar polyphenols) in Rosmarinus officinalis, folium. The operating characteristics of two handled spectrometers, microPHAZIR and MicroNIR 1700, were closely
compared. These two devices differ significantly in the employed technology, i.e.,
wavelength selectors and detectors. The evaluation of the analytical performance
of miniaturized devices was conducted through the comparison with a reference
benchtop NIR spectrometer Büchi NIRFlex N-500. Sophisticated data analytical
tools were employed to obtain exhaustive comparison, e.g., hetero-correlated 2D
plots visualized the differences in the relative sensitivity toward different NIR absorption bands measured on the three spectrometers. In that study, the benchtop spectrometer yielded the best prediction of the rosmarinic acid content in the plant extracts. The
moderate analyte concentration in the sample (less than 7%) and complex matrix, as
well as several NIR wavenumber regions in which the molecule absorbs significantly,
could have contributed toward the inferior capability of portable spectrometers,
because of their limited spectral windows and resolutions.
8.3.2 Example of an Application Where
an Ultra-miniaturized and Affordable NIR
Spectrometer Performed Semi-comparably
with a Benchtop Instrument
Wiedemair et al. have tested the performance of SCiO in comparison with Büchi
NIRFlex N-500 for the analysis of protein content in millet samples [18] and the
fat content in cheese samples [19]. As can be deduced from Tables 8.2 and 8.3,
they found that the analytical performance of portable devices may considerably
vary between different scenarios. Although clearly inferior in the former analytical
problem (Table 8.2), in the determination of fat content in cheese (Table 8.3), the
inexpensive SCiO sensor delivered the performance, evaluated by statistical values,
comparable to the high-performing benchtop instrument. In this case, the analysis of
major nutrient was more successful; presumably, because it was a more significant
chemical constituent in the sample.
These examples demonstrate somewhat uneven performance profiles of miniaturized spectrometers, strongly depending on the particular analytical scenario.