Infrared spectroscopy instrument calibration

Instrumental resolution, 23 132 Instrumentation. See also Instruments calibration of, 21 161 capillary electrophoresis, 4 633 composition measurement, 11 785 for fermentation, 11 36—40 flow rate, 11 781-783 flow visualization, 11 785-786 fluid mechanics, 11 781-786 food processing, 12 87-88 gas chromatography, 4 611 6 413-414 infrared spectroscopy, 14 225-228 23 137-138... 

Near infrared spectroscopy (NIRS), a technique based on absorption and reflectance of monochromatographic radiation by samples over a wavelength range of 400-2500 run, has been successfully applied for food composition analysis, for food quality assessment, and in pharmaceutical production control. NIRS can be used to differentiate various samples via pattern recognitions. The technique is fast and nondestructive method that does not require sample preparation and is very simple to use compared too many other analytical methods such as HPLC. The drawback of NIRS, however, is that the instrument has to be calibrated using a set of samples typically 20-50 with known analyte concentrations obtained by suitable reference methods such as FIPLC in order to be used for quantitative analyses. Simultaneous quantification of the... 

Infrared Spectrometers. Infrared spectroscopy is one of the most powerful tools for quantitative and qualitative identification of molecules, and this led to the early development of prism and grating spectrophotometers. Typically, these instruments cover the region from 400 to 4000 cm, give a resolution of 1 to 4 cm, and require calibration with polystyrene films or with standard gases such as H2O, CO2, CH4, or This al-... 

Unlike other typical analytical techniques, such as infrared spectroscopy, ESR measurements require a high level of technical skill and expertise. ESR sample measurements are highly dependent on sample collection, sample preparation, types of solvents, temperature, choice of spin trap, and instrument calibration of electrical and magnetic fields, among other things. 

Consider infrared spectroscopy in which absorbance is plotted as a function of a wavenumber. Most users take for granted that if a peak appears at 1700 cm on a screen or a printout, an actual absorbance of electromagnetic radiation with a frequency of 1700 cm occurred. That assumption, however, rests on another that the instrument has a reliable wavelength and frequency calibration. What if there were problems with the instrument, and a peak at 1700 cm really represented the sample absorbing light at 1600 cm The only way to detect such a problem would be to obtain a spectrum with known and reliable absorbances of a material in which the frequencies of absorbance are certified. NIST provides... 

Near-infrared spectroscopy (NIRS) is also a rapid nondestructive technique, able to measure a large number of seed components in one rapid (about 2 min) analysis. It is a secondary technique. NIRS results are predicted as they are calculated from the calibration data sets. As for NMR or any secondary method, the chosen reference methods used to calibrate the instrument strongly affect the results obtained by the NIR method. 

The particle concentration of the eluent is normally measured by means of infrared or ultraviolet photometers. Additionally, fluorescence photometer, interferometric measurements (for the refractive index), or mass-spectroscopic methods (e.g. induced coupled plasma mass spectroscopy—ICP-MS, Plathe et al. 2010) are employed. The combination of different detection systems offers an opportunity for a detailed characterisation of multi-component particle systems. Note that the classification by FFF is not ideal and the relevant material properties are not always known moreover, the calibration of FFF is rather difficult. The attribution of particle size to residence time, thus, bears some degree of uncertainty. Recent developments of FFF instrumentation, therefore, include a particle-sizing technique additional to the flow channel and the quantity measurement (usually static and dynamic light scattering, Wyatt 1998 Cho and Hackley 2010). 

The purpose of this chapter is to provide a quick reference/overview to near-infrared (NIR) spectroscopy calibrationists on the important aspects of quantitative or qualitative calibration techniques as illustrated by the flow chart in Figure 7.1. The main task of the computer in NIR spectroscopy, aside from driving the instrument or collecting data, is to interpret the spectra using a variety of multivariate mathematical techniques. These techniques are used to produce a mathematical calibration model. Figure 7.2 illustrates the various sample sets used for testing calibration models and the conditions where recalibration is indicated. The purpose of the calibration model is... 

As IR spectroscopy is a secondary method of analysis, the development of quantitative analysis methods requires calibration with a set of standards of known composition, prepared gravimetrically or analysed by a primary chemical method, to establish a relationship between IR band intensities and the compositional variable(s) of interest. The precision of the infrared quantitation cannot be better than the (instrumental) technique employed to provide the concentrations used for the calibration standards [156]. Mid-IR may be more accurate than near-IR if the solid sample presentation is correct. 

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