Contents 2 Wavelength Calibration

Simultaneous determination of the water and rice bran contents in solid media material was also attempted (25). To obtain a calibration equation for water content in the mushroom media material, a simple linear regression was carried out on the NIR spectral data at 1450 nm and on the water content of calibration sample set (n = 113) obtained by a drying method. The values of r and SEC were 0.995 and 1.33%, respectively. On the basis of the result of the NIR on the content of rice bran in the solid media, a calibration equation using the second-derivative reflectance data at the wavelengths of 672 and 2100 nm was obtained with values for R and SEC of 0.978 and 1.73%, respectively. To validate the calibration equations obtained, water and rice bran content in the prediction sample set (n = 56) were calculated using the calibration equations. For both the water and rice bran contents, excellent agreement was observed between the results of the conventional method and those of the NIR method. The r and SEP were 0.997 and 1.33% for water content and 0.975 and 1.84% for rice bran content, respectively. The NIR method is a useful method for rapid measurement of the cell mass, growth rate of mycelium, and constituent content in the solid media of mushroom cultivation. 

A double-beam atomic absorption spectrophotometer should be used. Set up a vanadium hollow cathode lamp selecting the resonance line of wavelength 318.5 nm, and adjust the gas controls to give a fuel-rich acetylene-nitrous oxide flame in accordance with the instruction manual. Aspirate successively into the flame the solvent blank, the standard solutions, and finally the test solution, in each case recording the absorbance reading. Plot the calibration curve and ascertain the vanadium content of the oil. 

It is obvious that Figure 3-6 serves as a calibration curve with the help of which the chlorine content of unknown, similar materials could be readily determined. It will now be shown that the solid line agrees closely with kf values calculated from the mass absorption coefficients of benzene, hydrogen, and chlorine small variations in effective wavelength will be disregarded. 

Many methods are available for measuring TCA-soluble peptides. Possibly the easiest is to measure the absorbance of the solution at 280 nm, as the absorbance at this wavelength is a function of the aromatic amino acid content of the solution. This approach requires a UV spectrophotometer, and the sensitivity of the assay is likely to be lower than that of some of the colorimetric assays. There are also several colorimetric peptide assays that can be applied to this type of peptidase assay, such as the Biuret, Lowry, and Bradford dye-binding methods (for comparison see Piyachomkwan and Penner, 1995). All of these methods measure a relative value rather than an absolute amount of peptide in solution. The results should thus be reported in terms of equivalents, such as BSA equivalents when using a calibration curve prepared using a BSA standard solution. 

Determination in Solutions. The content of active substance is determined by photometric measurement of the extinction (absorbance) in solution [158], Both the wavelength and the height of the absorption maximum depend on the solvent. Concentrations of FWAs in application baths can be monitored quantitatively by comparative fluorescence measurements against calibrated standards [165], When dilute FWA solutions are handled, their photosensitivity must be kept in mind. Lighting that includes UV wavelengths can lead to rearrangement... 

Another task often required is the determination of the water content. Quantification of moisture in hard gelan-tin capsules was described by Berntsson, Zackrisson, and Oestling who discussed its importance in monitoring for at-line process control. ° A sparse MLR calibration model with three optimized near-infrared wavelengths yielded an absolute prediction error of... 

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