Detection and Determination of Minor Components in Nominally Pure Solids by Raman Spectroscopy

1987 ◽  
Vol 41 (8) ◽  
pp. 1324-1329 ◽  
Author(s):  
Charles K. Mann ◽  
Thomas J. Vickers ◽  
James D. Womack
Keyword(s):  
Raman Spectroscopy ◽  
Least Squares ◽  
Sulfanilic Acid ◽  
Qualitative And Quantitative Analysis ◽  
Case Scenario ◽  
Worst Case ◽  
Least Squares Fitting ◽  
Correlation Data ◽  
Treatment Procedures

The problems encountered in applying Raman spectroscopy to direct qualitative and quantitative analysis for minor impurities in nominally pure, colorless solids have been examined. Samples of sulfamethoxazole spiked with 0.5 to 5% of sulfanilamide and sulfanilic acid were used as test materials. A procedure is described which permits detection of spectral features of the specified impurities at the 0.5% level. Least-squares fitting and cross-correlation data treatment procedures for the determination of sulfanilamide in sulfamethoxazole, with limits of detection of about 0.1% for either approach, are described. Computer simulations have been used to examine detection of impurity peaks for a variety of conditions, including the worst-case scenario in which the impurity features coincide with the strongest features of the spectrum of the host material. A least-squares fitting approach is described which permits detection of the impurity peak at the 0.5% level, even under worst case conditions.

scholarly journals Experimental Determination of Scan-truncation Losses from Low-temperature (16 K) Single-crystal X-ray Measurements

1988 ◽  
Vol 41 (3) ◽  
pp. 503 ◽  
Author(s):  
Riccardo Destro
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Experimental Determination ◽  
Least Squares ◽  
Spectral Distribution ◽  
Experimental Measurements ◽  
Fourier Methods ◽  
X Ray ◽  
Least Squares Fitting

Model intensity profiles have been obtained for biscarbonyl[ 14]annulene by convoluting the Mo Ka spectral distribution with two functions derived from experimental measurements at 16(1) K, up to 26Mo = 110�, of a spherical crystal mounted on a four-circle diffractometer equipped with the Samson low-temperature apparatus. The process includes accurate measurement of the inherent background, treatment of the profiles by numerical Fourier methods, and least-squares fitting. Owing to the instrumental configuration of the diffractometer used in this investigation, the first step of the process has required a careful determination of the X dependence of the background, besides the usual 26 dependence. Truncation losses for the crystal under study, evaluated for several scan ranges, are far larger than usually assumed or predicted.

Fast, cross cultivar determination of total carotenoids in intact carrot tissue by Raman spectroscopy and Partial Least Squares calibration

2016 ◽  
Vol 204 ◽  
pp. 7-13 ◽  
Author(s):  
Anders J. Lawaetz ◽  
Signe M.U. Christensen ◽  
Sabine K. Clausen ◽  
Bjarne Jørnsgaard ◽  
Søren K. Rasmussen ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Least Squares ◽  
Partial Least Squares ◽  
Total Carotenoids

Chain Length Determination of Fatty Acids by Raman Spectroscopy

1973 ◽  
Vol 51 (23) ◽  
pp. 3901-3904 ◽  
Author(s):  
Charles H. Warren ◽  
Donald L. Hooper
Keyword(s):  
Fatty Acids ◽  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Long Chain Fatty Acids ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Odd Order ◽  
Length Determination ◽  
Long Chain

For saturated long chain fatty acids, as for hydrocarbons, the odd order "accordion mode" vibrations are Raman active. These "accordion mode" vibrations have been used to provide qualitative and quantitative analysis of mixtures of acids in the range C12–C24.

scholarly journals Molecular Constants of the 2\(^1\Pi\) State of \(\text{NaLi}\) Molecule

2013 ◽  
Vol 23 (2) ◽  
pp. 135
Author(s):  
Nguyen Tien Dung ◽  
Le Canh Trung ◽  
Dinh Xuan Khoa ◽  
Nguyen Huy Bang
Keyword(s):  
Least Squares ◽  
Spectral Lines ◽  
Experimental Uncertainty ◽  
Linear Least Squares ◽  
Molecular Constants ◽  
Least Squares Fitting ◽  
Fitting Method

We report our determination of molecular constants for the 21Π state of NaLi from set of 732 spectral lines. Using the linear least-squares fitting method, an optimum set of molecular constants, which corresponds to dimensionless root mean of squares of deviation σ = 0.62 within 0.1 cm-1 experimental uncertainty, have been derived.

An X-ray determination of the thermal expansion of the intermetallic compound Ni3Zr

1983 ◽  
Vol 16 (6) ◽  
pp. 645-646 ◽  
Author(s):  
S. K. Shadangi ◽  
S. C. Panda ◽  
S. Bhan
Keyword(s):  
Thermal Expansion ◽  
Intermetallic Compound ◽  
Least Squares ◽  
Temperature Interval ◽  
X Ray ◽  
Least Squares Fitting ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Ray Methods

The lattice spacings of the intermetallic compound Ni3Zr have been measured by X-ray methods in the temperature interval 298–1033 K using a Debye–Scherrer camera. In all the cases the measured lattice spacings have been found to increase non-linearly with temperature and the dependence has been expressed by a polynomial of second degree from the least-squares fitting of the data. The thermal expansion coefficients for both parameters have been found to decrease with increase in temperature.

scholarly journals Market risk stress testing for internationally active financial institutions

2011 ◽  
Vol 56 (188) ◽  
pp. 62-90 ◽  
Author(s):  
Petar Markovic ◽  
Branko Urosevic
Keyword(s):  
Financial Institutions ◽  
Stress Testing ◽  
Stress Test ◽  
Data Gathering ◽  
Market Risk ◽  
Case Scenario ◽  
Worst Case ◽  
Thomson Reuters ◽  
Comprehensive Framework

The paper develops a comprehensive framework for market risk stress testing in internationally active financial institutions. We begin by defining the scope and type of the stress test and explaining how to select risk factors and the stress time horizon. We then address challenges related to data gathering, followed by in-depth discussion of techniques for developing realistic shock scenarios. Next the process of shock application to a particular portfolio is described, followed by determination of portfolio profit and loss. We conclude by briefly discussing the issue of assigning probability to stress scenarios. We illustrate the framework by considering the development of a ?worst case? scenario using global financial market data from Thomson Reuters Datastream.

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