In vivo1H MR spectra analysis by means of second derivative method

2001 ◽  
Vol 12 (2-3) ◽  
pp. 177-183 ◽  
Author(s):  
Maria Sokól
Keyword(s):  
Second Derivative ◽  
Spectra Analysis ◽  
Derivative Method ◽  
Second Derivative Method

Different Spectrophotometric and Chromatographic Methods for Determination of Mepivacaine and Its Toxic Impurity

2017 ◽  
Vol 100 (5) ◽  
pp. 1392-1399 ◽  
Author(s):  
Nada S Abdelwahab ◽  
Nehal F Fared ◽  
Mohamed Elagawany ◽  
Esraa H Abdelmomen
Keyword(s):  
Particle Size ◽  
Stationary Phase ◽  
Second Derivative ◽  
Spectrophotometric Measurement ◽  
Spectrophotometric Methods ◽  
Derivative Method ◽  
Tlc Plates ◽  
Second Derivative Method ◽  
Developing System

Abstract Stability-indicating spectrophotometric, TLC-densitometric, and ultra-performance LC (UPLC) methods were developed for the determination of mepivacaine HCl (MEP) in the presence of its toxic impurity, 2,6-dimethylanaline (DMA). Different spectrophotometric methods were developed for the determination of MEP and DMA. In a dual-wavelength method combined with direct spectrophotometric measurement, the absorbancedifference between 221.4 and 240 nm was used for MEPmeasurements, whereas the absorbance at 283 nm was used for measuring DMA in the binary mixture. In the second-derivative method, amplitudes at 272.2 and 232.6 nm were recorded and used for the determination of MEP and DMA, respectively. The developed TLC-densitometric method depended on chromatographic separation using silica gel 60 F254 TLC plates as a stationary phase and methanol–water–acetic acid (9 + 1 + 0.1, v/v/v) as a developing system, with UV scanning at 230 nm. The developed UPLC method depended on separation using a C18 column (250 × 4.6 mm id, 5 μm particle size) as a stationary phase and acetonitrile–water (40 + 60, v/v; pH 4 with phosphoric acid) as a mobilephase at a flow rate of 0.4 mL/min, with UV detection at 215 nm. The chromatographic run time was approximately 1 min. The proposed methods were validated with respect to International Conference on Harmonization guidelines regarding precision, accuracy, ruggedness, robustness, and specificity.

scholarly journals Trigonometrically-fitted second derivative method for oscillatory problems

SpringerPlus ◽  
2014 ◽  
Vol 3 (1) ◽  
Author(s):  
Fidele Fouogang Ngwane ◽  
Samuel Nemsefor Jator
Keyword(s):  
Second Derivative ◽  
Derivative Method ◽  
Second Derivative Method

Usefulness of a Curve Fitting Method in the Analysis of Overlapping Overtones and Combinations of CH Stretching Modes

2002 ◽  
Vol 10 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Yukiteru Katsumoto ◽  
Daisuke Adachi ◽  
Harumi Sato ◽  
Yukihiro Ozaki
Keyword(s):  
Curve Fitting ◽  
Second Derivative ◽  
Downward Shift ◽  
Fitting Method ◽  
Derivative Method ◽  
Structural Differences ◽  
Alcohol Mixtures ◽  
Curve Fitting Method ◽  
Second Derivative Method ◽  
Water Alcohol

This paper reports the usefulness of a curve fitting method in the analysis of NIR spectra. NIR spectra in the 7500–5500 cm−1 (1333–1818 nm) region were measured for water–methanol, water–ethanol and water–1-propanol mixtures with alcohol concentrations of 0–100 wt% at 25°C. The 6000–5600 cm−1 (1667–1786 nm) region, where the overtones and combinations of CH3 and CH2 stretching modes are expected to appear, shows significant band shifts with the increase in the alcohol content. To analyse the concentration-dependent spectral changes, a curve fitting method was utilised, and the results were compared with those obtained previously by a second derivative method. It was found that the first overtones of CH3 asymmetric and symmetric stretching modes of alcohols show a downward shift by about 15–30 cm−1 with the increase in the concentration of alcohols. The shifts are much larger for water–methanol mixtures than for water–ethanol and water–1-propanol mixtures. The first overtones and combinations of CH2 stretching modes of ethanol and 1-propanol also show a small downward shift. These shifts support our previous conclusion that there is an intermolecular “CH⃛O” interaction between the methyl group and water in the water–alcohol mixtures. The curve fitting method provided more feasible results for the band shifts than the second derivative method. It was revealed from the curve fitting method that the first overtone of the CH3 asymmetric stretching mode of water–methanol, water–ethanol and water–1-propanol mixtures shows different concentration-dependent plots. The first overtone of CH3 asymmetric stretching mode of water–methanol mixtures shifts more rapidly in the high methanol concentration range while that of water–1-propanol concentration shifts more markedly in the low 1-propanol concentration range. That of water–ethanol mixtures shows an intermediate trend. Based upon these differences structural differences among the three kinds of water–alcohol mixtures are discussed.

Second-Derivative UV Spectrometric Microdetermination of Dithiocarbamate Residues as Methyl Xanthate

1995 ◽  
Vol 78 (2) ◽  
pp. 458-462 ◽  
Author(s):  
Wolfgang Schwack ◽  
Steven Nyanzi
Keyword(s):  
Classical Method ◽  
Residue Analysis ◽  
Molar Absorptivity ◽  
Calibration Graph ◽  
Second Derivative ◽  
Acid Decomposition ◽  
Negative Peak ◽  
Fungicide Residues ◽  
Derivative Method ◽  
Second Derivative Method

Abstract The microdetermination of dithiocarbamate fungicide residues as methyl xanthate using second-derivative UV spectrometry is described. The residue analysis is based on a hot-acid decomposition, scrubbing the evolved CS2 with lead acetate and concentrated H2SO4, and absorbing the CS2 in methanolic KOH. The absorbance of the xanthate system (conventional method) and the height of the negative peak at 302 nm (second-derivative method) are used to quantitate the CS2. The molar absorptivity of the xanthate system within the range of 0.3–2.4 μg CS2/mL where Beer’s law is obeyed, was 1.70 × 104 L mol-1 cm-1. The derivative procedure was more selective and sensitive to CS2 than the classical method. The calibration graph of the derivative procedure was rectilinear from 0.1–1.1 μg/mL of CS2. The coefficient of variation for the determination (n = 10) of a 0.28 (μg/mL standard of CS2 was 2.6%. The detection limit for CS2 was 0.08 μg/mL. The second-derivative procedure was applied to the residue analysis of thiram on tomatoes.

THE SECOND DERIVATIVE METHOD OF GRAVITY INTERPRETATION

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 29-50 ◽  
Author(s):  
Thomas A. Elkins
Keyword(s):  
Horizontal Plane ◽  
Graphical Method ◽  
Gravity Data ◽  
Three Dimensional ◽  
Horizontal Cylinder ◽  
Resolving Power ◽  
Theoretical Formula ◽  
Second Derivative ◽  
Derivative Method ◽  
Second Derivative Method

The second derivative method of interpreting gravity data, although its use is justifiable only on data of high accuracy, offers a simple routine method of locating some types of geologic anomalies of importance in oil and mineral reconnaissance. The theoretical formula by which it is possible to compute the second (vertical) derivative of any harmonic function from its values in a horizontal plane is derived for both the two‐dimensional and the three‐dimensional cases. The graphical method of computing the second derivative is discussed, especially as to the sources of error. A numerical coefficient equivalent of the graphical method is also presented. Formulas and graphs for the second derivative of the gravity effect of such geometrically simple shapes as the sphere, the infinite horizontal cylinder, the semi‐infinite horizontal plane, and the vertical fault, are presented with discussions of their value in the interpretation of practical data. Finally, the gravity and second derivative maps of portions of some important oil provinces are presented and compared to show the higher resolving power of the second derivative.

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