Infrared Studies of DDT, Structurally Related Halogenated Pesticides, and Some Metabolites

1972 ◽  
Vol 55 (1) ◽  
pp. 15-31
Author(s):  
Jo-Yun T Chen ◽  
Roland W Dority
Keyword(s):  
Ir Spectra ◽  
Pesticide Residue ◽  
Characteristic Frequencies ◽  
Mass Effects ◽  
Infrared Studies ◽  
The Stability ◽  
Correlation Tables

Abstract Reference IR spectra of 29 purified halogenated pesticides are presented. The spectra were recorded with micro quantities of the purified pesticide compounds to facilitate identification of pesticide residue isolates. The compounds included DDT and related structures. The observed characteristic frequencies are tabulated in correlation tables, and their significance is interpreted in terms of the substituents and of the electromesomeric and mass effects of the substituents. The relevance of these effects to the stability and persistence of this class of pesticides is noted.

Infrared Studies of Chlorinated Dibenzo-p-dioxins and Structurally Related Compounds

1973 ◽  
Vol 56 (4) ◽  
pp. 962-975
Author(s):  
Jo-Yun T Chen
Keyword(s):  
Infrared Spectra ◽  
Electronic Effects ◽  
Absorption Bands ◽  
Characteristic Frequencies ◽  
Infrared Studies ◽  
Bond Strengths ◽  
Related Compounds ◽  
Correlation Tables

Abstract Reference infrared spectra of 24 chlorinated dibenzo-p-dioxins (DPD) and structurally related compounds are presented. These reference spectra are recorded using micro quantities of synthesized compounds in order to obtain spectra like those expected from chlorinated DPD residue isolates. The observed characteristic frequencies are tabulated in correlation tables. Their significance is interpreted in terms of the substituents and electronic effects. The positions of various absorption bands depend on the total number and positions of the chlorine substituents. The positions of the absorption bands indicate relative bond strengths.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

scholarly journals Investigation and Validation of Detection of Storage Stability of Difenoconazole Residue in Mango

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Fangfang Zhao ◽  
Jingkun Liu ◽  
Bingjun Han ◽  
Jinhui Luo
Keyword(s):  
Food Safety ◽  
Pesticide Residue ◽  
Storage Stability ◽  
Sample Solution ◽  
Sample Storage ◽  
Fruit Samples ◽  
Different Temperatures ◽  
The Stability ◽  
Food Safety And Quality ◽  
Accuracy And Stability

To investigate the stability of the pesticide residue in storage samples is a part of detection, which is also an improvement to the accuracy of analytical results. In this work, the UPLC-MS/MS method with perfect accuracy and stability was established for determining residues of difenoconazole in mango. The stability of the residue under different temperatures (4°C and −20°C) and media (fruit samples and pretreated sample solution) was investigated. At 0.1 mg/kg, the residue degraded in 6 months by 12% when at −20°C, while in a week by only 12.2% at 4°C. However, when pretreated and preserved in the solution, the residue remained more than 90% for 6–8 weeks. The results indicated that the main causes of degradation are biochemical factors, and the factors are affected by temperature. The findings also provided appropriate conditions for sample storage. This investigation promotes the accuracy in detection and hence guarantees food safety and quality.

Infrared Studies of the Effects of Acid, Base, Heat, and Pressure on Asbestos and Structurally Related Substances

1977 ◽  
Vol 60 (6) ◽  
pp. 1266-1276
Author(s):  
Jo-Yun T Chen
Keyword(s):  
Room Temperature ◽  
Chemical Properties ◽  
Aqueous Sodium Hydroxide ◽  
Acid Base ◽  
Characteristic Frequencies ◽  
Asbestos Fibers ◽  
Related Substances ◽  
Sea Sand ◽  
Infrared Studies ◽  
Saturated Aqueous Sodium

Abstract Reference infrared (IR) spectra of 5 asbestos fibers (amosite, anthophyllite, chrysotile, crocidolite, and tremolite), talc, and sea sand are presented. These reference spectra were recorded using microgram amounts of commercial samples, and the observed characteristic frequencies were tabulated. Some chemical properties of asbestos were investigated by IR spectroscopy. In acid, chrysotile is rapidly hydrolyzed to silicic acid at room temperature; amphibolic asbestos and talc are degraded under heat and pressure ; sea sand is most stable in acid. The asbestos fibers, talc, and sea sand are stable in saturated aqueous sodium hydroxide at room temperature for 1 day or potassium hydroxidemethanol (10+90) at 65°C for 3 hr. All of the samples except sea sand degrade to sodium silicate under heat and pressure in alkali.

Infrared Studies of “Hard” and “Soft” Woods

1989 ◽  
Vol 43 (3) ◽  
pp. 451-455 ◽  
Author(s):  
N. L. Owen ◽  
D. W. Thomas
Keyword(s):  
Ir Spectra ◽  
Diffuse Reflectance ◽  
Spectral Features ◽  
Soft Or ◽  
Infrared Studies ◽  
Ft Ir

FT-IR spectra of 24 different woods have been studied with the use of whole wood pieces and a diffuse reflectance accessory. Three absorptions have been identified, the positions or relative intensities of which are characteristic of the holocellulose/lignin ratio or of the type of lignin present in the wood. These spectral features serve as useful indicators to distinguish between “soft” or “hard” woods.

scholarly journals Quark mass effects on the stability of hybrid stars

2004 ◽  
Vol 595 (1-4) ◽  
pp. 36-43 ◽  
Author(s):  
M. Buballa ◽  
F. Neumann ◽  
M. Oertel ◽  
I. Shovkovy
Keyword(s):  
Quark Mass ◽  
Mass Effects ◽  
Hybrid Stars ◽  
The Stability

Spectral, Magnetic and Thermogravimetric Studies of Some Dimeric Oxovanadium(IV) Complexes

1986 ◽  
Vol 41 (11) ◽  
pp. 1443-1446
Author(s):  
P. K. Nath ◽  
N. C. Mishra ◽  
V. Chakravortty ◽  
K. C. Dash
Keyword(s):  
Thermal Decomposition ◽  
Schiff Base ◽  
Ir Spectra ◽  
Magnetic Moment ◽  
Epr Spectroscopy ◽  
Anthranilic Acid ◽  
Room Temperature ◽  
Thermogravimetric Studies ◽  
Epr Signal ◽  
The Stability

Abstract The tridentate dibasic Schiff base anthranilic acid salicylideneimine (H2SB) reacts with VOCl2 in the presence o f NaOAc and imidazole (or its derivatives) to form dimeric oxovanadium (IV) complexes of the type [VO(S B)(D)]2. These green or yellow -green compounds have a magnetic moment of 1.4 B.M . at room temperature, and are non-electrolytes in MeOH . The compounds are characterised on the basis of electronic and IR spectra as well as EPR spectroscopy. The IR spectra shows a strong band due to v(V = O) at 880 cm-1 in addition to the bands of H2SB and imidazole. [VO(SB)(Im)]2 shows a single unresolved EPR signal at g = 1.9715 whereas compounds containing other imidazole derivatives show both a broadening and shifting of the signal. The thermogravimetric measurements indicate the stability of the complexes and their stepwise thermal decomposition.

scholarly journals A reducing-difference IR-spectral study of 4-aminopyridine

2004 ◽  
Vol 2 (4) ◽  
pp. 589-597 ◽  
Author(s):  
Michail Arnaudov ◽  
Bojidarka Ivanova ◽  
Shishman Dinkov
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Spectral Study ◽  
Fermi Resonance ◽  
Characteristic Frequencies ◽  
Band Assignment

AbstractThe IR-spectra of 4-aminopyridine (4-AP) in solution and in the solid state have been analyzed, using the reducing-difference procedure. Defining a more precise band assignment of a part of the characteristic frequencies of 4-AP, the data obtained proved in particular a Fermi-resonance splitting of the symmetric NH2-stretch.

Differential thermal analysis and infrared studies on the effect of impurities on aragonite–calcite transformation

1978 ◽  
Vol 56 (1) ◽  
pp. 32-35 ◽  
Author(s):  
Chebrolu RamaMohan Rao ◽  
Pratap Narain Mehrotra
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Ir Spectra ◽  
Pure Form ◽  
Energy Of Activation ◽  
Absorption Bands ◽  
Infrared Studies ◽  
Effect Of Impurities

The transformation of aragonite to calcite (A–C) is an irreversible reconstructive transformation involving a change from 6 to 9 in the primary coordination. Cationic impurities like Na+, Mg2+, Zn2+, Y3+, La3+, Nd3+, Gd3+, Dy3+ have been doped in pure aragonite and their effect on the kinetics and energetics of its transformation to calcite is studied. By employing a DTA technique, the enthalpy and energy of activation for the transformation have been calculated. The ir spectra of aragonite and calcite in pure form and with various impurities have been studied and the effect of impurities on absorption bands discussed.

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