THE APPLICATION OF GAS–LIQUID PARTITION CHROMATOGRAPHY TO PROBLEMS IN CHEMICAL KINETICS

1955 ◽  
Vol 33 (7) ◽  
pp. 1256-1267 ◽  
Author(s):  
A. B. Callear ◽  
R. J. Cvetanović
Keyword(s):  
Chemical Kinetics ◽  
Chromatographic Method ◽  
Partition Chromatography ◽  
Order Of Magnitude

A gas–liquid partition chromatographic method for analysis of samples of the order of magnitude of a micromole is described. Examples of application are given.

D-GLYCERO-D-MANNO-HEPTOSE AS A COMPONENT OF LIPOPOLYSACCHARIDES FROM GRAM-NEGATIVE BACTERIA

1967 ◽  
Vol 13 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
G. A. Adams ◽  
C. Quadling ◽  
M. B. Perry
Keyword(s):  
Chromatographic Method ◽  
Simultaneous Detection ◽  
Gram Negative Bacteria ◽  
Partition Chromatography ◽  
Chemical Methods ◽  
Gram Negative ◽  
E Coli ◽  
Physical And Chemical

Lipopolysaccharides have been isolated from seven species of Gram-negative bacteria and their acid hydrolysates have been examined by gas–liquid partition chromatography for the presence of aldoheptoses. All contained D-glycero-D-manno-heptose in addition to the well-known aldoheptose component L-glycero-D-manno-heptose. The relative proportions of these two aldoheptoses varied widely between species of bacteria and to a lesser extent between members of the same species. Both aldoheptoses were isolated from a lipopolysaccharide prepared from E. coli cells and were positively identified by physical and chemical methods. The chromatographic method used for determining the aldoheptoses also provided means for simultaneous detection of 3-deoxy-D-manno-octulosonic acid (KDO).

scholarly journals New Spectrophotometric Method for Determining Nitrogen Dioxide in Air Using 2,2-Azino-Bis(3-Ethyl Benzothiazoline)-6-Sulfonic Acid-Diammonium Salt and Passive Sampling

2011 ◽  
Vol 6 ◽  
pp. ACI.S6969 ◽  
Author(s):  
Alaa A. Salem ◽  
Ahmed A. Soliman ◽  
Ismail A. El-Haty
Keyword(s):  
Nitrogen Dioxide ◽  
Spectrophotometric Method ◽  
Sulfonic Acid ◽  
Chromatographic Method ◽  
Ambient Air ◽  
Passive Samplers ◽  
Nitrite Ion ◽  
Diammonium Salt ◽  
Order Of Magnitude ◽  
Insignificant Difference

A new simple and highly sensitive spectrophotometric method for determining nitrogen dioxide in air was developed. The method is based on converting atmospheric nitrogen dioxide to nitrite ions within the IVL passive samplers used for samples collection. Acidifying nitrite ions with concentrated HCl produced the peroxynitrous acid oxidizing agent which was measured using 2,2-azino-bis(3-ethyl benzothiazoline)-6-sulfonic acid-diammonium salt (ABTS) as reducing coloring agent. A parallel series of collected samples were measured for its nitrite content using a validated ion chromatographic method. The results obtained using both methods were compared in terms of their sensitivity and accuracy. Developed spectrophotometric method was shown to be one order of magnitude higher in sensitivity compared to the ion chromatographic method. Quantitation limits of 0.05 ppm and 0.55 μg/m3 were obtained for nitrite ion and nitrogen dioxid, respectively. Standard deviations in the ranges of 0.05-0.59 and 0.63-7.92 with averages of 0.27 and 3.11 were obtained for determining nitrite and nitrogen dioxide, respectively. Student-t test revealed t-values less than 6.93 and 4.40 for nitrite ions and nitrogen dioxide, respectively. These values indicated insignificant difference between the averages of the newly developed method and the values obtained by ion chromatography at 95% confidence level. Compared to continuous monitoring techniques, the newly developed method has shown simple, accurate, sensitive, inexpensive and reliable for long term monitoring of nitrogen dioxide in ambient air.

Chromatographic Determination of Rubber in Plant Latexes

1956 ◽  
Vol 29 (3) ◽  
pp. 1026-1033 ◽  
Author(s):  
Dorado E. Bernal
Keyword(s):  
Partition Coefficients ◽  
Chromatographic Method ◽  
Rapid Determination ◽  
Chromatographic Determination ◽  
Partition Chromatography ◽  
Biological Cycle

Abstract Partition chromatography on paper makes possible the separation of rubber hydrocarbon from latex. This method offers a means which is both simple and rapid for determining the presence of rubber in plant latexes and for the subsequent estimation of its percentage in a given latex. The method also gives a fraction which is composed of the nonrubber components. In addition to this, the method makes possible a comparison of the partition coefficients of rubber hydrocarbon isolated from latexes of different plants. Experiments are now in progress, the purpose of which is the application of the chromatographic method to the rapid determination of plant rubbers. By its simplicity, this method unquestionably has certain advantages in the identification of rubber in any particular flora and in studies of this hydrocarbon in its various phases of the biological cycle of the plant.

PREPARATIVE PARTITION CHROMATOGRAPHY OF CARBOHYDRATES ON CELITE COLUMNS

1956 ◽  
Vol 34 (10) ◽  
pp. 1365-1371 ◽  
Author(s):  
R. U. Lemieux ◽  
C. T. Bishop ◽  
G. E. Pelletier
Keyword(s):  
Chromatographic Method ◽  
Partition Chromatography ◽  
Analytical Work ◽  
Derivatives Of ◽  
Yield And Purity ◽  
Partially Methylated

Partition on Celite columns, using both elution and extrusion techniques, was found to be a convenient and satisfactory chromatographic method for preparative or analytical work involving carbohydrates and their derivatives. The method is superior to other chromatographic procedures for carbohydrates in resolution of mixtures; cost, ease, and speed of operation; yield and purity of products; and range of applicability. To illustrate these advantages a number of specific examples are given involving partially methylated derivatives of D-glucose and D-xylose and isolation of products from reaction mixtures.

THE GAS–LIQUID PARTITION CHROMATOGRAPHY OF CARBOHYDRATE DERIVATIVES: PART III. THE SEPARATION OF AMINO GLYCOSE DERIVATIVES AND OF CARBOHYDRATE ACETAL AND KETAL DERIVATIVES

1962 ◽  
Vol 40 (8) ◽  
pp. 1559-1563 ◽  
Author(s):  
H. G. Jones ◽  
J. K. N. Jones ◽  
M. B. Perry
Keyword(s):  
Chromatographic Method ◽  
Hydroxyl Groups ◽  
Partition Chromatography ◽  
Free Hydroxyl

Gas–liquid partition chromatography has been used to separate the anomeric acetates of 2-amino-2-deoxy-D-glucopyranose (D-glucosamine) and of 2-amino-2-deoxy-D-galactopyranose (D-galactosamine) and also their fully acetylated reduction products, 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-glucitol and 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-galactitol. The gas–liquid partition chromatographic method has also been successfully applied to the separation of unsubstituted carbohydrate acetal and ketal derivatives and to those derivatives in which the free hydroxyl groups have been substituted by O-acetyl, O-benzoyl, O-benzyl, carbonate, O-methanesulphonyl, O-methyl, and O-toluene-p-sulphonyl groups.

A controller for safe, convenient operation of LaB6 emitters on electron-beam instruments

1983 ◽  
Vol 41 ◽  
pp. 408-409
Author(s):  
W. J. Abramson ◽  
H. W. Estry ◽  
L. F. Allard
Keyword(s):  
Electron Beam ◽  
Control System ◽  
Thermal Shock ◽  
Appropriate Care ◽  
Electron Guns ◽  
Tungsten Filaments ◽  
Order Of Magnitude ◽  
Main Components

LaB6 emitters are becoming increasingly popular as direct replacements for tungsten filaments in the electron guns of modern electron-beam instruments. These emitters offer order of magnitude increases in beam brightness, and, with appropriate care in operation, a corresponding increase in source lifetime. They are, however, an order of magnitude more expensive, and may be easily damaged (by improper vacuum conditions and thermal shock) during saturation/desaturation operations. These operations typically require several minutes of an operator's attention, which becomes tedious and subject to error, particularly since the emitter must be cooled during sample exchanges to minimize damage from random vacuum excursions. We have designed a control system for LaBg emitters which relieves the operator of the necessity for manually controlling the emitter power, minimizes the danger of accidental improper operation, and makes the use of these emitters routine on multi-user instruments.Figure 1 is a block schematic of the main components of the control system, and Figure 2 shows the control box.

Novel magneto-optical recording materials: Bi-substituted garnet films

1991 ◽  
Vol 49 ◽  
pp. 776-777
Author(s):  
Takao Suzuki ◽  
Hossein Nuri
Keyword(s):  
Grain Size ◽  
Amorphous Film ◽  
Nitrogen Atmosphere ◽  
Optical Recording ◽  
Garnet Film ◽  
Media Noise ◽  
Garnet Films ◽  
Order Of Magnitude ◽  
A New Technique ◽  
A Current

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.

Atomic-level imaging of the surface structure of Ag2O

1984 ◽  
Vol 42 ◽  
pp. 656-657
Author(s):  
William Krakow
Keyword(s):  
High Vacuum ◽  
Atomic Level ◽  
Ultra High Vacuum ◽  
Research Groups ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Order Of Magnitude ◽  
High Resolution Electron Microscope ◽  
Saturated Structure ◽  
Transmission And Reflection

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.

Near-field scanning optical microscopy

1986 ◽  
Vol 44 ◽  
pp. 642-643
Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis
Keyword(s):  
Near Field ◽  
Optical Microscope ◽  
Visible Radiation ◽  
Field Methods ◽  
Optical Elements ◽  
Optical Region ◽  
Order Of Magnitude ◽  
Nondestructive Imaging ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

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