Name, column material

A hazardous material is a material listed by DOT in the Hazardous Materials Table ( 172.101) by technical name, or, if not listed by technical name, a material that meets the specific criteria of a hazard class. A plus sign (+) on Column I of the Hazardous Materials Table fixes the hazard class and proper shipping name for that material without regard as to whether that material meets the definition of that hazard class. If petitioned, an alternate hazard class, in that case, may be authorized by the Associate Director, Office of Hazardous Materials Regulation, MTB ( 172.101(b)(l)). If a material listed by technical name on the Hazardous Materials Table meets the definition of a hazard class other than the class shown in association with the technical name, the material must be classified in accordance with the appropriate hazard class. It must then be described by the shipping name that best describes the material listed in association with the correct hazard classification. If the... 

Three fundamental kinds of materials used in gel chromatography will be discussed in this section, namely column fillings, mobile phases and reference materials. 

There are stationary-phase material names that give no information, such as INTERCHROM and ASAHIPAK, and others that do tell you something about themselves, such as LiChrospher and Inertsil. This subject cannot be dealt with in detail, but in the Table below you should find some help. Listed are numbers, letters, prefixes and suffixes from names that give an indication of properties of column materials. 

The most frequently apphed technique for the separation of polymers, namely size-exclusion chromatography (SEC), is based on the well-balanced interactions between the column material, the solvent, and the polymer sample. In order to achieve a complete separation according to size, and also to determine reliable polydispersity values, enthalpic interactions between the sample and column material must be excluded, as only entropic interactions lead to SEC separation. This is not always possible in the case of dendritic polymers which, being multifunctional architectures, have interactions with the column material that are effectively predestined. It has been repeatedly observed that this problem is more severe for higher molar mass products. An example of aromatic hb polyesters with different... 

Although the known methods of chemical treatment of capillary walls are readily realizable, they have a serious disadvantage, namely, they are not universal and are restricted as a rule to glass and metal columns. Moreover, the composition and properties of the adsorption layer formed strongly depend on the composition of the column material, which may vary widely. 

Column 9 indicates the location and names of other reactant materials Column 10 is used to list hazard... 

Size exclusion was first noted in the late fifties when separations of proteins on columns packed with swollen maize starch were observed (Lindqvist and Storgards, 1955 Lathe and Ruthven, 1956). The run time was typically 48 hr. With the advent of a commercial material for size separation of molecules, a gel of cross-linked dextran, researchers were given a purposely made material for size exclusion, or gel filtration, of solutes as described in the classical work by Porath and Flodin (1959). The material, named Sephadex, was made available commercially by Pharmacia in 1959. This promoted a rapid development of the technique and it was soon applied to the separation of proteins and aqueous polymers. The work by Porath and Flodin promoted Moore (1964) to apply the technique to size separation, gel permeation chromatography of organic molecules on gels of lightly cross-linked polystyrene (i.e., Styragel). 

The injection device is also an important component in the LC system and has been discussed elsewhere (2,18). One type of injector is analogous to sample delivery in gas chromatography, namely syringe injection through a self-sealing septum. While this injection procedure can lead to good column efficiency, it generally is pressure limited, and the septum material can be attacked by the mobile phase solvent. 

An additional material based on the extractant octyl-phenyl-N,N-diisobutyl-carbamoylmethylphosphine oxide, or CMPO, (marketed under the name TRU-Spec) has also been widely utilized for separations of transuranic actinides (Horwitz et al. 1993a) but is also useful for uranium-series separations (e.g., Burnett and Yeh 1995 Luo et al. 1997 Bourdon et al. 1999 Layne and Sims 2000). This material has even greater distribution coefficients for the uranium-series elements U (>1000), Th (>10000), and Pa. As shown in Figure 1, use of this material allows for sequential separations of Ra, Th, U, and Pa from a single aliquot on a single column. Separations of protactinium using this material (Bourdon et al. 1999) provide an alternative to liquid-liquid extractions documented in Pickett et al. (1994). 

The liquid stationary phase in a GLC packed column is adsorbed on the surface of a solid substrate (also called the support). This material must be inert and finely divided (powdered). The typical diameter of a substrate particle is 125 to 250 ft, creating a 60- to 100-mesh material. These particles are of two general types diatomaceous earth and Teflon . Diatomaceous earth, the decayed silica skeletons of algae, is most commonly referred to by the manufacturer s (Johns Manville s) trade name, Chromosorb . Various types of Chromosorb, which have had different pretreatment procedures applied, are available, such as Chromosorb P, Chromosorb W, and Chromosorb 101-104. The nature of the stationary phase as well as the nature of the substrate material are both usually specified in a chromatography literature procedure, and columns are tagged to indicate each of these as well. 

Chromosorb is the trade name given to diatomaceous earth, the decayed silica skeletons of algae. It is the substrate material on which the liquid stationary phase is adsorbed in packed columns. Low-molecular-weight alcohols are highly polar, thus FFAP or Casterwax would be useful in their separation. 

Act = 226.5 the naming of the parents follows the nomenclature employed by Fajans in which the element uranium is referred to as UrI. A place in the periodic table is then defined by a specific row and a specific column. From the data, one then readily obtains the row and column of each of the elemental daughters. Since the characterization of decay products emphasized the fact that many of these products are chemically indistinguishable from one another, it is of course expected that many of the places in the last two rows of the periodic table are occupied by more than one elementary material. What is surprising is that these chemically equivalent materials have different atomic weights, some differing by as much as eight units. 

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