Technical Materials

Normally one can assume that most metallic samples contain elemental traces in a homogeneous distribution. Lead, Bi, Zn, Ag and Sb in steel and nickel-base alloys were determined, first by using the graphite boat technique for routine analysis. Several calibration approaches were studied and it was found that the best results could be obtained by using various amounts of a number of solid alloyed steel or pure iron CRMs and to plot absorbance against concentration of the element sought (Backman and Karlsson 1979). 

This technique was subsequently modified for the determination of Co, Cu and Mn in pure iron and steel samples (Sommer and Ohls 1979). 

Solid sampling is, so far, the only method that allows the speciation of Mg contained in metals and other materials. At a temperature of i8oo°C, the metalhc Mg is completely vaporized and e.g. MgO appears at 28oo°C. So, RMs or synthetic sample mixtures can be analyzed to prepare new RMs (Ohls 1981). 

For the determination of Pb, Zn and Mn in coal samples with solid sampling GF-AAS, calibration curves were prepared either from three appropriate NIST coal SRMs or solution standards. Identical results were obtained for Pb and Zn, while only solid SRMs gave correct results for Mn (Ah et al. 1989). 

Mercury in various cement products was determined with a special mercury oven for solid samples. Calibration was performed with four BCR CRMs and one NIST SRM with different Hg content as well as with a reference solution and excellent agreement found (Bachmann and Rechenberg 1991). 

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The theme of this book has a strong emphasis on the structure of chemical compounds, its representation, and its correlation with properties. However, there are compounds whose structure is either unknown or ill-defincd. This is true, for example, for many polymers, particularly those that have been prepared from several components, or for many technical materials, such as glues, washing powder, etc. 

The yield of iso-propylbenzene is influenced considerably by the quality of the anhydrous aluminium chloride employed. It Is recommended that a good grade of technical material be purchase in small bottles containing not more than 100 g. each undue exposure to the atmosphere, which results in some hydrolysis, is thus avoided. Sealed bottles containing the reagent sometimes have a high internal pressure they should be wrapped in a dry cloth and opened with care. 

Sulphenone /5 (9-J(9-, /)-chlorophenyl phenyl sulfone (142), is a white soHd (mp 98°C). The technical material consists of ca 80% of this compound, with small amounts of 0- and y -isomers, bis(/)-chlorophenyl) sulfone, and diphenyl sulfone. Sulphenone is effective against all stages of mites. Its oral LD q to the rat is >2000 mg. 

The dermal adsorption of DEBT in humans has been studied in the Netherlands by appHcation of DEBT as undiluted technical material or as 15% solutions in alcohol. Labeled material was recovered from the skin, and absorption of DEBT was indicated by the appearance of label in urine after two hours of skin exposure. About 5—8% of the appHed treatments was recovered as metaboHtes from urine, and excretion of metaboHtes in the urine came to an end four hours after exposure ended. DEBT did not accumulate in the skin, and only a small (less than 0.08%) amount ended up in feces. Curiously, less has been absorbed through skin from 100% DEBT appHcation (3—8%, mean of 5.6%) than from 15% alcohol appHcation (4—14%, mean of 8.4%). These results have been described as consistent with previous absorption/metaboHsm studies using guinea pigs, rats, and hairless dogs. Other pubHcations on DEBT toxicology have been cited (92). 

A purified grade of l,l-di-( -chlorophenyl)-2,2,2-trichloro-ethane (DDT) melting at 105-106° should be used. It can be obtained by crystallizing the technical material from alcohol. Thus, 100 g. of technical DDT melting at 81-96°, when crystallized from 550 ml. of 95% ethanol, gave about 70 g. of material melting at 105-106°. 

Aluminium fluoride (anhydrous) [7784-18-4] M 84.0, m 250°. Technical material may contain up to 15% alumina, with minor impurities such as aluminium sulfate, cryolite, silica and iron oxide. Reagent grade AIF3 (hydrated) contains only traces of impurities but its water content is very variable (may be up to 40%). It can be dried by calcining at 600-800° in a stream of dry air (some hydrolysis occurs), followed by vacuum distn at low pressure in a graphite system, heated to approximately 925° (condenser at 900°) [Henry and Dreisbach J Am Chem Soc 81 5274 1959]. 

Technical grade DMF is available from the Grasselli Chemicals Department of E. I. duPont de Nemours and Company. The 1,4-dichlorobutane was obtained from the Electrochemicals Department, E. I. duPont de Nemours and Company. Technical Baker and Adamson fused chip sodium sulfide assaying 60% sodium sulfide was used. The checkers obtained somewhat lower yields when the appropriate amount of reagent grade Na2S OHjO was employed instead of the technical material. 

Technical material of Badische Anilin Soda-Fabrik is satisfactory. 

Weinmann WD. 1970. [Analytical methods for the determination of alpha- and beta-endosulfan in technical material and their formulations.] Nachrichtenbl Deut Pflanzenschutzdienstes 22 24-27. (German)... 

In discussing the enviromnental fate of technical DDT, the main issue is the persistence of p,p -DDT and its stable metabolites, although it should be bom in mind that certain other compounds— notably, o,p -DDT and p,p -DDD—also occur in the technical material and are released into the environment when it is used. The o,p isomer of DDT is neither very persistent nor very acutely toxic it does, however, have estrogenic properties (see Section 5.2.4). A factor favoring more rapid metabolism of the o,p isomer compared to the p,p isomer is the presence, on one of the benzene rings, of an unchlorinated para position, which is available for oxidative attack. p,p -DDD, the other major impurity of technical DDT, is the main component of technical DDD, which has been used as an insecticide in its own right (rhothane). p,p -DDD is also generated in the environment as a metabolite of p,p -DDT. In practice, the most abundant and widespread residues of DDT found in the environment have been p,p -DDE, p,p -DDT, and p,p -DDD. 

If we assume that the TCDD is contained in the surface 6 inches of the soil profile since it is relatively immobile (5), then the 2,4,5-T at the 947 lbs of active ingredient/acre treatment would have had to contain 2.1 ppm TCDD to be observed. At the lower application rates of 584 and 160 lbs/acre, the 2,4,5-T would have had to contain 3.5 and 12.5 ppm TCDD in the technical materials to have 1 ppb in the top 6 inches of soil. Since the soil is sandy and high rainfall occurred in the area, maximum movement of materials in soil may occur causing TCDD to be present deeper in the profile. If the TCDD moved uniformly throughout the 36 inch soil profile, then six times more TCDD would have had to be present in the original 2,4,5-T for detection. This would have required the presence of 12.6, 21.0, and 75.0 ppm TCDD in the 2,4,5-T applied in the three treatments. These calculations are based on the assumption that no degradation occurred in or on the soil. 

The reaction occurs with technical material only, and, once formulated, the nitrosamine content is not altered as a function of time at ambient formulation temperatures. This intra-molecular rearrangement requires careful attenticn to conditions in the formulation of dinitroaniline herbicides. 

The classical approach for particle size determination, or more correctly for particle size selection - which is still used for solids like soils, sediments and other technical materials like coal, and also for biological materials - is sieving analysis. The raw material is milled, generally after drying, see Section 2.1, and if the required particle size is obtained, typically ranging from <0.1 to a few mm, it is allowed to pass sieves with different apertures to discard coarse particles and remaining materials. For materials consisting of numerous different particles microscopical inspection is used. 

The technical material has a brown color, a refractive index that may differ slightly in the third place, and a density that is approximately the same as that of the pure material. Parathion is soluble in water to the extent of about 20 to 25 p.p.m. It is completely... 

Normal curves for the polarograms were obtained with the technical materials as well as with the purified sample. The decomposition potential of —0.30 volt and a half-wave potential of —0.39 volt were obtained against the saturated calomel electrode. 

Ethylene Dibromide. Technical material was washed three times with concentrated sulfuric acid, rinsed with water, and dried over calcium chloride. It was then distilled through 1 foot of glass beads. The fraction boiling between 130.2° and 131.2° C. was used. Every third day an aqueous solution was prepared by weighing approximately 0.5000 gram of ethylene dibromide into 2000.0 grams of water. It was stored in a dark bottle to minimize light decomposition. 

During reciystallisation of technical material from acetone, explosive decomposition occurred. Non-explosive decomposition occurred when the nitrile was heated alone, or in presence of methanol. 

Mixtures containing less than 0.1% of zinc dust or other assorted technical materials are not explosive or combustible on impact or friction. 

The pure material is not impact-ignitable in absence of electrostatic charges, but technical material (possibly containing dichlorosilane) is [1]. Hazards are reviewed and an Ait of 182°C established [2],... 

Physical state The technical material is a white, crystalline, noncombustible, noncorrosive substance... 

Lemke, D. Heat accumulation tests of medium scale samples of thermally unstable technical materials in adiabatic storage. 

To start with, the reader may have noticed that all the quoted advantages are never combined together in the same polymer class. Moreover, polymers meet certain general obstacles as technical materials. Let us quote for example sensitivity to impact, ageing, low rigidity, thermal behaviour, rate of production, recycling. 

Haider, S. and InbaraJ, R.M. Relative toxicity of technical material and commercial formulation of malathion and endosulfan to... 

The sulfonylureas described here are new herbicides with unprecedented activity. Activity at extraordinarily low rates of application has been demonstrated by both preemergence and postemergence applications (Ref. 1). These rates are best describee in grams per hectare compared to kilograms per hectare for most herbicides currently marketed. Furthermore, the combination of low application rates, half lives of generally less than two months in the soil (Ref. 2) and excellent safety to mammals [LD5o s of generally >5000 mg/kg for technical material in male rats] (Ref. IC) makes these compounds attractive products from an environmental viewpoint. 

Therefore, I decided to list a relatively small number of books that I thought would be of interest to the non-specialist reader. I haven t shied away from listing two scholarly works that contain a fair amount of technical material. These books are well enough written that the lay reader can skip the more difficult parts and read them for their engrossing accounts of the subjects lives. 

Pais, Abraham. Niels Bohr s Times. Oxford Oxford University Press, 1991. Some of the technical discussions in this magisterial book might be daunting to the lay reader. However, it contains the best and most comprehensive account of Bohr s life. The reader who skips the technical material and reads only the narrative is likely to be richly rewarded. 

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