Standard Beryllium

The variation in response for the same amount of beryllium in different crudes prohibits the use of calibration curve techniques. Consequently, the method of standard additions was adopted to circumvent the variation in response. The applicability of the standard addition technique was evaluated by analyzing several types of petroleum samples that had been spiked with known amounts of beryllium using the Conostan beryllium standard. The results are shown in Figure 6.2. If the analyses were 100% accurate, all data points would fall on the diagonal match line. All experimental values agree with the known spike level within the precision of the method, suggesting that the standard addition technique compensates for the variation in response. 

Beryllium Oxalate. BeryUium oxalate trihydrate [15771 -43-4], BeC204 -3H20, is obtained by evaporating a solution of beryUium hydroxide or oxide carbonate in a slight excess of oxaHc acid. The compound is very soluble in water. Beryllium oxalate is important for the preparation of ultrapure beryllium hydroxide by thermal decomposition above 320°C. The latter is frequentiy used as a standard for spectrographic analysis of beryUium compounds. 

Sample cells include Lindemann/capillary tubes (normally < 1 mm in diameter) and aluminium holders. In the latter, thin aluminium windows sandwich the sample in a cylindrical aluminium sample holder. The diffraction from the aluminium is observed in this case, and may be used as a calibration standard. For low-temperature materials, the aluminium window can be replaced by the polymer Kapton. Beryllium may also be used [14]. Sample volumes of between 50 and 100 pL are typically required. 

Beryllium is a light metal (s.g. 1 -85) with a hexagonal close-packed structure (axial ratio 1 568). The most notable of its mechanical properties is its low ductility at room temperature. Deformation at room temperature is restricted to slip on the basal plane, which takes place only to a very limited extent. Consequently, at room temperature beryllium is by normal standards a brittle metal, exhibiting only about 2 to 4% tensile elongation. Mechanical deformation increases this by the development of preferred orientation, but only in the direction of working and at the expense of ductility in other directions. Ductility also increases very markedly at temperatures above about 300°C with alternative slip on the 1010 prismatic planes. In consequence, all mechanical working of beryllium is carried out at elevated temperatures. It has not yet been resolved whether the brittleness of beryllium is fundamental or results from small amounts of impurities. Beryllium is a very poor solvent for other metals and, to date, it has not been possible to overcome the brittleness problem by alloying. 

In its general corrosion behaviour, beryllium exhibits characteristics very similar to those of aluminium. Like aluminium, the film-free metal is highly active and readily attacked in many environments. Beryllium oxide, however, like alumina, is, a very stable compound (standard free energy of formation = —579kJ/mol), with a bulk density of 3-025g/cm as compared with 1 -85 g/cm for the pure metal, and with a high electronic resistivity of about 10 flcm at 0°C. In fact, when formed, the oxide confers the same type of spurious nobility on beryllium as is found, for example, with aluminium, titanium and zirconium. 

Furthermore, even though a consistent quality of beryllium is now produced, the chemical composition falls far short of the standards found for instance in aluminium generally, the main impurities consist of about 1% of beryllia at grain boundaries, about 0-15% of iron and 0-05-01% of other elements such as silicon, aluminium and carbon. 

While from the energy point of view, the correlation effects seem to be overestimated, the RDAf s are particularly satisfactory. Thus, when comparing the 2-RDAf s obtained with these approximations for the ground state of the Beryllium atom with the corresponding FCI one, the standard deviations are 0.00208236 and 0.00208338 for the MPS and IP respectivelyFor this state, which has a dominant four electron configuration of the type, 1122 >, the more important errors, which nevertheless can be considered small, are given in table 2. 

Hazardous waste burning incinerators, cement kilns, and LWAKs do not follow a tiered approach to regulate the release of toxic metals into the atmosphere. The MACT rule finalized numerical emission standards for three categories of metals mercury, low-volatile metals (arsenic, beryllium, and chromium), and semivolatile metals (lead and cadmium). Units must meet emission standards for the amount of metals emitted. For example, a new cement kiln must meet an emission limit of 120pg/m3 of mercury, 54pg/m3 of low-volatile metals, and 180 pg/m3 of semivolatile metals. 

Low-volatile metals (arsenic + beryllium + chromium) 92 pg/dscm 2.1 E-5 lb/MMBtu and 56 flg/dscm 9.5 E-5 lb/MMBtu and llOpg/dscm 380 pg/dscm 1.26 E-4 lb/MMBtu or 370pg/dscm depending on Btu content of hazardous TCI standard as surrogate... 

Vandecasteele et al. [745] studied signal suppression in ICP-MS of beryllium, aluminium, zinc, rubidium, indium, and lead in multielement solutions, and in the presence of increasing amounts of sodium chloride (up to 9 g/1). The suppression effects were the same for all of the analyte elements under consideration, and it was therefore possible to use one particular element, 115indium, as an internal standard to correct for the suppressive matrix effect, which significantly improved experimental precision. To study the causes of matrix effect, 0.154 M solutions of ammonium chloride, sodium chloride, and caesium chloride were compared. Ammonium chloride exhibited the least suppressive effect, and caesium chloride the most. The results had implications for trace element determinations in seawater (35 g sodium chloride per litre). 

The standard reduction potential for Be2+ is the least negative of the elements in the group and by the same token beryllium is the least electropositive and has the greatest tendency to form covalent bonds. The bulk metal is relatively inert at room temperature and is not attacked by air or water at high temperatures. Beryllium powder is somewhat more reactive. The metal is passivated by cold concentrated nitric acid but dissolves in both dilute acid and alkaline solutions with the evolution of dihydrogen. The metal reacts with halogens at 600°C to form the corresponding dihalides. 

Be NMR spectra are often referenced to aqueous beryllium sulfate as an external standard. Unfortunately, many workers using the standard appear to be unaware that the frequency of the observed line shifts to higher field with increasing concentration of sol-... 

A new area of research concerns exposure assessment for beryllium in the production of nuclear weapons at nuclear defense industries. A safe level of exposure to beryllium is still unknown. Potential explanations include (1) the current exposure standard may not be protective enough to prevent sensitization, or (2) past exposure surveillance may have underestimated the actual exposure level because of a lack of understanding of the complexity of beryllium exposures. Task-based exposure assessment provides information not directly available through conventional sampling. It directly links exposure to specific activity associated with contaminant generation and provides in-depth evaluation of the worker s role in a specific task. In-depth task analysis is being used to examine physical, postural, and cognitive demands of various tasks. 

National Institute for Occupational Safety and Health, US Department of Health, Education and Welfare Criteria for a Recommended Standard... Occupational Exposure to Beryllium, (NIOSH) Pub No 72-10268. 

Elemental composition Be 11.28%, Cl 88.72%. Beryllium may be analyzed in aqueous solution or in solid form by different instrumental techniques (see Beryllium). Chloride may be measured in aqueous solution (after appropriate dilution) by titration with a standard solution of silver nitrate or mercuric nitrate or by ion chromatography or a selective chloride ion electrode. 

A number of objections have been raised to the use of the term. In the first place, the list of so-called heavy metals usually includes some elements that are not even metals, such as the semimetals arsenic and antimony. Also, some of the "heavy metals" are not really very "heavy" by almost any standard. Beryllium, for example, has an atomic mass of about 9, and aluminum, an atomic mass of about 27. Yet both are often classified as "heavy metals." For these reasons, some authorities now prefer the term toxic metals to the more traditional term heavy metals. Either term can refer to elements in both their free and combined states. The table on pages 120-121 provides an overview of the sources and health effects of some heavy metals,... 

Assay of beryllium metal and beryllium compounds is usually accomplished by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryllium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryllium content of the sample is calculated from the titration volume. Standards containing known beryllium concentrations must be analyzed along with the samples, as complexation of beryllium by fluoride is not quantitative. Titration rate and hold times are critical therefore use of an automatic titrator is recommended. Other fluoride-complexing elements such as aluminum, silicon, zirconium, hafnium, uranium, thorium, and rare earth elements must be absent, or must be corrected for if present in small amounts. Copper—beryllium and nickel—beryllium alloys can be analyzed by titration if the beryllium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

Operations capable of generating airborne beryllium particulate, such as melting, machining, welding, grinding, etc, are effectively controlled by local exhaust ventilation or other control measures. To assure a safe environment and measure compliance with the OSHA standards, employee exposures should be periodically measured by prescribed air sampling and analytical methods. 

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