Leachable

Alkalinity (Soluble Soda) Determination. The surface alkalinity or soluble or leachable soda is determined by making a fixed weight percent slurry in water and determining the alkalinity of the solution by pH measurement or acid titration. Sodium ion-sensitive electrodes have been investigated. 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

Laugriickstand, m. — Laugeruckstand. X augung,/. lyeing, bucking leaching, lat ngsfaiiig, a. leachable. 

Flange face areas experience stagnant conditions. Additionally, some gasket materials, such as asbestos fiber, contain leachable chloride ions. This creates crevice and stress corrosion cracking problems on sealing surfaces. Where necessary, flange faces that are at risk can be overlaid with nickel-based alloys. Alternatively, compressed asbestos fiber gaskets shrouded in PTFE may be used. 

Wood preservatives appear not to affect emission of corrosive vapours from wood, suggesting that the hydrolysis of acetyl polysaccharides is chemical, not biochemical. Some copper-base preservatives can give enough leachable copper ions to cause galvanic corrosion of other metals, notably aluminium and steel. 

Allard, B. Andersson, K. "The Influence of Groundwater Chemistry on the Leachability of Bitumenized Waste" Nordisk Kontakt-organ for Atomenergisporsmal in press. 

In summary, none of the individual components necessary for recombinant resilin curing were cytotoxic, and there were no leachables from the cured resilin that caused cell death. The cured resilin polymer was not a good surface for cell adhesion, but cells can survive and proliferate in the resilin on a gelatine bead. The curing of recombinant resilin in the presence of cells on beads has no effect on the cells ability to migrate and proliferate with new tissue formation. The resilin is seen to degrade with time, but it is believed that this could be controlled by the type and extent of cross-linking. 

Nandanan et al. [35] reported the utilization of linseed oil as an MFA in nitrile rubber vulcanizates. Linseed oil not only acted as a plasticizer but also as the fatty acid component of the activator in the NBR vulcanizates. Use of linseed oil gave appreciable increase in properties like tensile strength, tear resistance, etc. while the viscosity of the compound was marginally lower than that of the control compound (which used di-octyl phthalate as the plasticizer). The vulcanizates containing linseed oil also exhibited increased cure rate as well as reduced leachability compared to the control at a dosage of 2-5 phr. This loading was seen to replace 6 phr DOP and 2 phr stearic acid in conventional NBR vulcanizates thereby reducing compound costs. 

E1 Beit lOD, Wheelock JV, Cotton DE. 1981c. Factors involved in the dynamics of pesticides in soils The effect of pesticide concentration on leachability and adsorption. Int J Environ Stud 16 181-187. 

Wilson, A. D. (1975c). Dental cements based on ion-leachable glasses. In von Fraunhofer, J. A. (ed.) Scientific Aspects of Dental Materials, Chapter 6. London and Boston Butterworths. 

Acid aqueous solution, % by mass Powder liquid, g cm Setting time, minutes Compressive strength (24 hour), MPa Water-leachable material," % mass... 

Water-leachable material 7 minute cure, % mass 0-88 2-1 0-74 1-25... 

Water-leachable material 1 hour cure, % mass 0-40 0-45 0-46 0-70... 

Christensen JM, Byrialsen K, Vercoutere K, Cornelis R, and Quevauviller Ph (1999) Certification of Cr(VI) and total leachable Cr contents in welding dust loaded on a filter (CRM 545). Fresenius J Anal Chem 363 28-32. 

The Standards, Measurements and Testing Programme of the European Commission launched a few years ago a project dealing with the development and, ultimately, the production of air filters realistically exposed to welding dust occurring during stainless steel welding (Christensen et al. 1999). This project resulted in the production and certification of a batch of 1100 filters for the Cr (VI) content (40.16 0.60 pg/g dust) (CRM 545). In addition, the total leachable Cr content ( 39.37 1.30 pg/g dust) was certified as a means to check for total Cr recovery. 

Speciated Components Little information is available for RMs with respect to the chemical forms or species in which elements occur. In the first approximation, bioavaila-ble, extractable, or leachable levels of elements are of interest. Secondly, at a higher degree of sophistication, data on the levels of the actual species or inorganic moieties such as nitrate, ammonium, phosphate, bromide, bromate, iodide, iodate, and molecular species of which the elements are constituents would be of relevance to those conducting mechanistic and speciation research. Reference materials that are certified for extractable elemental concentrations are not available to monitor the usual procedures in soil science based on extraction. 

---