Contamination from preparation equipment

Drying Contamination, loss of PAHs, Hg, phenols, cyanides low CEC values 

Coarse crushing (jaw or roller) Contamination, cross-contamination 

Coarse milling (shatterbox, Tema) Caking, loss of volatile/labile analytes 

Despite their insubstantial nature, plant materials are also subject to contamination by sample containers and milling equipment. Paper sample bags may act as sources of contamination including boron (Standing Committee of Analysts 1986). Normally, vegetation is comminuted in high shear cyclone mills or blenders fitted with stainless steel or titanium-coated blades. As with other more resistant materials the amount of contamination from the mill can be related to the abrasiveness of the sample (Allan etal. 1999). 

---

Contamination from entrained BW and solids may render steam unsuitable for process operations, including food preparation, sterilization of surgical equipment, textile dyeing, hydrolysis reactions, vulcanizing, and the like. 

LA-ICP-MS can be used to quickly analyse solid samples, such as filters or scrapings from the equipment. A minute amount of sample is consumed and analysis is fast, as no sample preparation is required. LA-ICP-MS is especially useful when analysing solid samples with distinct discolourations, since the laser can be focused on the area of interest to increase sensitivity. Each discoloured area can be ablated and assayed separately to determine its metallic composition. Often, these areas are caused by contamination from an oil or coolant that has leaked from the equipment. This affords the spectroscopist great selectivity over a conventional dilute-and-shoot method in which the small discoloured areas cannot be analysed separately. 

Brine Preparation. Sodium chloride solutions are occasionally available naturally but they are more often obtained by solution mining of salt deposits. Raw, near-saturated brines containing low concentrations of impurities such as magnesium and calcium salts, are purified to prevent scaling of processing equipment and contamination of the product. Some brines also contain significant amounts of sulfates (see Chemicals FROMBRINe). Brine is usually purified by a lime—soda treatment where the magnesium is precipitated with milk of lime (Ca(OH)2) and the calcium precipitated with soda ash. After separation from the precipitated impurities, the brine is sent to the ammonia absorbers. 

---