The 10.255 is an online analyser for hydride forming elements such as As, Se and Sb. Based on hydride generation atomic fluorscence spectrometry the systems offer part per trillion detection limits and linearity to ppm levels. The system is a single element analyser with high selectivity defined by the use of an element specific boosted discharge hollow cathode lamp.
All of the hydride forming elements are considered highly toxic, environmentally sensitive and they are difficult to remove from drinking water supplies and wastewater discharges.
High levels of Arsenic can be found in drinking water supplies in many countries causing major health effects such as cancer. The Arsenic is naturally occurring from the presence of Arsenic rich minerals in the aquifer layers. Arsenic may also be emitted from various industrial processes including mining activities, smelting of non-ferrous metals, oil and gas refining, waste incineration, coal burning, pesticide production and uses. Safe drinking water limites are less than 10ppb whereas wastewater discharges tend to be much higher and limits are set by regulatory agencies.
Most drinking water contains concentrations of selenium are lower than 10ppb except in certain seleniferous areas where ppm levels of Se have been reported. Selenium in drinking water supplies is not considered to be a major health concern and safe limit is considered to be less that 50ppb. Selenium is however released to the environment from various industrial processes such as mining, smelting, petrochemicals, waste incineration and coal burning.
Antimony levels in drinking water are generally quite low and not considered a major health concern. However it is used in various industrial processes and is discharged in wastewater. Antimony compounds are used as catalysts in the production of polyesters and flame retardants and these ultimately causes releases of antimony to the environment during production and disposal.
In June 2013, the EPA proposed a new rule "40 CFR Part 423" which relates to effluent limitation guidelines to limit the amount of toxic metals being discharged to surface waters. Arsenic, Selenium, Antimony and Mercury are the main elements of concern because of their high toxicity and potential impact to the environment and wildlife. The proposed effluent limitation guideline is based on the treatment technology utilized on site and is currently set to between 4 and 8 ppb for Arsenic, x and x ppb for Selenium and x to x ppb Antimony. The reliable determination of hydride forming elements below 10ppb in a FGD wastewater matrix is very difficult using ICP-MS because a relatively large dilution is required to lessen the total dissolved solid content of the sample. In addition to this there are isobaric interferences which have to be overcome.
There is an increasing need to remove and monitor As, Se and Sb from drinking water supplies and wastwater discharges. Abatement systems have to be monitored in real time using online measurements to ensure discharge limits are being achieved.