Speciation has been defined as ‘the distribution of an element amongst defined chemical species in a system’. Chemical species include isotopic composition, electronic or oxidation states and molecular structures. Speciation analysis is the analytical process of identifying and/or measuring the amounts of one or more individual chemical species in a sample.
Why is speciation important? Speciation analysis has become important for food, environmental, and pharmaceutical industries, where simply measuring the total amount of an element is insufficient. Identifying the different species and concentrations of those species provides a more informed understanding of the environmental or health related impact associated with a particular sample. The clinical or environmental approach would be very different depending on the concentration of the toxic species. For example, an exposure to toxic inorganic arsenic (arsenite and arsenate) is a much bigger concern than an exposure to the mildly toxic organic arsenic species. In contrast, organic mercury species are more toxic than inorganic mercury species, so an exposure to methylmercury or ethylmercury poses a more severe health risk.
How is speciation analysis performed? IC-ICP-MS provides a complete inorganic elemental analysis solution for speciation analysis.
-Metal-free ion chromatography (IC) separates the individual ionic species without contributing trace metal contamination -Ion Chromatography-Inductively Coupled Plasma Mass Spectrometry (IC-ICP-MS) performs trace elemental detection and quantification
Metal-free IC (with high resolution ion exchange columns and simple online connectivity) together with high sensitivity ICP-MS and integrated software are a powerful combination for fast and efficient metal speciation.
Arsenic
Location: Group 15, Period 4 Atomic Weight: 74.9216 Coordination Number: 6 Chemical Form in Solution: H3AsO4 and HAsO2
Storage & Handling: Keep tightly sealed when not in use. Store and use at 20 ± 4°C. Do not pipet from container. Do not return portions removed for pipetting to container.
Chemical Compatibility: Arsenic has no cationic chemistry. It is soluble in HCl, HNO3,H3PO4, H2SO4 and HF aqueous matrices water and NH4OH. It is stable with most inorganic anions (forms arsenate when boiled with chromate) but many cationic metals form the insoluble arsenates under pH neutral conditions. When fluorinated and/or under acidic conditions arsenate formation is typically not a problem at moderate to low concentrations.
Stability: 2-100 ppb levels - stable for months alone or mixed with other elements at equivalent levels - in 1% HNO3 / LDPE container. 1-10,000 ppm solutions chemically stable for years in 1-5% HNO3 / LDPE container.
As Containing Samples (Preparation & Solution): Metal (soluble in 1:1 H2O / HNO3); Oxides (the oxide exists in crystalline and amorphous forms where the amorphoric form is more water soluble. The oxides typically dissolve in dilute acidic solutions when boiled); Minerals (one gram of powered sample is fused in a Ni0 crucible with 10 grams of a 1:1 mix of K2CO3 and KNO3 and the melt extracted with hot water); Organic Matrices (0.2 to 0.5 grams of the sample are fused with 15 grams of a 1:1 Na2CO3 / Na2O2 mix in a Ni0 crucible. The fuseate is extracted with water and acidified with HNO3).
Atomic Spectroscopic Information: (red text indicates severe at ~ concs.)
