Thallium

Location:  Group 13, Period 6
Atomic Weight:  204.383
Coordination Number:  6
Chemical Form in Solution:  Tl(H₂O)₆¹⁺

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:  Soluble in HCl, HNO₃, and H₂SO₄. Stable with most metals and inorganic anions. The sulfite, thiocyanate, and oxalate are moderately soluble; the phosphate and arsenite are slightly soluble and the sulfide is insoluble.

Stability:  2-100 ppb levels stable for months in 1% HNO₃ / LDPE container. 1-10,000 ppm solutions chemically stable for years in 2-5% HNO₃ / LDPE container.

Tl Containing Samples (Preparation & Solution):  Metal (is best dissolved in HNO₃ which forms chiefly the Tl¹⁺ ion); Oxide (the thallous oxide is readily soluble in water. The thallic oxide requires high levels of acid); Ores (carbonate fusion in Pt⁰ followed by HCl dissolution); Organic Matrices (Sulphuric / peroxide digestion or dry ash and dissolution in HCl).