Potassium

Location:  Group 1, Period 4
Atomic Weight:  39.0983
Coordination Number:  (6)
Chemical Form in Solution:  K⁺(aq)
(coordination number in parentheses is assumed, not certain)

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, H₂SO₄, and HF aqueous matrices. Avoid use of HClO₄ due to insolubility of the perchlorate. Stable with all metals and inorganic anions except ClO₄^-.

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

K Containing Samples (Preparation & Solution):  Metal (dissolves very rapidly in water); Ores (sodium carbonate fusion in Pt⁰ followed by HCl dissolution - blank levels of K in sodium carbonate critical); Organic Matrices (Sulphuric / peroxide digestion).