Stability of Mercury Dilute Aqueous Solutions: An Open Issue

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Trace element analysis is vital for regulatory bodies like the European Commission Reference Laboratory (CRL).
• The stability of dilute mercury (Hg) aqueous solutions presents challenges for accurate analytical quality control.

Purpose of the Study:

• To determine optimal conditions for stabilizing dilute mercury solutions.
• To ensure reliable mercury concentration measurements in analytical quality control trials.

Main Methods:

• Prepared mercury solutions (1-10 ng g-1) in deionized water.
• Investigated the effects of nitric acid (HNO3) and potassium dichromate (K2Cr2O7) on Hg stability.
• Utilized inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) for Hg determination.

Main Results:

• Mercury solutions with 5% (w/w) HNO3 and 0.01% (w/w) K2Cr2O7 remained stable for at least one month.
• Stabilization was also effective in solutions mimicking meat sample digests (containing CaCO3, NaCl, NaNO3, KH2PO4, KNO3, Mg(NO3)2.6H2O).

Conclusions:

• The addition of specific concentrations of HNO3 and K2Cr2O7 significantly enhances the stability of dilute mercury solutions.
• This stabilization method improves the reliability of mercury analytical quality control trials.