Stability of Mercury Dilute Aqueous Solutions: An Open Issue

Authors: Caroli S.; Forte G.; Iamiceli A.L.; Lusi A.

Source: Microchemical Journal, Volume 54, Number 4, November 1996 , pp. 418-428(11)

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Abstract:

In the framework of the activities of the European Commission Reference Laboratory (CRL) for residues at the Istituto Superiore di Sanita a number of analytical quality control trials on determination of trace analytes are being carried out. As regards trace elements it soon became apparent that the stability of Hg dilute aqueous solutions is rather unsatisfactory. An investigation was thus undertaken to ascertain the conditions under which the concentration of this metal does not appreciably change. Mercury solutions were prepared in high purity deionized water in the concentration range 1-10 ng g -1 and the effect of various amounts of HNO 3 and K 2 Cr 2 O 7 (alone or in combination) was elucidated by measuring the variations with time in the actual concentration of Hg. Determinations were performed by both inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. Results show that solutions added with 5% (w/w) HNO 3 and 0.01% (w/w) K 2 Cr 2 O 7 do not undergo any significant alteration in the nominal content of the analyte for at least 1 month. Similar conclusions are reached in the case of solutions enriched in CaCO 3 , NaCl, NaNO 3 , KH 2 PO 4 , KNO 3 , and Mg(NO 3 ) 2 ?6H 2 O to mimic acid digests of meat samples. The improvement ensuing from the adoption of this approach on the performance of the Hg analytical quality control trials is discussed in detail.

Language: English

Document Type: Research article

Affiliations: Istituto Superiore di Sanita, V.le Regina Elena 299, Rome, 00161, Italy

Publication date: 1996-11-01