abstract
Article history:
Received 8 July 2009
Accepted 21 July 2009
Available online 28 July 2009
Keywords:
TMAH treatment
Microwave-assisted digestion
Biological samples
CV AAS
Mercury fractionation
A simple and reliable method to determine total and inorganic mercury in biological certified reference
material (CRM) by cold vapor atomic absorption spectrometry (CV AAS) is proposed. After the CRM
treatment at room temperature with tetramethylammonium hydroxide (TMAH), inorganic mercury is
determined by CV AAS. Total mercury is measured by the same technique, after sample acid digestion in a
microwave oven. Organic mercury, basically methylmercury, is obtained by difference. In both procedures,
the quartz tube is kept at room temperature. By means of analysis of the following reference materials: pig
kidney, lobster hepatopancreas, dogfish liver and mussel tissue, it was clear that the difference between the
total and inorganic mercury concentrations agrees with the methylmercury concentration. Only one
calibration curve against aqueous standards in acidic medium was carried out for both procedures. The
concentrations obtained by both procedures are in agreement with the certified values according to the t-test
at a 95% confidence level. The relative standard deviations were lower than 3.0% for digested CRM and 6.0%
for CRM treated with TMAH for most of the samples. The limits of detection in the samples were 0.02 µg g−1
and 0.04 µg g−1 for inorganic and total Hg, respectively, since the sample mass for total mercury was half of
that for inorganic mercury determination. Simplicity and high efficiency without using chromatographic
techniques are some of the qualities of the proposed method, being adequate for fractionation analysis of
mercury in biological samples.