7th International Conference on Mercury as a Global Pollutant
Mercury semi quantitative determination in urine: a low cost
alternative for preliminary intoxication diagnosis
Allegra Yallouz1, Ricardo Melamed1, Débora Pereira1, Elen Pacheco2, Fátima Moreira3
1- Centre for Mineral Technology, Av. Ipê, 900, 21941-590, Rio de Janeiro, Brazil.
2- Instituto de Macromoléculas, CP 68525 CEP 21945-970 Rio de Janeiro, Brazil.
3-CESTEH- Centro de Estudos da Saúde do Trabalhador e Ecologia Humana- Rua
Leopoldo Bulhões, 1480 - CEP: 21041-210 Rio de Janeiro, Brazil.
Abstract: A low cost and easy method was used for determining mercury in urine at a
semi quantitative level. In this paper the method was described, and the analytical
results compared with the ones from the quantitative CVAAS (cold vapour atomic
absorption spectroscopy) method and a small application study using exposed workers
urine. It was observed that it is possible to determine mercury at levels as low as 10
ng/mL, demonstrating that it is a good tool for preliminary diagnosis for elemental
mercury intoxication.
Key words: semi quantitative, mercury determination, urine, low-cost
Introduction
Elemental mercury is used in different industrial activities, such as the ones in the
chlor-alkali and fluorescent lamp plants, and for hand made activities as gold mining
workers and dentists. It is known that the exposition to elemental mercury occurs mainly
with workers chronically exposed to atmospheres with high mercury concentration
(Azevedo, 2003).
As a preventive measure, in addition to periodical medical examinations, bioindicators are useful and recommended as a complement for diagnosis. Urine is the
best one to evaluate the exposure level to elemental mercury vapour. The usual methods
for mercury determination are based on Cold Vapour Atomic Absorption Spectrometry
or Cold Vapour Atomic Fluorescence Spectrometry (Herber, 1994). Looking for
alternative low cost method, it was chosen a semi quantitative method, formerly
developed for mercury determination in fish samples (Yallouz, 2000). The chemical
principle on which the method is based, is the specific reaction of elemental mercury
with cuprous iodide resulting in a red colourful complex (HgI42-) (Equation 1).
Hgo + 2Cu2I2  2Cu[HgI4] + 2Cuo
Equation 1
In general, a safety index is the concentration up to 10 ng/mL, that is adopted as
health reference for non-exposed humans, while the range from 50 ng/mL to 150 ng/mL
is considered as a warning level. (Azevedo, 2003).
The present work reports the results of the application studies of an alternative,
semi-quantitative mercury determination method and a small application study
performed with volunteers from a hand made fluorescence lamp recycling factory.
To evaluate the method efficiency, recovery tests were performed using artificial
samples prepared by doping a homogeneous urine sample with different mercury
7th International Conference on Mercury as a Global Pollutant
concentrations. The expected final concentration for those samples would be equivalent
to 0, 5, 10, 25 and 50ng of Hg/mL of urine, giving samples U-0, U-5, U-10, U-25 e U-50
respectively. The samples were stored with 10% nitric acid and in the freezer until the
determination. Exposed workers and neighbours from a hand made fluorescent lamp
recycling factory, located at the Metropolitan area of Rio de Janeiro, were volunteers for
the application tests. Samples were collected in three dates: June and October 2003 and
February 2004 and each one was analysed using two methods: cold vapour atomic
absorption spectrometry and the SMQ one. The results were compared for quality
assurance evaluation.
For quantitative mercury determination it was used an oxidant digestion (Akagi,
1991). Sample was heated to 230-250 oC with HNO3:HClO4(1:1), H2SO4 and water,
during 20 min. The determination was performed using spectrometer Automatic
Mercury Analyser Hg-3500.
For semi quantitative determination, 100 mL of sample was heated to boiling
temperature with 10 mL of HNO3, as recommended by Jungreis (1984), during 15 min,
using a reaction flask similar to the one shown in Figure 1. After cooling, the solution
was transferred to a determination flask (figure 2), and 10mL of the reducing solution
were added (50% w/v of tin chloride in hydrochloric acid 50%). The mercury vapour is
forced to pass through a detecting paper covered with an emulsion containing cuprous
iodide. A colourful complex is formed (Equation 1), with a characteristic reddish colour,
whereas the colour intensity is proportional to the mercury concentration in the sample
(Figure 3).
Figure 1: Digestion system
Erlenmeyer with cold finger
Figure2: Determination system
Glass made flasks and simple materials
Simultaneously, standard solutions were prepared, with concentrations similar to
the expected in the urine samples analysed (0, 5, 10, 25 e 50ng HgmL-1. At the end, a
visual comparison was made of the colours generated on the paper discs of each one of
the systems. The developed colours are similar to those shown in Figure 3.
0 ng/mL
10 ng/mL
25 ng/ mL
50 ng/mL
Figure 3: Similar colors to those developed in the detecting papers, using
standard solutions equivalent to 0, 10, 25, 50 ng/mL
7th International Conference on Mercury as a Global Pollutant
It was observed that for samples with high turbidity, the addition of 15 ml
KMnO4 5% w/v, and heating more 5 min, was efficient to clarify the final solution. Just
before the determination, some drops of hydroxylamine chloridrate solution are used, for
eliminating excess of permanganate.
Results and discussion
The results for the recovery tests are shown in Table 1, and for volunteers’ urine
in Table 2
Table 1: Comparison of the quantitative and semi-quantitative results for spiked
samples
Sample
Expected
SMQ*(ng/mL)
QM**(ng/mL)
concentration
U- 0
0
Similar to O
1.93 0.63
U- 5
5
Similar to 5
5.33 0.55
U-10
10
Similar to 10
13,3 0.28
U-25
25
Similar to 25
22.93 1.48
U-50
50
Similar to 50
49.43 3.46
*SMQ= semi-quantitative method; **QM= quantitative method
Table 2: Comparison of the quantitative and semi-quantitative results for volunteer’s
urine samples.
Volunteer
SQM(ng/mL)
QM(ng/mL)
V01A
20-40*
37.75.6
V02A
10-20*
23.93.9
V03A
<10
3.131.81
V01B
50
58.12.08
V08B
<10
2.854.96
V09B
10-20*
16.242.02
V11B
10-20
14.72.89
V01C
50-100*
96.8 1.39
V05C
10-25
17.32.05
V12 C
<10
6.81.1
V13 C
<10
2.70
V14 C
10-25
20.60
V 15 C
0-10
6.81.10
Sampling A= June 2003; B= October 2003; C= February 2004
* closer to
7th International Conference on Mercury as a Global Pollutant
The results obtained for recovery tests confirmed that the alternative
methodology is efficient and the results found were coherent with the expected values.
For volunteers’ urine, SMQ and QM results comparison demonstrated that the results
obtained of the expected concentration are inside the concentration range predicted by
the SMQ.
Conclusions and future
The results obtained by the SMQ method are comparable with the quantitative
results, even in a semi-quantitative level. As the SMQ method is simple and low-cost, it
could be recommended, as an alternative method for screening programs of
environmental health surveillance. In the near future this methodology will be included
in training programs for new users of the SMQ method for mercury determination in fish
that already started in August and September 2003 (Yallouz, 2004 a).
The volunteers’ group are now being guiding to use individual protection
equipment and will participate in the near future in a Health Surveillance Program from
the Núcleo de Estudos da Saúde Coletiva (NESC), for medical assistance.
References
Akagi, H. & Nishimura, H. (1991): Speciation of Mercury in the Environment.
Toxicology. In: Suzuki, T.; Imura, N. (eds.). pp. 53-76. Advances in Mercury. New
York: Plenum Press.
Azevedo,F. (2003) Toxicologia do mercúrio. ed. Rima, São Carlos, SP, p.272. 2003.
Jungreis, E. (1984) Spot-Test – Clinical Environmental, Forensic, and Geochemical
Applications. Jonh Willey & Sons.
Yallouz, A., Campos, R., Paciornik, S.(2000) A low-cost non instrumental method for
semi quantitative determination of mercury in fish. Fresenius Journal of Analytical
Chemistry 366: 461-465.
Yallouz, A., Hacon, S., Calixto, T.(2002) Semi quantitative mercury determination in
fish: a tool for poisoning prevention. Anais da Academia Brasileira de Ciências 21(2).
p.187-191.
Yallouz, A, Pereira, D, Rodrigues Filho, S., Villas Boas, R., Veiga, M.,Beinhoff, C.
(2004a). Alternative low cost method for mercury semiquantitative determination in fish
Training of local users in Itaituba, Brazil and Manado, Indonesia. In press, to be
presented at the 7th International Conference on "Mercury as a Global Pollutant",
Ljubljana, Slovenia.