ABSTRACT
The quantification of blood/plasma ethanol
concentration (BEC/PEC) is of great importance in experiments involving basic
research, clinical studies, and bioethanol production. Traditional methods commonly
used to measure BEC can be expensive and require high-cost equipment and
qualified labor. The aim of this study was to develop a low-cost method that
can be performed with simple infrastructure commonly available in research
laboratories. For this, we developed a protocol to quantify PEC in mice, using
the method of reduction of potassium dichromate by ethanol. However, this
oxidation-reduction (redox) reaction is not specific to ethanol. Thus, the PEC
was measured following a sequence of chemical reactions to eliminate the
reductive interfering substances presented in the samples. Firstly, we
evaluated the sensitivity of the dichromate reactive to ethanol and to
different reducing substances found in the plasma, in order to determine which
the main interfering substances are. Next, once the main interfering substances
were determined in the dichromate reduction, plasma was assayed for PEC. First,
mice received intraperitoneally (i.p.) saline (basal reading, 0% ethanol) or
ethanol injections (0.5, 1, 2, 3, and 4 g/kg) and had their plasma collected.
After plasma deproteinization and plasma glucose oxidation, it was mixed with
the dichromate/acetic acid reactive, and then the products of the redox
reaction were determined by the spectrophotometric method. Then, we determined
the PEC with the same plasma samples using a commercial ethanol assay kit as a positive
control. We found an excellent correlation between the administered ethanol doses and PECs in both the methods analyzed. The
values of PEC found in the
dichromate reaction method were similar to those obtained in the literature
with the same ethanol doses, and to the commercial enzyme activity assay.
Therefore, despite the need for a background reading, this method can be
successfully applied to determine PEC using low-cost chemical reagents.