S. Turcat et al., USE OF CAPILLARY ELECTROPHORESIS TO MONITOR CONCENTRATIONS OF ORGANIC-ACIDS IN SNOW AND RAIN WATER, Science of the total environment, 158(1-3), 1994, pp. 21-29
The concentrations of six organic acids present in snow and rain water
were determined during the spring of 1992, in order to test the possi
bilities of capillary electrophoresis for measurements in the environm
ent. The sampling sites were located in the French Alps. Fourteen samp
les were taken. This method allows routine analysis. The following aci
ds, normally found in snow and rain waters, were satisfactorily separa
ted after 5 min: formic, acetic, propionic, butyric, oxalic and benzoi
c, with concentrations of the order of 10(-6) M. The sample size was v
ery small since a 100-mu l aliquot is sufficient to perform an analysi
s without previous treatment or preliminary concentration. For these t
hree reasons - time, sensitivity and sample amount - capillary electro
phoresis is suitable for measurements in the environment. Short sampli
ng times can be used, for example, in order to follow rain events. Mon
itoring organic acids in hydrometeors collected at high altitude shows
that their concentrations are fairly constant for the various individ
ual rain or snow samples but are different for rain and snow samples.
The total concentrations observed for the five acids detected (all org
anic acids except oxalic) ranged from 5 to 10 mu M for rain water and
0.5 to 5 mu M for snow. The profile established from the relative abun
dance of the acids differs from snow to rain and depends on the season
, which confirms that formic acid is a biogenic tracer and acetic acid
is an anthropic tracer. Furthermore, we show, for the first time, tha
t butyric acid is a good tracer of bacterial activity.