The working
principle of the system is based on the continuous flow method. First the
mercury contained in the sample is transformed into the elemental state by
addition of a reducing agent to the sample flow. In a crossflow reactor the
mercury is stripped with a gas stream and carried into the optical cell which
is made entirely of fused silica. There the quantitative determination of
mercury is obtained by measuring UV absorption at a wavelength of 253,7 nm at
room temperature. This analytical technique is commonly known as cold vapor
atomic absorption spectrometry (CVAAS), a method that has proved itself as
extremely sensitive and selective over many years. In contrast to a typical
multi-element AAS the AULA is specially designed for mercury determination.
This allows top performance in analytical applications. The use of a highly
stable low-pressure electrodeless mercury discharge lamp (EDL) in connection
with the latest UV detector techniques result in excellent baseline stability
and low detection limits. Surprisingly easy to use the AULA-WIN offers all
features of a modern analytical software. It has been developed with extensive
input from our users. Samples, calibration standards and quality control
standards (QCS) are entered into the carrousel screen. With an optional barcode
stick sample data can be entered comfortably. A sample table is created
automatically and can be viewed in the table screen. Sample dilution factors as
well as sample weight and final fill up volume for digestion of solid samples
can be entered in the table. The result of the measurement is calculated
automatically from the chosen calibration function and displayed in µg/l
or µg/kg. The QCS function assures a high level of reliability of the
analytical results. The results of the analyses together with the data
necessary for quality assurance (date, time, user ID, sample number,
calibration data, instrument parameters) are stored in a file. They are
available at any time for display and printout. Worksheet templates can be
created and stored to minimize setup time for routine work. No long purging or
rinsing procedures even when samples with high concentrations are analyzed. The
typical duration of a full measurement cycle is 80 ... 280 seconds. The quick
screening mode allows performing analyses in even a shorter time.