7
Advantages of the Double-Beam System
Support for Developing Analytical Conditions
Optional Autosampler Reduces Analysis Workload
Long-term stability
The graph shows the results of
measurements on 2 ppm copper (Cu)
conducted over at least one hour.
(The plot shows mean values for 11
repeated measurements.) Over the
course of more than 600
measurements, the instrument
achieved a relative standard
deviation within 1%.
High sensitivity
The graph shows the direct
measurement results for 0.1
ppm lead (Pb).
Automatic gas flow rate optimization
Automatic searching for optimal fuel gas flow rate (Japanese Patent 2099886). It is important
to determine the optimal gas flow rate for the flame when using an organic solvent or after
changing the burner height. The AA-7000F Series automatically optimizes the gas flow rate
by measuring the changes in absorbance between a blank and a standard sample. The
difference between the two is displayed on the screen. The gas flow rate achieving the
highest sensitivity is detected and this value is automatically set as the gas flow rate value.
Automatic burner height optimization (AA-7000F/AAC)
The absorption sensitivity for flame analysis is also affected by the burner height. This results
from variations in the flame temperature due to the burner height. The flame temperature is
also affected by the matrix components. AA-7000F/AAC adjusts the burner height in 0.5 mm
steps to automatically search for the optimal conditions.
AA-7000F enables above function by AAC-7000 (option).
Low carryover
Great care must be taken to avoid carryover during flame analysis. The new ASC-7000
autosampler rinses the nozzle at the rinsing port on the overflow mechanism after each
sample measurement is complete. This ensures 10
-4
max. carryover during the
measurements of multiple samples. The graph shows the results of consecutive analyses
of 10 ppm, 20 ppm, and 50 ppm sodium (Na) standard solutions in the EMISSION mode.
No carryover could be detected when measuring the 10 ppm standard sample
immediately after the measuring the 50 ppm Na standard sample.
Example of micro sampling analysis
Examples of the measured waveforms (overlaid) and calibration curve for micro
sampling analysis are shown to the right.
A 2-ppm Cu standard solution was prepared by auto-dilution using the autosampler.
The autosampler can also be used to conduct dilution measurements of the sample.
(Injection volume: 90 µL)
Trace Sample Analysis Using Micro Sampling
Micro sampling
At least 1 mL (1000 µL) volume of a liquid sample is required for the continuous intake of
sample during normal flame analysis. With micro sampling, however, approximately 50 to 90
µL of sample is injected in one shot into the flame and quantitation is based on the height
and area of the peak signal obtained. This method offers the advantages below.
Advantages
.
Permits analysis of small sample volumes
.
Multi-element analysis of small sample volumes
.
No blockage of burner slot with samples having a high salt concentration
.
Synchronized with the autosampler for auto-dilution measurements
* Synchronization with the autosampler requires the optional micro sampling kit.
Data Showing Long-Term Stability for
Flame Cu Measurements
0.1 ppm to 0.4 ppm Calibration Curve for Lead (Pb)
A
b
s
Conc(ppm)
Conventional method Overflow method
Discharge
Data showing low carryover
1. Sample injected into
micro sampling port.
2. Solenoid valve opens to inject sample
in one shot into the flame.
Sampling port
Solenoid
valve
(opened)
Solenoid
valve
(closed)
Sampling port
Absorbance
Measurement time
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