According to Japan ’s “Provincial Decree on Partial Revision of Water Quality Standards and Related Provincial Orders†(Ministry of Health, Labour and Welfare Decree No. 18) (February 17, 2010), the standard of cadmium in tap water has been revised from 0.01 mg / L or less to 0.003 mg / L or less . The new standard has been implemented since April 1, 2010. In the new standard, the flame atomic absorption method is deleted from the past four analytical methods. The three analytical methods used are 1. Flameless atomic absorption method, 2. ICP emission spectrometry, 3. ICP mass spectrometry. This article introduces the non-flame atomic absorption method for the sample prepared by JAC0302 river water reference material (addition) as a certified reference material provided by the Japan Society for Analytical Chemistry and cadmium added to tap water at a concentration equivalent to 1/10 of the standard An example of analysis is carried out, and a simple automatic dilution re-measurement function is introduced.
Device and measurement conditions
Device
Host AA-7000
Atomic Department GFA-7000
Autosampler ASC-7000
ASK-7000
Analysis wavelength
228.8 nm
Slit width
0.7 nm
Current value
8 mA
Lighting method
BGC-D2
Graphite tube type
Pyrolysis graphite tube
Injection volume
2 ～ 20 μL (total injection volume is 25 μL)
Temperature program
Dry 120 ℃
Ashing 500 ℃
Atomization 1800 ℃
Purification 2400 ℃
Standard solution concentration
Upper limit concentration 0.0012 mg / L (1.2μg / L)
Interference inhibitor
5 μL of palladium nitrate aqueous solution (containing 100 ppm of palladium)
The measurement results
The automatic dilution and addition functions of the autosampler are used when making the working curve. Therefore, only the diluent, standard stock solution (2 ppb) and interference inhibitor (palladium nitrate aqueous solution) need to be placed in the autosampler Make a working curve. According to the measurement results. The river water reference material obtained the same result as the certified value. Adding a sample with a concentration of 1/10 of the standard value in tap water, good results have been obtained regardless of the truth or accuracy.
The AA-7000's autosampler (ASC-7000 + ASK-7000) is equipped with an automatic dilution and re-measurement function. If this function is used, when the concentration of the unknown sample exceeds the set upper limit, the sampling volume can be automatically reduced and the measurement can be performed again. Enter the upper limit concentration of the unknown sample and select automatic dilution to measure again. When the sample exceeds the set upper limit concentration, the sampling volume is automatically reduced to perform re-measurement. The dilution ratio measured again by automatic dilution is automatically entered in the automatic dilution column and displayed in the actual concentration column. By using this automatic dilution re-measurement function, it is possible to reduce the burden on the analyst when performing re-measurement.
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