HS 55 (Batch Mode)
Operation
35
5
Operation
How to prepare the AAS device for the hydride or HydrEA method is described in the
user manual for the AAS device.
The software manual describes the following:
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how to set the method and the operating mode
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how to check the functionality of the Hg/hydride system
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how to set a hydride or HydrEA method
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how to set the method parameters for the autosampler
5.1
Preparing operating materials and standards
WARNING
Risk of chemical burns
Sodium borohydride and sodium hydroxide are highly corrosive, hygroscopic and, in so-
lution, extremely aggressive. Concentrated hydrochloric acid is highly corrosive.
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Wear protective goggles and protective clothing when handling these corrosive sub-
stances. Work under an extractor.
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Observe all instructions and specifications in the safety data sheets.
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When preparing diluted acids and lyes, always fill in water first. Only then add con-
centrated acid or lye.
WARNING
Risk of poisoning due to arsenic
The arsenic standard solution (1000 mg/l) causes severe skin and eye irritation. The so-
lution is carcinogenic.
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Wear protective goggles and protective clothing when handling this hazardous sub-
stance.
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Observe all instructions and specifications in the safety data sheets.
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When preparing diluted acids, always fill in water first and slowly stir in the concen-
trated standard solution.
The following solutions are required for the operation of the Hg/hydride system:
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reduction agent (NaBH
4
/NaOH)
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standard solutions for the hydride method
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arsenic standard solutions for the HydrEA method
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reduction solution (e.g., KI/ascorbic acid) for reducing As(+V) to As(+III)
Samples can contain arsenic ions in various oxidation states. Treating the sample is
therefore recommended to achieve a better measuring sensitivity and a correct mea-
surement.
Recommendation:
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Treat the samples with the reduction solution (KI/ascorbic acid) before transferring
them to the Hg/hydride system to ensure that arsenic is available in the oxidation
state +III. Make sure that As(+V) is completely converted to As(+III).