4 - 1
4 MEASUREMENT USING FOUR LIQUIDS
This chapter describes the procedure in which a reducing agent is
automatically added by the pump. This procedure is applicable to the
measurement of arsenic only.
4.1 Principle
Arsenic (As) in aqueous solution produces gaseous hydrides through
reaction with nascent state hydrogen. However, the sensitivity of the
produced hydrides varies with the trivalent or pentavalent state of the
arsenic. Therefore, it is usually required to add a reducing agent to
convert the arsenic in the sample to the trivalent form in advance of
measurement.
When using the four-liquid flow channel, however, the reducing agent
is automatically added by the pump. This allows users to skip the
process of adding a reducing agent to each sample.
Fig. 4-1 shows a diagram of the four-liquid flow channel.
In the four-liquid flow channel, a sample is mixed with hydrochloric
acid first. Then, it is mixed with the reducing agent and delivered to
the reaction coil (1 m), in which the pentavalent arsenic in the sample
is reduced to the trivalent form. After that, it is mixed with sodium
borohydride and reacts with hydrogen in nascent state to form a
hydride, which is delivered to the atomizer of the AAS.
Fig. 4-1 Four-liquid Flow Channel of HFS-4
AAS
Pump
Pressure
regulator
Sample
Hydrochloric acid
Sodium borohydride
Argon gas
Reaction coil
Hydride
Pressure
switch
Flow control valve
Waste
Separator
Reducing agent
Содержание ZA3000 Series
Страница 267: ...3 1 11 3 43 Fig 3 31 Parameter List Window Common conditions The setting of method is thus completed ...
Страница 357: ...5 5 Twin Injection 5 28 Fig 5 24 Dialog Box for Confirming Nozzle Position 7 Click Start measurement ...
Страница 423: ...9 3 5 9 11 Fig 9 14 Diagnosis Log Dialog Box ...
Страница 449: ...10 5 Reflecting on Analysis Conditions 10 24 Fig 10 16 Method Window Unmark the checkbox ...
Страница 455: ...INDEX 4 V Verify 3 34 W Working curve graph 4 1 Wavelength accuracy 9 1 ...
Страница 456: ...INSTRUCTION MANUAL 7J1 9027 000 Ver 1 February 2016 MODEL HFS 4 HYDRIDE FORMATION SYSTEM ...