How metalloids samples are converted to volatile hydride in HGAA
Through adding HCl and sodium borohydride (NaBH4)
Type of pump used in HGAA
What type of container is used for waste collection in AA and why?
The container if glass because 50% of the waste is high in acid
What type of AA causes sepeciation?
Which of the following is/are affected by HGAA
As3+, As5+, Se2+,Se4+
As3+ and Se4+
What is the optical cell in HGAA
Silica glass tube
Characteristics of Silica tube in HGAA
Transparent to UV/Vis light
thermally stable at high T
What is the purpose of optical cell in HGAA
It is where the decomposition of metalloides to their elemental form takes place, so they can absorb HCL light beam
How to oxidize and reduce Se
Reduce: Boiling HCl
Oxidized: Adding HNO3 or H2O2 ( Strong Oxidizing agent)
_________ is the metal that is volatile at room T
Hg can be measured on AA without the use of atomizer (T/F)
True, because Hg has a high vapour pressure due to it volatility
This reduces the interferences, for the sample evaporates while the matrix are left behind
Gaseous mercury is acheive by________
using a reduction reaction ( Oxidizing agent ex: KMNO4) to convert Hg to it elemental form :Hg22+
How does the A is measured in Cold AA
Peak height vs Hg conc.
How to solve the problem of spectral interferences?
Use another wavelength
use chemicals which precipitate the matrix and free the analyte
Use ICP if possible
Alternating between AA lamp and D2 lamp
Background correction relies on _________ and usually is ___
atomic line being very narrow
____________ has a broader band of light.
Composition of background in D2 depends on ___________
position on a flame
what is Zeeman Effect
Graphite Furnace is covered with strong and big magnatic field. this cause a line up of molecules based on their charge. This results in the change of the excitation wavelength.
In Zeeman effect, pi compoundas polarized________ to the direction of magnatic field, and absorbed by ___________; while Sigma compounds polarized ________ to the direction of magnatic field and is absorbed by ___________.
parallel; analyte and background
perpendicular; only background
What are the outcome of chemical interferences and how they are solved?
Chemical interferences :
1-A compound will react with other chemicals
causes a low detection limit
2- Ionization Interferences
To solve the problem:
Use releasing agent ( Sr or La): so the reagent reacts with matrix, leaving the analyte free
2-use Masking agent
EDTA: bonds with analyte, preventing the anlayte from forming precipitation with other interferences
Form stable but volatile complex with analyte
How to solve ionization interferences?
Add ionization suppressor in which it will provide the needed electrons ( EIE: Easily Ionized Elements)
Why Polyethylen bottoles are not suitable for holding up HC's