1. a) 25%
b)86%
2. For my opinion, I think the way to make correction for background absorption caused by sample
matrices is require storage of a reference spectrum from a biomembrane before the interaction with a
substrate. Alteration of this membrane caused by external influence are then stored in a sequence of single
channel spectra which are then converted into a transmittance or absorbance spectra by means of the
stored reference spectrum.
3. Single beam UV-Vis Spectrometer
It is used to determine the absorption light from a sample and it can be used as a detector of HPLC. The
concentration of analyst in solution can be determined by measuring the absorbance of single wavelength
and applying the Beer-Lambert Law. First, place the sample in the Uv-Vis beam and record the
absorbance versus wavelength. Then, the single beam spectrometer utilizes one beam of light that oases
through the sample and the intensity of the light reflected from a reference is measured without the
sample.
4. Flame atomization absorption spectrometry (FAAS)
It is a common technique to detect the metals and metalloids in environmental samples. It can be used to
measure the solutions at the parts per million levels which equivalent to one gram of element per 100kg of
solution. It is suitable to be used for wide range of analysis. This technique is based on the fact that
ground state metals absorb light at specific wavelengths. Metal ions of a solutions are converted to atomic
state by means of a flame. Light of appropriate wavelength is supplied and the amount of light absorbed
can be measured against a standard curve. The stages of sample preparation / preconcentration,
nebulization and atomization can be used to improve the sensitivity of the technique. The sample
preparation stage is the simplest methods to improve the sensitivity of the technique by increasing the
concentration of the sample solution. The nebulization method is the physical process of changing the
bulk solution into a spray of fine droplets and mixing the droplets with the combustion gases. The
atomization method is the physical process changes occurring to the solution aerosol in a flame. The basic
principal of this technique is requiring a liquid sample to be aspirated, aerosolized and mixed with
combustible gases. The mixture is ignited in a flame whose temperature ranges from 2100 to 2800℃.
During combustion, atoms of the element of interest in the sample are reduced to free, unexcited ground
state atoms which absorb light at characteristic wavelengths.
5. Graphite furnace atomization absorption spectrometry (GAAS)
The technique is used to The technique is used to perform the quantitative analysis of metals in a wide
variety of samples. It uses a graphite-coated furnace to vaporize the sample. Briefly, the technique is
based on the fact that free atoms will absorb light at frequencies or wavelengths characteristic of the
element of interest (hence the name atomic absorption spectrometry). Within certain limits, the amount of
light absorbed can be linearly correlated to the concentration of analyte present. Free atoms of most
elements can be produced from samples by the application of high temperatures. In GFAAS, samples are
deposited in a small graphite or pyrolytic carbon coated graphite tube, which can then be heated to
vaporize and atomize the analyte. The atoms absorb ultraviolet or visible light and make transitions to
higher electronic energy levels. Applying the Beer-Lambert law directly in AA spectroscopy is difficult
due to variations in the atomization efficiency from the sample matrix, and nonuniformity of
concentration and path length of analyte atoms (in graphite furnace AA). Concentration measurements are
usually determined from a working curve after calibrating the instrument with standards of known
concentration.
6.
Application
Flame atomization absorption
spectrometry (FAAS)
 Low to accuracy
determine of mercury as
the limited atom number
density in the light path
associated with poor
nebulization and
atomization.
 0.2 mg L–1 at 253.7 nm
graphite furnace atomization
absorption spectrometry (GAAS)
Can be extremely low
Applicable for relatively
clean samples
Achieved by chemical
vapor generation
Reviewed for the
determination of As, Bi,
Ge, In, Pb, Sb, Se, Sn, Te
and Tl (as well as Hg).
0.0598 mg L–1 for a 2 min
Cloud point methodology
Carbon Rod Atomizer 63