ICP/AA Lab Report
Introduction: Inductively Coupled Plasma is an emission spectroscopy technique that produces
excited atoms which emit electromagnetic radiation with wavelengths of certain elements. The
intensity of the instrument is based on the concentration of the element in the sample. It uses a
plasma flame that can reach temperatures of 10,000 ºC through the use of Argon gas. The ICP
can run up to 70 different elements at the same time. It is used primarily for the detection of trace
elements in various samples including metals in wine, arsenic in foods, and elements that are
bound to proteins as well as the concentration of elements in different kinds of liquid samples.
Atomic Absorption is the absorption of optical radiation or light by free atoms in a gaseous state.
The AA is a highly specific instrument or having a high selectivity rate where it only analyzes
one element at a time. The AA is used to assess the concentration of an analyte in a sample. For
the AA an analyte is referring to the elements or metals in a sample. There are multiple atomizers
that can be used but the one being used is the flame atomizers. Some applications of the AA
include the determination of trace elements for drinking water, food industry, and gunpowder
residues.
Purpose: The purpose of this experiment was to determine the amount of concentration of
copper and zinc in various water samples available in lab as well as know how to make standard
solutions of elements.
Methods: Day 1: We worked on the ICP, we made standards first before turning on the
instrument. We made standards of copper and zinc at various concentrated levels. They were
made in 100mL volumetric flasks and they were 10ppm with 1mL of each element, 20ppm with
2mL of each, 30ppm with 3mL of each, 40ppm with 4mL of each, 50ppm with mL of each, and
a blank which was just distilled water and filled up to the 100mL mark with distilled water. We
also made three water samples to determine the concentration of copper and zinc in them. The
samples came from different areas in the building: water fountain in the hallway, women’s
bathroom, and the faucet in lab. When everything was ready we turned on the argon gas, cooling
system, exhaust vent, and the instrument. Setup software, checked parameters, and lite the flame;
allowed the instrument to warm up and then ran all standards and samples and followed on
screen instructions. We made a calibration curve and determined sample concentrations.
Day 2: We used the AA and used the same standards and samples from the ICP with
10ppm to 50ppm of copper and zinc. We turned on the instrument and turned on the acetylene
and compressed air in the gas room and on the bench top, and exhaust fan. Checked to make sure
the copper and zinc lamps were installed and started the software. We then turned on the lamps
and let them warm up before running standards and samples. We did this twice; once for copper
and the other for zinc. Set parameters and ran the samples. Created a calibration curve for both
elements and determined the concentration of copper and zinc in the water samples.
Results: All the concentration and calibration data are located in the lab notebook. Both of the
instruments calculated the calibration curve and gave us the concentration levels for copper and
zinc in our three samples. The following are our sample concentration results for both
instruments. ICP results:
Sample
Fountain
Chem Lab
Bathroom
Copper(Cu) ppm
.050973
.039475
.022311
Zinc(Zn) ppm
.042034
.045879
.038690
Copper(Cu) ppm
-5.727
-5.695
-5.758
Zinc(Zn) ppm
-5.727
-5.687
-5.757
AA results:
Sample
Fountain
Chem Lab
Bathroom
For the AA results, even though we got a positive linear regression graph, we still
received negative results.
Conclusion: The experiment was overall a success and we were able to determine the
concentration of copper and zinc in water samples found in the building. The ICP was fast and
efficient and actually gave surprising results. As seen in the table above, there was a higher level
of copper in the drinking water than the others and had the second highest concentration of zinc.
This is surprising because we expected to find higher levels of the elements in either the
bathroom or faucet water and not in the drinking water. This could be due to possible copper
piping in the water fountain or some other piping issue. The AA on the other hand was not as
successful. Even though it was fast and efficient like the ICP, we received negative
concentrations for our samples. Upon looking at our standard data it was shown that the 50ppm
standard actually had 43.65ppm for copper and 40.37ppm for the zinc 50ppm standard. This
miscalculation in making the standards could have been a factor in determining the sample
concentrations. Some other factors that could have led to negative concentrations could be misentered data into the software or the instrument itself. Also since we used the same standards
from the ICP, the elements were mixed and since the AA is highly selective, maybe there was
interference between the elements during analysis.