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Describe the extraction, separation, and detection of each of the following samples using any
resources available to you
1.) Solid, white powder containing trace amounts of lead
Extraction of lead from the powder form:
(SPE) Solid-phase extraction is the one of the important preconcentration method and can be utilized to
extract lead from the powder and it can be used in a normal phase, reversed phase or ion-exchange.. It
provides dual advantages, which includes an increase in analyte concentrations to measurable levels and
the removal of potentially interfering matrices. A number of sorbents have been broadly employed for the
preconcentration and isolation of trace metal ions from various matrices. Sorbents used in
preconcentration systems for lead determination can be unloaded, loaded or chemically modified with the
help of complexing reagents. Unloaded supports like activated carbon, natural adsorbents, polyethylene,
and others are possible collectors of analytes, existing either in a single ion form or in a complex with
other species. The flame atomic absorption spectrometry (FAAS) detection will be used for lead detection
due to its high sensitivity.
How to improve:
_How to recover lead????
-lead was eluted with HNO3
http://proj3.sinica.edu.tw/~chem/servxx6/files/paper_11066_1258362434.pdf
-Should I provide the abs wavelength for lead??? I believe to be ~ 283.3 nm will be great.
http://www.cdc.gov/niosh/docs/2003-154/pdfs/7082.pdf
2. Blood sample for measurement of blood pH and total iron concentration
Blood pH measurement from Blood sample:
A solid-phase extraction (SPE) procedure can be used for the isolation of acidic molecules from whole
blood. A blood sample will be first sonicated, diluted with phosphate buffer, and the acidic molecules or
other molecules will be extracted.
Ion-exchange chromatography (or ion chromatography) is a form of solid phase chromatography though
which process ions can be separated based on their physical attraction to the ion exchanger. The solution
to be injected in this case is blood (sample), and the individually separated components will be known as
analytes. In this type of chromatography, analyte molecules will be retained on the column according to
the basis of their ionic interactions. The stationary phase will have ionic functional groups (R-X), which
will interact with analyte (acidic) ions of opposite charge. This type of chromatography is further
subdivided into cation exchange chromatography and anion exchange chromatography. The ionic
compound consisting of the cationic species M+ and the anionic species B- can be retained by the
stationary phase. The acidic analyte will be separated from the column by changing the pH. As our
molecule of interest is acidic and it is bound to the positively charged beads (column), it will be eluted by
increasing the pH of the mobile phase. The acidity or pH content of the eluted analyte can be determined
by using electrochemical techniques.
- Hemoglobin from blood is separated by cation-exchange chromatography (functional group:
sulfonic acid). Mobile buffer phase should maintain at pH 6 or 7. At higher pH, side-chains
deprotonated. At low pH, depends on the number of amino acid in protein.
- One of the application for this extraction is helping diabetic patients
?????There is an experiment here with a lower pH
- http://www.seaviewsci.com/vydac/vydacpubs/vhpionex.pdf (page 13). They have an
experiment to separate hemoglobin by cation chromatography using citrate as buffer at pH 5.5.
Initially, they tried to separate with pH 4.5 then increases to 4.9 then 5.5. The results the resolution
increases while retention time decreases.
Iron extraction from blood:
Immunoaffinity chromatography is a method of parting biochemical mixtures on the basis of their
biological interactions such as that between the receptor and ligand. Here, we will use the transferrin
receptor bound column and blood will be passed though this column, which will leads to the binding of
iron bound transferrin to column bound transferrin receptor. Modulation (reduction) of pH will induce the
release of iron from transferrin due to the conformational change in the protein from a closed to an open
form. The released iron will be detected by using colorimetric approach, TPTZ, 2,4,6-tripyridyl-s-triazine,
which reacts with Fe2+ to form a deep blue-purple color. Reducing agents will be utilized to change iron
in the sample to the Fe2+ form.
- I couldn’t find any relevant resource for iron extraction from blood by Immuniaffinity chromatography.
However, I found one method to separate iron from blood using ferene reagent for spectrophotometric
analysis
purpose????????????
Here
is
more
information
http://www.nrcresearchpress.com/doi/pdf/10.1139/v84-121
- Detection by AAS for more simple procedure.????????
- Disadvantage of the above method is a small trace of copper (and very small trace of other metals of
course!) present in human blood which has similar characteristics as iron and can interfere with your
result??
3. Liquid, aqueous fluid suspected of low-level PCB impurities
The quantitation of PCBs found in biological samples is usually carried out in three distinct steps:
extraction of PCBs from the sample matrix using a solvent or a combination of solvents; cleanup of PCBs
from the impurities either using single or multiple columns; and finally quantitation by GC with a suitable
detector.
Thermal desorption is often used as an intermediate clean-up step after initial extraction before the analyte
is analyzed on a GC system. Thermal desorption can be used for both liquid and solid samples but is nonselective for the analyte – rather, all volatile compounds that are extracted at a certain temperature from
the sample will enter the separation and detection system.
PCBs are extracted from blood or serum using solvent extraction techniques employing hexane, benzene
or mixed solvents such as hexane/ethyl ether or by solid phase micro-extraction techniques. A range of
adsorbents can be used for cleanup and/or fractionation of extracts: like deactivated silica gel, alumina or
multiple columns. GC/ECD is employed most often for determination of PCBs in biological samples.
- good website with more detail for extract PCB using matrix-specific method with information about
possible
interference
with
PCB
detection.
http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/8082a.pdf
- Do I need some information about physical and chemical properties about PCB.
- Microorganisms can be decomposed PCB
- Also PCB is very toxic and cause a lot of diseases.
4. Air particulate matter tested for methane concentrations
Air sampling can be classified into two distinct themes: vapor/gas sampling or particulate sampling. In
the case of the latter, particles are collected on filters (e.g. fiberglass, cellulose fibers) which act as
physical barriers whereas in the former case air-borne compounds are trapped on a sorbent (e.g. ionexchange resins, polymeric substrates) which provide active sites for chemical/physical retention of
material.
In sorbent tube sampling, volatile and semi-volatile organic compounds are pumped from the air and
trapped on the surface of the sorbent. Quantitative sampling is possible by allowing a measured quantity
of air (typical volumes of 10–500m3) to pass through the sorbent. The sorbent tube is then sealed and
transported back to the laboratory for analysis. As the organic compounds collected are either volatile or
semi-volatile they will be analyzed by gas chromatography (see Section 1.5.1). First however, they need
to be desorbed by either the use of organic solvent (solvent extraction) or heat (thermal desorption). The
latter approach can be done in a fully automated manner using commercial instrumentation and is
therefore the preferred analytical approach.
- I think I need more detail by providing specific GC carrier gas or what organic solvent you would use
to extract CH4???????
- Will I have other traces if O2, N2, CO2 in sample -great to mention order of elution on GC spectra.
See http://www.chem.agilent.com/Library/applications/5988-9260EN.pdf PAGE 5 ?????
5. Solid sample, 14th century painting tested for tin concentration and age authenticity
Powdered tin was added to red paint layer to increase the final luminosity of the polychromy. Tin was
found to increase the glazed look of the paintings.
A Method was developed for the determination of total tin in marine sediments by employing Zeeman
GFAAS was studied. The optimum temperatures for pyrolysis and atomization for tin estimation were
1100ºC and 2300ºC, respectively. When different matrix modifiers were used, like a mixture of
NH4H2PO4/Mg (NO3)2 and Mg (NO3)2 alone exhibited the optimum signal for tin. No remarkable effect
on the tin signal was observed when HNO3 was used as a diluent. The extraction of total tin from marine
sediments was most effectively performed by digestion of the sample with 6 M HCl and diluting the
sample extracts with 1% HNO3.
Graphite-furnace atomic absorption spectrometry (GF-AAS) is in many respects identical to FAAS but
utilizes higher atomization temperatures (up to 3,000 K) which results in LODs that are 10-100 times
better than FAAS. The sample is vaporized and atomized on the surface of a heated graphite furnace which
allows for more uniform heat and higher atomization efficiency. However, certain refractory elements
may still be difficult to analyze with this technique and it is mostly utilized for single-element analysis.
Both liquid and solid samples can be analyzed in low quantities without significant matrix interferences
if appropriate sample extraction techniques have been used.
- extraction little more simple by using EPA method??
fuse my sample with a 20 to 1 ratio of sodium carbonate to soil at 1000 C for about 15 mins in a Pt
crucible. dissolve and dilute the sample using 1:1 HCl/water. good for extraction tin but also for
thallium.
http://www.inorganicventures.com/advice/tin-and-thallium-soil-extraction
References
http://www.sekisuidiagnostics.com/resources/PI/Iron%20(Total).pdf
http://proj3.sinica.edu.tw/~chem/servxx6/files/paper_11066_1258362434.pdf
http://www.atsdr.cdc.gov/toxprofiles/tp17-c7.pdf
http://www.ncbi.nlm.nih.gov/pubmed/11536559
http://www.engg.ksu.edu/HSRC/95Proceed/martgonz.pdf