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Ziyue-Yi-Analytical-Problem-Aflatoxin in the Oil

My analytical problem is that develop a safe way (can't cheatable) to find out the concentration of aflatoxin in the vegetarian oil.
I want to do such an analytical problem because aflatoxin contamination is serious in China. Most cases of such contamination are found in the food oil in Chinese market. The small restaurant repeatly use the oil simple recycled from the sewer and the hood from the big restaurant. After several days transport and process, the oil touch too much fungi for a long time, the fatty acid is transferred to be aflatoxin. (1) Aflatoxin is a dangerous thing which can cause cancer. (1) Aflatoxin processed by liver and become a kind of oxide product which is the real poisonous stuff. (1)
The central hypothesis is that there's excess aflatoxin in the recycled oil which come from the old oil, and the excess aflatoxin makes people unhealthy. Of course, the analyte is aflatoxin. The aflatoxin come from a matrix of fatty acid/heavy metal (because one of the process of recycling)/food/water and some aromatic impurities.
1). Watanabe, Coran M.H.; Townsend, Craig A. Initial Characterization of a Type I Fatty Acid Synthase and Polyketide Synthase Multienzyme Complex NorS in the Biosynthesis of Aflatoxin B. Chemistry & Biology; Sep2002, Vol. 9 Issue 9, p981, 8p.
UV-Vis absorption spectrometry
The aflatoxins in the food are four type B1/B2/G1/G2. However, they're almost the same structures, so they have the same maximum absorption wavelength. The other types of aflatoxins are ignored because they arent common exsits in decaied food oil.
In methanol, 265nm and 360-362nm wavelength
B1 12400e 21800e
B2 12100e 24000e
G1 9600e 17700e
G2 8200e 17100e
Fact sheet of aflatoxin. http://www.micotoxinas.com.br/aflafacts.pdf (accessed Sept 2011).
Similar Analytical Problem(s)
Pesticides and Toxins in fragrances and natural flavors
Topic: presence of residual pesticides, or natural toxins in natural flavors and fragrances
Hypothesis: these toxins and pesticides are concentrated in the raw materials for naturally flavors and fragrances
Analytes: common pesticides, naturally produced plant toxins, heavy metals
Matrixes: alcohol, powdered, in oil emulsions, and occasionally in water
Relevance: health
Simialr: we all focus on the things that come from a natural resource. So, the studies base on the toxins are produced with a process independent way (the toxins are not produced by the process/the tools of the process or the environment of the factory). A studies about the environment and planting method of the natrual raw material of the products is also needed to prove that the toxins come/not come from the natral raw material (flowers/beans etc.). The studies on other toxins exsitence in the product should also included in the research (so the problems caused by these toxins). A studies of customer method for using the product is another important studies. The same condition lab/sample comparison studeis should also me performed.
Different: he need to studies on eliminate the effect of the natrual flavor matrix on the signal while I will do the studeis on the interference of the food oil matrix on the signal.

Topic: proteins and Fruit Allergies
Hypothesis: any minor genetic altering of a plant will not affect the proteins that cause the allergic reactions
Analytes: minor genetic altering of a plant's protein won't cause diease
Matrix: juice would also contain carbohydrates and other organic molecules
Relevance:Health

Similar: we all focus on the things that come from a natural resource. So, the studies base on the toxins are produced with a process independent way (the toxins are not produced by the process/the tools of the process or the environment of the factory). A studies about the environment and planting method of the natrual raw material of the products is also needed to prove that the toxins come/not come from the natral raw material. The studies on other toxins exsitence in the product should also included in the research. A studies of customer method for using the product is another important studies.The same condition lab/sample comparison studeis should also me performed.
Different: he need to studeis on all the types minor genetic modification of the fruites don affect the proteins levels, and secure the signal from the fruite matrix. I need to make sure the signal is OK from the matrix of the food oil.
Blog6
View image
Properties of aflatoxin and it producing fungi. http://www.icrisat.org/aflatoxin/aflatoxin.asp (accessed October 2011).
Sigma-Aldrich company's Aflatoxin B1/B2/G1/G2 Standard Solution (46323-U 46324-U 46325-U 46326-U) will be used.
For now, I will need two sets (4 solutions * 2) of the solutions, one is for atomic spectra, and the other one is for the mass spectra, if I will use the light based instrument (probably wont use because they are not accurate as I expected), there are will be another set of the soultions.
Each solution is 0.5 μg/mL (1 mL per pkg) in acetonitrile with a price of 43 USD.
http://www.sigmaaldrich.com/catalog/Lookup.do?N5=All&N3=mode+matchpartialmax&N4=aflatoxin+standard+solution&D7=0&D10=aflatoxin+standard+solution&N1=S_ID&ST=RS&N25=0&F=PR
Blog13
The aflatoxin has electronactive property.
For identify, they have half potential near 1.2V. (chapter 3.22)
For quantify, there's calibration curve for them. (chapter 3.2.2.1)
http://eprints.utm.my/2889/1/75152.pdf (2011 DEC acessed).

Comments

Blog 13. Explain in more detail how the calibration curve is built. What is being measured? -0.12 pt)

The aflatoxin has electronactive property.
For identify, they have half potential near 1.2V. (chapter 3.22)
For quantify, there's calibration curve for them. (chapter 3.2.2.1)
http://eprints.utm.my/2889/1/75152.pdf (2011 DEC acessed).

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Blog 13
The aflatoxin has electronactive property.
For identify, they have half potential near 1.2V. (chapter 3.22)
For quantify, there's calibration curve for them. (chapter 3.2.2.1)
http://eprints.utm.my/2889/1/75152.pdf (2011 DEC acessed).

Blog 13
The aflatoxin has electronactive property.
For identify, they have half potential near 1.2V. (chapter 3.22)
For quantify, there's calibration curve for them. (chapter 3.2.2.1)
http://eprints.utm.my/2889/1/75152.pdf (2011 DEC acessed).

Blogs 9, 10, 11. The answers are correct. However, some of the statements do not make too much sense. For example: Be careful to choose ... Make sure that you do not repeat what other tell you, but that everything that you use your own words when you write any text.

Blog 11
1.Suitable:CZE and MEKC. CIEF is not OK because my analyte is not amphiprotic compounds. CGE is not suitable for small molecules.
2.Both of them can do this separation (MEKC maybe better on data), but I will choose CZE because it's seems easier to access than MEKC (econmic and familiarities).
3.For buffer:50 mM sodium deoxycholate,6 mM sodium borate, and 10 mM dibasic sodiumphosphate, pH 9.1; 1:100 sample:buffer. Sample is injected: 5.0 s at 0.5 psi, equivalent to 30 nL, a voltageof 20 kV was applied. Capillary doesn't metioned, but the author said he gets the "easy" insturment, so I guess he doesn't modify it, so it's plastic coated one (I called the company).
4.The dector is fluorescent UV, it's the one which can have the best accuracy and fit the analyte. The sample should be 0.05-10ug/mL.
Chris M. Maragos* and Judith I. Greer. Analysis of Aflatoxin B1 in Corn Using Capillary Electrophoresis with Laser-Induced Fluorescence Detection. J. Agric. Food Chem; 1997, 45 (11), pp 4337–4341

Blog 10
I will use reverse phase chromotography.
Chen Chuxin also use RPC because her analyte is simialr to mine. The stationary and mobile phase maybe a little different, but our techniques are quite the same.

Blog9
My analyte is aflatoxin which is an organic toxin. The matrix is complex, but after proper extraction and filtration, there only some organic interference there. The aflatoxin has a polarity between methanol and water, also can be called a polar compound. Both HILIC and reverse phase are OK to deal the situation. The aflatoxin is easy to be destoryed in high temp, and is not violtile, so GC can't be used; there's no ionic/inorganic problems here, so ion-exchange and affinity can't be used; there's no big defference between matrix and analyte, so size also useless; chiral is not the topic talked about here, so chiral chromatography is not useful.
The first choice would be reverse phase chromatography. First, RPC (rever phase) is more common to see on the market, which means easier to access; second, on book HILIC just reach the polarity of aflatoxin, I doubt that it will work or not.
I would choose Waters Spherisorb NH2 Column (http://www.waters.com/waters/partDetail.htm?partNumber=PSS832315), it's 3um for the particle size, with 4.6mm diameter, and 250mm length. The pore size is found on the PDF of this company (http://www.waters.com/webassets/cms/support/docs/WAT094178.pdf, be careful, the reverse phase NH2 is ODS1, not NH2 on the form which is for normal phase), which is 80A. The column is OK to take 2-8 PH, and 20-45C temp, both enough for aflatoxin. The pressure cant be over 5000Psi if you want to use it for long term. The company is Water, and the catalog number is PSS832315.
The moblile phase probaly will be methanol and water mixture, the ratio is pending until do some test for the mobile phase.
The flurorecent detector is the best choice. The aflatoxins have significant detection wavelegth in UV area, and the fluorescent detector has a good sensitivity. The other detectors metioned by the book, shows low sensitivity/wrong analyte or gives out not suitable data.
http://www.waters.com/waters/partDetail.htm?partNumber=PSS832315
http://www.waters.com/webassets/cms/support/docs/WAT094178.pdf

I will use HPLC (reverse) to separate matrix and detect the analyte. Chen Chuxin's problem also need a separation for polar organic compounds ( and they are not very big) from a matrix, so I think maybe we will use the same technique.

I believe that you mean "activated" carbon. Would aflatoxins be trapped by the activated carbon? In most methods you cannot directly analyze oil. Further processing will be needed. References? (-0.85 pt)

Blog 8
I will need four samples: the oil just used, the oil from the sewer (before recycle and the one stay there for the time long as the recycling), the oil after recycled.
(1) filter: the 4 samples will be put living carbon to remove the impurities which cant be dissolved, then filtrated to remove the carbons;
(2) storage: the sample must be used immediately at the prper time of the lab because the lab need to close to the real situation, so no storage.

Blog 6. Good Answers.
Blog 7. AES cannot be used to analyze aflatoxins. Example of mass spectrum? (-0.35 pt)

Yes, they can.
Aflatoxin B1/B2/G1/G2. All of them have wavelengths around 365nm (absorb) and 455nm (emission), but I just need the sum of the aflatoxins concerntration for my test, so it doesnt matter if there's little difference between them. I would choose AES. The reason: AAS are not suitable for the oragnic compounds; ICP is too expensive and hard to use, and I don't need that accurate; AES is the best one base on the consider of accurate and easy acess.
Aflatoxin B1/B2/G1/G2 (312/314/328/330). I would like to use chemical ionization sourse with the FT-MS (not tandem).

The answer to Blog 5 is ok. Your grade will be updated.

The aflatoxins (B1 B2 G1 G2) I'm interested in have an excitation wavelength of 365 nm and an emission wavelength of 455 nm.
The solution is chloroform.1

The nature of my sample is that: the sample is mixed with some orgnaic impurities which can't be purified before the detection process. Aflatoxins are fluorecent substances while the impurities (most are not rigid) are not fluoresecnt, so I don't need to worry about the interference from the organic impurities. My studies on the lab decaied oil and the sample (use them as a comparsion to prove there's excess aflatoxins in the decaied oil, not from any else factors during the recycling of oil) will need an exact concerntraion of the aflatoxin. An array spectrofluorometer is needed to determine the intensity of the light which can derive the concerntration of the aflatoxin.

1.Saqer M. Herzallah. Determination of aflatoxins in eggs, milk, meat and meat products using HPLC fluorescent and UV detectors. Food Chemistry; Jun2009, Vol. 114 Issue 3, p1141-1146, 6p

Blog 4. The descriptions of the proposed studies are not clear. What is being done in each study that helps you test the hypothesis? Grammar needs revision (-1 pt).

Blog 5. There was not answer posted (-1 pt).

Blog 4. I cannot understand the studies that you are proposing (-1 pt).

Blog 5. (-1 pt)?

Hypothesis: the aflatoxin is excess in the recyclced food oil which uses the old oil as raw material, the excess aflatoxin is harmful to human.
The studies needed to be done:
the aflatoxin should not come from the beans which made the oil;
the alfatoxin is not the product of the improper process/storage/transport both for the new oil (before they're used, and pured to the sewer) and the recycled oil (so the aflatoxin brought by the oil, not the factory);
the aflatoxin is not made by the wrong using/storage method of the customer;
the signal is come from the aflatoxin, not any interference;
the concertration should be determined in a comparison of the sample and the decaied oil come from the lab;
if the aflatoxin is not excess in the lab one, the studeis on the transformation of the toxins and the level of fungi (maybe the lab is too clean, the normal condition even in the proper ways is not clean as lab because it also need to have a reasonable cost) in the oil should be done.
the estimatation is that: 10^3-20ug/kg in the matrix.

BLOG 2 - Units for molar absorptivity? (-0.15 pt)
Find references besides web pages (-0.05 pt)
Posting in other entries (-0.15 pt)

BLOG 3 - Parts (b) and (c)? (-0.5 pt)

Ziyue,
see instructions for BLOG 3. You need to modify your entry. If you do not know how to do it, consult with Chad. Once you have modified your entry your grade will be released. Please notify Chad when this is done. Thanks. Edgar

Regarding your answers....
- (a) Good answers.
-(b) Answers? (-0.25 pt).
-(c) Answers? (-0.25 pt).

These problems are the same as me, and they can be analysis the same way:
Osman-Jamshed-Analytical-problem-Detecting prions by analytical methods
Sara Baldvins - Analytical Problem: Geochemical Mobilization of Arsenic to Ground Water
Ian Ronningen- Pesticides and Toxins in fragrances and natural flavors

Overall the problem looks interesting. I would suggest to revise grammar to improve clarity. We can talk more about it.

The hypothesis needs more context to make it clear.