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Mathematical problems!

Basic questions from students; resources for projects and reports.

6 posts Page 1 of 1
Hi. Im new to this chromatography and have some problem to solve some questions! I will be grateful if you just take a look at the questions and give me answer or some tips!

1: How does the retention time of a substance if the flow rate of the mobile phase is increased?

2: Which parameter would remain unaffected if you use a temperature gradient instead of an isothermal run? 1) elutionorder, 2) retention times, or 3) peak heights?

3: Extinction coefficient of hemoglobin (55 kDa Mw) is at 577 nm, 1.46 x 104 M-1 cm-1. Whitch length of a cuvette would be to have an absorbance of 1.05 when measured by a blood test containing hemoglobin 105g / L?

4: You have access to 8 ml of a polyclonal antibody to use in an immunoassay. For this you need 5 ml with a concentration of antibody at 1 mg / ml. You decide antibody concentration photometrically when you know that 1 mg of IgG / ml exhibits an absorbance of 1.26 in a 1cm cuvette at 280 nm. The results of your measurements show that the absorbance at 280 nm of your solution is 0.875. What is the purity of% with respect to IgG in your original antibody solution? If you find that the antibody concentration is less than what the analysis requires what can you do to overcome this problem so that you can use the antibody in your analysis?

5: The analysis of our sample which we received at ammoniumsulfatutfällningen with SDS-PAGE, we found two proteins of interest A and B in the second pellet.
Determine the molar mass of protein A (28mm) and B (54mm). Walking distance and molecular weight of standards and samples are; serum albumin (67kDa, 11mm), ovalbumin (45kDa, 23 mm), carbonic anhydrase (32 kDa, 34), trypsininhibitor (21.5 kDa, 46 mm) and lysosym (14.4 kDa , 59 mm).

6: 3rd The fraction of the interesting proteins A and B being analyzed with SEC-chromatography because we are interested in the native molar mass of each protein. The bottom line obtained from the gel filtration was Vo = 5.2 ml, Vt = 13.3 ml and Ve for A = 9.9 ml, B = 10.3 ml, tyroglobulin (669 kDa) = 7.7 ml, catalase ( 232 kDa) = 9.4 ml, alcohol dehydrogenase (150 kDa) = 9.8 ml, serum albumin (67 kDa) = 10.0 ml, ovalbumin (43 kDa) = 10.7 ml and RNase (13.7 kDa) = 12 , 0 ml.
a. What is the molar mass of A and B with this method?
b. How are the results of this method compared to those obtained with SDS-PAGE. Provide a reasonable explanation for deviations.
c. Give some way to determine Vt.

The best "tip" I can give you is to go back and re-read the notes and/or textbook from the course that this examination covers.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374

Check out point No. 6 of the "Forum Do's and Don'ts" in the "Policies" Forum
Good judgment comes from bad experience, and a lot of that comes from bad judgment.

Aw come on guys, let's give the poor soul some answers (I'll provide a few suggestions - the Pigs are becoming tired):

1 how does the retention time? - with a stopwatch.

2 Parameter that will remain unaffected: Grade on exam.

5 Molar masses are determined by how you chew the proteins. They are greater if you use the verry back molars.

6
b how are the results of one method compared to the other? We write down the ansers in columns side by side and look for differences.
c A way to determine Vt: Drive west from New Hampshire.

Somehow the apparent error in typing exam question number 1 triggered my evil streak.

Ok, the answer to 3 is "one that fits in your spectrophotometer"

4) the answer to the last part is "buy another immunoassay kit"
Good judgment comes from bad experience, and a lot of that comes from bad judgment.

1. The opposite of what happens if the flow rate of the mobile phase is decreased. Assuming of course that the same column is used.

2. Can't use a coin for this one, use a die. Since the answer is 1, 2, or 3 the correct answer is a multiple of the number shown on the die.

4. Reminds me of an experiment in sophmore analytical lab where one of the reagents had degraded. Most people failed that lab.

6. Ask at a gas station the way to Vt. Follow directions until the person looks at you real funny, at that point you are more than likely in Vt.

Better hope your professor doesn't read the forum regularly, faculty are generally aware of the ways students try to get info without working at it.
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