sheanhung

cool.... thanks!

I used 6M HCl to hydrolyse gelatin at 150 degree celcius. I tried to introduce the hydrolysed amino acids into LC-MS system using C18 column, and mobile phase (A & B) A= 0.2% formic acid in water, B= 0.2% formic acid in acetonitrile. I used gradient method, i.e. 2-60% B in 60 minutes. However, most of the amino acids eluted out from the column within 5 minutes. I guess the amino acids are very polar and they are not well retained by the column. If I'm still using C18 column, what mobile phases are more suitable? or what else should i reconsider?

I plan to analyse the fingerprint of different gelatins in HPLC. My supervisor suggested me that i should hydrolyse the gelatins into amino acids before they can be introduced into HPLC or HPLC-MS. I guess it is not an easy experiment for a degree student like me.

I have bought some pure gelatin solid, for information, gelatin is protein. My question is how big is the protein polymer? I want to know it because i plan to dissolve it in water and introduce it into HPLC ( high performance liquid chromatography). Basically, the analyte molecules introduced into the HPLC column shouldn't be too big, otherwise the molecules will stuck inside the column. But the references didn't mention how big is the analyte is consider "big" to column? The term 'big' is so abstract.

If I perform classical acid hydrolysis using same materials, the hydrolysis temperature would be 110 degree celcius and time frame is 24 hours and above. Can I perform the classical acid hydrolysis in separate days (3 days, 8 hours per day)?

Materials: 6M HCl and protein solution Condition : nitrogen gas atmosphere (to prevent oxidation), 150 degree celcius for 65 mins. What apparatus or instruments to be used to do this hydrolysis?

HPMC is Hydroxymehthyl cellulose and pullulan is polysaccharide. Any method to breakdown each of them into small fragments so that they can be analyse under HPLC?

Tq. The samples i have prepared are: 1. the whole capsule dissolved in water. the ingredients of capsule that i found out might be gelatin (>85%), water (~10%), methyl paraben, propyl paraben and Sodium Lauryl Sulphate (< 1%) 2. pure gelatin solution. Now i am seaching for the HPLC-MS method to analyse my samples. Any suggestion regarding the method? such as what type of mobile phase, flow rate, buffer....

both are in one phase. Am i right?

In present days, most medicines are in tablet and capsule forms. The one i am interested in is capsule. Currently, i am doing an project on capsules, including the ingredients. Is there any method to remove the colouring agent in the capsules?

i know what are molarity and molality. Anyway, thx~

I know 'partial molar volume' is the increament of volume per mol of A by addition of small amount of A into large amount of B. Am i correct? But now the question is, what is 'partial molal volume'? I failed to find the definition of 'partial molal volume' via google. Hope you guys can help. Thanks~

I believe it is just another type of diamond. If it is shiny enough, i guess it would be another thing that drive women crazy!

Which one is the hottest?

I am just like you when i was in secondary school, get excited when experiment dealing with mixing solution, cause bubble..... However, since I get to university, I found it is not interesting as you think. Now i am dealing with some hazadous materials such as H2O2 (a strong oxidizing agent), concentration acids and bases..... I have to pay extra 200% careful when doing experiment!

My experimental value = 68 kJ/mol

The H2SO4 put on the bench is diluted solution already. Diluted solution is made by mixing 1 volume of H2SO4 and 2 volume of H2O. (Eg. 5mL of H2SO4 + 10mL of H2O). The molarity of the diluted H2SO4 should be 6M if the formula MV = MV is applied. Am i correct? If yes, is 6M of H2SO4 safe to use outside fume cupboard? (From mt knowledge, 6M is very concentrated too!)

I have calculated the molarity of the solution = 18 M After dilution, the new molarity is roughly 6M. However, is this possible to use this diluted solution outside fume cupboard? What i understand is 6M is too concentrated to be used outside fume cupboard. But, during my experiment, this diluted solution was placed on the bench only. Hmm......i think i have make mistake in calculation!

Thank you. This website is useful!

Thanks a lot. The website is useful.

Yuen Chee, next time we should discuss before post this thread.

I have problem to determine the molarity of H2SO4 from 95%-98% H2SO4 solution with volume of 2.5 L stated on the bottle. Besides, i am not sure what is the meaning of 95%-98%. Is this percentage is in term of volume, number of moles or weight of H2SO4? If the molarity above is obtained, suppose i mix 1 volume this H2SO4 with 2 volume of water, what is the new molarity and number of moles of the diluted solution? These problems are killing me. :confused: Please help~! *Are these informations useful?* density of H2SO4 = 1.841 g/cm3 Molecular mass of H2SO4 = 98.08 g/mol

From my knowlegde: t-butyl alcohol is a tertiary alcohol. It does not react with chromic acid in room temperature ( no reflux). Cr^+6 ions in the chromic acid are red-brown in colour. If reduction occur, the Cr^+6 ions will be reduced to Cr^+3 ions which are green in colour. I have done the above test ( no reflux) using a test tube, what i can observed is two distinct layers with colourless on the upper layer and dark green solution (precipitate?) on the lower layer. Theoretically, t-butyl does not react with chromic acid, but why the colour of Chromic acid changes from red brown to green??

From my knowlegde: t-butyl alcohol is a tertiary alcohol. It does not react with chromic acid in room temperature ( no reflux). Cr^+6 ions in the chromic acid are red-brown in colour. If reduction occur, the Cr^+6 ions will be reduced to Cr^+3 ions which are green in colour. I have done the above test ( no reflux) using a test tube, what i can observed is two distinct layers with colourless on the upper layer and dark green solution (precipitate?) on the lower layer. Theoretically, t-butyl does not react with chromic acid, but why the colour of Chromic acid changes from red brown to green??

Do u mean during compression, the work done ON the system= - work done BY the system? For expansion, the work done BY the system = - work done ON the system?