Dear Chromatographers: We have a new UV detector for our isocratic HPLC system (Bio-Rad with RI detector). We are trying to analyze Ascorbic acid (vitamin C)...
Yousef Hassan
yhassan@...
Oct 1, 2002 8:32 am
1415
Hi everyone, I want to calculate the Factor of Resolution (Rs) of the peaks that I analyze and I do not find width calculation. The program makes this? Or I...
the range of your detector must be 3 for maximum performance(9 touches in the func key until you find AUX RANGE if it's not 3, change it ) I detect 50 ng of...
Hi, What software are you using? Most software packages will calculate resolution. Mike ... ze and I do not find width calculation. The program makes this?...
shiffty@...
Oct 2, 2002 9:50 am
1418
Hi Elango, With the sodium nitrate eluent, you should observe a large negative peak, when injecting sample dissolved in water at the position where the salt...
Ivan Vins
i_vins@...
Oct 3, 2002 7:12 am
1419
I am familiar with standard linear regressions as applied to standard curves. Can anyone tell me what a weighted standard curve is (1/x^2. for example)? Thanks...
Chris.Knutsen@...
Oct 3, 2002 8:50 am
1420
Chris, this topic is well covered in a recent paper: Almeida AM et al (2002) Linear regression for calibration lines revisited: weighting schemes for...
Ellis, Andrew
a.ellis@...
Oct 3, 2002 8:53 pm
1421
Hello Chemists! If anybody is interested in this opportunity - please email me your resume. Thanks! AG. EDUCATION/EXPERIENCE: Prefers a BS in Chemistry or...
Dear members of this list, I would appreciate your help in getting some articles which I did not get them in internet. Its will be very important for my work...
DRDN
tequila2@...
Oct 5, 2002 2:14 pm
1423
I found an old method to detect Ethylene Oxide and Ethylene Chlorohydrin down to 1ppm using the following packed column: 3% Carbowax 20M on Chromosorb 101...
Dear All We are wanting to detect e-caprolactone monomer in solution via HPLC. Does anybody have any experience and routines for doing this? Thanks in advance ...
Dr Jonathan Knowles
j.knowles@...
Oct 9, 2002 9:31 am
1425
We are currently looking at a method that results in a calculation of dextrose equivalent from HPLC sugar data. We know that the matrix is corn syrup using a...
Hurst, William
whurst@...
Oct 11, 2002 6:26 pm
1426
Almost any capillary column will separate these two components, the problem lies in how one will deliver them to the column, in solution, in vapor? And what...
Hi all, I'm analyzing two phospholipids-- phosphatidylcholine (PC) and phosphatidylserine (PS)-- by running them through a silica column, and detecting them on...
Dear All Can anyone help. We are wanting to measure the degradation of polycaprolactone in water. Does anybody know of a suitable assay for performing this? ...
Dr Jonathan Knowles
j.knowles@...
Oct 14, 2002 2:26 pm
1429
Dear All I have a problem with hydroxyzin and its USP related compound sepration we have a compeletly overlap between hydroxyzine and its USP related compound ...
Is there any formula or rule of thumb in determining how many standard injection is appropriate for a given method. I've seen various ways, however I recently...
Hello, How do i calculate mg/tab assaya and impurities using excel function is there any web site where i can get excel function for hplc Thanks in advance ...
That is not an uncommon request in a method. For an adapaline run, we usually do triplicate std. injections preceding, triplicate std. injections between each...
Hi, This has become a hot topic with the FDA which has driven up interest in the topic. The USP lists to differnt methods of determing system suitability: 1....
shiffty@...
Nov 4, 2002 10:59 am
1434
Dear Alls
It is my first mail to all of u.
i want to introduce myself as MOHD LUQMAN(INDIA),a
research scholar working on the topic"TLC studies on
inorganic...
mohd luqman
luqmank@...
Nov 4, 2002 10:59 am
1435
Hi, I have three questions: 1. Who is the manufacturer of the column that you are using? 2. What is the silica particle size? 3. have you tried an adjustments...
shiffty@...
Nov 4, 2002 10:59 am
1436
I met with Bill Furman (now retired) of the Atlantic region of the FDA back in 1996/1997 during their "forums" regarding chromatographic methods. At the time...
Dear members, I have a problem with GC analyses of essential oils. I'am using an HP-5 colum for the analyses of essential oils. the Kovats indices I abtained...
KI are a. temperature dependent (a little on some phases, a lot on more polar phases) b. Dependent on the phase. HP-5 is 5% phenyl methyl polysiloxane, so...
You may find that KI values may change with the increase of film thickness. I do not know if this is the case for DB-5 columns. Make certain you are using the...
hello members: i am working actually in vitamins determination (lipo and Hydro)and i am searching a postgrade course in analitycal chemistry in order to learn...
jannethruiz@...
Nov 8, 2002 12:01 am
1441
I am having trouble calculating the amounts of cAMP present in rat lung tissue samples and would appreciate help if anyone has worked on or knows anything...
Hello momebers, is there anybody that have already developed HPLC analysis method for polyphenolic compounds (e.g. ferulic acid, veratric acid, p-coumaric ...
In my past life, I have used an HPLC method for anthacene and phenanthracene in coal tar medications. I think that a customer had asked that we perform the...
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