hie .. does anyone know how to prepare the sample of tooth brush for analysis of triclosan usin c18 reverse phase coloum?how to make the tooth brush n the...
Hi everybody, I am working on restoring a stop flow spectrophotometer. The problem it has is there is a leak in the stream switching valve, wherein the two...
hi I was wondering if anyone can help me with little problem.. Im currenlty doing a Reverse phase HPLC with 70%water: 30% acetonitrile:1% acetic acid, analysis...
Methanol is less non-polar than acetonitrile, so the same concentration of MeOH will result in longer retention times. Selectivity (relative spacing of your...
Tom Jupille
joop@...
Sep 9, 2002 5:37 pm
1385
Use High-purity Helium. I would recommend adding one of the heated traps to the line. The methane in the Ar/CH4 will cause you some problems. Use this as your...
Patrick Calway
Patrick_Calway@...
Sep 9, 2002 5:59 pm
1386
We use nitrogen as carrier, and don't need a make-up gas (Agilent GC). If your GC is reasonably modern and has a low flow detector design (assuming you are...
Hi Tom Jupille, being still a bit browsy from just getting up, I hope that I don´t confuse things. But to " Methanol is less non-polar than acetonitrile, so...
Hans W. Mueller
Hans.W.Mueller@...
Sep 10, 2002 6:30 am
1388
Hi. Does anyone have any suggestions for starting HPLC conditions for two amine compounds. They are triproplyamine and tetrapropyl ammonia. Right now I only...
Dirk Holstege
dmholstege@...
Sep 10, 2002 9:21 am
1389
Hi Julie, I really would not recommend using Ar/CH4 or N2 as a carrier gas for capillary columns. In order to obtain a good deal of efficiency using these...
ELLIS,JASON (A-Folsom...
jason_ellis@...
Sep 10, 2002 3:08 pm
1390
Hi, Hans. As usual, you are quite right. In my defense, however, I didn't say that MeOH was more polar than ACN, I said it was "less non-polar". Looking at the...
Tom Jupille
joop@...
Sep 10, 2002 4:15 pm
1391
Hi, Tom, now it´s my turn to agree, liquid polarity is a complicated matter. For instance, the dipole moment of MeCN = 3.92 MeOH = 1.7 H2O = 1.85 yet...
Hans W. Mueller
Hans.W.Mueller@...
Sep 11, 2002 6:08 am
1392
I am currently reviewing a Validation Protocol. Under the Recovery section it mentions that the MS/MSD for each sample should be be less less than or equal to...
Hi, Why flow rate in Water's 616 pump fluctuates, once you change flow rate from 2 ml/min. to 1 ml/min. For example, when I programmed flow rate for 2 ml/min.,...
Kersti Karu
kersti.karu@...
Sep 11, 2002 8:13 am
1394
Julie, As Jason Ellis said, either hydrogen or helium can be used as a carrier gas. However, we have tried both, and had much better results with the hydrogen....
Jan & Al
alekat@...
Sep 12, 2002 1:50 am
1395
Sorry, almost forgot about this; ... From: <john.kennedy@...> On: Only simple acetonitrile (20-30%) buffer systems ... 0.1M), ... fronting ... Wheras...
Hans W. Mueller
Hans.W.Mueller@...
Sep 12, 2002 11:19 am
1396
Julie I still will not recommend the use of hydrogen even with new equipment unless it is absolutely unavoidable. Agilent has a web page ...
Patrick Calway
Patrick_Calway@...
Sep 12, 2002 9:06 pm
1397
... From: Patrick Calway <Patrick_Calway@...> To: <chrom-L@yahoogroups.com> Sent: Thursday, September 12, 2002 2:05 PM Subject: [chrom-L] RE: carrier...
Hans W. Mueller
Hans.W.Mueller@...
Sep 13, 2002 6:11 am
1398
Hi, I have some doubts about the concentration of salts in buffer solutions.For example, I use 50 mM of KH2PO4 in deionized water and I adjust the pH of the...
Dear Andrea, the concentration is not too high. If I understand you correctly then you want to use this buffer in HPLC. We usually use 20 - 25 mM. My motto in...
matthias.kummer@...
Sep 13, 2002 11:55 am
1400
... From: uomoditeresa <palanca_andrea@...> To: <chrom-L@yahoogroups.com> Sent: Friday, September 13, 2002 1:23 AM Subject: [chrom-L] buffer solutions ...
Hans W. Mueller
Hans.W.Mueller@...
Sep 14, 2002 9:03 am
1401
1. If resolution is the problem, nitrogen will give slightly better results as it is denser - refer to the Van Deemter eqn (?has anyone ever tried SF6 as a...
I am in need of some advice about a novel method my supervisor wants me to try out to purify immunoglobulin that is specific for the bacterium Neisseria...
is there anybody that knows Vydac column 3021C4.6? I need some informations because I'm not able to open vydac homepage. In particular I'd want know if is...
Hi, somebody knows if the ECD also detects elementary Iodine (I2)? Thanks Guilherme Brazil ... Yahoo! GeoCities Tudo para criar o seu site: ferramentas fáceis...
Guiherme, The ECD will detect halogens, including iodine, although it is less sensitive the other halogens. But I doubt you could chromatograph I2 as such. I...
Dirk Holstege
dmholstege@...
Sep 19, 2002 4:47 pm
1406
Dear all Is anyone doing column chromatography of flavonoids. Which is the suitable adsorbent for doing so and any journal references ....Please suggest. ...
I am doing a research on fish and I have to analysis the amino acids in the muscles.I have to work with HPLC but I am not familiar with this instrument. I know...
Hi, For faster amino acid analysis, you could try the Phenomenex derivitization method with GC, but I have yet to see someone be sucessful with it. Give them...
Hi All- I need some help. I am trying to analyze "polyethylene polypropylene glycol" also known as poloxamer (a polymer with M.Wt of about 2000). I am trying...
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