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I'm trying to assay an anthracycline using HPLC (UV detection). I've run
into problems and it has been suggested to me that this may be due to pH
fluctuations affecting UV absorbance. As I understand it, this process
is known as the "bartochromic effect". Does anyone know where I can find
information on this effect???
Thanks.
Wendy Ingram
Dept. of Pharmacy
Derriford Hospital
PLYMOUTH
PL6 8DH
UK
Tel: 01752-763414
Fax: 01752-763418
email: wendy.ingram.-a-.phnt.swest.nhs.uk
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[A few replies - db]
X-Lotus-FromDomain: NEXSTAR
From: vpalaniappan.aaa.nexstar.com
To: PharmPK.aaa.pharm.cpb.uokhsc.edu
cc: wendy.ingram.at.phnt.swest.nhs.uk
Date: Tue, 8 Sep 1998 17:29:51 -0700
Subject: Re: PharmPK bathochromic effect
Mime-Version: 1.0
Hi there,
It is bathochromic effect. Anthracyclines have highly pH dependent
spectroscopy. One can construct pH versus absorption curves, and pick the
isosbestic point for analytical purposes. For pH dependent spectroscopy of
anthracyclines, see papers by A. Garnier-Suillerot among others. In
particular, MML Fiallo et al, J. Pharm. Sci. 1998, 87, 967-975.
Good Luck,
V. Palaniappan
Senior Scientist
NeXstar Pharmaceuticals
San Dimas, CA 91773
--
From: Hall Mike M
To: "'PharmPK.-a-.pharm.cpb.uokhsc.edu'"
Subject: RE: PharmPK bartochromic effect
Date: Wed, 9 Sep 1998 09:37:17 +0100
Mime-Version: 1.0
Wendy,
Any shift in absorption wavelength to a longer wavelength is a
bathochromic effect, a shift to a shorter wavelength is a hypsochromic
effect. These shifts can be caused by a change in pH (eg aniline
absorbs at 230nm but in acid solution this shifts to 203nm - a
hypsochromic effect), the cause is an alteration in conjugation due to
protonation. The best solution is careful control of pH by using a
buffer in your mobile phase and always check and adjust the pH prior to
use.
Most spectroscopy text books will give an explanation, try anything by
Fleming eg Spectroscopic Methods in Organic Chemistry from McGraw-Hill.
Mike Hall
Pharmacokineticist
Zeneca Central Toxicology Laboratory
Alderley Park
Macclesfield
Cheshire
---
X-Sender: rasams.at.pop.service.ohio-state.edu
Date: Wed, 09 Sep 1998 07:39:05
To: PharmPK.-a-.pharm.cpb.uokhsc.edu
From: "Richard Sams PhD."
Subject: Re: PharmPK bartochromic effect
Mime-Version: 1.0
Ms. Ingram:
You are probably referring to a bathochromic shift which is a displacement
of an absorption band maximum to a longer wavelength by a change in the
medium or molecular structure. Information describing this effect can be
found in most textbooks of pharmaceutical analysis.
---
From: Varun Garg
To: "'PharmPK.-a-.pharm.cpb.uokhsc.edu'"
Subject: RE: PharmPK bartochromic effect
Date: Wed, 9 Sep 1998 09:05:44 -0500
X-Priority: 3
MIME-Version: 1.0
I think you mean "Bathochromic Shift" which is the shift of absorption
to a longer wavelength due to substitution or solvent effect (a "red"
shift). The opposite is Hypsochromic Shift or blue shift.
Hope this helps,
Varun
~~~~~~~~~~~~~
Varun Garg, Ph.D.
Aronex Pharmaceuticals, Inc.
8707 Technology Forest Place
The Woodlands, TX 77381-1191
Tel: 281-367-1666 x317
Fax: 281-367-1676
email: vgarg.at.aronex-pharm.com
~~~~~~~~~~~~~
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Dear all,
As far as I know while using HPLC though there is always a possibility
for hypso... or bathochromic effict due to change of PH , if one use
wavelength of max. absorbtion there is no need to adjust PH coz thereis
little change in absorption(if using UV methods) for trivial changes of PH.
Am I right?
Ahmad M.
PK student
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[Twp replies - db]
X-Lotus-FromDomain: NEXSTAR
From: vpalaniappan.aaa.nexstar.com
To: PharmPK.at.pharm.cpb.uokhsc.edu
cc: ahmadmir.-a-.nrcgeb.ac.ir
Date: Fri, 11 Sep 1998 11:40:46 -0700
Subject: Re: bathochromic effect-isoresponsive points
Mime-Version: 1.0
Dear Ahmad M.
To effectively get rid of the pH fluctuation induced effects during HPLC,
one should use detection at isosbestic points rather than band maxima.
So.. first, one should acquire optical spectra of the analyte under
different relevant pHs, and then see if there is isoabsorptive or
isoemittive point. Essentially, the analyte response is identical at these
points under different pH conditions. One could do the same exercise for
solvent induced changes too, an determine isoresponsive points to use in.
If one wants to use detect at band maxima, then one may have to verify that
under the condition of variation in pH there is no change in the response.
That's it for now.
V. Palaniappan
---
Date: Fri, 11 Sep 1998 23:19:21 +0200
From: harald.aaa.mertes.inka.de
MIME-Version: 1.0
To: PharmPK.aaa.pharm.cpb.uokhsc.edu
Subject: Bathochromic effect
No,
I disagree totally. Whenever you work in aequous systems you should use
buffered solutions in order to maintain the pH. I know many substances,
like the 6-thioguanosine I worked during writing my thesis, with a
shifting of the absorption coefficient due to pH changes. Any
quantitative determination won't be reliable in unbuffered systems.
Regards,
--
Harald Mertes, MD
Anaesthesiologist
Rastatt/Germany
mailto:harald.aaa.mertes.inka.de
http://sites.inka.de/sites/mertes/index.html
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