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Immunoasaay Enhancers
for Researchers and Manufacturers
HRP CONJUGATE STABILIZERS
-new non PBS formualtion II now available
HRP-CONJUGATE STABILIZER
The major advantage of a liquid HRP-conjugate is it eliminates the chance for
human error when dissolving or diluting the lyophilized or concentrated
conjugate. Adding too much or not enough buffer results in assay to assay
variation. Until now, the disadvantage of this format was the inherent
instability of the liquid HRP-conjugates. This problem has now been addressed!
The HRP-CONJUGATE STABILIZER is formulated to allow you to provide pre-diluted,
READY-TO-USE CONJUGATES. This product contains Phosphate buffered Saline with
BSA and other proprietary reagents, 0.01% thimerosal added*.
cat#HRP-Stab READY-TO-USE : This formulation was designed to reconstitute
lyophilized or concentrated HRP-conjugates. Conjugates are titered and diluted
to working concentrations with the HRP-CONJUGATE STABILIZER. Many HRP-conjugates
prepared in this manner will maintain HRP activity for up to 2 years at 4 Deg C.
HRP Stabilizing Diluents (additional formulations)
We recommend our HRP-Conjugate Stabilizer cat#HRP-STAB-1X as the best overall
stabilizer for HRP conjugates. This formulation has additional stabilizers and
formulary products to meet more demanding needs.
However, we also offer 4 other formulations at a lower cost for
applications that might not need our full featured product. As always, you must
independently test these products for your own application.
CAT#RDI-HRPSTAB-1X or HRP-STAB-1X
ALSO AVAILABLE PRESERVATIVE FREE
€600.00/Liter
Allows you to add other presevatives as
microcide I).
€538.00/Liter for 11+ liters use cat#RDI-HRPSTAB-1XP
€425.00/Liter
€ 412.00/Liter 50 or more €300.00/liter 50+
Special: POLY-HRP Conjugate Stabilizer
(with microcide preservative/no thimerosal)
SA-PolyHRP Stabilizer HT (High Temperature), ready-to-use,
#RDI-23.31.7 (€250.00/500ml, $400.00/1 Liter ,Bulk on request) will provide
real-time stability for ready-to-use SA-PolyHRP conjugates at +2°C/+8°C and
+18°C/+22°C (room temperature) storage regimens that is comparable or better
than stability with product #RDI-21.17.4 €200.00/500ml). This product will
secure longer stability at higher temperatures compared to product #RDI-21.17.4.
cat#HRP-STAB-2P10X1 €319.00/100ml €1975.00/Liter
-this is also a 10X formulation which can be used with
pre-diluted HRP conjugates but also contains proprietary inert proteins that act
to further stabilize peroxidase conjugates.
Horseradish Peroxidase (HRP) -CONJUGATE
STABILIZER
FORMULATION II (non PBS system)
The major advantage of a liquid HRP-conjugate is it eliminates
the chance for human error when dissolving or diluting the lyophilized or
concentrated conjugate. Adding too much or not enough buffer results in assay to
assay variation. Until now, the disadvantage of this format was the inherent
instability of the liquid HRP-conjugates. This problem has now been addressed!
The HRP-CONJUGATE STABILIZER Formulation II is formulated to
allow you to provide pre-diluted, READY-TO-USE CONJUGATES (in an non/minimal
Phosphate Buffer System).
This product is prepared in a proprietary buffer system and
contains a non mercury containing preservative (no azide, no thimerosal).
cat#HRP-Stab2 READY-TO-USE : This formulation was designed to reconstitute
lyophilized or concentrated HRP-conjugates. Conjugates are tittered and diluted
to working concentrations with the HRP-CONJUGATE STABILIZER II.
Use at full strength or dilute 1:1 with 10mM MOPS Buffer, pH 6.8-7.2 or 0.85%
NACL. The use of Phosphate buffers at more than 10% or 1.5mM Phosphate will
cause precipitation).
See our cat#RDI-HRPSTAB-1X. for our regular formulation.
Store at 4 DEG C and protect diluted material from light.
Conjugates prepared in this manner will maintain HRP activity for up to 2 years
at 4 DEG C. (actual time must be determined with your particular conjugate and
assay characteristics).
CAT# RDI-HRPSTAB2 =€475.00/Liter
€444.00/Liter for 5-9
liters
€425.00/liter 10-20
Liters
Please allow 2 weeks for delivery on multi-liter quantities (to
ensure product from same production lot!).
You should titer your conjugate with each batch.
Minimize the number of times you open and close the bulk stabilizer bottle. Try
to maintain aseptic techniques. Ideally, sterile filter your conjugate prior to
addition to the stabilizer (or after dilution for maximum stabilizing effect).
FOR RESEARCH OR FURTHER MANUFACTURING USE ONLY.
Technical Recommendations for HRP
Stabilizing Solutions:
You should titer your conjugate with each batch. Our testing
shows you may need slightly more of your conjugate but the long term stability
of the "working conjugate" makes for a much more reproducible product.
Minimize the number of times you open and close the bulk
stabilizer bottle. Try to maintain aseptic techniques. Ideally, sterile filter
your conjugate prior to addition to the stabilizer (or after dilution for
maximum stabilizing effect). DO not Sterile filter POLY-HRP products, maximum
filtration at 1.0 microns. Package diluted conjugates in oxygen barrier bottles
(PET or brown glass lyophilization vials with stoppers and tight caps). NOTE:
Stability of HRP conjugates is prolonged by keeping conjugates cool and reducing
exposure to light and oxygen. Thorough vacuum degassing with nitrogen flushing
of all buffers, conjugates and diluents will extend diluted conjugate stability
under severe conditions.
Our primary formulation of HRP Stabilizer is a proprietary formulation made with
certified reagents under a standardized GMP production protocol. I regret that I
cannot give you any additional details on its preparation or formulation,
howvere it is a PBS buffer based system. For those assays that might owrk better
with non PBS based buffers, see our HRP-STAB2 (Formulation II).
As for validating an extended stability with such a product, this is also too
dependent on the product to give you much information. However, the following is
a "SAMPLE" protocol of process that must be investigated for using such a
product.
1) You should first titer your conjugate with the HRP stabilizer (full strength
or 1:1 with sterile degassed bufer) to obtain a working dilution. Generally, you
will need approx 10% more conjugate initially than if used with a standard
buffer diluent.
2) Then , you should sterile filter the conjugate (if possible, or 0.45 micron
filtration with our POLY-HRP products) and add it to the stabilizer. If you have
the capabilities and you have a very unstable conjugate, you may also wish to
add the components, mix in a teflon, glass or plastic (not metal) lined
container under a nitrogen atmosphere. Degas with 3 or 4 flushes of nitrogen. DO
NOT agitate or mix vigorously in a regular air atmosphere. Keep mix at 4 DEG C
or lower during process.
-if you conjugate is susceptible to bacterial decay, you can add additional
thimerosal or other non azide preservatives as desired (as our
microcide I).
3) Bottle the cold, diluted material with nitrogen pressure or gravity fill into
pre-chilled low oxygen transfer bottles. Ideally, brown borosilicate glass with
stopper and screw cap or tight crimp seals. Also good is PETE type cell culture
bottles (which have low O2 and CO2 transfer).
4) Stability testing: The only truly applicable method is real time studies in
various packages at your intended storage conditions 4-8 DEG C. One generally
would perform 24 hours at 37 DEG C and then 24 hours at 20 DEG C and then
regular store at 4-8 DEG C (this simulates generally shipping conditions of one
stressful day in a delivery truck, one day waiting for receiving to put kit in
refrigerator and then the remaining time for storage as needed).
5) Some initial accelerated stability testing can be performed to stress the
conjugate and see if any changes in packaging methods will have an effect. These
include the following: a) make up 16 bottles each of your conjugate ( 8 in the
stabilizer, and 8 in your regular assay buffer or HRP diluent).
Before bottling, remove enough to run your assay (to set baseline
characteristics).
Additional bottles may be made if your decide to test different packages (ie,
glass versus plastic etc). Each bottle MUST be made up to the volume intended
for final use so that head space/void space is at actual dimensions.
b) Place Two sets in 37 DEG C bath, two at room temp, two at 4-8 DEG C and two
at -20 DEG C (to study frozen effects long term).
c) Each 24 hours, open one designated set, remove only enough to run a standard
curve . Close vial and place back in designated temp. Repeat every 48 hours
until such time that the 37 DEG C conjugate looses enough activity to make it
unsuitable for your assay. Then continue testing once per week observing the
room temp studies. At conclusion of study, check the unopened vials and compare
that activity with activity at beginning and from the last of your sampled vials
(this checks to see if some of the additional loss of activity was due to
opening and closing the vials themselves).
As you can see, this requires a comprehensive evaluation. Since there are too
many factors involved, we cannot say what effect any one item might have on the
result. The varied stability/purity of the HRP conjugate itself will have a
great effect on the stability of any stabilizer to be of help. NOTE:The
conjugate stabilizer is formulated to protect the HRP moiety (not the antibody
or any protein bonds).
From various customer response, the combination of our HRP-STAB-1X and our TMS-S
has made for a very stable and well received assay.
