Hello Mary,

I cannot comment on the Vector kit that you use.  I know it's a ubiquitous product line so I'm sure someone will be able 
to address the rapid color change of the diaminobenzidine solution.  I am a bit surprised that Vector Labs suggested that 
you purchase another kit while they perform a quality control check.  I've always known them to be a reputable 
company in the immunohistochemistry world but this "solution" certainly does not help you during a critical juncture in 
your study.  Perhaps you could perform a trial run on a sacrificial specimen to see if the solution is viable.  Since you are 
already dependent on the Vector kit to conclude this particular study, it would appear that you'll have to abide by 
Vector's rules and purchase a new kit.  This is probably done to ensure that someone doesn't siphon off portions of the 
kit to be mixed with other reagents and get a free replacement from Vector.  The manufacturing company wants to 
maximize profits and minimize liability so they want to make sure the whole kit is purchased and not "componentized" 
after the sale.

The new question is...what to do next time?  These ready made kits are a godsend in many scenarios because R&D 
has already been performed to make a staining process more like a cookbook than investigative science.  A great time 
and resource saver when everything is going well.  On the flip-side, you lose some flexibility and can get tied into a 
particular company's reagent product line.  We usually found a combination of approaches to be most beneficial - 
purchase universally applied bulk-rate solutions when possible for the different stages and use a prediluted kit for the 
link-and-label stage.  This process allowed enough flexibility in our protocols to be applied to the detection of many 
different antibodies with some guarantee of consistency.  By getting a link-and-label kit rather than mixing our own, we 
knew some uniformity between lots would exist.

Since you might be changing your source of reagents, I would second Patsy Ruegg's endorsement of Research 
Genetics Stable DAB.  This solution never failed (well, I can't prove a negative so that might be overstated), was easy 
to use, and VERY reasonable compared to the tiny volumes purchased in kits.  Just a great product for DAB peroxidase 
detection.  For the secondary Ab link and label we had great success with DAKO's product line - and more specifically, 
the LSAB2 series.  Entire labeling kits (whole and portions) were available as were large volume, single component 
solutions.  I am no longer in a position to use or need to purchase the DAKO products but their support was excellent.  
The Dallas-Fort Worth (USA) representative was knowledgeable, helpful, and quite accommodating whenever a 
question or problem arose.  If she is representative of the company, you'd do well to stay with DAKO for after purchase 
support if they have the products you need.  (OK DAKO, if you're reading this, please forward my fee to the swiss 
account on record.)  But seriously, they were helpful for us, too. 

Good luck with your interrupted study,
Todd

Todd Sherman
t-sherman@home.com


7/30/2001 3:02:04 PM, "Georger, Mary"  wrote:

>Good Afternoon All,
>I have a question for those of you out there doing Immunos. I am having a
>problem with the Vector DAB kit that I just bought, when you add the DAB
>drops to the buffered double distilled water it immediately turns dark
>brown. This has not happened with any previous kits. To make matters worse I
>am in the middle of a study and hate to risk any study slides with this
>chromagen. I called technical support for Vector and was told I could fed-ex
>back the kit and they would do another QC on it, but in the interim I would
>have to buy an additional kit to finish the work I am in the middle of.
> Now I have been off the bench for 2 years, but it seemed to me that
>previously when there was a question with a reagent the supplier sent out a
>replacement first so that you were not left high and dry. This has still
>been my experience with DAKO, they have been great! 
>My question- Is this type of non-service the hallmark for companies now? 
>I have learned a valuable lessen about who I will buy from in the future.
>Mary Ge