GeneQuant-Summary of responses

[John Hachey]

** High Priority **

Herewith are (most of) the responses I got to my enquiry regarding
people's  
experience with the genequant spec. Seeing how it is about half
the price of a  
full-blown spec and all we really would use a spec for is for
DNA/RNA, it may 
be worth putting up with its annoying piccadillios. 
 P.S. All standard disclaimers apply to the folowing replies; and
thanks again  
to all the respondees. -JH 
 
P.P.S. I still haven't made up my mind. 
------------------------------- 
 
From:     Alan Schoenfeld <aschoen at aecom.yu.edu> 
          (INTERNET:"aschoen at aecom.yu.edu") 
To:       DLETHRB.WLETHRB(HACHEY) 
Date:     January 11, 1996, (Thursday) 5:59am 
Subject:  (no subject) 
 
  
HACHEY at EM.AGR.CA (John Hachey) wrote: 
>Subject:  Genequant II-comments? 
 
>We are thinking of purchasing a GeneQuant II unit primarily for 
>DNA and RNA quantitation. 
>Can some owners of this machine share their reviews of this 
>instrument? 
 
 
Our lab has been using a Gene Quant II for a year and a half.  
While the  rest of the lab has no problem with it, I do.  My 
complaints: 
 
1) Can only be used for DNA and RNA (260, 280 nm only; no visible)

2) I have found it to be unreliable when determining
concentrations 
of  plasmids, especially at concentrations above 1 
microgram/microliter;   sometimes I get a reading that is way off 
for no apparent reason 
3) Is awkward to use because you have to insert and remove the 
cuvette  at specific times when the machine beeps; if you're too 
slow, you have  to do it again (sometimes annoying) 
 
It has been useful when quantitating oligos however and the nice 
part  about it is that if you enter the sequence, it figures out 
the molarity  (in picomoles) for you.  This has been fairly 
reliable. 
 
I hope this helps. 
 
                                                       Alan 
 
 
-------------------------- 
 
 
 
From:     Jennifer L. Potter <jras at post.its.mcw.edu> 
          (INTERNET:"jras at post.its.mcw.edu") 
To:       DLETHRB.WLETHRB(HACHEY) 
Date:     January 10, 1996, (Wednesday) 8:35pm 
Subject:  Re: Concealed 
 
  
 
 
Dear John, 
 
We have (I believe) the older version of the Gene Quant II, the 
Gene  Quant.  We use it for both DNA and protein measurements.  As

far as I know, no one in the lab uses the fancy calculator part of

the machine. 
 
A few comments that may or may not be pertinent to the Gene Quant 
II: 
 
The machine is a single beam spec...and therefore has greater 
variability at lower absorbances.  For example, I blanked the 
machine with water and then tested the exact same sample about 10 
times.  The A260 varied  between -0.01 and +0.01.  Our double beam

spec, however, does not deviate in this manner (I am told this is 
an intrinsic difference between single  and double beam specs).  
Comparing highly absorbing samples (>1.0) with  our double beam 
showed the two readings to be identical.   
 
As a personal preference, I really don't care for the way the 
machine beeps at you to tell you when to insert and remove the 
cuvette.  If  you're not alert and focused, you'll be too slow and

it will beep at you again and make you start all over.  Pharmacia 
people use this,however, as a selling point because it conserves 
lamp time. 
 
One other point, our manual did not describe all the different 
functions  and how to use them in great detail.  I'd expect the 
manual for the Gene  Quant II to be better. 
 
I'm sorry I can't fill you in on more detail about the calculator 

function, etc. but hope I've given you some useful information. 
We 
use  ours quite frequently and it has held up fine for the 2-3 
years we've  owned it.  The only down side that I see is the 
variability at low  absorbances...before I actually tested the
same 
sample 10 times in a row,  I kept wondering where my DNA went! :) 
 
Best of luck, 
 
Jennifer L. Potter 
Medical College of WI 
Dept of Biochemistry 
 
 
-------------------------------- 
 
From:     sathish <sathish at biokemi.su.se> 
          (INTERNET:"sathish at biokemi.su.se") 
To:       John Hachey <HACHEY at EM.AGR.CA> 
Date:     January 10, 1996, (Wednesday) 2:58am 
Subject:  Re: Genequant II 
 
  
Hello: 
 
We have been using GeneQuant II from Pharmacia for about 7 or 8  
months.  We have mixed feelings about it.   
 
It is good because: 
1. We do not have to wait for the machine to warm up. 
2. It does most of the calculations, such as picomols, etc. 
3. It is especially useful for quantitating oligos. 
4. People from neighbouring labs also use it. 
 
Some of the negative aspects: 
1. If you have contaminations such as polysaccharides (RNA
preps!), 
     silica (geneclean), etc, the readings may not be true. 
2. The software is designed in a round-about fashion, i.e. one  
   has to push the setup, enter buttons a few times before being 
   able to select DNA/RNA/Oligo, dilution factor etc. 
3. The printer is not included (they gave free printers for a  
   month, a month after we purchased it.  We were not lucky to 
   get one free.  They have still not answered us if we can 
   somehow plug it to our computer network and download the data, 
   either.) 
4. Measuring O.D. from very little volumes is posible only if you 

   are ready to shell out some money for the cappillary cuvettes! 
 
Hope this helps. 
 
sathish http://grolsch.biokemi.su.se/sathish/sathish.html 
 
P.S. GeneQuant is different from GeneQuant II 
 
----------------------------- 
 
From:     Steve Stelman <steves at burn.ucsd.edu> 
          (INTERNET:"steves at burn.ucsd.edu") 
To:       John Hachey <HACHEY at EM.AGR.CA> 
Date:     January 9, 1996, (Tuesday) 1:50pm 
Subject:  Re: Concealed (Genequant II) 
 
  
John Hachey wrote: 
>  > Subject:  Genequant II-comments? 
> We are thinking of purchasing a GeneQuant II unit primarily for 
> DNA and RNA quantitation. 
> Can some owners of this machine share their reviews of this 
> instrument? 
>  Thanks, John. 
 
In short, here are a few of the pro's and con's 
 
Pros: 
-more accurate quantitation than using a spec 
-easier than our fluorometer, which is difficult to zero 
-light source does not need to warm-up before use 
-calculates concentrations based on A260 and A280 in single read 
-has many calculation functions built in 
 
Cons: 
-cuvette not included (expensive to purchase from them) 
-cuvette must be inserted and removed on cue from machine 
   within a few seconds, or reading is aborted. This 
   gets to be REALLY annoying, as you have to hover 
   over the machine with the cuvette waiting for the 
   beep. 
 
Nevertheless, I use this machine regularly as opposed to the 
alternatives. 
      
--  Steve Stelman steves at burn.ucsd.edu 
 
------------------------ 
 
From:     Beverly Steele Allen, Ph.D. <ALLENB at moffitt.usf.edu> 
          (INTERNET:"ALLENB at moffitt.usf.edu") 
To:       John Hachey <HACHEY at em.agr.ca> 
Date:     January 9, 1996, (Tuesday) 11:21am 
Subject:  Re: Concealed 
 
  
We have one as a piece of core equipment (2-3 labs use it) and so 

far, we all love it. It's basically a narrow-range 
spectrophotometer  with a fancy calculator in it; doesn't take up 
as much bench space as  a full-size spec, and calculates your 
recovery or whatever for you. 
 
Good luck, 
Beverly 
    __ 
    ||         Beverly S. Allen          
   ====        Bone Marrow Transplant Program 
   |  |__      University of South Florida 
   |  |-.\     12901 Bruce B. Downs Blvd., MDC 19 
   |__|  \\    Tampa, FL  33612  (813)979-3960 
    ||   ||    allenb at moffitt.usf.edu 
   =====__|    My .sig is a .glock 
 ________||__  Grand piano + mineshaft = C# or Bbmin    
/___<><______\  
 
----------------------- 
 
From:     Beverly Steele Allen, Ph.D. <ALLENB at moffitt.usf.edu> 
          (INTERNET:"ALLENB at moffitt.usf.edu") 
To:       DLETHRB.WLETHRB(hachey) 
Date:     January 9, 1996, (Tuesday) 11:33am 
Subject:  Genequant 
 
  
PS.-Saw a posted reply about the genequant being quirky--so was 
ours,  until we plugged it into a surge-suppressor.  It was giving

us really  wierd and irreproducible readings one day while plugged

into the  recepticle that was running a thermal cycler.  Noticed 
that when the  thermal cycler kicked on, the genequant went 
squirrelly.  No problems  with reproducibility after putting the 
genequant plug into the  computer's surge suppressor outlet. 
 
No connection with whomever sells the thing! 
Beverly 
    __ 
    ||         Beverly S. Allen          
   ====        Bone Marrow Transplant Program 
   |  |__      University of South Florida 
   |  |-.\     12901 Bruce B. Downs Blvd., MDC 19 
   |__|  \\    Tampa, FL  33612  (813)979-3960 
    ||   ||    allenb at moffitt.usf.edu 
   =====__|    My .sig is a .glock 
 ________||__  Grand piano + mineshaft = C# or Bbmin    
/___<><______\  
 
-------------------------- 
 
From:     <Jfloring at aol.com> (INTERNET:"Jfloring at aol.com") 
To:       DLETHRB.WLETHRB(HACHEY),GW1.INTERNET("methods-and- 
Date:     January 9, 1996, (Tuesday) 10:36am 
Subject:  Re: Genequant 
 
  
Re:  Genequant:  Ours was covered with graffiti within a month,
and 
despised. 
 We did use it, but only when it wasn't important.  It's 
inaccurate, and liable to freakouts.  You can't really control 
anything.  Arghhhhhhhh!!!  The memory is painful! I use the spec, 
now, for everything. 
Cheers, Jeanne (happily genequantless)