ecolog-l:
Thank you for the helpful responses to my query on tissue grinders and
mills. The replies were diverse and highly creative, so rather than a
summary I've created a digest. Since most replied off-list I've dropped
the contact info from senders. Along with votes of confidence for
various models off the shelf, two intriguing ideas were: 1) paint
shaker, and 2) used hardware via an online trader, to try several models
on the cheap. Notably, no one recommended a Wiley mill - what's wrong
with a 2cm blanket of organic dust coating the lab??*
(*individual results may vary)
Best regards,
Dan Gruner
Original post, with wig-l-bug model # revised:
We are looking into tissue grinders to homogenize a range of plant and
animal tissues for nutrient & isotope analyses. We know of strong
alternatives for single samples on the low cost end of the scale
(below), but we are interested in units that can simultaneously
process multiple samples of variable mass (mg to g). Preferably, small
samples could be homogenized and stored in the same vials, to avoid
the extra time and error associated with subsampling, transfer loss,
and frequent cleaning.
Single sample mills, in the range of $800-$1200:
Analytical Mill (Cole-Parmer, 04301-00)
ShakIR (Pike, 161-1070)
Wig-l-bug (ICL) ** NOT the digital models -- either model 3110-3A or 3B
For example, the Retsch Ball Mill MM301 will do everything we need (up
to 20 samples at a time), but it is on the high end for cost ($8-10K,
plus accessories). We would welcome testimonials about ball mills or
other equipment that you've used and would recommend, particularly
those that split the difference in cost.
Please reply to me and I will compile a summary.
Dan Gruner
#########
I've been happy with the SPEX6870. I use a cryo-grinder for stable
isotope and metal analysis. I have ground everything from muscle,
inverts, soil, plant, and whole chicks (sorry). The cro-grinder really
gives you the best homogenous grind.
#########
In our labs one of my friends came up with the idea of paint shaker
along with grinding balls. He got old paint shaker with two arms each
for 1 gallon paint bucket and now we use it to grind and homogenize
large quantities of samples by number and volume of biomass, soil etc.
for analysis in this paint shaker. In this case you can load big
containers for big samples, or small containers but multiple number into
the box (I use sometimes carton box) organize them, pack tightly and put
into each sample container from 2 to 4 balls or more especially if that
will be bigger container. Then all what is left to figure out how long
you will need to shake it. For instance from my experiences I was able
to grind 200 samples of broad leaf and needles pack into 2ml vials with
two stainless steel balls within couple of hours. I used the same vials
for storing and sub-sample for nutrients analysis. It saved me tons of
work time and giving the fact the we got that shaker for free if I
remember correctly I believe it is way to go.
Although, smaller samples need less time and are easier and big sample
especially woody needs to be still pre-grind.
#########
Dan, not sure how many samples you are trying to run at a time or the
upper end of sample weights but I have had good experiences with the
Qiagen tissuelyser II. It is expensive (~$10K) plus the price of the
adapter kit for doing two plates of 24 or two plates of 96 ($700-900).
This product is capable of turning a few grams of plant material into a
fine dust in a few minutes. The beads can be re-used after autoclaving
and you have bead options (tungsten carbide, glass, etc) and the racks
of 2mL tubes are suitable for storing samples after disruption. The
drawback is that these tubes get clogged when using more than a few
grams (~3-5g depending on plant) of plant material. I cannot attest to
their efficiency for grinding insects but based of the job it does to
tough plant tissue I imagine insects don't stand a chance. The benefit
is that it is super quick and can disrupt 192 samples at once.
##########
Our lab recently finished a large project (soil and plant tissue for CN
and 15N analysis), largely dividing our samples between two methods:
large woody samples (>2g) on the Spex 8000D, and small samples and
leaves rolled in vinyl scint vials loaded with steel balls, then packed
in coffee cans set on roller mills--48 samples per can, three cans per
roller. The latter method was cheap, but took up to 7 days to process
144 20mL vials, some of which contained one large sample portioned into
many vials. The Spex Mill, though fast, sometimes heated the samples to
the point of burning them, and our machine, which was loaned by another
lab, broke down in the middle of our project and needed an overhaul.
After the overhaul I tried running smaller samples on the Spex mill
using small steel canisters and a holder we purchased for that purpose,
but the really small samples tended to burn and stick to the sides of
the canisters, and the canisters themselves sometimes shook out of the
holders. The 8000D is really best for large samples, woody material and
soils.
I also found that samples <0.1g were best done by 2 very dedicated and
patient undergrad students using a mortar and pestle and elbow grease.
Each of them spent about 10-15 hrs/week at $10/hr for two semesters
working for us. They not only ground the tiniest samples by hand but
they took charge of organizing all samples and running and
troubleshooting the Spex, which itself was worth the cost of hiring them.
#########
We made a "roller grinder" that could process several dozen fairly large
samples of dried leaves or soil simultaneously. The basic idea is to
have your sample in a sturdy glass jar (c. 100ml) that is rolled on its
long axis. A metal grinding bar inside gradually breaks up the material
as it tumbles 1000s of times over a period of a day or so.
The drive mechanism was a low RPM motor that turned some long rollers,
suspended between which were the jars. Maybe you can visualize it, don't
think I have a photo. Might be able to dig up the plans for this thing,
which I believe was retired a few years ago for lack of use. It was a
good approach for the sample materials we were using.
#########
Have you thought about buying a used machine? I bought a Mini-Beadbeater
(BioSpec products Inc., OK, USA) from Hitechtrader.com and have used it
for 4 years without problem. It was only $200.
http://www.hitechtrader.com/listings.cfm?show=1&CatID=2266
<http://www.hitechtrader.com/listings.cfm?show=1&CatID=2266>
##########
I have been using a spex mixer/mill I think the D version. It has two
chambers and I have 2 extra so I can cycle through samples "fairly"
fast. This can handle wood samples which others I looked at could not. I
bought it for $8000 so pricey. After 3 years, our motor just blew and we
have it limping along.
#########
I analyze mainly plant and soil samples. I've had excellent experience
from the Cianflone ball mill. This is better for larger samples, and it
does 3 at a time.
##########
I have the Retsch Ball Mill that you refer to and it is AWESOME! I got
mine w/ all of the accessories (the 20 sample holders and balls) and
shipping for $8493 (they worked with me on the price so call a Rep to
see what they can do). I love it. And I think that in the long run it
pays for itself in under a year (actually a month by the calculations I
did when I was trying to decide what to get - see below).
I know from too much experience that I can do 12-15 plant samples in an
hour on the wiley mill (grinding sample, vacuuming it all out, resetting
for next sample = about 5 minutes per sample, 3 if I'm really cooking,
but most undergrads it takes 5 or more b/c they dont' really care how
long it takes since they are getting paid by the hour. So let's say
that a motivated undergrad can get through 12 in an hour). You can get
through 20 in 5 minutes on the Ball mill (2 minutes of grinding, about a
minute to put in the balls and about 2 minutes to take all the balls
out). So in an hour, a motivated undergrad can get through about 240
samples. Let's even say the student is slow and takes breaks - they can
get through 200 in an hour easy. 200-12 = 188 extra samples that one
student can get through in an hour. So you would have to pay an
undergrad about 16 more hours to grind the same amount on a Wiley as on
a Ball grinder. If you consider that you pay students about $10/hour
that is $160 to grind the same amount of material. So doing the
calculations that way I figured out that the ball grinder paid for
itself in only 40 hours of use ($6500 difference in price divided by
$160 extra to pay students to do same amount as ball grinder in 1 hour =
40 hours of ball grinder use).
We've found that some samples, like roots, can take more like 20-30
minutes to grind up. But beauty of a ball grinder is that it's doing
this all by itself so when my students are grinding roots, they just
move over and roll samples for a half hour and then switch out the samples.
The other thing that I love about my ball grinder is that you don't need
very much sample and you don't lose any of it - so we can just collect
small amounts from the field, which makes everything so much easier.
### end ###
--
Daniel S. Gruner, Assistant Professor
Department of Entomology
4112 Plant Sciences Bldg
University of Maryland
College Park, MD 20742 U.S.A.
(o) 301-405-3957 (f) 301-314-9290
[email protected]
http://grunerlab.umd.edu
