Hi @benjimaruyama, we own one solid dispensing solution and have tried several others. Here are my experiences:
Freeslate / Unchained (currently own)
Pros:
- Good for small masses (as low as 0.5 mg), high precision (as good as +/-0.1 mg, easily <+/-0.5 mg).
- SV system uses small disposable vials (4 ml) so you don’t need a lot of powder
- Plastic SV caps are relatively cheap and don’t have artificial dispense number limits
- Powdernium Classic can be used for larger masses
- Near the top in terms of range of powders dispensed (50-70% of powders)
- Can dispense into microplates or individual vials
Cons:
- Slow. ~1 min/vial, or even slower when learning a new powder.
- Not practical for large masses (>100 mg). Really optimized for the 1-10 mg scale.
- Disposable plastic SV caps can break. If your robot has a service contract, sometimes Unchained will give you free replacements.
- Hoppers have to be stored on the robot deck, which can take up a lot of space (esp. the large mass Classic hoppers).
- Unchained robots are expensive, even at the low end (Junior)
Mettler Toledo Quantos (demo’d)
Pros:
- Accurate dispensing. One of the best powder dispensers, but maybe not as accurate at the low end as Unchained. Precision varies a lot with powders, about +/- 0.3-1 mg, sometimes even 2-3 mg.
- Generally very impressive hardware (hoppers) and powder range (near the top)
- Can dispense larger masses than Unchained
- Hoppers have RFID tags for identification and for remembering trainings
Cons:
- Powder hoppers are expensive, larger than Unchained SV vials. Price per dispense is pretty high (see below)
- Initially, powder hoppers were artificially limited to a set # of dispenses. Apparently things are better now and there are workarounds.
- Cannot dispense into microplates. Mettler only offers a carousel multi vial changer.
- (in Mettler form), have to manually change out hopper
- You can contract with LabMan to integrate a Quantos with a multi-axis robot arm that can automatically change out powder hoppers and sample containers from a hotel (see A-Lab by Prof. Gerd. Ceder). Pricey.
- Quantos price w/ autosampler is also quite high.
Chemspeed (demo’d and input from current users)
Pros:
- Price can get significantly lower than Unchained, although still high
- Negative gravimetric dispenser can move to vials/wells, saving time
- Can dispense quite large volumes decently (100 mg - grams)
- No dispense limits. Hopper heads are not disposable.
Cons:
- Has trouble with a lot of powders – range of powders much lower than Unchained / Mettler
- Cannot dispense low masses (mg), precision is worse than competitors
- Hopper volumes are large (requiring lots of sample).
- Dispense mechanism (screw or whisk) is not as advanced as Unchained/Mettler, prone to jamming, and can leak powder unintentionally.
- If the gravimetric overhead dispenser misses the vial, recorded masses are inaccurate.
- Software is pretty bad.
- Generally, you have to optimize the dispense head and workflow for each powder, which is time consuming.
