Can the Dispensette® dispense _________?
With the addition of the Dispensette® Organic and new Dispensette® TA, the Dispensette line of dispensers can now dispense nearly any laboratory chemical. The notable exceptions are:
NaN3 (sodium azide): Found in many biology labs, and used as a preservative for buffers. It removes the fluorine in PFA, FEP, Teflon and other Teflon-like materials. It also attacks these materials in almost any other bottle-top dispenser using these materials. You should consider our seripettor® bottletop dispenser, which is resistant to sodium azide. Because sodium azide is often used in solution with other chemicals, confirm the compatibility of all components of the liquid before use.
Br (Bromine): Bromine is too dense to be dispensed by a Dispensette®.
Carbon Disulfide (CS2): Carbon disulfide presents an explosion risk, and should never be dispensed by a Dispensette®.
Suspensions: The Dispensette® should not be used to dispense liquids that contain particles, as they will clog or damage the insides of the instrument.
Physical Limitations: Any liquid that has a density of over 2.2 g/cm3 can not be dispensed by the Dispensette® III or Dispensette® Organic, as it will be more dense than the borosilicate glass filling valve, and the ball will float, preventing it from closing.
Temperature of 59°F to 104°F (15°C to 40°C) for instrument and reagent. Temperatures of up to 250°F (121°C) will not damage the Dispensette®, although some of the materials may get soft enough to get damaged by use at these temperatures. The major consideration for hot applications is that liquids dispensed at higher temperatures, like agar, usually are done so because the liquid becomes less viscous at these temperatures. When the liquid cools, these type of liquids can clog the Dispensette®. A customer may try these temperatures, but at their own risk, as it will void the warranty. For dispensing agar, we recommend our seripettor® bottletop dispenser.
Viscosity over 500 mm²/s. Liquids that are too thick will tend to clog the Dispensette®, impair valve function, piston movement, etc.
Vapor pressure over 500 mbar (375 torr) or extremely volatile liquids. Liquids that have a high vapor pressure tend to vaporize inside the dispenser, causing liquid to flow out of the dispenser even when the instrument is not being operated. A common volatile liquid is Acetone (aka "Nail Polish Remover") which has a vapor pressure of 184 mbar at room temperature, and will work fine. Diethyl ether has a vapor pressure of ~450 mbar at 20°C, so can be dispensed with a Dispensette®, but it would not be recommended if the room temperature was significantly higher.
The Dispenser selection chart listing many commonly used laboratory liquids can be found in the BrandTech catalog, or on our website: click here.
What is the difference between a Dispensette® III and a Dispensette® Organic?
The Dispensette® Organic has much in common with a Dispensette® III, however there are two major differences. The Dispensette® Organic has a glass piston, rather than a PFA-coated piston. This optimizes it for use with concentrated acids and organic solvents that can interact with the PFA, but makes it less useful for bases. In addition, the valve spring was changed in the Dispensette® Organic to tantalum (from platinum-iridium alloy) to allow it to be used with peroxides, again, at the expense of compatibility with bases. Because of the different construction and chemical compatibility, parts from a Dispensette® III should not be used with a Dispensette® Organic, and vice versa.
How do I clean my Dispensette®?
Cleaning instructions are located in the manual. If you do not have a copy, click here for the electronic version. All current Dispensette® models disassemble easily for cleaning.
My Dispensette® seems to leak at the base, especially after priming. How do I stop this?
It's probable that the recirculation tube was not reinserted into the underside of the instrument. This directs liquid down the side of the bottle, to help keep from generating additional bubbles when priming. When absent, some liquid can dribble down the side of the instrument. If you need a replacement, the part number is 8317 and can be ordered from your favorite supplier.
I broke my piston or cylinder. Can I purchase a replacement?
Unfortunately, the piston on a Dispensette® is matched to the cylinder to very close tolerances at the factory. This is so that the instrument can have smooth one-handed operation without the need for a seal. However, this makes piston replacement impossible. If you break either your piston or cylinder, call Customer Service (888.522.2726), and ask about our Exchange Program.
The piston of my Dispensette® is moving roughly. What should I do?
Crystals have probably gotten between your piston and cylinder, and are grinding away the piston and seal. (If the instrument has been operated in this condition, it is possible that the piston and cylinder are scored. To avoid this happening, the Dispensette® should be cleaned at the first sign of roughness.) Gently remove the piston, and follow the cleaning procedure as described in the manual. Retry the dispenser. The best way to avoid this issue is to clean your Dispensette® at regular intervals. Continued use of the dispenser in this condition can destroy it.
The cylinder of my Dispensette® doesn't fill. What is happening?
There are several different causes that could keep a Dispensette® cylinder from filling: 1) The discharge tube and/or SafetyPrime™ valve are not fitted properly. Check to ensure they are attached properly, and that the sealing washers are in place. 2) The filling valve is not tight or the filling tube is not pushed in enough. Recheck the connections. 3) The filling valve is dirty. This case can be determined easily because the Dispensette® piston will be difficult to lift, and it gets "sucked back down" when released. Clean the valve.
My Dispensette® is drawing up bubbles and liquid? What should I do?
Your Dispensette® has an air leak somewhere. Good places to look are at the junction of the filling tube and filling valve. If it does not make a tight seal, trim some of the tube off, and reattach. Check to see if the filling and discharge valves are tight, and the sealing washers are in place. If the Dispensette® was dropped the cylinder may have cracked, or come loose from the valve block (unrepairable). Lastly, is there any liquid in the bottle?
What size adapter do I need for this bottle?
It's hard to say definitely without seeing the bottle. Most 1 liter and 1 quart bottles in the United States have a 33mm thread. Most 4 liter or 1 gallon bottles in the US have a 38mm thread, as do many scintillation fluid bottles. All sizes of the Dispensette® fit 45mm bottles, and come with adapters to fit 33mm and 38mm threads. Smaller Dispensette® dispensers come with additional adapters for smaller bottles.
Why doesn't a Dispensette® come with a bottle?
The Dispensette® is designed to fit onto most common reagent bottles with the supplied adapters, and many additional adapters are available. By mounting the instrument directly onto the reagent bottle, poured transfer, and associated spilling, is eliminated. Additionally, the likelihood that we would be able to guess your preferred bottle is extremely small.
A performance certificate came with my Dispensette®. Is this the performance for my specific instrument?
The Dispensette® is lot tested for accuracy and precision. They are not provided with individual calibration certificates.
Can I use my Dispensette® with a bulk chemical container?
Probably, as long as it's unpressurized. To mount a Dispensette® Organic directly onto the ¾" bung of a chemical drum, order catalog number 704280. A longer filling tube may be required. Order catalog number 704261 for a Dispensette® Organic to remotely dispense from the drum. For NOWPak containers, use catalog number 704284. As each circumstance is different, additional parts may be required.
What is the purpose of the elastomer ring that came with my Dispensette®?
The elastomer ring should be installed if the Dispensette® is autoclaved. It should NOT be installed for general purpose dispensing, as it has limited chemical resistance. Complete instructions are in the manual. If you do not have a copy of the manual, click here for the electronic version.
Are there any precautions I should take when dispensing scintillation fluid?
Many scintillation fluids precipitate in the presence of water. These precipitates can impair the function of the Dispensette®. You should make sure the instrument is completely dry before use. Additionally, in humid climates, it may be necessary to use a drying tube to keep atmospheric moisture from contaminating your scintillation fluid.
What is the function of the drying tube?
When a dispenser dispenses liquid, air needs to enter the container to displace the liquid. If the liquid is sensitive to components in the air, for example, water vapor, a drying tube is recommended, so that an appropriate drying agent can remove the water. BrandTech® does not sell drying agent, only the drying tube.
Why don't you sell drying reagent?
The quantities of drying reagent that we could possibly sell in a year would not be enough to assure that our customers would get fresh reagent at a reasonable price. Drierite is a popular drying reagent available from most laboratory supply dealers.
Is a discharge tube available with a Luer Lock fitting?
A discharge tube with a Luer Lock fitting for the attachment of filters can be ordered as catalog number 707928. This discharge tube is not suitable for peroxides. Care must be taken while dispensing not to create excess back pressure.
What is accuracy, and what is precision?
Accuracy is how close to a desired target value a test result is. Precision is how close a series of test results are to each other.
What do "calibration", "gravimetric testing", and "adjustment" mean?
The word calibration gets used incorrectly quite a bit, even in our own literature (we're working on it). Calibration actually refers to the act of measuring results from an instrument, and determining its accuracy and precision. Gravimetric testing is one method of performing calibration. In the case of liquid handling instruments, it usually means the repeated weighing of dispensed amounts of distilled water (water free of impurities). Distilled water has a defined density at specific temperature and atmospheric pressure. By knowing the mass of water dispensed, it is possible to know the actual volume dispensed, and from that, determine the accuracy and precision of the instrument. Adjustment is the physical changing of the instrument that was calibrated. This can be in two ways. The conventional way is to change the volume dispensed to represent more closely the display. This requires at least two, usually more calibrations. One to check the instrument, another to check the instrument after adjustment, readjustment of the instrument if the first correction was done improperly, and so on. The second way, the way BRAND does it, is to change the display to accurately show the actual amount dispensed. This requires only one calibration, as no physical change is made to the dispensing mechanism.
Does temperature make a big difference in gravimetric testing?
Yes it does. Ideally, calibrations should be done in a climate controlled room. At a minimum, when the calibration is performed, temperature should be recorded with a thermometer having a measuring error of max. ± 0.2°C.
Does atmospheric pressure make a big difference in gravimetric testing?
Not under most cases. EASYCAL™ allows for this to be adjusted for use in extreme cases, or if required by the customer's SOP.
All through the catalog, it mentions that the "Standard Operating Procedure" for instrument calibration is available. How do I get one?
The SOP for the Dispensette® is available here. Additionally, all of the SOP's for BRAND's liquid handling instruments, as well as the BLAUBRAND volumetric glassware are compiled in EASYCAL™ 4.0 for easy reference.