The gas orifice is at the center of the face of the nebulizer. It is machined directly in the Teflon® body which is VERY SOFT. This orifice is very easily damaged and should NEVER be touched with fingers, tissues, or anything else. The only major caution on a Legere Nebulizer is DO NOT TOUCH THE FACE. If the orifice is accidentally touched, and the nebulizer continues to operate, then it is still functional, and its use can be safely continued.
2. Dropping and Breakage
The Burgener Legere Nebulizer body is 100% Teflon® . If you drop it, it may be dented where it hits. If you dent the body of the nebulizer, it will not effect its performance. If it is dropped such that the face is damaged, then it will be irreparably damaged. If it continues to operate after being dropped, then it has not been affected, and its use can be safely continued.
Your new Legere Nebulizer is unique. It should give you a long and convenient service on almost any liquid you can pump to it. The operation and care of your nebulizer is different from glass nebulizers in several important ways.
1. Starting Your New Legere Nebulizer
Legere Nebulizers are made of 100 % Teflon. Teflon is non-wetting, which prevents any buildup of salts around the sample or gas orifices. However, the non-wetting nature of Teflon also prevents smooth flow of water or aqueous solutions and can cause the solution to travel away from the gas orifice. Once the nebulizer is wet, the solutions will flow perfectly for many months or years. A new Legere nebulizer will have dried during shipment, and may need to be "Started" by gently wiping a wet piece of Kleenex down the face of the nebulizer while you are pumping water and running the Argon. A spitting nebulizer is usually DRY. Generally, the nebulizers will start themselves if in a chamber. They spit at first, but get wet after a few seconds, and then create a proper mist. If after a few minutes of running in the chamber, it is still spitting, then try the gentle wipe with a wet Kleenex.
They have a tiny gas orifice (4/1000 inch diameter). This allows for the use of higher pressures, and produces the fine mist. However, the tiny holes can be easily plugged from the inside. This form of plugging can stop up to 1 in 5 nebulizers in the first few hours of operation. If your nebulizer does not operate properly during the first trials, it may be plugged by dust, and should be returned for replacement.
Note: The face of a new Legere Nebulizer is etched with graphite to help it wet and minimize the drop buildup on the face during operation. This etching produces a gray color ranging from light gray to black. The gray color decreases with usage, but the etching effect remains. Please do not try to wash off the gray color upon receipt of the nebulizer.
2. Gas Line Fittings
Your Legere Nebulizer is supplied with a nylon gas line fitting, with a 1/4" swagelock for the gas line. Nylon does not corrode as easily from acid fumes as brass, but for some gas line types, a brass fitting may be necessary to hold tightly enough. In many cases, you can use a brass nut and ferules on the nylon body. First attach the brass nut on the gas line: 1.25 turns after finger tight. Then finger tight or finger tight plus 1/4 turn with a wrench to attach to the nylon body. Brass fittings are available from Burgener Research & other sources. Note: Gas leaks around the gas line fittings will degrade the performance of the nebulizer. Be sure that all connections are tight.
3. Washing Your Nebulizer
Please DO NOT wash your nebulizer in acid or solvents to 'prevent salt build up'. Teflon doesn't wet. So Salts do not form. For the longest life and best performance, wash your nebulizer by simply running water as a sample for 10 minutes at the end of the day before turning your spectrometer off. Any other form of washing is excessive, unnecessary, of no advantage, and often detrimental.
4. Optimum Gas Flow Rate & Pressures
Legere Nebulizers will operate safely at pressures up to 150 psi. Higher pressures produce finer mists, and larger Argon flow rates. The normal pressure will be 75 to 120 psi, depending on the optimum volume required by the spectrometer. Test it at various pressures to optimize. An initial pressure can generally be found by observing the central channel of the plasma while aspirating a solution of 1,000 ppm Y. Adjust the pressure until the red tongue is just level with the upper turn of the work coil. This is easy to observe with a relatively new torch, but, once the torch becomes discolored, it may be difficult to see this tongue. In this case, there is little alternative but to begin at 50 psi and increase until the best precision is found.
5. Sample Uptake
Normally, 0.5 - 2 ml/min seems to work best. You may pump faster, (4 or 5 ml/min will not harm the nebulizer), but there may not be increased signal, & you may drown the torch. For lower pressure settings, an Increase in sample rate may improve %RSD. Some liquids may work well at higher or lower pumping rates.
6. Humidified Argon
The Legere Nebulizer is 100 % Teflon®. Teflon doesn't wet, so salts do not begin to form at the gas orifice. This allows you to run high salts without the tip plugging. It also saves you the nuisance of having to run Humidified Argon to the nebulizer. You may use humidified Argon, but it will not improve the nebulizer's performance.
7. Using Surfactants
Legere Nebulizers do not pulse unless the pump tubing is very poor. If you are getting pulsations, you should change the peristaltic pump tubing first. DO NOT soak the nebulizer in surfactants to decrease any pulsing. You may succeed, but the surfactant will also allow salts to form at the gas orifice, and plug the orifice.
Many chambers have baffles designed for nebulizers that extend a shorter length into the chamber. You may have to move the baffle farther into the chamber, or you may require a different style of chamber. A baffle too close to the nebulizer catches fine and coarse mists, and severely degrades the nebulizer's performance.
9. Adjusting your Plasma Height
The Legere Nebulizer will produce excellent mists over a large pressure range. You can adjust the plasma height by varying the nebulizer pressure, with little change in sensitivity due to the nebulizer.
10. Nebulizer Orientation
Burgener Legere Nebulizers are designed to use gravity to help the flow of the sample down from the sample capillary tube to the gas orifice. However, most Legere Nebulizers will operate in other orientations besides sample capillary at the top. Some will operate 'upside down' for some liquids, and some are reported to work better upside down. It may be difficult to start a Legere in an orientation different from sample capillary at top. In general, use whatever orientation works best for your system and samples. The nebulizer will not be harmed by being operated in different orientations.
How to replace the capillary tubing:
Clearing and Replacing the Capillary Tubing
The Burgener Legere Nebulizer is designed with a Bavington 'V' groove configuration. The only portion of the sample path that is actually part of the nebulizer is at the front. It will not plug with dust or sand or other tiny particles. However, the capillary tubing may occasionally plug. Generally, the capillary tubing plugs at the joint between the pump tubing and the capillary tubing. To clear such a plug, just cut off 1 mm of the capillary tubing closest to the pump, and use it again. For plugs in the middle of the tubing, or eventually, if the tubing is getting too short, you will have to replace the capillary tubing.
TO REPLACE THE CAPILLARY TUBING:
1. Pull out the old capillary tubing. It is just held in place by tension.
2. Take a piece of new tubing, e.g. Polyethylene Tubing, with O.D. 1.09 mm (0.043 "); I.D. .38 mm (0.015 "). Measure out the desired length (About 15 " or 38 cm).
3. Wrap it around your fingers and stretch out about 4 inches to about 1/2 its original diameter.
4. Push the stretched portion through the Nebulizer's sample path until it extends out past the end of the nebulizer. Use the stretched portion to pull unstretched tubing past the tip of the nebulizer.
5. Cut off the stretched portion. Pull back the unstretched portion, until the tubing is recessed about .25 " (about 6 mm) from the tip. The distance of the recess is not critical, as long as it is about .25 " or more.