Care of ICP-MS Cones

When to clean

The frequency at which the cones are cleaned depends very much on the application and the workload of the instrument. If the samples are clean and the usage is low, the cones may only need cleaning monthly. But if the instrument is in continuous use and/or the samples contain high levels of dissolved solids or are highly corrosive, the cones may need cleaning daily.

The cones should be cleaned if there are visible deposits near the orifice or if the orifice is blocked or distorted. Deterioration in the performance of the ICP-MS can also indicate that the cones may need cleaning. In particular, watch for increased background signal, memory effects, loss of sensitivity or distorted peak shapes. A change in the instrument vacuum reading can also be an indication of cone problems. If the orifice gets blocked, the vacuum will increase (pressure decrease), although there will usually be a deterioration in performance before this point. If the vacuum decreases (pressure increases), this could indicate that the orifice is worn and has increased in size. If this happens the cone needs to be replaced.

The sampler cone, being exposed to the plasma, will usually need cleaning more often than the skimmer cone. If the performance of the instrument does not recover when the cones are cleaned, then you may need to replace them.

What to use

The method of cleaning will also depend on the application. If the samples are relatively clean, a gentle cleaning process will be sufficient. But, if the samples contain high levels of dissolved solids or are highly corrosive, a more aggressive cleaning procedure will be required. A Citranox solution is a gentle and effective cleaning agent and we recommend that it be tried first. If Citranox is not effective, it may be necessary to use a more aggressive cleaning agent such as nitric acid. However, we recommend that nitric acid not be used unless it is necessary. Nitric acid is more corrosive than Citranox and prolonged use will reduce the lifetime of the cones. Note that even Citranox will attack copper cones so the cones should not be exposed to high concentrations of Citranox or exposed for long periods. When cleaning cones which have a screw thread, be particularly careful that the thread is not contacted by nitric acid. Pre-soaking the cones in a detergent such as Fluka RBS-25 (P/N FLUKA25) prior to cleaning with Citranox or nitric acid will help the cleaning process. Citranox is manufactured by Alconox Inc. (www.alconox.com) and Fluka RBS-25 by Sigma-Aldrich. Both are available from most suppliers of laboratory chemicals.

How to clean

WARNING: Always use safety glasses and protective gloves. Be careful when handling the cone the tip is very easily damaged. Hold the cone by its edge and only use light pressure with your hand when cleaning the tip. Never use tools for cleaning cones.

The cleaning process does not necessarily need to reproduce the original as-new polished appearance. Sample deposits need to be removed, but it is not usually a problem if the cone is discolored. This may actually result in a more stable signal.

There are three common methods of cleaning cones. From the simplest and gentlest to the most thorough and aggressive, these are:

A. Soak in Citranox - daily or weekly, depending on application:

  1. Soak the cone overnight in a 25% solution (4x dilution) of Fluka RBS-25.
  2. Rinse with deionized water.
  3. Place the cone in a 2% Citranox solution and soak for about 10 minutes.
  4. Wipe with a soft cloth or Kimwipe dipped in the Citranox solution.
  5. Wash thoroughly with deionized water.
  6. Place the cones in deionized water and soak for 2 minutes to remove any residual Citranox.
  7. Replace the deionized water and repeat Step 6 at least twice, ie. the cones should be washed at least 3 times, using fresh deionized water each time.
  8. Rinse with deionized water and allow to dry or blow-dry with clean argon or nitrogen. Make sure the cones are completely dry. It may help to heat them in a laboratory oven at about 60C.

B. Sonicate in Citranox - daily or weekly, depending on application:

  1. Soak the cone overnight in a 25% solution (4x dilution) of Fluka RBS-25.
  2. Rinse with deionized water.
  3. Be very careful to avoid damaging the cone tip. The cone should not be placed in the ultrasonic bath without being supported or contained. One way to avoid damage is to place the cone in a ziplock plastic bag half filled with a 2% Citranox solution and float the bag in the ultrasonic bath. Ensure that the bag is floating so that the cone is not resting on the bottom or touching the walls of the bath. This also minimizes the volume of Citranox used since the bath can be filled with water.
  4. Sonicate for 5 minutes.
  5. Wipe with a soft cloth or Kimwipe dipped in the Citranox solution.
  6. Wash thoroughly with deionized water.
  7. Replace the Citranox with deionized water and sonicate for 2 minutes to remove any residual Citranox.
  8. Replace the deionized water and repeat Step 6 at least twice, ie. the cones should be washed in the ultrasonic bath at least 3 times, using fresh deionized water each time.
  9. Rinse with deionized water and allow to dry or blow-dry with clean argon or nitrogen. Make sure the cones are completely dry. It may help to heat them in a laboratory oven at about 60C.

C. Sonicate in nitric acid - weekly or monthly, depending on application:

  1. Soak the cone overnight in a 25% solution (4x dilution) of Fluka RBS-25.
  2. Rinse with deionized water.
  3. Be very careful to avoid damaging the cone tip. The cone should not be placed in the ultrasonic bath without being supported or contained. One way to avoid damage is to place the cone in a ziplock plastic bag half filled with 5% nitric acid and float the bag in the ultrasonic bath. Ensure that the bag is floating so that the cone is not resting on the bottom or touching the walls of the bath. This also minimizes the volume of nitric acid used since the bath can be filled with water.
  4. Sonicate for 5 minutes.
  5. Wipe with a soft cloth.
  6. Wash thoroughly with deionized water.
  7. Replace the nitric acid with deionized water and sonicate for 2 minutes to remove any residual nitric acid.
  8. Replace the deionized water and repeat Step 6 at least twice, ie. the cones should be washed in the ultrasonic bath at least 3 times, using fresh deionized water each time.
  9. Rinse with deionized water and allow to dry or blow-dry with clean argon or nitrogen. Make sure the cones are completely dry. It may help to heat them in a laboratory oven at about 60C.

The recommended concentrations of the Citranox and nitric acid, and the wash times, should be used as a guide only. Given the wide range of ICP-MS applications, you may need to experiment a little to find the best cleaning procedure for your application. We recommend that you do not use nitric acid any more than is necessary since it will attack the cone materials. If nitric acid is used excessively, the size of the cone orifice may be increased. If this happens, or if the tip is damaged or deformed, then the cone needs to be replaced.

ConeGuard Thread Protector

When cleaning cones which have a screw thread, it is important that the thread is not contacted by any corrosive solution. If the thread gets corroded, the cone may not seal correctly or it may bond to the base and be difficult to remove. And with Pt cones, the thread is likely to wear out before the Pt insert. The ConeGuard Thread Protector seals the thread and protects it from corrosion during the cleaning process.
See ConeGuard Thread Protector for details.

ConeGuard with Agilent Sampler Cone

Platinum Cones

The cleaning procedures outlined above can be used for platinum cones as well as nickel cones. Since platinum is more chemically resistant than nickel, platinum cones can usually be used for longer before they need cleaning. Platinum cones consist of a platinum insert in a nickel or copper base, so aggressive cleaning solutions still need to be avoided as they may attack the base. Platinum cones also run hotter, which helps slow deposition. The lifetime of a platinum cone is typically much longer than that of a nickel cone, and can be further extended by refurbishment.

We offer free refurbishment on the platinum cones that we sell for the life of the cone. Note that, if the orifice is worn to the extent that the diameter is outside specification, or if the tip is badly damaged, the cone may not be able to be refurbished. In this case, we will give a credit for the value of the platinum.

Please contact enquiries@geicp.com if you have any questions regarding the care of your ICP-MS cones.

Customer comments

We use tons of GE stuff in our lab. I am very satisfied with everything, especially the ICP-MS cones we recently purchased. Keep up the great work!

Nutritional science laboratory - USA

Thank you so much for repairing our 2 skimmer cones. I was so happy when I received those two repaired skimmers, shiny like brand new. Thank you!! Everyone in the lab actually impressed by the work and this service. We all think this service deserve a star, and a thanks card.

Clinical laboratory - Australia