ICP-MS USER GUIDE

FOR X-SERIES UNIT IN LAB 236

THIS DOCUMENT IS A WORK IN PROGRESS MAY

CHANGE OFTEN. - DON

Table of ContentsStarting and Stopping the ICP-MS...................................................................................... 2

INSTALL TUBING ON PERISTALTIC PUMP........................................................... 4RESOLVING PROBLEMS.................................................................................................7

PLASMA LIGHTS, BUT DOES NOT STAY ON FOR SOMETIME..........................9SHUTTING DOWN..................................................................................................... 10

SHUTTING DOWN THE VACUUM PUMP FOR ICP-MS........................................... 11MAKING A NITRIC ACID DILUTION.......................................................................... 12MIXING A 10 ppb TUNE A DILUTION......................................................................... 14CLEANING THE CONES WITH ULTRASOUND.........................................................16TAKING THE COVER OFF OF THE INSTRUMENT...................................................17OTHER GENERAL TIPS AND GUIDELINES ..............................................................18

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STARTING AND STOPPING THE ICP-MS

TURN ON THE ARGON1. Turn the Argon gas valve on. The pressure on the secondary lower

pressure regulator will need to maintain at ≥85 psi to light the plasma.

Note: To check whether the pressure is correct, turn off the argon to the regulator if it is connected. Loosen the nut holding the hose to the regulator to relieve any left over pressure in the regulator; tighten after releasing gas. Turn the knob to “Decrease” several turns. Turn the gas on again and adjust to the 80 psi or so pressure by turning the knob in the direction of “Increase”. If the tank has adequate pressure, it should be ready for use.

Figure 1: Use the side labeled GAS on the liquid argon tank to attach the regulator. Use a CGA 580 adapter.

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TURN ON THE CHILLER

2. Turn on the chiller. The chiller is set for a water temperature of 20°C. If operating properly, the chiller should reach its target temperature in less than 3 minutes. Otherwise, when trying to ignite the plasma, an error message will appear.

Again wait until the chiller reaches a temperature of 20°C before trying to ignite the plasma.

The chiller requires that enough water in the tank for operations. Never putDI water into the chiller or this will hasten corrosion. Mix the DI water witha 50/50 mix of tap water and DI Water. Fill the tank to the point indicated.

Figure 2: The water chiller.

If fresh water, add about a gram of chloramine to inhibit bacterial growth.

If chiller is not cooling, open backside to check if radiator fan is moving. This model has been known to have a stuck solenoid valve; to dislodge stuck valve, lift front of instrument about 3 inches from floor and drop it. Yes, that is right, actual solution from tech support for a stuck valve.

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INSTALL TUBING ON PERISTALTIC PUMP

3. Tighten the tubing on the peristaltic pump on the ICP-MS. The tubing sections around the pump should be replaced after 40 hours of use. This is a peristaltic pump, so make sure to align the tubing so that the liquid from the samples will uptake by the pump.

Figure 3: Proper configuration for tubing to be mounted onto peristaltic pump. Tighten the tubing with screws on top. Make firm, but not too tight.

From the Practical Guide to ICP-MS, page 167:

• Manually stretch new tubing before use.• Maintain the proper tension on tubing.• Ensure tubing is placed correctly in channel of the peristaltic pump.• Periodically check flow of sample delivery-throw away tubing if in

doubt.• Replace tubing in there is any sign of wear-do not wait until it breaks.• With a high sample workload, change tubing every day or every other

day.

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• Release pressure on pump when not in use.• Pump and capillary tubing can be a source of contamination.• Pump tubing is a consumable-keep a large supply on hand.

Connect sample tubing from auto-diluter or auto-sampler and check the configuration.

NOTE: For most of our purposes, there are two types of tubing. One is Black-White/Orange-White and another is Black-White/Black-White. The latter is 1-mm diameter tubing and this should go after the nebulizer since it has a large diameter. The tubing is PVC material and that is fine for most of the acid/water solutions. If using the HPLC and organic compounds are used, check the tubing for compatibility with organic materials.

Make sure that the tubing connections stay together, otherwise any exposure to air from an unconnected tubing setup will kill the plasma.

Before sampling, pay attention to the nebulizer pressure on the status bar; it should be between 1.5 mbar to 2.0 mbar. Too little pressure and there is leak somewhere; too much and the nebulizer may be plugged.

If running no more samples for the day, always make sure to relieve the tension on the tubing.

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COLLECT EXCESS SAMPLE

4. Make sure to have container ready for the excess sample and DI water rinse. The container may be laboratory glassware or any container that is made of HDPE (high density poly ethylene). Even a small amount of diluted nitric acid will lower the pH to around 2 or below. Neutralize the acid and water solution with ordinary before pouring down the drain.

5. Turn on auto-sampler.

Once these items are in place, start Plasma Lab and press “ON” to ignite the plasma.

Figure 4: Ice build up on a tank of argon. The hose popped off of the regulator and the valve on the tank was not closed. The argon vented at low pressure for several hours and because of the rapid escape of gas, the ice formed.

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RESOLVING PROBLEMS

On occasion, there will be problems igniting the plasma. The errorsdisplayed by Plasmalab are at times not directly related to the problem athand.

First, check that the gas is at the required 90-lbs or so. Remove the air pipefrom the ICP-MS and check whether there is any flow or suction through theair pipe. Make sure the chiller is at operating temperature. Check the tubingconnected to the nebulizer and make sure there are no leaks.

Check that PlasmaLabService has started. Restart if necessary. Thecomputer typically stays on to monitor for errors from the ICP-MS. It maybe good to reboot the computer and make sure PlasmaLabService hasstarted. To find the service, click the “Gears” that are on the task bar.Try again.

If this still does not work, call Thermo-Fisher technical support at1-800-642-6538 and describe the problem. The serial number X0448 iswritten on the instrument. Write down the reference number. Log theproblem in the MS-Word “Logbook-ICPMS.doc” located on the desktop.

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It is possible under certain circumstances, for the plasma to not light because the cone hole is too big. The increased hole size will not allow the plasma to light because the proper vacuum is not obtainable.

Another trick that helps, and this from Thermo tech support, is to disconnect the multi-pin cable on the backside of the instrument near the hose to the output vent. Disconnect this cable and re-connect leaving it disconnected for several seconds; repeat about 3 to 5 times and try starting plasma again.

Pages 130 to 131 from the X Series ICP-MS Getting Started Guide start-up guide has a flowchart for troubleshooting plasma start issues.

OTHER PARAMETERS FOR PLASMA

The Load can range from 0 to 255, but should be greater than 90. The Tune value can range from 0 to 255, but should be AROUND 200.

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PLASMA LIGHTS, BUT DOES NOT STAY ON FOR SOMETIMESometimes the plasma will run for a few minutes and then turn off. First, make sure that the all the tubing to the nebulizer and from pump is connected correctly. Any substantial amount of air will interfere with the plasma staying on for a period of time.

Check to make sure that the silver screen is touching the grounding pin on the teflon torch holder (inside the cage).

Check the Event Log under the instrument guy icon (the person wearing a lab coat) to see what errors may have occurred.

Sometimes, after several attempts, the problem will work itself out and the plasma will stay on for the duration of the available argon.

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SHUTTING DOWN

Once the samples are run, turn off plasma, loosen tubing from peristaltic pump, turn off the chiller, turn off the argon gas. Leave the desktop computer on and the vacuum pump on.

Figure : After using, loosen guides from tubing and loosen the tubing.

Sometimes, the Plasmalab software loses contact while the plasma is operating. Close Plasmalab, and check to see the status of Plasmaservices. Restart the services and try Plasmalab again. If this still does not work, restart the computer and try again. Usually, this should allow a regaining of control to the ICP-MS.

10

SHUTTING DOWN THE VACUUM PUMP FOR ICP-MS

There are times when it is necessary to totally shutdown the ICP-MS. The only acceptable times for this is when maintenance is required on the vacuum pump like changing the oil or to replace the detector that is located inside the vacuum chamber.

Another acceptable time is if a known power outage to the building is scheduled.

After the maintenance is completed or the power is back on, return the pump to a vacuum state.

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MAKING A NITRIC ACID DILUTION

The guidelines for diluting samples requires a 2% to 5% nitric acid solution. To make it, one needs ultra-pure nitric acid (Nitric Acid-TraceMetal, Fisher Chemical , 2.5L Catalog #: A509-212-or equivalent) and DI water.

To mix it, a 1-L volumetric flask, and a graduated cylinder is needed. A beaker might be good to pour the acid into initially before pouring into the graduated cylinder.

WARNING: When pouring a concentrated acid directly from the container, this must be done under a fume hood.

Safety Note: When pouring a strong acid, wear laboratory nitrile or latex gloves, goggles, and a lab coat or apron. Pour under a fume hood!

Start with the following equation:

V1 C1 = V2 C2

In this example, a 2% solution of HNO3 will be mixed from an approximately 68% concentrated solution of nitric acid in a 1-L volumetric flask. The label on the jar of acid should indicate a percentage concentration of acid or a range. Choose the lower range and up the percentage. Again, the HNO3 should work out to between 1% to 5%.

V1(68-%) = (1-L) (2-%)

V1 = 0.0294-L

V1 = 29.4-mL

To mix, pour water in a 1-L volumetric flask until it is about ¾ full. Pour 30-mL of the nitric acid into a clean beaker (do this under the fume hood and wear goggles, nitrile or latex gloves and a lab coat or apron).

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Slowly mix the DI water into the flask and mix contents; a bit of heat will be released. Mix and swish contents until the line is reached on the volumetric flask.

This is the base for mixing calibration standards and diluting prepared samples. It is recommended to prepare much since it will be used in other sample preparations.

The HNO3 dilution does not need to be poured into other containers under a fume hood.

Most nitric acid purchased is around 68% to 70% concentrated. The following table is provided for the volumes of nitric acid to mix different percent solutions. The numbers based on a weight/weight ratio of nitric acid and water.

Diluting 68% HNO3 with 1-L of DI WaterPercent Volume Required

1 % 14.7 - mL2 % 29.4 - mL3 % 44.1 - mL4 % 58.8 - mL5 % 73.5 - mL

Note: Since the HNO3 solution is for preparing a sample or calibration solution to improve the solubility of metal ions, the volumes can be rounded up to make preparation easier.

Suggested References: Any MSDS on Nitric Acid.

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MIXING A 10 ppb TUNE A DILUTION

Materials necessary: Tune A Solution, a 1% to 5% nitric acid dilution,volumetric flasks of appropriate volumes to mix the desired ranges, transferpipettes, DI water.

A 10 ppb Tune A solution is required for the calibration of the ICP-MS and obtaining the performance reports. The Tune A solution can be mixed to other concentration values either higher or lower depending upon the samples for analysis.

The Tune A Solution from Thermo is at a concentration of 10 mg/L in 5 % HNO3. The concentration is equivalent to 10 ppm (1 mg/L = 1 ppm) or 10,000 ppb. If purchasing Tune A standard from another vendor, make sure to beware of the concentration on the label and adjust calculation accordingly.

How many millilieters of Tune A at 10 mg/L (10, 000) are needed to prepare 1 L (1000 mL) of 10 ppb Tune A?

Ci Vi = Cf Vf

(10,000 ppb) Vi = (1000 mL) (10 ppb)

After rearranging and dividing out the ppb units, the final result is:

Vi = 1 mL

Take 1 L volumetric flask and put the 1 mL first; file to the line with the 1% to 3% nitric acid solution. Repeat the mathematic and procedure for other concentrations of Tune A or other necessary standards. Since Tune A is used to autotune and for the daily performance report, 1L is not too much.

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Application note: If using an Eppendorf, make sure to practice the manual actions of taking a sample. The best method for checking whether the pipette and one's technique is good by taking some DI water and pipette 1 mL; weigh this 1-mL of DI water on a 3 to 4 digit scale. If weighs close to 1 gram, then the equipment and technique are good. Remember that for DI water, 1 mL = 1 gram = 1 cubic centimeter.

What if 250 mL of 5 ppb Tune A solution was necessary?

Ci Vi = Cf Vf

(10 ppb) Vi = (250 mL) (5 ppb)

After rearranging, 125 mL of 10 ppb Tune is necessary. Pour 125 mL of Tune A into 250 mL volumetric flask and fill the rest with 1% to 5% nitric acid solution to the fill mark on the flask.

Use this formula and procedure for making other concentrations of standard.

Reference:

Calculating Concentration http://chemistry.about.com/library/weekly/aa081003a.htm

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CLEANING THE CONES WITH ULTRASOUND

After some hours of sample analysis, the cones at the entry point of mass spectrometer will become dirty.

Follow the instructions in the manual for removing the cones from the ICP-MS.

Fill the ultrasonic unit pictured below with DI water to about an 1 inch to 1.5 inches of the top. Find a small beaker to put the cones in with some DI water filling the beaker. Do each cone separately for about 15 minutes.

Rinse the cones a couple of times with DI water while in the beaker. Try to minimize contact with the cones unless wearing gloves. Set the cones out to dry. After drying, reinstall the cones.

After cleaning the cones or installing new ones, run some 300 ppm Ca+ conditioning solution to prepare cones. The Ca+ in a plasma deposits a ceramic surface.

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TAKING THE COVER OFF OF THE INSTRUMENT

Sometimes it is necessary to remove the cover from the ICP-MS to access the circuit breakers, vacuum cage, or vacuum chamber.

If turning off the breakers to reset the instrument, leave them off for at least 30 seconds before turning back on. This should allow for most of the electronics to discharge.

The breaker to the far right says “Electronics Embedded PC Rotary Pump Turbo Pump”. This breaker also controls the roughing pump on sitting on the floor beneath the table. If it does not come back on after resetting the breaker, press the RED button on the board just to the right. The GRAY button stops the roughing pump.

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OTHER GENERAL TIPS AND GUIDELINES

(TUNING, AUTOTUNES, PERFORMANCE REPORTS)

Most of this if from the class instruction provided by Thermo.

1. Before tuning, doing a performance report, or running samples, run instrument for about 15 minutes.

2. Run a performance report at the beginning; unless there are problems, no need to run again. The PlasmaLab software records every performance report ever done.

3. Auto-tunes are only necessary after replacing the cone and torch, but only do an autotune if it fails the performance reports.

4. Instrument requires a good Tune to acquire a good mass calibration, but no required often.

5. Detector set-up: voltages set by cross calibration; should be done regularly.

6. Must have >400,000 counts for analogue counting to be engaged.

7. Never use an AA standard for ICP-MS.

8. Calibration: (2) points are enough. A blank and an upper limit. Could be validated by preparing a standard in between those values.

9. Boron, antimony, and molybdenum “stick” to tubing and glass. May require an alkaline solution to wash out effectively.

10.If the elements are unknown, run sample with out the internal standards and see what is in the sample. Then adjust or choose the procedure depending upon elements that you are looking for.

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11.Pay attention to interferences when setting up experiment. To reduce interferences, choose an isotope that is less abundant.

12.As the argon gas decreases in the tank, Kr (Krypton) does not bail off as fast and that may generate interferences that require a correction for certain analysis (like with arsenic and selenium).

13.If the plasma is flickering, this may indicate the flow is too high. Call maintenance to have Siemens adjust the flow rate within an acceptable range

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