Transcript
ICP-Optical Emission Spectroscopy (Perkin Elmer Optima 7300DV) FEB 2013
ICP-OES Sample Preparation 1.
Completely dissolve solids (including nanoparticles) in your samples into aqueous solutions and/or filter to remove solids (pore size of 0.45 µm or less). Samples containing biological matter or polymers should be digested with concentrated acid AND hydrogen peroxide. (See page 24-25 for more information on digestions.)
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Use 1% nitric acid (trace metal grade, ≤1ppb) to dilute your samples and standards and prepare a blank solution of just 1% nitric acid. Samples should be diluted to a final concentration of acid of less than 5%. If you are not diluting your samples, or your dilution factor is less than 1:5 please speak with the instrument manager about sample preparation methods.
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Use HDPE or LDPE bottles for long-term storage of solutions. The NRF will not be responsible for any contamination issues resulting from improper storage.
Start-up • •
Open the software “WinLab32” Click on “Plasma” icon (If autosampler pump starts to spin after click on plasma, press “F11” on the key board)
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If plasma is off check if spectrometer is ready (open “System diagnostics”, and click on “Spectrometer” tab)
If not ready, find the instrument manager immediately.
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Start-up – cont. • Stretch tubing so plastic tabs fit in slots on both sides of the pump and clamp the tubes in place on the pump making sure each tube fits in the groove of the corresponding clamp. Sample tubing has black tabs, internal standard tubing has orange-blue tabs and drain tubing has red tabs. • Check to make sure the sample will flow into the spray chamber and that the waste (drain tubing) will flow out of the spray chamber. (The pump rotates clockwise.) • Immerse sample and internal standard (int. std.) tubing into acid solution (1% nitric acid)
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Start-up – cont. • Turn on the plasma by clicking on “plasma on” • When the plasma lights you will see a green glow in the shielded window • Check to make sure that the sample and internal standard lines are flowing into the spray chamber (can lift the lines out the solution to introduce an air bubble) and that waste is flowing out of the bottom of the spray chamber through the drain tubing (if the spray chamber is not properly drained the plasma will shut off) If the flow directions are not correct turn off the plasma and fix the tubing positions before restarting the plasma
• Wait for 30 minutes for the instrument to warm up, you may make or edit a method (Page No.9) during this time
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Tuning • • • • •
Immerse sample and internal standard tubing into Mn Solution Open “Tools Spectrometer Control” Click on “Hg Realign” and press “OK” Wait till Spectrometer window shows “Hg Lamp Off” Immerse sample and internal standard tubing into acid solution
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Method • Go to “File New Method” and press “OK” in “Create New Method” window or go to “File Open Method” and choose your method
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Method – cont. • Set “Spectrometer” • Define Elements: click on empty cell, click on “Periodic Table”, select element from the table, click on “ Table”, highlight desired wavelengths, and press “Enter Selected Wavelengths in Method”, repeat for all elements of interest
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Method – cont. • Set “Spectrometer” (Internal standard) • Define Elements: click on empty cell, click on “Periodic Table”, select an element for int. std. from the table. (Please refer to attached table of ionization potential and ionization state of analytes) • Select “Int. Std.” as “Function”.
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Method – spectrometer cont. • •
Settings: set “Time(sec)” as min of 5 and max of 20 and “Replicates” as 3 Spectral Windows: default
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Method – cont. • Set “Sampler” • Plasma: set “Plasma Conditions” as “Same For All Elements” and select “Plasma View” as “Axial” for samples with low concentration and “Radial” for samples with high concentration (Speak with the Instrument Manager if you have a broad concentration range and need to use the plasma condition “vary by element”)
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Method – cont. • Peristaltic Pump: set “Flush Time” as 45 sec or longer • Autosampler: select “Between Samples” and set “Normal Time” as 60-120 sec
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Method – cont. • Set “Process” • Internal Standards: Under “Internal Standard” select the int. std. element to be used for each analyte
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Method – cont. • Set “Calibration”: • Define Standards: name IDs for blanks and standards, and define “A/S Location”
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Method – calibration cont. • Calib Units and Concentrations: change units and set standard concentrations, use 2 – 3 standards per order of magnitude in concentration (0-1, 1-10, 10-100)
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Method – calibration cont. • Blank Usage: Select blank solution from the list. Select “None” for int. std. • Equation and Sample Units: Change units to same as calibration and choose a line type. Line type for int. std. is “n/a”. • Others: default • Set “Checks” and “QC”: default • Set “Options”: check “Start each sample on a new page” “Detailed Cal Summary” and “Spectral Data”
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Method – cont. • Open “Edit Check Method” • If method has no errors go to “File Save as Method” and name the method • If method has errors go back and correct the reported error
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Sample Info • Open “File New Sample Info File”, name your samples, and define “A/S Location” • Open “File Save as Sample Info File” and name the sample information file. • If you haven’t done “Tuning” Please go back to page “6”
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Calibration and Measurement • Click on “Auto” icon • Choose “Method” by clicking • Choose “Sample Info File”: a) All Defined: measure all the samples
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Calibration and Measurement • Immerse sample tubing into auto sampler and int. std. tubing into int. std. bottle • Choose “Sample Information File” • Select “Save Data” and define the data file • Select “Print Log During Analyses”
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Calibration and Measurement • Click on “Analyze” tab • Click on “Rebuild List” to insert all the sample information • Click on “Analyze All” (including calibration and measurement), “Calibrate” (calibration only), or “Analyze Samples” (measurement only) • View calibrations via “Calib” • Save results in PDF format in your folder in the C drive “user data” folder
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Shut-down • Go to “Analysis” and “AutoSampler”. Click on “A/S Probe Up/Down”. • Wash the system: immerse the sample and int. std. tubing in acid solution for 10 min and then in water for 5 min • Take the sample and int. std. tubing out of solution, put it in the empty tube, and wait until the spray chamber is dry (no more bubbles leave the bottom of the spray chamber)
• Click on “Plasma”, and turn off plasma by clicking “off” • Unclamp and loosen the sample, int. std. and drain tubing
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Data Reprocessing •
Reprocess data after making adjustments to your method (you can change your calibration line type, remove standards, remove internal standard weighting, etc… but must save the method as the same name for reprocessing to work correctly)
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Click on the “Reproc” icon click “Browse” by “Data Set To Reprocess” and highlight your data set click “Ok”
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Data Reprocessing • • •
Click “Browse” by “Reprocessed Data Set” and name the reprocessed data file Check “Print Log” and “Save Reprocessed Data”, uncheck all other boxes Highlight your blank, standards, and samples click “Reprocess”
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Data Export • •
Go to the computer desktop and open “Data Manager” software Highlight the dataset you want to export and click the “Export” icon
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Data Export • • •
In the Data Export Wizard click “Use Existing Design” open “Basic export.xpt” or your own design Click “Finish” to go directly to the export step or click “Next” to modify the design If you clicked “Finish” click “Export Data” click “Finish” data will be saved in C:\userdata\Data Manager Export\dataset name
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Digestion Methods • Nitric acid is typically the primary component of acid digestions. • Hydrochloric acid is useful as a complexation reagent for precious metals. HCl should always be used when Ag or Sb are analytes of interest to ensure good recovery. • The use of hydrogen peroxide enhances the oxidation properties of nitric acid especially in the digestion of organics. Caution should be used when digesting with peroxide as it increases reactivity. !! IMPORTANT : Hydrofluoric acid (HF) should NOT be used for digestion of materials to be analyzed by ICP-OES as the torch, spray chamber, and nebulizer are quartz. !! 1. 2. 3. 4. 5.
Place up to 1.0 g (or up to 1 mL) of sample into each reaction vessel. Add 9 mL of nitric acid to each vessel. Add hydrochloric acid and/or hydrogen peroxide and allow to react for 1 minute. Heat reaction vessels to 180°C over 5-10 minutes and hold at 180°C for another 10 minutes to 1 hour. Allow to cool then dilute with ultrapure water to an acid content of 5% or less.
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Digestion Methods – Application Notes • Always use extreme caution and wear protective gear when performing digestions! • If the amount of sample is limited scale down the amount of acid and peroxide proportionally. • Never fill a reaction vessel more than half way! Overfilling may cause unsafe pressure levels in enclosed vessels or bubbling over in open vessels. This is especially true when hydrogen peroxide is used. •The amount of time you heat a sample depends on your heating method and your sample. • Microwave or oven digestions systems usually require 10-30 minutes of heating. • Hot block or hot plate digestions usually require 30-60 minutes of heating.
• The type of reaction vessel depends on your heating method. • For microwave or oven digestions use the appropriate sealed vessel, usually teflon. • For hot block digestions use glass or plastic tubes manufactured specifically for digestions. Do not cap or seal tubes! • For hot plate digestions use heavy duty glass erlenmeyer flasks. Do not cap or seal flasks!
• If your sample still has solid particles in it after digestion: • If you require a complete digestion you may need to use a smaller amount of sample or heat your sample longer. • If you do not require a complete digestion you should dilute your sample, centrifuge it, carefully remove the supernatent, and then filter the supernatent to be used for analysis using 0.45 µm, or smaller, pore size filters.
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