Avoiding Matrix Interferences in Ion Chromatography Using Solid Phase Extraction

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Avoiding Matrix Interferences in Ion
Chromatography Using Solid Phase Extraction

• Alltech Associates, Inc.
• Brandstraat 12, 9160 Lokeren
• Phone [phone] Web Site
  www.alltechweb.com

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Types of Sample Matrix Interferences in Ion
Chromatography

• Samples with components that will damage the
  column.
• Samples that are too acidic for cation analysis.
• Samples that are too basic for anion analysis.
• Samples that contain high concentrations of
  interfering ions.

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Problems with Common Sample Preparation Techniques

• Dilution and Filtration are not suitable when
• The analytes are present at trace levels.
• The analytes differ greatly in concentration.
• Interfering compounds and analytes are both
  soluble.

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Solid Phase Extraction (SPE) Cartridges for Ion
Chromatography

• Stable from pH 2 to 13.
• Low IC interference levels.
• Requires only 2 - 3mL of samples.

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The Alltech Maxi-Clean IC Cartridge Construction
Polypropylene Housing
Packing Material
Female Luer Inlet
Male Luer Outlet
Polyethylene Frits
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Types of Maxi-Clean IC SPE Cartridges

• Maxi-Clean IC-RP
• Maxi-Clean IC-Ag
• Maxi-Clean IC-Ba
• Maxi-Clean IC-OH
• Maxi-Clean IC-H
• Maxi-Clean IC-Na
• Maxi-Clean IC-Chelate

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General Procedure for Using Maxi-Clean IC
Cartridges

• 1. Precondition the cartridge by passing 5-10mL
  of IC grade water (use 5mL of methanol followed
  by 5mL of Water for Maxi-Clean IC-RP).
• 2. Load the sample at a rate of 1mL/min or less.
  (Adjust the sample size to use 50 or less of the
  devices capacity).
• 3. Discard the first 1mL eluate.
• 4. Collect and analyze the remaining eluate.

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Maxi-Clean IC-RP
Product Specifications

• Packing Polystyrene
• Particle Size 300µm
• Retains Hydrophobic components by a
  reversed-phase mechanism
• Applications Removal of hydrophobic organic
  components

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Maxi-Clean IC-RP Removes Organic Contaminants

5351

• Trace Anions in Aniline

1. Chloride 2. Nitrate 3. Sulfate
Column Anion/S, 250 x 4.1mm

Mobile Phase 4mM KHP pH 4.5 Flowrate
2.0mL/min Detector Alltech
Conductivity
Original Sample
After Cleanup with Maxi-Clean IC-RP
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Average Recovery of Ions with Maxi-Clean
IC-RP Cartridge
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Sample Preparation by Precipitation

• Maxi-CleanTM IC-Ba
• For removal of sulfate and phosphate prior to
  analysis
• Resin-2-Ba2 M2SO4-2 Resin-2-M2
  Ba2SO4-2
• Maxi-CleanTM IC-Ag
• For removal of halides prior to analysis
• Resin--Ag MX- Resin--M AgX-
• MSample cations X Cl-, Br-, I-

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The Solubility of Barium and Silver Salts in
Aqueous Solutions
Compound Solubility (g/100mL) Temperature
(C) BaF2 0.12 25 BaCl2 37.5 26 Ba(NO2)2 67.5 20
Ba(NO3)2 8.7 20 BaHPO4 0.01 - 0.02 N/A Ba2SO4 2.2
x 10-4 25 AgF 182 15.5 AgI 2.8 x
10-7 25 AgCl 8.9 x 10-5 10 AgNO2 0.155 0 AgBr 3.7
x 10-4 100 AgNO3 122 0 Ag2SO4 0.57 100
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Maxi-Clean IC-Ba
Product Specifications
Packing Strong cation exchanger in the Ba2
form Particle Size 106µm Capacity 0.8/2.4
meq. Retains Sulfate by precipitation
Applications Removal of sulfate before the
analysis of other anions
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Maxi-Clean IC-Ba Removes Sulfate
5348
Anions in Battery Acid

• 1. Fluoride
• 2. Chloride
• 3. Nitrite
• 4. Bromide
• 5. Nitrate
• 6. Phosphate
• 7. Sulfate

Column Anion/R, 250 x 4.1mm

Mobile Phase 5mM p HBA, pH 8.5 Flow
rate 1.5mL/min. Detector Alltech Conductivity
Original Sample
After Cleanup with Maxi-Clean IC-BA
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Average Recovery of Ions with Maxi-Clean
IC-Ba Cartridge
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Maxi-Clean IC-Ag
Product Specifications
Packing Strong cation exchanger in Ag
form Particle Size 106µm Capacity 0.8/2.4
meq. Retains Halides by precipitation Application
s Removal of halides before analysis of other
anions
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Maxi-Clean IC-Ag Removes Chloride
5347
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Nitrite in Brine
1. Chloride 2. Nitrite
2

• Column 250 x 4.1mm
  
• Packing Anion/R
• Mobile Phase 5mM p HBA, pH 8.5
• Flow rate 1.5mL/min.
• Detector Alltech Conductivity

Original Sample
After Cleanup with Maxi-Clean
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Average Recovery of Ions with Maxi-Clean
IC-Ag Cartridge
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Maxi-Clean Cartridges to Adjust Sample pH

• Baseline disturbances and/or system peaks result
  when sample pH differs from eluant pH.
• Strong anion exchange resin in the hydroxide form
  removes anions and neutralizes an acidic sample.
• Cation exchange resin in the hydrogen form
  removes cations and neutralizes an alkaline
  sample.

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Maxi-Clean IC-OH
Product Specifications
Packing Strong anion exchanger in OH-
form Particle Size 75µm Capacity 0.6/1.8
meq Retains Anions Applications Adjusting
sample pH before cation analysis
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Maxi-Clean IC-OH Neutralizes Acid
5352
Monovalent Cations in 1M Nitric Acid
1. Sodium 2. Potassium

• Column Cation/R, 100 x 43.1mm
  
  
• Mobile Phase 3.2mM nitric acid
• Flowrate 1.0mL/min
• Detector Alltech Conductivity

Original Sample
After pH Neutralization with Maxi-Clean IC-OH
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Recovery of Ions with Maxi-Clean IC-OH Cartridges
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Maxi-Clean IC-H
Product Specifications
Packing Strong cation exchanger in H form
Particle Size 106µm Capacity 0.8/2.4 meq.
Retains Cations Applications Adjusting sample
pH before anion analysis
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Maxi-Clean IC-H Neutralizes Hydroxide
5349
Trace Anions In Caustic Solution
1. Fluoride 2. Bicarbonate 3. Chloride 4.
Nitrite 5. Bromide 6. Nitrate 7. Phosphate 8.
Sulfate

• Column Anion/R, 150 x 4.1mm
  
  
• Mobile Phase 5mM pHBA, pH 8.5
• Flowrate 1.5mL/min.
• Detector Alltech Conductivity

Original Sample
After pH Neutralization with Maxi-Clean IC-H
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Recovery of Ions with Maxi-Clean IC-H Cartridges
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Maxi-Clean IC-Na
Product Specifications
Packing Strong cation exchanger in Na form
Particle Size 106µm Capacity 0.8/2.4 meq.
Retains Cations (exchanges cations for
sodium) Applications Removal of cations from
sample without changing sample pH
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Maxi-Clean IC-Na Isolates Iron (III)
5813
Analysis of Iron (III) Procedures 1.
Precondition IC-Na cartridge with 5mL water. 2.
Load the sample to preconcentrate iron (III)
present. 3. Wash with 10mL water. 4. Elute the
iron (III) with 5mL of 25mM EDTA, disodium
salt. 5. Analyze the eluant for iron (III).
1. Iron (III)

• Column Alltech Universal Anion, 150 x 4.6mm
  
  
• Mobile Phase 2mM EDTA, disodium salt
• Flowrate 1.0mL/min.
• Detector UV at 330nm
• Problem with IC-H--gt the precipitation of H4EDTA

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Maxi-Clean IC-Chelate
Product Specifications
Packing Styrene-divinylbenzene copolymer
containing iminodiacetate ion Particle
Size 225µm Capacity 0.2/0.6
meq. Retains Polyvalent metal ions (exchanges
cations for sodium) Applications Removal of
polyvalent metal ions from sample
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Benefits of Alltech Maxi-Clean IC Cartridges

• Remove interfering components from the sample
  matrix.
• Little or no loss of sample.
• Easy, quick, and convenient.
• Disposable.