Avoiding Matrix Interferences in Ion Chromatography Using Solid Phase Extraction

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Avoiding Matrix Interferences Avoiding Matrix Interferences in Ion Chromatography in Ion Chromatography

Using Solid Phase ExtractionUsing Solid Phase Extraction

Alltech Associates, Inc.Brandstraat 12, 9160 Lokeren

Phone: 09 340 65 65 • 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

Female LuerInlet

Polyethylene Frits

Packing Material

Male LuerOutlet

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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 device’s capacity).

3. Discard the first 1mL eluate.

4. Collect and analyze the remaining eluate.

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Product Specifications

Maxi-Clean™ IC-RP

Packing: PolystyreneParticle Size: 300µmRetains: Hydrophobic components by a

reversed-phase mechanismApplications: Removal of hydrophobic organic components

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Maxi-Clean™ IC-RP Removes Organic Contaminants

Trace Anions in Aniline

Original Sample After Cleanup with Maxi-Clean™ IC-RP

Column: Anion/S, 250 x 4.1mm Mobile Phase: 4mM KHP pH 4.5Flowrate: 2.0mL/minDetector: Alltech Conductivity

1. Chloride2. Nitrate3. Sulfate

5351

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Average % Recovery of Ions with Maxi-Clean™ IC-RP Cartridge

90929496

98100102104

Ions

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Sample Preparation by Precipitation

Maxi-CleanTM IC-Ba• For removal of sulfate and phosphate prior to

analysisResin-2-Ba+2 + M+2SO4

-2 Resin-2-M+2 + Ba+2SO4-2

Maxi-CleanTM IC-Ag• For removal of halides prior to analysis

Resin--Ag+ + M+X- Resin--M+ + Ag+X-

M=Sample 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 25BaCl2 37.5 26Ba(NO2)2 67.5 20Ba(NO3)2 8.7 20BaHPO4 0.01 - 0.02 N/ABa2SO4 2.2 x 10-4 25AgF 182 15.5AgI 2.8 x 10-7 25AgCl 8.9 x 10-5 10AgNO2 0.155 0AgBr 3.7 x 10-4 100AgNO3 122 0Ag2SO4 0.57 100

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Maxi-Clean™ IC-Ba

Product Specifications

Packing: Strong cation exchanger in the Ba2+ formParticle Size: 106µmCapacity: 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

Original Sample After Cleanup with Maxi-Clean™ IC-BA

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

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Anions in Battery Acid

1. Fluoride2. Chloride3. Nitrite4. Bromide5. Nitrate6. Phosphate7. Sulfate

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Average % Recovery of Ions with Maxi-Clean™ IC-Ba Cartridge

0102030405060708090

100110

Ions

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Maxi-Clean™ IC-Ag

Product Specifications

Packing: Strong cation exchanger in Ag+ formParticle Size: 106µmCapacity: 0.8/2.4 meq.

Retains: Halides by precipitationApplications: Removal of halides before analysis of

other anions

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5347

Maxi-Clean™ IC-Ag Removes Chloride

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

Original Sample After Cleanup with Maxi-Clean™

Nitrite in Brine

1. Chloride2. Nitrite

1

2

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Average % Recovery of Ions with Maxi-Clean™ IC-Ag Cartridge

0102030405060708090

100110

Ions

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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- formParticle Size: 75µm

Capacity: 0.6/1.8 meq

Retains: AnionsApplications: Adjusting sample pH before

cation analysis

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5352

Maxi-Clean™ IC-OH Neutralizes Acid

Column: Cation/R, 100 x 43.1mm Mobile Phase: 3.2mM nitric acidFlowrate: 1.0mL/minDetector: Alltech ConductivityOriginal Sample After pH

Neutralization with Maxi-Clean™ IC-OH

Monovalent Cations in 1M Nitric Acid

1. Sodium 2. Potassium

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Recovery of Ions with Maxi-Clean™ IC-OH Cartridges

0102030405060708090

100110

Ions

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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: CationsApplications: Adjusting sample pH before

anion analysis

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5349

Maxi-Clean™ IC-H Neutralizes Hydroxide

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

Original Sample After pH Neutralization with Maxi-Clean™ IC-H

Trace Anions In Caustic Solution

1. Fluoride2. Bicarbonate3. Chloride4. Nitrite5. Bromide6. Nitrate7. Phosphate8. Sulfate

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Recovery of Ions with Maxi-Clean™ IC-H Cartridges

0102030405060708090

100110

Ions

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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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5813

Maxi-Clean™ IC-Na+ Isolates Iron (III)

Column: Alltech Universal Anion, 150 x 4.6mm Mobile Phase: 2mM EDTA, disodium saltFlowrate: 1.0mL/min.Detector: UV at 330nm*Problem with IC-H+--> the precipitation of H4EDTA

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)

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Maxi-Clean™ IC-Chelate

Product Specifications

Packing: Styrene-divinylbenzene copolymer containing iminodiacetate ionParticle Size: 225µmCapacity: 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.