The Separation of Beryllium from Spectral Interfering Elements in Inductively Coupled Plasma –...

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expertise. commitment. results.

The Separation of Beryllium from Spectral Interfering Elements in Inductively Coupled

Plasma – Atomic Emission Spectroscopic Analysis

Daniel R. McAlister and E. Philip HorwitzPG Research Foundation, Inc.

8205 S Cass Avenue, Suite 109

Darien, IL 60561

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Problems with Current Method

Interfering elements in the AES spectrum of Beryllium

Analyte Peak (nm) Intensity Analyte Peak (nm) IntensityCr 312.870 15.0 Nb 313.079 2200.0U 312.879 6.0 Ti 313.080 6.0Zr 312.918 400.0 Ce 313.087 65.0Nb 312.964 22.0 Th 313.107 27.0

U 312.973 15.0 Beb 313.107 41000.0Zr 312.976 550.0 Tm 313.126 2300.0Th 312.997 10.0 U 313.132 8.0V 313.027 1020.0 Hf 313.181 20.0

OH 313.028 0.0 U 313.199 15.0Ce 313.033 50.0 Cr 313.206 1000.0

Beb 313.042 64000.0 Zr 313.207 7.0U 313.056 6.0 Th 313.226 5.0

OH 313.057 0.0 Mo 313.259 1800.0U 313.073 0.0 Ce 313.259 30.0

Table 1. Potential Spectral Interferences for Be determination by ICP-AESa

aAs listed in Varian Plasma96 software version 1.12bCommonly used peaks for beryllium determination by ICP-AES

Beryllium lines very intense method is very sensitive for the determination of beryllium

Interfering lines from other elements could lead to false positives.

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10-2 10-1 100 101

10-1

100

101

102

103

104

105

a

Cr

V

Be

Ce

Nb

Be(II) Ce(III) Zr(IV) Nb(V) Cr(III) V(V)

k'

[HNO3]

k' for U(VI) and Th(IV)

> 104 for all HNO3

Zr

Uptake of Selected Elements on Dipex Resin

Several EXC materials evaluated

Dipex offered the most promising beryllium retention characteristics

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expertise. commitment. results. 10-2 10-1 100 101

10-1

100

101

102

103

104

105

b

Hf

Be

Tm

Ti

Be(II) Mo(VII) Ti(IV) Hf(IV) Tm(III)

k'

[HNO3]

Mo


Single column should remove all ICP-AES interferences

Load pH 2-4

Rinse 0.2 M HNO3

Strip Be with 4 M HNO3

Potential for 2-10 x concentration of Be depending on sample size

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10-2 10-1 100 101

10-1

100

101

102

103

104

105

Mg

Sr

Ba

Ca

Be(II) Mg(II) Ca(II) Sr(II) Ba(II)

k'

[HNO3]

Be

a


Resin selective for Be over other alkaline earth metal ions

Ca and Mg common matrix impurities

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10-2 10-1 100 101

10-1

100

101

102

103

104

105

Be(II) Fe(III) Cu(II) Pb(II) Al(III)

Pb

Cu Al

Fe

Be

k'

[HNO3]

b


Fe(III) strongly retained

Al(III) and Pb(II) have similar retention to Be(II)

Cu(II) more weakly retained

Large amounts of Fe(III) could interfere with Be(II) uptake

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10-2 10-1 100 101

10-1

100

101

102

103

104

105

Mn

Be(II) Cd(II) Zn(II) Hg(II) Mn(II)

Hg

Zn

CdBe

k'

[HNO3]

c


Resin selectively retains Be(II) over most other divalent metal ions

Be(II) can be separated from samples containing large quantities of divalent metal ion impurities

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Proposed Method for Beryllium Purification

Prepare samples as before (Digest with H2SO4/H2O2, dilute with HNO3)

Neutralize samples to pH 1-2 with sodium aceate

Buffers to maximum pH of 4.5

Monitor pH with methyl violet or crystal violet or pH strip

pH

0.0 0.3 0.5 1.1 1.6 2.8 3.4 4.0 4.5

pH Range over which separation is effective

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Elution of Be and Selected Elements on Dipex Resin

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 4010-3

10-2

10-1

100

101

102

103

Load 5.5 cm digested ashless filter + 140 g Be, Al, V and Cr neutralized to pH 2.0 with 3.4 M Sodium Acetate

Cr mL %Be 6 66 8 79 10 92 12 95 14 97 16 97

V

Strip4.0 M HNO

3

1 mL/min

Background

Be

Al

Rinse0.2 M HNO

3

ppm

Bed Volumes

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0 5 10 15 20 25 30 35 40 45 5010-3

10-2

10-1

100

101

102

103

Strip0.2 M

Na4EDTA

U

Load 5.5 cm digested ashless filter + 140 g Be, Ce, Nb, U and Zr neutralized to pH 1.0 with 3.4 M Sodium Acetate

Zr

mL %Be 6 86 8 90 10 91 12 93 14 94 16 94

Nb

Strip4.0 M HNO

3

Background

Be

Ce Rinse0.2 M HNO

3

ppm

Bed Volumes

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0 5 10 15 20 25 30 35 40 45 5010-3

10-2

10-1

100

101

102

103

Ti

Strip0.2 M

Na4EDTA

Tm

Load 5.5 cm digested ashless filter + 140 g Be, Hf, Mo, Ti, Tm and Th neutralized to pH 1.0 with 3.4 M Sodium Acetate

Th

mL %Be 6 84 8 89 10 91 12 94 14 94 16 97

Mo

Strip4.0 M HNO

3

Background

Be

Hf

Rinse0.2 M HNO

3

ppm

Bed Volumes

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Simulated Sample Results

Successfully separated Be from samples digested with H2SO4/H2O2

Several different digested methods employed in Be analyses (HCl, H2SO4, HNO3, HF, H2O2, HClO4)

High levels of impurities

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Digestion Methods using HF

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

10-3

10-2

10-1

100

101

102

103

98% of Be

2% of Be

0.1 M Boric Acid

No Boric Acid

Load Strip

4.0 M HNO

3

(1 mL/min)

Background

Rinse0.2 M HNO

3

ppm

Bed Volumes

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Separation of Be from Large Amounts of Interferences

Dipex® capacity mg to reduce

mg/2 mL bed Be yeild to 90%c

Cr(VI) N/A > 100Mo(VI) N/A 25

U(VI) 102.6a 25

Ti(IV) 12.5b 7.5

Th(IV) 60.6a 10

Fe(III) 22.6a 10

Pb(II) 53.8b 50

Ca(II) 10.4a >100

Be(II) 0.9b 0.5

Capacity of Dipex® Resin for Selected Metal Ions

Metal Ion

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Separation of Be from Large Amounts of Interferences

100 mg Cr 50 mg Fe 10 mg Ti 100 mg U

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10-4 10-3 10-2 10-1

10-1

100

101

102

103

104

105

10-4 10-3 10-2 10-1

k' for U, Th, Ti, Fe

>103 for all [HNO3]

k' Ca

Be

[HNO3]

k' for Mg, Sr, Ba<1 for all [HNO

3]

k' for U, Th, Ti

>103 for all [HNO3]

k' for Mg, Ca, Sr Ba<1 for all [HNO

3]

Be

LN3

[HNO3]

LN2

Uptake of Selected Metal Ions on LN2 and LN3 Resins

U(VI), Th(IV), Ti(IV) retained from all [HNO3]

LN2: Strongly retains Fe(III)

LN3: Be not retained from pH < 2

Choice of LN2/LN3 depends on desired operating conditions and amount of Fe in samples

O

OHP

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Elution of Be on LN2 and LN3 Guard Columns

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

10-3

10-2

10-1

100

101

102

103

LN2

LoadpH 2

1 % Be

85% Be

6 % Be

10% Be

Strip4.0 M HNO

3

(1 mL/min)

Background

LN3

Rinse0.2 M HNO

3

2.0 mL Resin, 50-100 m, Assisted Gravity Flow 2.0 mL/min, 22(2) oC

ppm Be vs. Bed Volumes of Eluate

ppm

Bed Volumes

93 % Be

5% Be

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Effect of Large Quantities of Uranium

% Be g U in % Be g U in % Be g U in

mg U in 12 mLb Be fraction in 12 mLb Be fraction in 12 mLb Be fraction

0.14 90 < 1.5c 85 < 1.5 N/A N/A10 92 < 1.5 N/A N/A N/A N/A25 86 < 1.5 87 < 1.5 97 < 1.550 61 < 1.5 88 < 1.5 97 < 1.575 N/A N/A 81 < 1.5 93 < 1.5

100 29 580 88 < 1.5 79 < 1.5

sodium acetate to pH 1.8bBeryllium Resin Strip Solution 4.0 M HNO3

cDetection limit for Uranium by ICP-AES under the experimental conditions

2 mL Beryllium Resin Beryllium Yields and Uranium Impurity vs mg Uranium in Load Solutiona

+ 2 mL LN2 + 2 mL LN32 mL Beryllium Resin2 mL Beryllium Resin

aWhatman filter paper spiked with 0.14 mg Be, digested with H2SO4/H2O2, and neutralized with

LN2 and LN3 Resins effectively increase the capacity for Uranium

With LN2, the GC remains connected through the load, rinse and strip

With LN3, the GC can be removed following the rinse

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ConclusionsEfficient, Reliable method for purifying Be from all ICP-AES spectral interfering elements has been found using a single column

Method is compatible with current monitoring and sample digestion methods

Method is robust and performs over a wide pH range

Inserting a LN2 or LN3 Resin guard column increases U capacity without changing the chemistry or significantly decreasing Be yields.

Working to develop methods to isolate Be from high levels of other impurities

Date post:	31-Mar-2015
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The Separation of Beryllium from Spectral Interfering Elements in Inductively Coupled Plasma –...

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