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

Acknowledgement

Darrin K. Mann

Analytical Chemistry Organization

Y-12 National Security Complex

P.O. Box 2009, MS 8189

Oak Ridge, TN 37831-8189

Outline

Background

Be Why it’s important/a problem

Current Method How it can be improved

Single column purification to remove all ICP-AES interfering elements

Guard column options to increase capacity of method for U(VI) (Key)

Method is pH sensitive Easy colorimetric method to monitor

Simple, fast, and reliable

More detail in paper prepared for Talanta (copies available)

Beryllium Uses and Properties

Lighter than Aluminum, Stiffer than Steel

High heat adsorption

Metal, alloys, salts and oxides used in a wide variety of industries

Neutron moderators or reflectors in nuclear reactors

Nuclear weapons components

Problems Associated with Beryllium

Physical Problems (Expensive, Brittle)

Health Hazard

Chronic Beryllium Disease (CBD)

No know cure (can only be treated)

Produces scarring of lung tissue

Chronic (average 10-15 year latency period)

2-5% of population acutely sensitive

Over 100 current and former DOE employees have CBD

Beryllium Monitoring

Controlled by US Dept of Energy CBD Prevention Program (10CFR part 850)

Requires monitoring of air and surfaces to determine Be risk

Y-12 analyzed nearly 40,000 samples for Be in 2003

50% more samples expected to be analyzed in 2004

Current method uses ICP-OES or GFAA on microwave digested samples

sensitive to certain interferences

Problems with Current Method

Interfering elements in the OES 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.

Positive determination of beryllium leads to shut down of operation until cleanup.

Problems with Current Method

Currently Interfering lines are corrected using inter element correction (IEC)

Uranium is particularly spectrally rich

Spectrum shifts depending on the degree of enrichment of the Uranium

Method for removing OES interfering elements from samples desired

Uranium in particular

Several EXC Resins evaluated for their ability to purify Be samples

Uptake of Selected Elements on Dipex Resin

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

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

Be retained at low acid and stripped at high acid

Most interferences strongly retained over entire range

Cr weakly retained over entire range

Single column should purify Be from all interferences

Uranium very strongly retained

Uptake of Selected Elements on Dipex Resin

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

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

10-2 10-1 100 101

10-1

100

101

102

103

104

105

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

Hg

Zn

Cd

Be

k'

[HNO3]

c

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

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

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

Elution of Be and Selected Elements on Dipex Resin

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

Elution of Be and Selected Elements on Dipex Resin

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

Effect of Large Quantities of Uranium

Uranium uptake on Dipex Resin is very high

Large amounts of Uranium could consume resin capacity and reduce Beryllium yields.

50 mg of U reduces Beryllium yield to ~60%.

100 mg of U reduces Beryllium yield to 29% and leads to U in Beryllium fraction

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

Load 5.5 cm ashless filter digested with 2.0 mL conc. HNO3

+ 0.62 mL of conc. H2SO

4 + 10 ppm Be + 50 mg U + 5 drops

H2O

2 diluted to 10 mL with H

2O and neutralized to pH 1.8 with

10 mL of 3.4 MSodium AcetatemL %Be 6 44 8 53 10 59 12 61 14 63 16 66

U

Strip4.0 M HNO

3

(1 mL/min)

Background

BeRinse0.2 M HNO

3

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

ppm vs. Bed Volumes of Eluate

ppm

Bed Volumes

Effect of Large Quantities of Uranium

An LN2 Resin guard column effectively separates U from Be

LN2 resin contains a substituted phosphonic acid

0 5 10 15 20 25 30 35 40 45

10-3

10-2

10-1

100

101

102

103

85 % Be10 % Be

Strip0.1 M

ammoniumoxalate

Load 5.5 cm ashless filter digested with 2.0 mL conc. HNO3

+ 0.62 mL of conc. H2SO

4 + 10 ppm Be and U + 5 drops H

2O

2

diluted to 10 mL with H2O and neutralized to pH 1.8 with

10 mL of 3.4 MSodium Acetate

Strip4.0 M HNO

3

(1 mL/min)

Background

Rinse0.2 M HNO

3

2.0 mL Bed of LN2 Resin, 50-100 m, Assisted Gravity Flow 2.0 mL/min, 22(2) oC

ppm vs. Bed Volumes of Eluate

ppm

Bed Volumes

5 % Be

Effect of Large Quantities of Uranium

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

Load 5.5 cm ashless filter digested with 2.0 mL conc. HNO3

+ 0.62 mL of conc. H2SO

4 + 10 ppm Be + 100 mg U + 5 drops

H2O

2 diluted to 10 mL with H

2O and neutralized to pH 1.8 with

10 mL of 3.4 MSodium AcetatemL %Be 6 69 8 77 10 83 12 88 14 93 16 94

U

Strip4.0 M HNO

3

(1 mL/min)

Background

Be

Rinse0.2 M HNO

3

2.0 mL Beds of Be Resin and LN2 Resin, 50-100 m, Assisted Gravity Flow 2.0 mL/min, 22(2) oC

ppm vs. Bed Volumes of Eluate

ppm

Bed Volumes

Coupling an LN2 Resin guard column increases Uranium capacity without decreasing Beryllium yields or changing chemistry.

Over 100 mg of Uranium does not decrease Beryllium yield or produce Uranium in Beryllium fraction.

GC attached through load, rinse and strip

Effect of Large Quantities of Uranium

An LN3 Resin guard column also removes U from Be and retains Be less than LN2.

LN3 resin contains a substituted phosphinic acid

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

1 % Be6 % Be

Load 5.5 cm ashless filter digested with 2.0 mL conc. HNO3

+ 0.62 mL of conc. H2SO

4 + 10 ppm Be, Al, V and Cr + 5 drops

H2O

2 diluted to 10 mL with H

2O and neutralized to pH 1.8 with

10 mL of 3.4 MSodium Acetate

Cr

V

Strip4.0 M HNO

3

(1 mL/min)

Background

Be

Al

Rinse0.2 M HNO

3

2.0 mL Bed of LN3 Resin, 50-100 m, Assisted Gravity Flow 2.0 mL/min, 22(2) oC

ppm vs. Bed Volumes of Eluate

ppm

Bed Volumes

93 % Be

Effect of Large Quantities of Uranium

Coupling an LN3 Resin guard column increases Uranium capacity without decreasing Beryllium yields or changing chemistry.

Over 100 mg of Uranium does not decrease Beryllium yield or produce Uranium in Beryllium fraction.

GC can be removed following rinse

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

Load 5.5 cm ashless filter digested with 2.0 mL conc. HNO3

+ 0.62 mL of conc. H2SO

4 + 10 ppm Be + 100 mg U + 5 drops

H2O

2 diluted to 10 mL with H

2O and neutralized to pH 1.8 with

10 mL of 3.4 MSodium AcetatemL %Be 6 45 8 60 10 70 12 79 14 86 16 90U

Strip4.0 M HNO

3

(1 mL/min)

Background

BeRinse0.2 M HNO

3

2.0 mL Beds of Be Resin and LN3 Resin, 50-100 m, Assisted Gravity Flow 2.0 mL/min, 22(2) oC

ppm vs. Bed Volumes of Eluate

ppm

Bed Volumes

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

Conclusions

Efficient, 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

pH can be monitored with indicator to ensure optimal performance

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

Dipex Resin currently available from Eichrom as Beryllium Resin