ASTM: ASTM 3972-02: Uranium isotopes in water by chemical separations and alpha pulse-height analysis.

Summary
Analytes
Revision
Data and Sites

Official Method Name

ASTM D3972-02. Standard Test Method for Isotopic Uranium in Water by Radiochemistry

Current Revision

ASTM 3972-02

Media

WATER

Instrumentation

Alpha Spectrometer/Counter

Method Subcategory

Radiochemical

Method Source

ASTM

Citation

Annual Book of ASTM Standards, Section 11, Water and Environmental Technology, Volume 11.02, Water (I)

Brief Method Summary

The water sample to be analyzed is acidified and uranium-232 is added to serve as an isotopic tracer. Samples that contain carbonate or bicarbonate ions are boiled under acidic conditions to convert these ions to carbon dioxide gas which is then expelled from the solution. The uranium is coprecipitated from the sample with ferrous hydroxide and then this precipitate is dissolved in an acidic solution. The uranium is separated from other radionuclides by adsorption on anion-exchange resin. The uranium is electrodeposited onto a stainless steel disk. Isotopic uranium radioactivities are measured by alpha pulse-height analysis with a silicon surface-barrier or ion-implanted detector and a multichannel analyzer. Uranium 233 and 234 usually cannot be resolved because their principal alpha energies differ by only 0.04 MeV. Uranium 235 and 236 peaks can be resolved only with difficulty.

Scope and Application

This method covers the determination of alpha-particle-emitting isotopes of uranium in environmental waters including processing effluents as well as substitute ocean water.

Applicable Concentration Range

none provided

Interferences

Protactinium-231 (3.28 x 10E4 yr half-life) is a possible alpha-emitting isotope that might interfere.

Quality Control Requirements

Determine detector efficiency monthly or prior to us, tracer yield should be calculated for each sample, analyze an LCS and reagent water blank, and sample duplicate with each batch of no more than 20 samples. At least quarterly an Independent Reference Material (IRM) should be analyzed. The IRM should be traceable to a National Standardizing Laboratory such as NIST or NPL.

Sample Handling

Collect the sample in accordance with Practices D 1066 and D 3370 and Specification D 1192 as applicable. Preserve the sample by adjusting the pH to 1 with concentrated HCl if the sample is not to be analyzed within 24 h. Record the volume of the sample and the volume of acid added.

Maximum Holding Time

none included

Relative Cost

$51 to $200

Sample Preparation Methods

This method has 4 analytes associated with it.

Analyte	Detection Level	Bias	Precision
Uranium-232(14158-29-3) Uranium-232	0.001 Bq	N/A	N/A
Uranium-234(13966-29-5) Uranium-234	0.001 Bq	N/A	N/A
Uranium-235(15117-96-1) Uranium-235	0.001 Bq	N/A	N/A
Uranium-238(7440-61-1) 238U 238U Element U U-238 Uranium Uranium (PM10) STP Uranium (TSP) Uranium 238 Uranium PM2.5 LC Uranium PM2.5 STP Uranium, natural Uranium-238	0.001 Bq	N/A	N/A

Precision Descriptor Notes:	A limited collaborative test of this test method was conducted with the uranium isotopes uranium-234, uranium-235, and uranium-238. Eight laboratories participated by processing samples at four levels. Outlier results from laboratories were rejected as per the statistical tests outlined in ASTM Practice D 2777. Of these four reference samples, two were prepared from actual environmental samples, one was prepared from a substitute ocean water sample, and one was prepared from a sample containing sediment.
Detection Level Note:	The MDA applies to a sample with a 75 % recovery of the uranium, a 60,000-s counting time, a 25 % alpha spectrometer counting efficiency and an 8.3 x 10E-5 cps (5 counts/1000 min) background, the MDA is approximately 5.6 x 10E4 Bq (Becquerel = 1 disintegration/s).

Precision Descriptor Notes:

A limited collaborative test of this test method was conducted with the uranium isotopes uranium-234, uranium-235, and uranium-238. Eight laboratories participated by processing samples at four levels. Outlier results from laboratories were rejected as per the statistical tests outlined in ASTM Practice D 2777. Of these four reference samples, two were prepared from actual environmental samples, one was prepared from a substitute ocean water sample, and one was prepared from a sample containing sediment.

Detection Level Note:

The MDA applies to a sample with a 75 % recovery of the uranium, a 60,000-s counting time, a 25 % alpha spectrometer counting efficiency and an 8.3 x 10E-5 cps (5 counts/1000 min) background, the MDA is approximately 5.6 x 10E4 Bq (Becquerel = 1 disintegration/s).

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ASTM 3972-02

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ASTM: ASTM 3972-02: Uranium isotopes in water by chemical separations and alpha pulse-height analysis.

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