Radiochemistry - Gross Alpha and Gross Beta
Method 900.0 is designed for the screening of water samples for alpha (α) and/or beta (β) particles to help determine if further analysis is needed. This method utilizes an alpha/beta counter to measure the activity level of the solid material left after the water is evaporated from the subsample. Samples with high dissolved solids can create matrix interference and may affect the results. Generally, most water samples are counted simultaneously for gross alpha and, if required, gross beta. Analysis is based upon measuring the rate of decay of the particles to determine the activity of the sample1.
EPA 900.0 vs. NJ ECLS-R-GA: What Is The Difference?
The State of New Jersey developed an in-state-use only method for analysis of water samples. The New Jersey Rapid Gross Alpha (ECLS-R-GA R8) method utilizes a tighter window for counting that requires the sample to be analyzed within 36-48 hours from the date of collection. Analysis and prep are similar between the EPA 900.0 method and the New Jersey method. The main factor is the time allotted between collection and analysis. Radium-224 has a short half-life of only 3.5 days, so the narrow analysis window will likely capture this isotope before it decays2.
What Is an Adjusted Gross Alpha Result?
With the combination of gross alpha and uranium (U) analysis on the same sample, a calculation can be made to adjust the initial result of the gross alpha. If you take the gross alpha result and subtract the uranium result, you can then use an adjusted gross alpha result in your final report to compare to the EPA drinking water standards.
Gross Alpha – Uranium = Adjusted Gross Alpha
The analysis is reported in a standard unit of picocuries per liter (pCi/L) or micrograms per liter (µg/L).
Water Sampling Container
Sampling Bottle: 500 mL
EMSL Product ID: 8714205
Preservative: 5 mL of nitric acid
Shipping Requirements: No ice needed
Hold-Time, EPA 900.0: 6 months from collection
Hold-Time, NJ ECLS-R-GA R8: 48 hours from collection
Gross Alpha EPA 900.0 Detection Limit: 3 pCi/L
Gross Beta EPA 900.0 Detection Limit: 4 pCi/L
Radiological Testing Guidelines
| Gross Alpha/Beta Results | Potential Contamination | Recommended Additional Test(s) |
|---|---|---|
| < 5 pCi/L | Background Levels | None |
| 5-15 pCi/L | Possible Radium | Radium 226 and 228 |
| > 15 pCi/L | Possible Radium and Uranium | Radium 226, 228, and Uranium |
Treatment Recommended If: |
||
| Radium-226 + Radium-228 > 5 pCi/L OR Gross Alpha – Uranium > 15 pCi/L OR Uranium > 30 µg/L |
||
| Safe Water Drinking Act (SDWA) Standards3,4 | Maximum Contaminant Limit (MCL) |
|---|---|
| Gross Alpha | 15 pCi/L |
| Gross Beta | 50 pCi/L5 |
Alpha/Beta Counter
Alpha/Beta Counter
1 (Gross Alpha) – https://www.epa.gov/sites/production/files/2015-06/documents/epa-900.0.pdf
2 (New Jersey Rapid Gross Alpha) – https://www.nj.gov/dep/watersupply/pdf/radium_bb_5_20_02.pdf
3 (Radionuclides)– https://www.epa.gov/dwreginfo/radionuclides-rule
4 (Radionuclides) – https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=30006644.txt
5 (Radionuclides, Beta/Photon Applicability) – https://www.epa.gov/sites/production/files/2015-09/ roduction/ files/2015-06/documents/epa-900.0.pdf
CAUTION:
Sampling bottles contain nitric acid as a preservative which can easily burn your skin and clothes. Please use gloves when handling bottles, avoid overfilling the bottles, and splashing the contents on you.
What is an isotope?
Any of two or more species of atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties.
What is a half-life?
The time required for a radioactive substance to lose 50 percent of its radioactivity by decay is known as the half-life.
State of Origin
As of 03/12/2020, we can accept samples from:
| Alabama | Indiana | New York |
| Colorado | Louisiana | Oklahoma |
| Connecticut | Maine | Pennsylvania |
| Delaware | Maryland | Rhode Island |
| District of Columbia | Massachusetts | Vermont |
| Florida | New Hampshire | Virginia |
| Georgia | New Jersey |
As of 03/12/2020, we cannot accept samples from:
| Alaska | Minnesota | Oregon |
| Arizona | Missouri | South Carolina |
| Arkansas | Mississippi | South Dakota |
| California | Montana | Tennessee |
| Hawaii | Nebraska | Texas |
| Idaho | Nevada | Utah |
| Illinois | New Mexico | Washington |
| Iowa | North Carolina | West Virginia |
| Kansas | North Dakota | Wisconsin |
| Kentucky | Ohio | Wyoming |
| Michigan |
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