The Argument on “Total” Metals

by | Mar 25, 2021 | Reports

Lab worker working samples

Why is there still an argument about which digestion method should be reported as “total” metals?

When you’re looking at an old QAPP, permit or analytical report, you might have noticed that there were different listings for how the metals were to be identified and reported out.  This was based upon what digestive method was designated at the project’s setup.  There was either a  Total Recoverable (TR) designation or a Total (T) designation.  While the two titles may sound similar, the acids used in each digestion may or may not have delivered a true “total” recovery from the sample based upon the matrix of said sample.

Total vs. Total Recoverable digestion has been the focus of many arguments over the years, with each camp claiming applicability of its selected digestion procedure to a non-filtered sampled aliquot.  When I say “camp,” I mean people developed preferences for the digestive procedure that they believed fit their sample matrix or they developed data baselines that they did not want to move away from with a new digestion procedure.

The EPA was probably tired of the amount of correspondence that they received on this issue and by legal action took it out of the hands of the many different players involved.  With guidance from the 2012 Method Update Rule (MUR), the permit writers no longer needed to request digestion procedures in order to use the “best” possible digestion.  The digestive methods for both TR and T were/are going to be reported as “Total Metals.” 

What the 2019 Method Update Rule Says

Starting with the 2012 Method Update Rule (MUR)  and continuing on with the most recent 2019 MUR, the EPA language contains a footnote (4)  to explain the current requirements on how a “Total” or “Total Recoverable” sample will be digested and reported, below is the verbiage as it relates to ICP/ICP-MS requirements:

For the determination of total metals (which are equivalent to total recoverable metals) the sample is not filtered before processing. A digestion procedure is required to solubilize analytes in suspended material and to break down organic-metal complexes (to convert the analyte to a detectable form for colorimetric analysis). The approved total recoverable digestion is described as Method 200.2 in Supplement I of “Methods for the Determination of Metals in Environmental Samples” EPA/600R- 94/111, May, 1994, and is reproduced in EPA Methods 200.7, 200.8, and 200.9 from the same Supplement. For analyses using inductively coupled plasma-atomic emission spectrometry (ICP-AES), the direct current plasma (DCP) technique or EPA spectrochemical techniques (platform furnace AA, ICP-AES, and ICP-MS) use EPA Method 200.2 or an approved alternate procedure (e.g., CEM microwave digestion, which may be used with certain analytes as indicated in Table IB); the total recoverable digestion procedures in EPA Methods 200.7, 200.8, and 200.9 may be used for those respective methods. Regardless of the digestion procedure, the results of the analysis after digestion procedure are reported as “total” metals.”

To be clear the above digestion requirements listed in the 2019 MUR supersede older EPA rules and digestion procedures and as such will be SVL’s default digestion (EPA 200.2). SVL upon request will use alternative digestive methods but will still report out our results as “Total Metals.”  You can visit the EPA’s site at: https://www.epa.gov/cwa-methods/methods-update-rule-2019.

We know change is difficult and recognize that our reporting format may no longer match what you have always been used to.  Please, contact your Project Manager and let them walk you through our report format and why we report your analyses in the manner that we do.

Join us for more information

about the environmental laboratory industry, plus events we’re attending and hosting.

Significant Figures Use by Laboratories

What determines the amount of numbers you see on your report? Each test that we do has a level of sensitivity associated with it.  Tests that you can do by visual inspection have the lowest sensitivity and are usually reported in whole numbers in a range of say 1 to...

New Drinking Water COC for Coliform Bacteria Available

We’ve updated our Drinking Water COC/Submittal Form for Coliform Bacteria. You can download it off of our  Resources page.    

The Argument on “Total” Metals

Why is there still an argument about which digestion method should be reported as “total” metals? When you’re looking at an old QAPP, permit or analytical report, you might have noticed that there were different listings for how the metals were to be identified and...

Exciting changes: a new location

After 16 years in our current location, we a relocating our Coeur d'Alene laboratory service to our Kellogg location and establishing a new sample drop-off location in Hayden. Here are some important dates to keep in mind: March 18, 2021: The last day to drop samples...

What to Do With a Result Above Your Permit Limit

When people come to SVL Analytical, they’re often looking for data to show that they’re in compliance with the applicable regulations or permits. What happens when the data you get back isn’t in compliance?  That can be a stressful situation and we want to help...

Reading your Report

If you’re not familiar with the format and terminology, your sample’s analytical report may be confusing. Here are some explanations to get you started.

My water tastes funny, what should I test for?

There are many reasons for household water to have an unusual odor or taste.

New Drinking Water COC Available

We’ve updated our Drinking Water (Chemistry) COC. You can download it off of our Resources page.

New Spectrometer at SVL

SVL is proud to announce our latest laboratory equipment acquisition: the? Agilent Model 5110 ICP-OES Spectrometer. The Agilent 5110 ICP-OES Instrument features unique Dichroic Spectral Combiner (DSC) technology that enables synchronous radial and axial measurements....

Field Filtering Samples for Dissolved Metals Analysis

To help our clients in the selection of field filtering apparatus and supplies we provide the following information and links. A peristaltic pump (also called a circulating pump or vein pump) and appropriate hosing is required with a 0.45? ?filter capsule and sample...