EPA Method 200.8 is the U.S. Environmental Protection Agency’s inductively coupled plasma-mass spectrometry (ICP-MS) method for determining trace elements in drinking water, surface water, groundwater, and wastewater under the Clean Water Act (CWA) and Safe Drinking Water Act (SDWA) monitoring programs. It is one of a small family of related ICP-based metals methods — alongside EPA Method 200.7 (ICP-atomic emission spectrometry) and the SW-846 RCRA method EPA Method 6020 — that a procurement officer, lab manager, or research administrator sourcing environmental water-testing services will routinely see specified in a proposal, a permit, or a laboratory’s certified method list. This guide explains what each method actually specifies, how they differ, and what to check before contracting or accrediting a lab against one.
What EPA Method 200.8 covers
EPA Method 200.8, “Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma-Mass Spectrometry,” is published by EPA’s Office of Research and Development as part of the agency’s Methods for the Determination of Metals in Environmental Samples series. It specifies ICP-MS as the detection technique: a sample is nebulized into an argon plasma, ionizing the elements present, and a mass spectrometer separates and counts ions by mass-to-charge ratio. That combination gives the method very low detection limits (typically low parts-per-trillion to parts-per-billion, element-dependent) and the ability to quantify roughly two dozen target elements — including arsenic, cadmium, chromium, lead, and uranium — from a single injection.
Method 200.8 is written for the Clean Water Act / Safe Drinking Water Act regulatory context: EPA lists it as an approved method under 40 CFR Part 141 (drinking water) and Part 136 (wastewater), which is why it shows up so often in NPDES permit monitoring requirements and public water system compliance sampling. It has gone through several revisions since its original publication; the version most commonly cited in current use is Revision 5.4. When evaluating a lab or a data package, always ask which revision was used and confirm it against the current version listed in EPA’s method index rather than assuming currency.
EPA Method 200.7: the ICP-AES/ICP-OES counterpart
EPA Method 200.7, “Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry,” uses a related but distinct technique: rather than mass spectrometry, it measures the characteristic light emitted by excited atoms and ions in the plasma (ICP-AES, also called ICP-OES for optical emission spectrometry). It targets a similar but broader list of metals and covers both trace and higher-concentration major/minor elements in one run.
The practical distinction for procurement purposes is sensitivity and cost trade-off, not regulatory validity: ICP-OES (Method 200.7) is generally less sensitive than ICP-MS (Method 200.8), with detection limits typically in the low parts-per-billion range rather than parts-per-trillion, but ICP-OES instrumentation and consumables are usually less expensive to run, and it handles some elements more robustly against certain spectral interferences. Both methods are EPA-approved alternatives under the same drinking-water and wastewater regulations; which one a permit or contract requires is often driven by the required detection limit for the analytes in question, not a strict technique preference. If a compliance limit sits close to or below an ICP-OES detection limit, ICP-MS (200.8) is usually the only option that can demonstrate compliance.
EPA Method 6020: the RCRA/SW-846 version of ICP-MS
EPA Method 6020 (now most commonly cited as 6020B) is functionally the same ICP-MS technique as Method 200.8, but it is published in a different EPA compendium: SW-846, “Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,” which governs testing under the Resource Conservation and Recovery Act (RCRA) rather than the Clean Water Act. Method 6020 is written to be applicable to a wider range of matrices than 200.8 — groundwater, aqueous samples, soils, sediments, sludges, and other solid-waste matrices — because RCRA testing routinely involves non-aqueous samples that 200.8 was never designed to cover.
For a procurement decision, the distinction matters because the two methods sit under different regulatory umbrellas and quality-control regimes, even though the underlying instrumentation is often identical. A lab running Method 6020 for a RCRA hazardous-waste characterization is not automatically demonstrating CWA/SDWA compliance capability under 200.8, and vice versa — the QA/QC requirements, calibration protocols, and matrix-specific interference checks differ between the two method families. Confirm which method your regulatory driver actually requires (permit language, consent decree, or program regulation) before assuming a lab’s SW-846 6020 certification substitutes for 200.8, or the reverse.
What to check before you contract or select a lab
These are ICP-MS/ICP-OES methods, not brand names, so “which vendor is best” is the wrong question — the useful comparison is whether a given laboratory’s accreditation and demonstrated performance actually cover the specific method, matrix, and analyte list your program requires. In practice that means checking the following before signing a testing contract or accepting a subcontracted lab:
- Scope of accreditation. Most state drinking-water and environmental laboratory certification programs operate under, or are cross-recognized by, the NELAC Institute (TNI) National Environmental Laboratory Accreditation Program (NELAP). Ask for the lab’s current scope-of-accreditation document and confirm it lists the specific method (200.8, 200.7, or 6020/6020B), the specific analytes you need, and the specific matrix (drinking water, wastewater, groundwater, soil). Accreditation for one method or matrix does not imply accreditation for another.
- ISO/IEC 17025 status. NELAP accreditation is built on the ISO/IEC 17025 general requirements for testing and calibration laboratories — confirm the lab’s accreditation body and certificate number, and check that the certificate is current rather than expired or under suspension. See CASRAI’s ISO/IEC 17025 guide for what that standard actually requires of a testing lab.
- Method detection limits (MDLs) and reporting limits. Ask for the lab’s current, matrix-specific MDL study for the exact method and analytes you need, not a generic instrument specification sheet. A lab may be accredited for a method but have a validated MDL too high to demonstrate compliance against your specific permit limit — this is the single most common gap between “accredited for the method” and “actually useful for your compliance need.”
- Calibration and traceability documentation. Confirm calibration standards are NIST-traceable and that the lab can produce calibration verification records on request. See CASRAI’s calibration certificate and metrological traceability guide for what “NIST-traceable” is actually supposed to mean on a certificate.
- Proficiency testing (PT) history. NELAP-accredited labs are required to participate in regular proficiency testing for accredited analytes. Ask for recent PT results (pass/fail history) for the specific method and analyte group, not just accreditation status. See CASRAI’s proficiency testing and external quality assessment guide for how PT programs work and what a result actually demonstrates.
- Holding times and preservation. Metals samples for 200.8/200.7/6020 generally require acid preservation (typically to pH <2 with nitric acid) and have defined holding times before analysis (commonly up to six months for most metals, shorter for mercury). Confirm the lab’s sample-receipt and chain-of-custody procedures actually enforce these, since a technically capable lab can still produce non-defensible data from improperly preserved or expired samples.
- Data package and QA/QC deliverables. Decide upfront whether you need a summary-level data package or a full data validation package (raw QC data, calibration curves, spike/duplicate results, chain-of-custody), since these differ significantly in cost and turnaround and the requirement is often driven by whether the data will be used in litigation, permit defense, or a regulatory submission.
One example of how this shows up on the supply side: laboratory-supply and distribution networks such as LAC Health list method-specific consumables (certified reference standards, ICP-MS/ICP-OES tuning solutions, matrix-matched calibration sets) against these exact method numbers — a useful illustration of how procuring the instrumentation and consumables side of this work is method-driven, distinct from procuring the analytical testing service itself. The same accreditation, traceability, and certificate-of-analysis questions above apply to any supplier of reference standards used to calibrate against these methods.
Frequently asked questions
What is the difference between EPA Method 200.8 and EPA Method 6020?
Both use ICP-MS and are analytically very similar, but they are published under different regulatory programs: Method 200.8 is a Clean Water Act / Safe Drinking Water Act method (40 CFR Parts 136 and 141), while Method 6020 (6020B) is published in SW-846 for RCRA hazardous-waste and multi-matrix testing (soils, sediments, and solid waste as well as water). Which one applies depends on the regulatory driver for the sample, not a technique preference — check your permit, consent decree, or program regulation to see which is actually required.
What is the difference between EPA Method 200.8 and EPA Method 200.7?
Method 200.8 uses ICP-MS; Method 200.7 uses ICP-AES/ICP-OES. Method 200.8 generally achieves lower detection limits (parts-per-trillion range) and is required when compliance limits are very low; Method 200.7 is generally less expensive to run per sample and can be more robust for certain elements or higher-concentration analytes. Both are EPA-approved alternatives under the same drinking-water and wastewater regulations.
Is EPA Method 200.8 the same as EPA Method 6020B?
They are not identical documents, but they use the same core ICP-MS technique and are often treated as functionally interchangeable for water matrices. They differ in regulatory program (CWA/SDWA vs. RCRA), applicable matrices (6020B explicitly covers soils and solid waste; 200.8 is written for aqueous samples), and their specific QA/QC and calibration requirements. A lab’s accreditation for one does not automatically cover the other — check the lab’s scope of accreditation for the specific method you need.
Do I need to specify a particular EPA method when contracting for water testing?
Yes, in almost every case. Regulatory programs (NPDES permits, public water system monitoring plans, RCRA waste characterization) typically specify an approved method by number, and a lab’s data will not be defensible for compliance purposes if analyzed by an unapproved or unspecified method. Confirm the required method in your governing permit or regulation before requesting a quote, and confirm the winning lab’s accreditation scope actually lists that method for the matrix and analyte list you need.
