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US EPA Method 200.7

Overview of "Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma–Atomic Emission Spectrometry (ICP-OES)"

US EPA Method 200.7 defines the analytical procedure for measuring metals and trace elements. The method specifies method detection limits (MDLs) for 31 elements, as well as recommended wavelengths, calibration procedures, and quality control requirements.

End-to-End Analytical Process

Sample Collection

According to EPA 200.7, samples intended for dissolved metals determination must be filtered (0.45 μm) and preserved to pH < 2 with nitric acid. Total‑recoverable samples (with particulates) must be acidified to pH < 2 upon collection. Preservation may occur in the lab if performed within two weeks and held at pH < 2 for at least 16 hours.

Sample Preparation

Dissolved metals: analyze acidified filtrate directly.
Total recoverable metals: acid pretreatment with HNO₃ + HCl, followed by gentle refluxing.
For boron and silica: only plastic, PTFE, or quartz labware is permitted.

Analysis & Maintenance

Analysis is carried out by ICP‑AES after nebulization into the plasma.
The EPA method requires:

Background correction
Spectral, physical, and chemical interference management
QC requirements: MDL studies, QCS, LFB, LFM, SIC, IPC, LRB, CB

Methods & Workflows

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