The PFAS List Is Growing. Your Method Options Are Too.

The regulated PFAS list has steadily expanded, and the trend is toward shorter-chain compounds that analysts did not previously monitor.

That expansion creates an analytical cost problem that is easy to miss. The more comprehensive the method, the slower and more expensive each sample becomes. When applied uniformly across a large program, this method adds up quickly.

THE COMPREHENSIVE OPTION

EPA Method 1633 is the thorough route. It covers a wide target list with rigorous quality control, and it is the appropriate choice when regulatory defensibility across the full compound range is required.

It is also time-consuming and, compared to other methods, more costly. These characteristics matter most when sample volume is high.

THE PAIRED ASTM METHODS

ASTM D8421 for water and ASTM D8535 for soil are paired laboratory methods using liquid chromatography with tandem mass spectrometry. They analyze the same core list of 44 target PFAS compounds and share compatible chromatography workflows, which means results across matrices remain comparable.

These methods provide answers at significantly lower costs for screening work, site characterization aimed at understanding distribution, and programs where sample volume is the primary factor influencing per-sample cost.

RJ Lee Group performs ASTM D8421 and D8535, which are performance-based methods that carry no accreditation of their own. A2LA has accredited our PFAS work by EPA 533, 537.1, and 1633 to ISO/IEC 17025.

CHOOSING BETWEEN THEM

The useful question is not which method is better. It is the decision that the result must support. Screening a site to understand where contamination exists requires a different analytical scope than a compliance submission. Using the comprehensive method for both is a common and expensive habit.

A sensible program often uses both: faster methods to characterize and prioritize and comprehensive analysis where the result must carry regulatory weight.

VOC ANALYSIS, THE SAME PRINCIPLE

The same reasoning applies elsewhere. ASTM D6520 and EPA 5021A are complementary headspace methods for extracting and preparing volatile organic compounds for gas chromatography analysis, and the choice between approaches follows the same logic.

If you are building a sampling program and the analytical budget is a constraint, the method-selection conversation is worth having before the samples are collected, not after the invoice arrives. 

Related reading: Unlocking the Secrets of PFAS Testing Methods