EnviroMail 132 - BIOSOLIDS: PFAS, TOP Assay & TOF


PFAS in biosolids is an emerging environmental issue as it is a pathway to human exposure / contamination through the reuse of biosolid in agriculture. ALS completed an R&D project which determined best practice for extracting PFAS from the complex matrix and is now NATA accredited for the analysis of PFAS, TOP assay and TOF in biosolids.


Given the prevalent use of PFAS in common household products, e.g., non-stick cookware, fabric/furniture/carpet stain protection, food packaging, etc., there is a growing need to offer accredited testing services for biosolids as the by-product of treated sewage/wastewater. This is of particular interest for determining the suitability of biosolids for re-use, e.g. in the agricultural industry, where they may constitute a significant source of contamination or exposure pathway to humans.  ALS is pleased to announce that NATA accreditation for PFAS analysis now extends to biosolids, covering 28 PFAS compounds, including the Total Oxidisable Precursor (TOP) Assay.  Accreditation for biosolids also extends to analysis of Total Organic Fluorine (TOF).  These services provide comprehensive fluorine accounting in biosolids and align with the requirements of the Queensland End of Waste (EOW) code on biosolid reuse.

Regulatory Responses to PFAS in Biosolids

Guidance and regulation are beginning to emerge for PFAS in biosolids. In December 2017, a research report issued by the Australian & New Zealand Biosolid Partnership (ANZBP) used tolerable daily intake levels from the Department of Health to derive recommended limits for safe unrestricted reuse of biosolids of 0.3mg/kg for PFOS and 2.4mg/kg for PFOA.  There is also guidance provided in the National Environmental Management Plan (NEMP) on PFAS to consider biosolids as an exposure pathway in risk assessment, though no guideline criteria are currently listed for biosolids in the NEMP.


In January 2020, the Queensland Government released version 2.0 of the End of Waste (EOW) code for biosolids.  The code requires monitoring of PFAS and Total Organic Fluorine in the raw biosolid resource, without specific trigger values. The soil to be used for amendment is to be screened using standard PFAS analysis and TOP Assay. The code then requires calculation of expected concentrations of the soil amended with the biosolid resource in consideration of PFAS concentrations determined in the biosolid.  It then sets specific trigger values for PFAS in the amended soil analysed after application and within 3 months of application occurring. The code requires all analysis “be carried out by a laboratory that has NATA certification, or an equivalent certification, for such analyses” (clause 6.14).

Summary of ALS NATA Accredited Testing Services for Biosolids

PFAS EP231X 0.0025-0.01* 
TOP Assay EP231X(TOP) 0.0025-0.01* 
TOF (Standard Level) EP040  1
TOF (Low Level)  EP040-LL 0.1 

* Refer to Table 1 for specific LORs offered for individual PFAS analytes

Sampling & Analysis

The standard HDPE specimen jar for soils is also applicable for sampling biosolids. Samples should be submitted to the laboratory chilled. It is important to clearly mark the samples as biosolids on the chain-of-custody to ensure safe handling by the laboratory.  

The high organic content of biosolids present unique analytical challenges for PFAS beyond standard soil matrices.  Extraction efficiency is typically poor for conventional solvent extraction techniques used for soils, resulting in low PFAS recoveries. In addition, co-extracted organics impart significant analytical interferences.  ALS has developed a unique QuEChERS extraction procedure to maximise PFAS recovery from biosolids, including a comprehensive extract clean-up to remove interfering co-extracted organics.  QuEChERS is a well-established technique for the extraction of pesticides from complex biological matrices and lends itself well to fluorinated organics such as PFAS.

Table 1. Limits of Reporting (LOR) for PFAS and TOP Assay in Biosolids. 
EP231X EP231X (TOP)
Perfluoroalkane Sulfonic Acids
Perfluorobutane sulfonic acid (PFBS) 375-73-5 0.0025 0.0025
Perfluoropentane sulfonic acid (PFPeS) 2706-91-4 0.0025 0.0025
Perfluorohexane sulfonic acid (PFHxS) 355-46-4 0.0025 0.0025
Perfluoroheptane sulfonic acid (PFHpS) 375-92-8 0.0025 0.0025
Perfluorooctane sulfonic acid (PFOS) 1763-23-1 0.0025 0.0025
Perfluorodecane sulfonic acid (PFDS) 335-77-3 0.0025 0.0025
Perfluoroalkane Carboxylic Acids
Perfluorobutanoic acid (PFBA) 375-22-4 0.01 0.01
Perfluoropentanoic acid (PFPeA) 2706-90-3 0.0025 0.0025
Perfluorohexanoic acid (PFHxA) 307-24-4 0.0025 0.0025
Perfluoroheptanoic acid (PFHpA) 375-85-9 0.0025 0.0025
Perfluorooctanoic acid (PFOA) 335-67-1 0.0025 0.0025
Perfluorononanoic acid (PFNA) 375-95-1 0.0025 0.0025
Perfluorodecanoic acid (PFDA) 335-76-2 0.0025 0.0025
Perfluoroundecanoic acid (PFUnDA) 2058-94-8 0.0025 0.0025
Perfluorododecanoic acid (PFDoDA) 307-55-1 0.0025 0.0025
Perfluorotridecanoic acid (PFTrDA) 72629-94-8 0.0025 0.0025
Perfluorotetradecanoic acid (PFTeDA) 376-06-7 0.005 0.005
Perfluorohexadecanoic acid (PFHxDA) 67905-19-5 0.0025 0.0025
Perfluoroalkyl Sulfonamides
Perfluorooctane sulfonamide (FOSA) 754-91-6 0.0025 0.0025
N-Methyl perfluorooctane sulfonamide (MeFOSA) 31506-32-8 0.005 0.005
N-Ethyl perfluorooctane sulfonamide (EtFOSA) 4151-50-2 0.005 0.005
N-Methyl perfluorooctane sulfonamidoethanol (MeFOSE) 24448-09-7 0.005 0.005
N-Ethyl perfluorooctane sulfonamidoethanol (EtFOSE) 1691-99-2 0.005 0.005
N-Methyl perfluorooctane sulfonamidoacetic acid (MeFOSAA) 2355-31-9 0.01 0.01
N-Ethyl perfluorooctane sulfonamidoacetic acid (EtFOSAA) 2991-50-6 0.005 0.005
(n:2) Fluorotelomer Sulfonic Acids
4:2 Fluorotelomer sulfonic acid (4:2 FTS) 757124-72-4 0.0025 0.0025
6:2 Fluorotelomer sulfonic acid (6:2 FTS) 27619-97-2 0.0025 0.0025
8:2 Fluorotelomer sulfonic acid (8:2 FTS) 39108-34-4 0.0025 0.0025
10:2 Fluorotelomer sulfonic acid (10:2 FTS) 120226-60-0 0.0025 0.0025