diPAP – A PFAS group drawing more attention

Over the last 10 years PFAS contamination of water and soil have to a great extent been linked to the use of AFFF foams e.g. at fire drill sites. In parallel investigations of products and other environmental matrices have been performed. This also means that other PFAS chemicals come into focus, substances that are typically not found in firefighting foams. Polyfluoroalkyl phosphate esters (PAP) and especially the diesters (diPAP) is such a “family” of PFAS. The ester structure of PAP is formed when different telomer alcohols react (FTOH) react with phosphate. PAPs have been used in the pulp and paper industry e.g. in food contact materials (FCM) but also in personal care products, cosmetics, cleaning products, coatings and paints (Eriksson, 2016; KEMI Rapport 5/21). For example, in a study of cosmetics (KEMI PM 9/21) the sum of diPAPs comprised up to 0.2% of the total content. In addition, the C8 sulphonamide based di-ester, diSAmPAP, can frequently still be detected in e.g. FCM (KEMI Rapport 5/21).

Presence in the Enviroment

Besides direct exposure to PAP compounds they can also be found in the environment. This e.g. applies to indoor dust where mono and diPAPs made up 39-94% of the total PFAS measured (tot PAP in SE dust 167 µg/kg; Eriksson 2016). Given the presence of the substances in consumer products, sewage sludge is a matrix that will reflect this usage. In the report by Yeung et al (2016) diPAP was found to be the major PFAS class (42-79%) in sludge from three Swedish WWTP (~120 µg/kg DM) with PFAS moieties ranging from 6:2 up to 16:2. High concentrations have also been found in sludge from other Nordic countries and occasionally low levels in effluent water (TemaNord 515, 2019). As a consequence, diPAP (6:2, 8:2, 10:2) was recommended in the current PFAS monitoring campaign by the Swedish sludge certification program REVAQ. DiPAPs are also occasionally found in biota e.g. fish, marine and terrestrial mammals in the Nordics (TemaNord 515, 2019). Another recent finding is the detection of diPAP (e.g. 8:2 and 10:2) in sediments outside a number of Swedish pulp and paper mills with concentrations summing up to 1100 µg/kg DM. In addition, diSAmPAP was found as well (max. 680 µg/kg DM; NV-06307-20, 2022). In March a study was published demonstrating the occurrence 6:2 diPAP in toilet paper from all over the world and that this was the case for both paper made from virgin and recycled fibers. It was calculated that toilet paper could correspond to 4-89% of the 6:2 diPAP found in sludge (Thompson et al, 2023)

Analysis of diPAPs and diSAmPAP

Eurofins now offers a range of PAP compounds in environmental solids and products (e.g. paper, tissue, building material etc). For solids the reporting limit (LOQ) is 0.1 µg/kg DM and for products 1 µg/kg. The tests can be ordered in addition to already existing packs for soil/sediment/sludge, see codes in the table below. If they are to be analysed on their own a preparation test needs to be added, LW153 (env solids) and LW24X (products). For products and waste, the four compounds can also be found in the new package PLWB0. Frequently a pretreatment is required for products such as milling, shredding and/or crushing (SL004 or LX001; additional cost). For sludge, sediment etc the LOQs are based on a dry matter content of at least 60%. Drying can be ordered separately if preferred (SL797). Development work is taking place to extend the scope with 10:2 diPAP and diSAmPAP (for env solids). Please contact us in advance if you are planning bigger jobs, especially for products.

Contact Eurofins experts!

Questions about PFAS can be answered by our analytical advisory service, which can be reached via customer support, 010-490 8110 or e-mail: SpecialBUMiljo@eurofins.se

Further Reading:

Eriksson, U.  (thesis 2016)
Yeung et al (2016), SE-EPA report
TemaNord 515 (2019)
KEMI PM 9/21: PFASs in Cosmetics
KEMI Rapport 5/21
NV-06307-20 (2022; sediment)
Thompson et al (Env Sci Tech Lett, in press 2023; free abstract)