Supplementary material

Biotransfer of perfluoroalkyl acids in dairy cows in a naturally contaminated environment

Robin Vestergren1*, Francis Orata1,2, Urs Berger1, Ian T. Cousins1

1Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91 Stockholm, Sweden.

2Pure and Applied Chemistry Department, MasindeMuliro University, Kenya (present affiliation)

*Corresponding author

Chemicals and reagents

All native and isotope labeled PFCA and PFSA standard compounds were purchased from Wellington Laboratories (Guelph, ON, Canada) in 2 µg mL-1 solution mixtures. The 9target analytes were perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorohexanesulfonic acid (PFHxS) and perfluorooctanesulfonic acid (PFOS). Internal standards were 13C2-PFHxA, 13C4-PFOA, 13C5-PFNA, 13C2-PFDA, 13C2-PFUnDA, 13C2-PFDoDA, 18O2-PFHxS and 13C4-PFOS. 13C8-PFOA and 13C8-PFOS were used as volumetric standards in the calculation of total method recovery of the internal standards. All isotope labeled standards were certified to contain <0.5% of their native analogues.

All reagents were analytical reagent grade. Tetrabutyl ammonium hydrogen sulfate (TBA) was purchased from MERCK, sodium hydroxide (NaOH) from Akzo Nobel, sodium carbonate (Na2CO3) from Riedel-de Haën, sodium hydrogen carbonate (NaHCO3) and ammonium acetate (CH3COONH4) from KEBO, formic acid (CH2O2) from Fluka, potassium hydroxide (KOH) from BDH, ammonium sulfate ((NH4)2SO4) from Sigma-Aldrich, and anhydrous granulated sodium sulfate (Na2SO4) from Scharlau. Florisil sorbent (60/100 mesh) and Supelclean graphitized carbon (ENVI-carb) were obtained from SUPELCO. The water used in the method was HPLC grade (PROLABO Chromanorm). Acetonitrile (Chromasolv grade) was purchased from Riedel-de Haën. Methyl tert-butyl ether (MTBE) was purchased from Rathburn chemicals. Methanol (MeOH, LiChrosolv grade) was supplied by MERCK.

Table S1. Method detection limits (MDLs) in ngkg-1or ng L-1for PFAAs in the different intake media, cow tissues and excretion media.

Sample medium / PFOA / PFNA / PFDA / PFUnDA / PFDoDA / PFOS
Intake media
Water (ng L-1) / 0.071 / 0.025 / 0.015 / 0.014 / 0.011 / 0.020
Silage (ngkg-1) / 6.3 / 1.5 / 1.8 / 1.6 / 1.0 / 2.0
Barley(ngkg-1) / 6.1 / 1.8 / 1.6 / 1.9 / 0.5 / 1.9
Supplements(ngkg-1) / 5.8 / 2.5 / 3.1 / 3.1 / 3.5 / 2.2
Cow tissues
Liver(ngkg-1) / 6.6 / 2.3 / 3.0 / 2.6 / 1.0 / 1.7
Blood(ngkg-1) / 6.8 / 2.0 / 2.9 / 2.6 / 1.2 / 1.9
Muscle(ngkg-1) / 5.3 / 1.3 / 1.3 / 0.8 / 0.5 / 1.6
Excretion media
Urine (ngL-1) / 3.3 / 0.9 / 0.7 / 1.3 / 0.5 / 0.8
Feces(ngkg-1) / 6.4 / 2.9 / 3.1 / 2.0 / 2.0 / 6.1
Milk(ngL-1) / 3.7 / 1.2 / 1.0 / 1.5 / 0.7 / 3.3

Table S2. Average total method recoveries (%)for the internal standards spiked at approximately 100 ng kg-1to the different matrices except drinking water where a spike concentration of 1 ng L-1 was used.

Sample medium / 13C4-PFOA / 13C5-PFNA / 13C2-PFDA / 13C2-PFUnDA / 13C2-PFDoDA / 13C4-PFOS
Intake media
Water / 90 / 82 / 65 / 59 / 58 / 73
Silage / 62 / 53 / 55 / 49 / 51 / 67
Barley / 61 / 56 / 53 / 52 / 49 / 68
Supplements / 53 / 52 / 50 / 49 / 52 / 65
Cow tissues
Liver / 68 / 71 / 60 / 53 / 50 / 64
Blood / 64 / 73 / 57 / 55 / 50 / 62
Muscle / 80 / 75 / 58 / 60 / 53 / 78
Excretion media
Urine / 70 / 68 / 65 / 58 / 59 / 74
Feces / 58 / 53 / 50 / 51 / 49 / 55
Milk / 78 / 72 / 71 / 68 / 63 / 80

Figure S1.Measured concentrations of PFAAs in milk samples from 6 individual cows that were milked by hand (arithmetic mean±1 standard error) and one pooled milk sample taken from the milk tank.

Figure S2. Measured concentrations of PFAAs in pooled milk samples over the sampling campaign November 2010 to April 2011.