Description of the Assay

This assay can measure more than 40 bile acids and bile acid conjugates from biological fluids and tissues. Additionally, 20 Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) can be included in the same method. The method can also be run in targeted/untardeted mode, slightly redusing sensitivity, but allowing for the detection of untargeted compounds.

Bile acids, a group of sterols which are end-products of cholesterol metabolism, are primarily involved in dietary lipid absorption and cholesterol homeostasis. Bile acids also act as signalling molecules, regulate systemic endocrine functions and their systemic composition reflects gut microbial metabolism.

PFASs are used in products and on materials due to their enhanced water-resistant properties, such as within Teflon. recently the environmental impact and toxicity to human and mammalian life been studied in depth. PFOS, PFOA and other PFASs are commonly described as persistent organic pollutants or “forever chemicals” because they remain in the environment for long periods of time.

Analytes Measured

The assay includes 20 PFAS compounds with 4 to 14 carbons and either an acid or a sulfonic acid headgroup.

Additionally, the following bile acids are included:

Jäntti, S.E., Kivilompolo, M., Öhrnberg, L. et al. Anal Bioanal Chem (2014) 406: 7799. https://doi.org/10.1007/s00216-014-8230-9

Sample Types Accepted

• Plasma
• ­Whole blood
• ­Serum (see note below)
• Adipose tissue
• Faecal / intestine contents
• Urine
• Bile / gallbladder tissue
• Cerebrospinal fluid(CSF)
• Cytoplasmic fraction of the brain

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Generic Sample Handling Guidelines

• Samples should always be stored at -80°C and transported in dry ice.
• Ideally, samples should be aliquoted into suitably-sealed, standard containers with labels, to avoid multiple freeze thaws (e.g. 1.5/2mL Eppendorf tubes, or larger volumes in Falcon tubes).
• Sample lists/grids should be provided in electronic format along with the samples.
• If possible, provide information on sample collection and handling procedures, including :
  • Sample source
  • Sample collection date
  • Freezing method, length of storage and temperature
  • Number and type of freeze and thaw cycles

Blood

• Ideally EDTA plasma tubes should be mixed five times directly after sampling.
• Blood samples need to be kept at 4°C during preparation.
• Recommended centrifugation parameters for serum and plasma are 15 minutes at 1600g at 4°C.
• Serum standing time recommended as 30 minutes at 4°C.

Tissue

• White adipose tissue samples should be taken from subcutaneous peri-umbilical fat.
• Tissues should be frozen immediately in liquid nitrogen after sampling.

Faecal

• Intact faecal samples should be collected, kept at 4°C for no longer than 24 h. For any longer, it should be stored at −80°C and transported using dry ice. If such a freezer is not available, intact faecal samples can also be stored in a −20°C freezer for no more than 24 h.