3-Hydroxy-Tetradecanoic Acid: A Chemicalmarker of Endotoxin and Gram-Negative Bacteria in Occupational Health Monitoring

E. Paci1, A. M. Marcelloni1, F. Marini2, G. Tranfo1, E. Paba1, and A. Chiominto1

1. Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, National Institute for Insurance against

Accidents at Work (INAIL), Italy

2. Department of Chemistry, University of Rome "Sapienza", Italy

Abstract: LAL assay is the most widely used method for endotoxin detection in occupational health monitoring but critical aspects have been reported.

This paper reports the results of a field study, in which the concentration of 3-hydroxy-dodecanoic and 3-hydroxy-tetradecanoicacidswere measured by HPLC-MS/MS on air samples collected on filters in workplaces in order to verify if a chemical approach can be used for the assessment of the environmental contamination from endotoxins and/or Gram-negative bacteria.

At each site, two sampling lines were used simultaneously: onefilter was analysed for endotoxin detection by LAL test, while the other was extracted for determining its content of fatty acids.All Gram-negative bacterial strains were identified to genera/species level in each sample.

Endotoxin contamination measured by LAL test was detected in all samples (range 0.04-210.7 EU/m3) as well as 3-OH C14 (range: 8.72-224.20 ng/m3) while 3-OH C12 levels were below the analytical detection limit in 23 out of 25 samples.

Principal Component Analysis shows that endotoxin levels positively correlate with the content of fatty acids. However, the main component of lipopolysaccharide detected in our samples is 3-hydroxytetradecanoicacid, and therefore it can be considered as a good marker of endotoxin presence.

Key words: 3-hydroxy fatty acids, LAL assay, HPLC/MS-MS, PCA analysis