A Rapid Method for the Estimation of Bile Salts in Complex Tanning Brines by RPHPLC

Abstract

To preserve bovine hides until they are processed into leather, they are often cured in large raceways of saturated brine. This process prevents the growth of most microorganisms, but under some conditions these hides are still susceptible to decomposition by halophilic archaebacteria. Low amounts of porcine bile added to the brine used for curing, have exhibited control of growth of these primitive microorganisms. Reversed‐phase high pressure liquid chromatography (RPHPLC) has been applied to monitor bile concentration in saturated brine mixtures containing contaminants associated with animal hides (bacteria, blood, dirt, fats, hair, manure, urine, etc.). With minimal sample preparation, this method can be used by either the hide curing, packing, or tanning industry to assess the need to charge brine solutions with additional porcine bile during the continuous process of hide addition and removal. Calibration curves of porcine bile added to highly contaminated raceway brine have demonstrated linearity of detection between 25–340 ppm bile. The method of standard addition was used to identify and quantify a porcine bile component, glycochenodeoxycholic acid. Reversed‐phase high pressure liquid chromatography was also used to determine the relative solubility of porcine vs. bovine bile in solutions of varying salt concentration.

Keywords:

• Archaebacteria
• Bile
• Brine
• Halophiles
• Reversed phase HPLC

Acknowledgments

Mention of brand or firm names does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned. We thank Jeffrey Brewster, Michael Kurantz, and Alan Lightfield, from the Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, for their technical support and assistance in this project. In addition, we acknowledge the advice and participation of our research partners, Southeast Applied Research (Diamondhead, MS), under Cooperative Research and Development Agreement # 58‐3K95‐M‐625.

Abbreviations
GCDC	=	glycochenodeoxycholic acid
RPHPLC	=	reversed‐phase high pressure liquid chromatography