Selective analysis of secondary amino acids in gelatin using pulsed electrochemical detection.
A method was developed for selective analysis of the secondary amino acids proline and 4-hydroxyproline from gelatin hydrolysates using anion-exchange high-performance liquid chromatography followed by integrated pulsed amperometric detection (HPLC-IPAD). An extraction scheme was implemented prior to HPLC-IPAD analysis to isolate the secondary amino acids by the removal of primary amino acids through derivatization with o-phthalaldehyde followed by solid-phase extraction with C18 packed columns. The use of the IPAD technique eliminated the need for a second derivatization step to detect secondary amino acids. The removal of interfering primary amino acids prior to chromatographic analysis allowed the use of isocratic mobile-phase conditions to achieve effective and efficient separation of the amino acids. This led to a more precise and accurate quantitation of their content in gelatin hydrolysates. Detection limits approach 10 parts per billion ( approximately 2 pmol/injection) with a chromatographic analysis time under 8 min. The ratios of secondary amino acids, in addition to their abundances, were used to distinguish gelatin manufactured from bovine, porcine, and fish raw material sources.
Department of Chemistry, University of South Dakota, Vermillion, SD 57069, USA.
Jason D
JD
Russell
John M
JM
Dolphin
Miles D
MD
Koppang
D000468:Alkalies; D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry*; D002138:Calibration; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005780:Gelatin / Q000032:analysis* / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation
D000468:Alkalies; D000596:Amino Acids; D006046:Gold; D005780:Gelatin