Rapid determination of cholesterol oxidation products in milk powder based products by reversed phase SPE and HPLC-APCI-MS/MS

Andrea Gorassini; Giancarlo Verardo; Scharina-Carol Fregolent; Renzo Bortolomeazzi

doi:10.1016/j.foodchem.2017.03.080

Rapid determination of cholesterol oxidation products in milk powder based products by reversed phase SPE and HPLC-APCI-MS/MS

Food Chem. 2017 Sep 1:230:604-610. doi: 10.1016/j.foodchem.2017.03.080. Epub 2017 Mar 15.

Authors

Andrea Gorassini¹, Giancarlo Verardo², Scharina-Carol Fregolent³, Renzo Bortolomeazzi⁴

Affiliations

¹ Department of Humanities and Cultural Heritage, University of Udine, Vicolo Florio 2/B, 33100 Udine, Italy. Electronic address: andrea.gorassini@uniud.it.
² Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via Sondrio 2/A, 33100 Udine, Italy. Electronic address: giancarlo.verardo@uniud.it.
³ Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via Sondrio 2/A, 33100 Udine, Italy. Electronic address: scharina88@gmail.com.
⁴ Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via Sondrio 2/A, 33100 Udine, Italy. Electronic address: renzo.bortolomeazzi@uniud.it.

PMID: 28407957
DOI: 10.1016/j.foodchem.2017.03.080

Abstract

A rapid and sensitive HPLC-APCI-MS/MS method for the determination of cholesterol oxidation products (COPs) in milk powder based foods is reported. The method consists in the direct saponification of the sample and purification of oxysterols by reversed phase C18-SPE followed by HPLC-MS/MS analysis. By this procedure, the extraction and enrichment of oxysterols are combined in a unique step, reducing sample manipulation and the possible formation of artifacts. LOD and LOQ were in the concentration ranges of 2-8ngg^-1 and 8-30ngg^-1, respectively. The precision (CV%) was in the range 10-36% in fresh samples with a total COPs amount from 212 to 645ngg^-1 and 6-14% for an oxidized sample with a higher amount (3651ngg^-1). The recovery ranged from 74±8% for 7-ketocholesterol to 101±12% for 7α-hydroxycholesterol at 200ngg^-1 and from 82±2% for 7-ketocholesterol to 117±10% for 5α,6α-epoxycholesterol at 500ngg^-1 spiked levels, respectively.

Keywords: Atmospheric pressure chemical ionization liquid chromatography-tandem mass spectrometry (HPLC-APCI-MS/MS); COPs; Cholesterol oxidation products; Infant formula; Instant formula products; Milk powder; Reversed phase C18 SPE; Solid phase extraction (SPE).

MeSH terms

Animals
Chromatography, High Pressure Liquid / methods*
Food Analysis / methods*
Milk / chemistry*
Oxidation-Reduction
Solid Phase Extraction / methods*
Tandem Mass Spectrometry / methods*