Analysis of patulin in apple products by liquid–liquid extraction, solid phase extraction and matrix solid-phase dispersion methods: a comparative study

Determination of patulin and hydroxymethylfurfural in beverages by UPLC-PDA

The present study describes using molecularly imprinted polymer (MIP) technology for determination of patulin (PAT) and 5-hydroxymethylfurfural (5-HMF) in beverages by ultra-high performance liquid chromatography coupled to photodiode array (UPLC-PDA). PAT (4-hydroxy-4H-furo[3,2-c]pyran-2(6H)-one) is a mycotoxin produced by Penicillium fungi and Penicillium expansum is probably the most commonly encountered species that infects apples during their growth, harvest, storage or processing. The occurrence of PAT as a natural contaminant of apples is a worldwide problem. 5-HMF (also known as 5-(hydroxymethyl) furan-2-carbaldehyde), is formed in the Maillard reaction as well as during caramelisation. It is a good storage time-temperature marker and flavour indicator, especially in beverages such as wine, beer, but also cider and apple juice which may contain PAT. PAT and 5-HMF were separated within 2 min using a Luna Omega C18 column and the PDA detector wavelength was set to 276 nm. The validation parameters of the analytical method such as linearity, limit of detection, limit of quantification, accuracy and precision were tested. The calibration curves were linear at least in the range 50-1000 ng/ml with a good linearity (R2>0.999) for both analytes, the limit of detection and the limit of quantification for PAT and 5-HMF were in the range 4.9-6.6 and 16.1-21.8 μg/l, respectively. The recoveries of the selected analyte were in the range 61.9-109.0% with a precision of <8.2% (relative standard deviation (RSD)) for PAT and in the range 50.8-98.0% with a precision of <10.0% (RSD) for 5-HMF. The validated procedure was successfully applied for the analysis of PAT and 5-HMF in beverages from retail shops.

Screening of a Combinatorial Library of Organic Polymers for the Solid-Phase Extraction of Patulin from Apple Juice

Patulin is a water-soluble mycotoxin produced by several species of fungi. Governmental bodies have placed it under scrutiny for its potential negative health effects, and maximum residue limits are fixed in specific food matrices to protect consumers’ health. Confirmatory analysis of patulin in complex food matrices can be a difficult task, and sample clean-up treatments are frequently necessary before instrumental analyses. With the aim of simplifying the clean-up step, we prepared a 256-member combinatorial polymeric library based on 16 functional monomers, four cross-linkers and four different porogenic solvents. The library was screened for the binding towards patulin in different media (acetonitrile and citrate buffer at pH 3.2), with the goal of identifying polymer formulations with good binding properties towards the target compound. As a proof of concept, a methacrylic acid-co-pentaerithrytole tetraacrylate polymer prepared in chloroform was successfully used as a solid-phase extraction material for the clean-up and extraction of patulin from apple juice. Clean chromatographic patterns and acceptable recoveries were obtained for juice spiked with patulin at concentration levels of 25 (64 ± 12%), 50 (83 ± 5.6%) and 100 μg L⁻¹ (76 ± 4.5%). The within-day and between-day reproducibility evaluated at a concentration level of 25 μg L⁻¹ were 5.6 and 7.6%, respectively.

Determination of trace patulin in apple-based food matrices

Patulin is a toxic metabolite of a number of fungi; its toxicity is serious and its contamination in food is a worldwide problem, especially in apple-based food. Effective control of patulin contamination strongly depends on reliable analytical methods. In this review, various analytical methods, especially those that have appeared in the last ten years, are summarized, including the highly reproducible chromatography and mass-spectrometry-based methods, highly selective sensor-based methods and indirect quantitative PCR methods. This review also summarizes the promising features of novel materials in sample preparation for patulin determination.

Determination of patulin in apple juice using magnetic solid-phase extraction coupled with high-performance liquid chromatography

An efficient magnetic sorbent consisting of benzofuran-2-carboxylic acid-loaded magnetic nanocomposite was successfully synthesised for pre-concentration of patulin from apple juice. The prepared magnetic nanocomposite was characterised by scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. Determination of enriched patulin was performed by high-performance liquid chromatography. The best adsorption conditions were 40 mg of sorbent, 50 ml of apple juice sample, pH 5, ambient temperature and 25 min; the elution conditions were 500 μl methanol, pH 5, ambient temperature, and 4 min. Under optimised conditions, pre-concentration factor was 100, linearity range was 1-400 μg l^-1 of patulin, limit of detection was 0.15 μg l^-1 and limit of quantification was 0.5 μg l^-1. When samples were determined 20 times, the recovery was 93.9-102.6% and the relative standard deviation was below 5.3%. In terms of proposed procedure, the developed method was successfully applied for patulin detection in apple juice samples.

Advances in isoflavone profile characterisation using matrix solid-phase dispersion coupled to HPLC/DAD in Medicago species

INTRODUCTION

Analytical methods used in phytochemistry analysis are limited by the sample preparation step, which should ideally be fast, accurate, ecofriendly and achievable using low quantities of the sample. Matrix solid-phase dispersion (MSPD) may be a good alternative for combining extraction and purification procedures, thereby reducing the indicated limitations.

OBJECTIVE

Applying an MSPD extraction procedure coupled to high-performance liquid chromatography diode-array detection (HPLC/DAD) as an alternative methodology to evaluate isoflavone profiles.

METHODS

Isoflavone profiles were determined for the leaves of nine species of Medicago in the late flower phenological stage (one or more nodes with 50% open flowers, no seed pods). Extraction was performed following MSPD, and isoflavone profiles were characterised using HPLC/DAD. The quantified amounts were compared with previous results in different species commonly recognised as good sources of isoflavones.

RESULTS

Formononetin was the major isoflavone in most species, except M. polymorpha and M. truncatula. The isoflavone amounts were significantly different among the assayed species, with M. orbicularis and M. arabica as the major isoflavone sources, while M. rigidula presented the lowest contents. Furthermore, the detected differences allow electing the best species as a primary source of a specific isoflavone.

CONCLUSION

The MSPD allowed good extraction efficiency, reproducibility and recovery. Some of the species showed relevant isoflavone contents, even when compared with acknowledged plant sources such as soy or red clover. To the best of our knowledge the results presented are reported for the first time in these species.