Development of a Stir Bar Sorptive Extraction Method for Analysis of Ochratoxin A in Beer

Abstract

A new, simple, and sensitive method was developed for extraction of ochratoxin A (OTA) in beer combined with HPLC-fluorescence detector. Samples were extracted by stir bar sorptive extraction (SBSE) followed by liquid desorption using commercially available Twister EG-Silicone. The main parameters influencing SBSE, including phase ratio, extraction time, stirring speed, ionic strength, organic modifier, pH, temperature, desorption mode, desorption solvent, and desorption time were optimized. Under the optimal conditions, assay was performed on 4 mL of samples acidified at pH 1.5. The samples were extracted for 180 min at a stirring speed of 800 rpm followed by desorption of analyte using 1 mL methanol under sonication for 45 min. The extract was evaporated at 50 degrees C under a gentle nitrogen stream, then redissolved in 200 microL of methanol-water (50 + 50, v/v). After each use, the stir bar was cleaned by sonication in methanol for 30 min three times. The method provided good linearity of the calibration curve with coefficients of determination greater than 0.999. Recoveries of OTA were greater than 83% with RSD lower than 10%, and LOD of OTA in beer was 0.64 ng/L. This method was applied to determine OTA in 19 beer samples. OTA was detected in 12 samples (63%) in the range of 0.01-0.27 ng/mL.

Thermolysin entrapped in a gold nanoparticles/polymer composite for direct and sensitive conductometric biosensing of ochratoxin A in olive oil

“…The response increased up to pH 6, remained stable in the 6-7 range and sharply declined afterwards, in good agreement with results reported for free TLN catalyzing the hydrolysis of either N-furylacryloylglycyl-l-leucinamide [52] or Z-Gly-Leu-Ala peptide [38]. Comparatively, the range of optimal working pH was slightly wider (6)(7)(8) for the TLN/BSA modified electrode. pH 7 was therefore retained for further measurements.…”

“…Moreover, the accuracy of immunoassays can be strongly affected by cross-reactivity of antibodies with interfering substances [5]. Chromatographic techniques using molecular fluorescence or mass spectrometric detections are more powerful and selective [6,7]. Nevertheless, these methods are costful and require a highly trained staff.…”

Development of sandwich dot-ELISA for specific detection of Ochratoxin A and its application on to contaminated cereal grains originating from India

“…( Kuruc et al, 2015 ; Palumbo et al, 2015 ). It is also present in beer ( Nguyen and Ryu, 2014 ), wine and grape juice ( Terra et al, 2013 ). OTA has been classified by the International Agency of Research in Cancer (IARC) as a carcinogen of 2B class ( Muscarella et al, 2004 ).…”

Advances in Mycotoxin Research: Public Health Perspectives

“…Among these, IAC based on the use of mono‐ or poly‐clonal antibodies has been preferred due to its specificity to the target mycotoxin and greater recovery (Valenta and others ; Chan and others ). Meanwhile, using stir bar sorptive extraction (SBSE) method was suggested for determination OTA (Nguyen and Ryu ). This equilibrium technique is based on extraction of the analyte from an aqueous matrix onto a sorbent phase coated on a magnetic stir bar.…”