Glacial acetic acid p a

HPLC-grade acetonitrile and methanol (purity ≥ 99.9%) were purchased from Lichrosolv Merck (Darmstadt, Germany), glacial acetic acid P.A. (purity ≥ 99.9%) and formic acid P.A. (purity ≥ 96%) were from Sigma-Aldrich (Saint Louis, MO, USA), and ultra-pure water (type 1) was obtained from a Milli-Q system (São Paulo, Brazil). The triene AnAc standard (15:3) used to obtain the analytical curve was obtained by the method described previously [11 (link)].

The analysis of sterigmatocystin was performed using an HPLC‐MS/MS method for the determination of 186 fungal and bacterial metabolites described by Vishwanath et al. (2009). Detection and quantification in the Selected Reaction Monitoring (SRM) mode was performed with a QTrap 4000 LC‐MS/MS System (Applied Biosystems, Foster City, CA, USA) equipped with a TurboIonSpray electrospray ionization (ESI) (Applied Biosystems, Foster City, CA, USA) source and an 1100 Series HPLC System (Agilent, Waldbronn, Germany). Chromatographic separation was performed at 25°C on a Gemini C18 column, 150  ×  4.6‐mm i.d., 5 μm particle size, equipped with a C₁₈ 4 × 3 mm‐i.d. security guard cartridge (Phenomenex, Torrance, CA, USA). Injection volume was 5 μl. For quantification, external calibration was performed using multi‐analyte standards prepared and diluted in a 1:1 mixture of extraction and dilution solvent.
All chemicals (LC gradient grade) were from J.T. Baker (Deventer, The Netherlands); ammonium acetate (MS grade) and glacial acetic acid (p.a.) were obtained from Sigma‐Aldrich (Vienna, Austria). Water was purified successively by reverse osmosis and a Milli‐Q plus system from Millipore (Molsheim, France). A certified standard for sterigmatocystin in acetonitrile was from Biopure Referenzsubstanzen GmbH (Tulln, Austria) and Sigma (Vienna, Austria).

Yeast extract, potato dextrose agar and sucrose were purchased from Biolife (Italy) while aflatoxin standard mix (B₁, G₁, B₂, G₂) was purchased from Biopure (Austria). Acetonitrile and methanol (both HPLC grade) were obtained from Merck (Germany). Ammonium acetate and glacial acetic acid (p.a.) were purchased from Sigma Aldrich (Vienna, Austria). A Purelab Ultra system (ELGA LabWater, Celle, Germany) was used for ultrapure water preparation. Standards of A. flavus metabolites were purchased from Various research groups or from the following commercial sources: Romer Labs®Inc.(Tulln, Austria), Sigma–Aldrich (Vienna, Austria), Iris Biotech GmbH (Marktredwitz, Germany), Axxora Europe (Lausanne, Switzerland) And LGC Promochem GmbH (Wesel, Germany) and prepared as described by Malachova et al.^{46 (link)}.

The starting material for this work was a concentrated, industrially produced crude grape seed extract (from Output Trade S.L., Villafranca del Penedés, Spain) with 288 NTU of turbidity and 26% of total soluble substances (TSSs).
For procyanidin purification by UF and SPE by diafiltration, demineralised particle-free water with electrical conductivity of 7–8 µS/cm was obtained inhouse by a Genius 300 reverse osmosis unit (Filtec Depuradoras, Girona, Spain). For HPLC analysis, Milli-Q grade water was produced inhouse by a Milli-Q^® Integral 3 purification system (Merck Millipore, Burlington, MA, USA). HPLC grade methanol and acetonitrile were purchased from Scharlab (Barcelona, Spain). Glacial acetic acid (p.a.) was obtained from Sigma-Aldrich (Madrid, Spain) and technical grade acetone and ethanol (96%) from PanReac AppliChem ITW Reagents (Barcelona, Spain).

Yeast extract, potato dextrose agar, malt extract agar and sucrose were purchased from Biolife (Italy). AFT standard mix (B₁, G₁, B₂, G₂) was purchased from Biopure (Austria). Acetonitrile and methanol (HPLC grade both) were obtained from Merck (Germany). Ammonium acetate and glacial acetic acid (p.a.) were purchased from Sigma Aldrich (Vienna, Austria). For ultrapure water preparation, a Purelab Ultra system (ELGA LabWater, Celle, Germany) was used. Standards of A. flavus metabolites were collected from various research groups or purchased from the following commercial sources: Romer Labs^®Inc.(Tulln, Austria), Sigma–Aldrich (Vienna, Austria), Iris Biotech GmbH (Marktredwitz, Germany), Axxora Europe (Lausanne, Switzerland) And LGC Promochem GmbH (Wesel, Germany). Purchased standards were prepared according to Malachova et al.^{50 (link)}.