Infinitylab poroshell 120 sb c18 column

We performed an MRM-based targeted metabolite method according to a previously described protocol (11 (link)). Briefly, sample analysis was performed using the AB SCIEX ExionLC AD system coupled with the AB SCIEX QTRAP 5500 mass spectrometry system. Furthermore, LC separation was performed on an Agilent InfinityLab Poroshell 120 SB C18 column. The ESI MRM positive mode was selected to scan all peptides, and data were collected and analyzed using the AB SCIEX analyst software.

Benzene polycarboxylic acids were used as an approximation of PyC, and the analysis was conducted following the protocol by Wiedemeier et al. (2016) (ref. ⁴¹ ) with some modifications. The dried and milled sample containing approximately 10 mg OC was weighed in digestion tubes and digested with nitric acid (65%) at 170 °C for 8 h. A glass fibre filter was used for filtration of the resulting solution. In a next step, the sample was passed over a cation exchange resin for further cleaning and subsequently freeze-dried. The sample was then redissolved in MeOH/H₂O (1/1), passed over a solid-phase extraction cartridge (C₁₈ SPE tube, Supelco), dried again and dissolved in deionized water for the transfer to a high-performance liquid chromatography vial. Separation and quantification were conducted on an Agilent 1290 Infinity high-performance liquid chromatography system (Santa Clara) equipped with an Agilent InfinityLab Poroshell 120 SB-C₁₈ column (100 mm × 4.6 mm × 2.7 mm) and coupled to a photo diode array detector. Ortho-phosphoric acid (Honeywell) dissolved in water (pH 1.2–1.3) was used as mobile phase A, and pure acetonitrile (Scharlau) was used as mobile phase B. For quantification, all acids with the different numbers of carboxyl functions were summed (B3CA, B4CA, B5CA and B6CA, respectively).

A Shimadzu LC-20A HPLC system was used for separating the target analytes on a InfinityLab Poroshell 120 SB-C18 column (Dim:75 mm × 2.1 mm, 2.7 µm particle size, Agilent, Palo Alto, USA) by using a column oven at 35 °C. The separation was performed through gradient elution with A (0.1% of formic acid aqueous solution) and B (MeCN) as the mobile phase, and the flow rate was kept constant (0.3 mL/min) during the complete analysis process. The gradient program was: 0–2 min 80% A–5% A, 2–3.5 min 5% A, 3.5–4.5 min 20% A, 4.5–6 min 20% A. Injection (5 μL) was conducted using an autosampler.
A triple quadrupole mass spectrometer (Shimadzu 8045; Shimadzu; Kyoto, Japan) equipped with electrospray ionization in the positive ion mode (ESI⁺) was used to quantify the target analytes. The oven temperature was set at 350 °C, the desolvation line was set at 250 °C, the temperature of the heating block was 400 °C, nitrogen was used as a nebulizer and collision gas, and multireactive ion monitoring (MRM) was selected to analyze the target analytes with a dwell time of 80 ms. The optimal precursor ions, product ions, collision energies, and other instrument parameters for each analyte were acquired by directly infusing each target pesticide at a concentration of 100 μg/L standard solution into the ion source in the instrument. All other relevant MS parameters are listed in Table 1.