Db 17ms column

GC analysis was performed using two Agilent 6890 chromatographic systems connected to ECD detectors, in splitless injector mode. Chromatographic separation was performed on a DB-5-MS column (30 m. 0.32 mm i.d. and 0.25 μm film thickness, Agilent J&W, Folsom, CA, USA) and a DB-17 MS column (30 m. 0.3 mm i.d. and 0.25 μm film thickness, Agilent J&W, Folsom, CA, USA). The use of two different columns was necessary for confirmation purposes. Both systems were under the control of ChemStation chromatography manager and processing software. The helium carrier gas flow rate was set at 1.5 mL/min for both columns. Injectors’ temperature was set at 230 °C and the splitless injection was carried out with the purge valve closed for 1 min. Injection volume was 1 μL. GC-ECD analysis was utilized for pyrethroids detection in bees and honey as well.

The UHPLC (ultra-high performance liquid chromatography) analysis of WE and EE was performed according to our previous work (Dong et al., 2018 ; Li et al., 2019 ). The UHPLC system was Agilent 1260 system (Agilent Technologies, Inc., United States), which consisted of a DGU-20A5R degasser, a G7129A vial sampler, a G7115A DAD WR, a G7116A MCT, and a G7111A Quat pump VL. The separation was carried out on an Agilent C18 column (2.1 × 100 mm, 1.8 mm, Agilent Technologies, Inc., United States) with temperature at 40°C. The mobile phase was composed of water (containing 0.1% formic acid, solvent A) and Acetonitrile (solvent B). The gradient elution procedure was (0.01–5 min, 30–50% B, 5–7 min, 50% B, 7–7.5 min, 50–30% B, 7.5–10.5 min, 30% B). The flow rate was 0.3 ml/min and injection volume was 5.0 μl.
The volatile oil samples were subjected to GC-MS analysis using an Agilent 7890A-5975c and a DB-17MS column (length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm) according to the modified method (Li et al., 2017 ).

The analysis was carried out based on gas chromatography (Agilent 7890A, Agilent Technologies, Santa Clara, CA, USA) equipped with a cold-jet modulator and a time-of-flight mass spectrometer (Pegasus 4D, LECO Corp., Saint Joseph, MO, USA). The volatiles were separated via the TG-WAX capillary column (30 m × 0.25 mm, 0.25 μm, Agilent Technologies, Santa Clara, CA, USA) and the DB-17 MS column (2 m × 0.1 mm, 0.1 μm, Agilent Technologies, Santa Clara, CA, USA) as the first- and second-dimension columns, respectively. Helium (99.999%) served as the carrier gas at a flow rate of 1.0 mL/min in splitless mode. The column temperatures adhered to the following protocol: maintaining an initial temperature at 40 °C for one minute, then raised to 160 °C at 3 °C/min. Subsequently, the temperature was raised to 250 °C at a rate of 10 °C/min and held there for 5 min. The offset temperature of the secondary column oven was +5 °C compared to the GC oven, while the modulator temperature had an offset of +15 °C relative to the secondary column oven. After separation via two capillary columns, the analytes were ionized at 70 eV, and the spectra were collected in a mass range of 33–450 amu. The temperature of the ion source was set to 230 °C, while the interface temperature was set to 250 °C. The cold zone temperature was set to −50 °C, and the modulation time was 6 s.

The samples of PRP1 and PRP2 (each 20.0 mg) were methylated with the method reported (Song et al., 2017 (link)) and detected by Infrared spectroscopy (IR). The methylated samples were hydrolyzed, reduced and acetylated, successively. The obtained alditol acetates were detected by Gas chromatography-mass spectrometry (GC–MS). PRP0 did not methylate because of no more sample. GC–MS analysis: Agilent 5975C system (Agilent Technologies Inc., USA), DB-17 MS column. The starting temperature of the column is 50 °C, then raised to 230 °C (4 °C/min), finally reached to 280 °C (10 °C/min, maintain 15 min). Ion-source: 230 °C. N₂: 1.0 mL/min.

The derivatized sample was injected into a gas chromatography-mass spectrometer (Shimadzu GCMS-QP2010; Kyoto, Japan) equipped with a DB-17 ms column (60 m long, 025 µm thick, 0.25 mm ID; Agilent). The carrier gas was helium at a flow rate of 0.8 mL/min. The column oven temperature was initially 50 °C and kept for 2 min, ramped up to 120 °C at 15 °C/min and maintained for 5 min, followed by 160 °C at 4 °C/min and 170 °C at 3 °C/min. The inlet, interface, and ion source temperatures were set at 250, 250, and 200 °C, respectively. The yields were calculated based on their peak areas using calibration lines prepared with commercial standards (Fig. S28a).

Polar phase samples, blanks and QC standards were chemically derivatized as described previously⁽²⁰⁾ to methoxime/trimethylsilyl derivatives, then analyzed by GS-MS using a Agilent/J&W DB17-MS column (30 m × 0.25 mm × 0.25 μm), a 3 m × 0.25 mm retention gap and helium carrier with a constant flow rate of 1.4 ml/min and a Pegasus high-throughput time-of-flight mass spectrometer (LECO; UK).