Chemstation rev b04

The conditions for the analysis were: detector temperature, 280°C; injector temperature 270°C; oven temperature program starting at 120°C, 3.67 min at 120–230°C (ramp 30°C min⁻¹), 5 min at 230°C, 2 min at 230–270°C (ramp 20°C min⁻¹), 2 min at 270°C; carrier gas, N₂ at 1 mL/min; injection volume 1.0 µL, in a splitless mode. A linear calibration curve was used and the calibration range was 0.01–5 mg kg⁻¹. Under these conditions chlorpyrifos retention times were approximately 7.52 min. The software was Agilent ChemStation Rev. B04.03 software for instrument control, data acquisition and processing.

The fatty acids composition was determined according to [44 (link)] using an Agilent Technologies 7683B Series gas chromatograph (USA) with a flame ionization detector and a 100 m Agilent J&W GC Columns Select FAME, 25 mm × 0.25 µm column (Netherlands). Oil samples (10–15 mg) were placed in a 5 mL tube, and then 2 mL of methanol, 20 µL of chloroform, and 2 µL of acetyl chloride were added. The tube was sealed tightly with a lid and spacer and placed in a thermostat (Binder FED 53, Germany) at 80 °C for 1 h. After cooling (about 10 min), 2.5 mL of hexane and 70 µL of distilled water were added to the samples. The samples were covered again and stirred on a vortex for about 30 s. The samples were allowed to stand for about 5 min, and then 1 mL of the upper phase was transferred to the vial for analysis. The sample introduction volume was 1 µL, the mode was 30:1 flow division, the carrier gas was nitrogen, and the flow rate was 0.9 mL/min. The injector temperature was 260 °C and the detector temperature was 240 °C. Separation conditions: initial temperature of 140 °C (isotherm for 5 min) and then increasing at a rate of 4 °C/min to 220 °C, isotherm 25 min. Data were collected and processed using Agilent ChemStation Rev.B.04.03 software. Ratios of LC methyl esters were calculated using the internal normalization method.

The chromatographic system used was an HS-GC/FID Agilent 7890A equipped with a FID and coupled to an Agilent 7697A HS sampler. A dual-column confirmation, which involves injecting a single sample and running it through two chromatographic columns, was performed. The two columns had different polarities and consisted of an Agilent DB-ALC1 column with dimensions of 30 m × 0.32 mm, 1.8 μm and an Agilent DB-ALC2 column with dimensions of 30 m × 0.32 mm, 1.2 μm.
The chromatographic gradient was programmed as follows: an initial oven temperature of 40 °C was held for 3 min and then increased in a linear fashion to 150 °C at 10 °C/min and held for 15 min. At the end of each run, the initial temperature was reset to the initial condition and held for 2 min. The injection port was maintained at 150 °C and had a split ratio of 10:1. The detectors were held at 300 °C. The gas flow rates were as follows: hydrogen 30.0 mL/min, air 400.0 mL/min and nitrogen 25.0 mL/min. The nitrogen flow rate was maintained at a constant 17 psi.
The HS injection port was maintained at 65 °C, the loop was maintained at 105 °C and the transfer line was maintained at 110 °C. Before injection of the sample, the vials were incubated for 10 min at 65 °C. The injection time was held constant at 1 min. The GC run time was 24 min. The analytical data were processed using the Agilent ChemStation Rev. B.04.03 software.