2010 plus gas chromatograph

Ground samples (2 g) were mixed with a chloroform and methanol (2:1; v/v) solution. The ampoules were sealed in the flame of a gas burner and placed in a thermostat (105 °C) for 2 h. The obtained supernatant was used to prepare the fatty acid methyl esters (FAME) by using a methanol/sulfuric acid mixture (95:5) and hexane following the esterification process outlined earlier. The measurement was performed using a 2010Plus gas chromatograph (Shimadzu Corporation, Kyoto, Japan). The chromatographic column was an SPTM-2560 (0.20 μm × 0.25 mm × 100 m). The column temperature was held at 50 °C for 1 min, and then the temperature was raised to 150 °C at a rate of 15 °C per min. The temperature was later increased to 175 °C at a rate of 2.50 °C and held for 5 min and finally increased to 220 °C at a rate of 2.50 °C per min and kept for 5 min. The injector and detector temperatures were 225 and 250 °C, respectively. The carrier gas was helium (flow rate: 1.2 mL/min). Fatty acids were identified by comparing the retention times of methyl easters in the analyzed samples and the standard mixture of fatty acid methyl esters (Sigma, St. Louis, MO, USA).

The analysis was performed using a Shimadzu (Japan) 2010 plus gas chromatograph equipped with a split/splitless injector and a QP2010 Ultra mass spectrometric detector. The MS was operated at the electron ionization (EI) mode (70 eV). The injection was operated in the splitless mode with an injector temperature of 270 °C. The analytes were separated on 30 m × 0.25 mm i.d. × 1.00 μm film thickness Rxi-5MS capillary column (Restek Corporation, Bellefonte, PA, USA) using helium (99.999%) as carrier gas with a flow rate of 1 mL min⁻¹. The initial oven temperature was held at 90 °C for 0.5 min and subsequently ramped to 220 °C at 30 °C min⁻¹, then increased to 280 °C at 15 °C min⁻¹ and held for 10 min. The MS ion source temperature and transfer line were kept at 250 °C and 280 °C, respectively. A solvent delay time of 5 min was used. In order to obtain maximum sensitivity and selectivity, the MS was operated in selective ion monitoring (SIM) mode. Table 1 shows the SIM parameters and retention times of each analyte. Confirmation of the PEs was achieved based on the retention times and the relative abundances of the monitored ions (Table 1). Shimadzu GCMS Solution® version 2.71 was used for data acquiring, processing and GC-MS control.

GC-MS analysis was conducted using a 2010 plus gas chromatograph (Shimadzu, Japan) equipped with a split/splitless injector and coupled to a QP2010 Ultra mass spectrometer. Electron ionization mode was utilized for the MS at 70 eV. The injection was done in the splitless mode and the injector temperature was kept at 280 °C. Chromatographic separation was achieved on Rxi-5MS capillary column (30 m × 0.25 mm i.d. × 1.00 µm) (Restek, Bellefonte, PA, USA). Helium was used as carrier gas with a flow rate of 1 mL/min. The temperature gradient started at 100 °C for 0.5 min and then increased to 280 °C at 30 °C/min, and held for 15 min. The ion source and transfer line temperatures were 250 °C and 280 °C, respectively. A solvent delay time of 5 min was applied. Selective ion monitoring mode was utilized to enhance method sensitivity and selectivity. Table 1 shows the MS parameters and retention times of target analytes. Positive identification of the target analytes was performed using the ratio of the monitored ions and retention times (Table 1). Data acquisition and processing was performed utilizing GC-MS Solution^® version 4.52 (Shimadzu, Japan). Figure 1 represents the total ion chromatogram of GC-MS analysis of the target phthalate esters in a spiked perfume sample. All investigated analytes were separated under the optimized conditions.