Pdms fiber

Volatiles were extracted by headspace solid-phase microextraction (HS-SPME) using MPS autosampler (Gerstel, Baltimore, MD, USA). Prior to fiber insertion, 4 g of infant formula in a 20 mL vial was placed at 70 °C for 2 min at an agitation rate of 500 rpm. A (1 cm 100 μm) polydimethylsiloxane (PDMS) fiber (Supelco, Bellefonte, PA, USA) was then introduced into the HS and the vial was agitated at 250 rpm for 5 min at 70 °C.
Afterward, volatiles were thermally desorbed into the injector of an Agilent 7890 gas chromatograph coupled to a time-of-flight accurate mass spectrometer (GC/Q-TOF-MS, Agilent technologies, Santa Clara, CA, USA). The injections were splitless for 1 min at 300 °C. A HP-5MS column (30 m × 250 µm i.d. × 0.25 µm film thickness) from Agilent Technologies Inc. (Santa Clara, CA, USA) was used. The column temperature was programmed as follows: initial hold for 2 min at 40 °C, followed by a 15 °C/min ramp to 185 °C and then, 120 °C/min ramp to 300 °C, 1 min hold. The carrier gas was helium (flow rate of 1.5 mL/min). The detector temperature was placed at 300 °C. The TOF-MS was operated in electron impact mode (ionization energy of 70 eV). All samples were analyzed, at least, in triplicates to measure the volatiles derived from lipid oxidation. Results were expressed as area responses (counts).

Headspace solid-phase microextraction (HS-SPME) was performed using a MultiPurpose Autosampler (MPS Dual Head, Gerstel GmbH and Co.KG, Mulheim, Germany). Samples of mead wort and young mead after 7 weeks of fermentation were stored at –20 °C prior to analysis. After heating to 20 °C, 1 mL of the sample was transferred to a 15 mL glass vial, 1 mL of saturated sodium chloride (pure p.a., Avantor Performance Materials, Gliwice, Poland) solution was added and the vial was capped and transferred to the autosampler tray. HS-SPME microextraction (30 min, 40 °C) was performed on PDMS fiber (100 μm, polydimethylsiloxane, SUPELCO, Sigma-Aldrich, St. Louis, MO, USA). Desorption was carried out in the inlet of the gas chromatograph at a temperature of 260 °C.
Calibration curves were prepared in the same way as the analyzed samples. Furfural and furfuryl alcohol (Sigma-Aldrich, St. Louis, MO, USA) were used to prepare calibration solutions.

The volatile compositions of EOEP from the rhizome were characterized by a headspace solid-phase microextraction system (HS-SPME) using a 50/30 μm divinylbenzene (DVB)/ polydimethylsiloxane (PDMS) fiber (Supelco, Bellefonte, PA, USA), according to the method of Morales-Soto et al. [5 (link)] and Saoudi et al. [6 (link)] with some modifications. The EOEP, 0.5 g, was weighed and 4.5 mL of ethyl ether was added to a SMPE vial of 15 mL fitted with a screw cap. After equilibration at 40 °C for 10 min, the fiber was exposed to the headspace above the sample for 30 min. The sample was kept under stirring at 40 °C and desorbed for 20 min in the GC injector at 250 °C. Analysis was done in triplicate. The GC-MS analysis of SPME extracts was carried out as described by Morales-Soto et al. [5 (link)]. Briefly, the volatile compounds were identified by comparison with mass spectra from NIST/EPA/NIH databases and confirmed in many cases by the comparison of their retention indices with databases (http://www.pherobase.com) and the ADAMS library. To confirm the identification, the linear retention index (LRI) was calculated for each volatile, using the retention times of a homologous series of C6–C25 n-alkanes. Semiquantitative determinations were expressed as the percentage of total peak area within each sample.

Higher alcohols and esters were analyzed based on a headspace solid-phase
microextraction (SPME) technique using a 100 µm poly-dimetylsiloxane (PDMS)
fiber (Supelco, Sigma-Aldrich, Spain). Aliquots of 1.5 ml of the sample were
placed into 15 ml vials and 0.35 g of NaCl and 20 µl of 2-heptanone (0.005%) was
added as an internal standard. Vials were closed with screwed caps and 13 mm
silicone septa. Solutions were attired for 2 h to obtain the required
headspace-liquid equilibrium. Fibers were injected through the vial septum and
exposed to the headspace for 7 min to then be desorbed for 4 min in a gas
chromatograph (TRACE GC Ultra, Thermo Scientific), with a flame ionization
detector (FID) equipped with an HP INNOWax 30 m x 0.25 mm capillary column
coated with a 0.25 m layer of cross-linked polyethylene glycol (Agilent
Technologies). The carrier gas was helium (1 ml/min) and the oven temperature
program utilized was: 5 min at 35°C, 2°C/min to 150°C, 20°C/min to 250 °C. The
injector and detector temperatures were maintained at 220°C and 300°C
respectively. A chromatographic signal was recorded by the ChromQuest program.
Volatiles compounds were identified by comparing the retention time for
reference compounds. Volatile compound concentrations were determined using
calibration graphs of the corresponding standard volatile compounds.

The quantification of volatile compounds was performed following the protocol defined previously (39 (link)). Extraction was performed using headspace solid-phase microextraction sampling (SPME) with polydimethylsiloxane (PDMS) fibers (Supelco; Sigma-Aldrich, Barcelona, Spain). Aroma compounds were separated by gas chromatography using a TRACE GC ULTRA chromatograph (Thermo Fisher Scientific, Waltham, MA) equipped with a flame ionization detector (FID). The column used for separation was an HP-INNOWAX 30-m by 0.25-mm capillary column coated with a 0.25-mm layer of cross-linked polyethylene glycol (Agilent Technologies, CA). Helium was the carrier gas (flow rate, 1 mL/min). The oven temperature program was 5 min at 60°C, 5 min at 190°C, 20 min at 250°C, and 2 min at 250°C. The detector temperature was 280°C, and the injector temperature was 220°C under splitless conditions. 2-Heptanone (0.05% [wt/vol]) was used as an internal standard. The volatile compounds were identified by the retention time for the reference compounds. Quantification of volatile compounds was performed using the calibration graphs of the corresponding standard volatile compounds.

Fresh tomato flowers (“4805Dahong”) were placed in a 20 mL vial sealed with 3 mL saturated NaCl solution and were equilibrated at 80 °C for 30 min. We then inserted 100 µL polydimethylsiloxane (PDMS) fibers (Supelco, St. Louis, MO, USA) into the vial for a 30 min extraction period at 80 °C. Before the test, PDMS fiber with tomato flower volatiles was placed in the inlet of the tube column at 240 °C for a 5 min desorption period.
Gas chromatography–mass spectrometry (Agilent 6890N-5975B) was used for qualitative and quantitative analysis as the following program: GC-fitted column: HP-5MS (0.25 mm × 30 mm × 0.25 µm); inlet temperature: 240 °C; helium carrier gas: percentage purity ≥ 99.99%; flow rate: 1.0 mL/min. The oven program was started at 45 °C, maintained for 5 min, heated from 45 to 130 °C at 6 °C/min, then from 130 to 240 °C at 10 °C/min, and finally maintained at 240 °C for 8 min. The injection was splitless. The MS parameters were as follows: the ion source temperature: 230 °C; the interface temperature: 250 °C. The ionization mode was electron ion source (EI). Full scanning was conducted at a mass scan range from m/z 45 to 500. Volatile compounds retrieval and identification were conducted using NIST 14 libraries, and the relative content of each component was analyzed by area normalization.