We collected the alveolar air samples using a standardized procedure [16 (link)]. Because VOC concentrations may be affected by diet, flow rate, and anatomical dead space [17 (link),18 (link)], all subjects were required to stop eating and smoking for 12 h before the air sampling. The air was then taken after intubation with an endotracheal tube and before surgery. To prevent contamination from the upper airway, we sampled alveolar air from the endotracheal tube with a capnometer (Masimo, Irvine, CA, USA). Under the visual control of a carbon dioxide-controlled sampling device, the alveolar air was taken from the breathing circuit during the alveolar phase of expiration [19 (link)] (Figure 1 ). To maintain a consistent flow rate of 125 mL/s, we set the ventilator to a tidal volume of 500 to 600 mL, a respiratory rate of 8–10/min, and an inspiratory-to-expiratory time ratio (I:E) of 1:2. To decrease the influence of humidity, all breath samples were dehumidified by a heat-moisture exchanger and then collected in a 1-L Tedlar bag (SKC Inc., Eighty Four, PA, USA).
1 l tedlar bag
Manufactured by SKC
Sourced in United States, United Kingdom
The 1-L Tedlar bag is a laboratory equipment used for sample collection and storage. It is designed to hold and contain gas or liquid samples. The bag is made of Tedlar, a specialized material known for its inertness and resistance to chemical interactions, ensuring the integrity of the samples. The bag has a capacity of 1 liter and can be used for a variety of applications in laboratory settings.
Automatically generated - may contain errors
Lab products found in correlation
Capnometer, by Masimo (2 mentions)
Hp plot q, by Agilent Technologies (2 mentions)
Rtx 5 column, by Restek (2 mentions)
Db 5ms column, by Agilent Technologies (1 mentions)
Gc 17a, by Shimadzu (1 mentions)
Agilent 7890a gc, by Agilent Technologies (1 mentions)
Gc 7890a, by Agilent Technologies (1 mentions)
6 protocols using 1 l tedlar bag
1
Standardized Alveolar Air Sampling Procedure
2
Ethyl Formate Sorption in Mangoes
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Analysis of EF sorption in mango fruits was conducted in a 0.8 m3 fumigation chamber with a 30% (w/v) loading ratio of mango fruits. The fruits were fumigated with 15 and 30 g/m3 EF for 4 h at 11 °C. For the determination of EF gas concentrations of each desiccator, gas was collected using 1 L Tedlar bag (SKC Inc., Dorset, UK) and vacuum pump (Gast, IDEX corp., Benton harbor, MI, USA) at the four time points (0.1, 1.0, 2.0, and 4.0 h) after EF fumigation. In addition, gas chromatography equipped with a flame ionization detector (GC-FID, a Shimadzu-GC 17A, Shimadzu, Kyoto, Japan) was used with a DB5-MS Column (30 m × 0.25 mm i.d., 0.25 µm, J & W Scientific, Folsom, CA, USA). The oven temperature was set at 100 °C, while the injector and detector temperatures were set at 250 and 280 °C, respectively. Helium carrier gas was supplied at a flow rate of 1.5 mL/min. The standard curve of EF was calculated with the peak area of a series in the range of 0.1–15 g/m3. Sorption rate of EF was calculated as ratio (C/C0), where the C (EF concentration was determined at one of the time intervals) and the C0 (EF concentration at 0.1 h).
3
Standardized Alveolar Air Sampling for Metabolite Analysis
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We collected alveolar air samples using a standardized procedure [14 ]. As concentrations of volatile metabolites could be influenced by the flow rate, diet, and anatomical dead space [15 (link), 16 (link)], we sampled alveolar air using specially designed equipment (Fig. 1 ). When expiratory carbon dioxide concentrations reached a high level representative of the expiratory alveolar phase, we collected alveolar air to prevent contamination of the respiratory or digestive dead space [17 (link)]. All subjects were not allowed to eat or smoke for 12 h prior to sampling. We used a fixed flow rate to obtain stable volatile metabolite concentrations and prevent the influence of the flow rate [16 (link)]. We followed a standardized cleaning protocol according to recommendations from the European Respiratory Society [18 (link)]. Each bag (SKC, Inc., USA) was flushed with nitrogen five times and then heated to 45 °C for approximately 12 h to prevent the influence of contaminated sampling bags.![]()
Schematic of the system framework and sample collection. We sampled alveolar air from the collecting device with a volatile organic compound filter, capnometer, flow meter, nonrebreathing bag, and a three-way control valve. The capnometer (Masimo, CA, USA) was monitored [49 (link)]. Breath samples were stored in a 1-L Tedlar bag (SKC Inc., PA, USA)
4
Calibration of Volatile Organic Compounds
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Standard samples for calibration were prepared by diluting the two standard mixtures in a sampling bag to desired concentrations. A 1-L Tedlar bag (SKC Inc., USA) was cleaned by filling it with highpurity helium gas and evacuating it with a pump at least ten times before use. The cleaned bag was then filled with known volumes of standard mixture and helium, using gastight glass syringes (SGE Analytical Science, Ringwood, Australia). The diluted mixtures were drawn to sorbent tubes immediately with a low-flow Pocket Pump TOUCH (SKC Inc., USA), which was calibrated to 50 mL min -1 prior to use. Seven concentration levels of calibration standards (0.35 ~ 208 ng) were prepared for each standard mixture. Calibration curves were then created by using the internal standard method, i.e. by correlating the relative response factors of an individual compound to its corresponding internal standard compound (IS1-3) and the spiked analyte mass. The calibration was repeated every month. All standard tubes used for performance testing were also prepared with the sampling bag dilution method.
5
Measuring Volatile Compound Concentrations
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To investigate the actual concentration in the treated samples, 60 mL of sample gas was extracted from all experimental groups using a 60 mL syringe and 1 L Tedlar bag (SKC, Dorset, United Kingdom). EF and MB samples were taken at 30 min and 1, 2, and 4 h, and PH3 samples were taken at 30 min and 1, 4, and 20 h after fumigation. If fumigation time was longer than 20 h, samples were extracted at 24-h intervals until the completion of the experiment.
The concentrations of EF and MB were measured using an Agilent GC 7890A equipped with a flame ionization detector (FID) after separation on an Rtx-5 column (15 m × 250 μm × 1 μm, RESTEK, Bellefonte, PA, USA) operating in split mode (10:1). The PH3 concentration was determined using an Agilent GC 7890A equipped with a flame photometric detector (FPD) and HP-PLOT/Q (30 m × 530 μm × 40 μm, Agilent, Santa Clara, CA, USA) operating in split mode (10:1). The injector and oven temperature were 200 °C. The detector temperature was 250 °C. The injection volumes and flow rates of EF, MB, and PH3 were 60, 60, and 20 μL and 1.5, 1.5, and 5 mL/min, respectively. The concentrations of EF, MB, and PH3 were calculated based on peak areas against external standards.
The concentrations of EF and MB were measured using an Agilent GC 7890A equipped with a flame ionization detector (FID) after separation on an Rtx-5 column (15 m × 250 μm × 1 μm, RESTEK, Bellefonte, PA, USA) operating in split mode (10:1). The PH3 concentration was determined using an Agilent GC 7890A equipped with a flame photometric detector (FPD) and HP-PLOT/Q (30 m × 530 μm × 40 μm, Agilent, Santa Clara, CA, USA) operating in split mode (10:1). The injector and oven temperature were 200 °C. The detector temperature was 250 °C. The injection volumes and flow rates of EF, MB, and PH3 were 60, 60, and 20 μL and 1.5, 1.5, and 5 mL/min, respectively. The concentrations of EF, MB, and PH3 were calculated based on peak areas against external standards.
6
Monitoring Fumigation Concentration Levels
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To determine the actual concentration of the fumigation treatment, monitoring was conducted for all experimental groups, and 60 mL samples were extracted per experimental group using a 60 mL syringe in a 1 L Tedlar bag (SKC, Dorset, UK). The samples were taken and monitored at 30 min and 1, 2, and 4 h after fumigation.
The concentration of EF was measured using an Agilent GC 7890A equipped with a flame ionization detector (FID) after separation on an Rtx-5 column (15 m × 250 μm × 1 μm, RESTEK, Bellefonte, PA, USA) operating in the split mode (10:1). The PH3 concentration was determined using an Agilent GC 7890A that was equipped with a flame photometric detector (FPD) and HP-PLOT/Q (30 m × 530 μm × 40 μm, Agilent, Santa Clara, CA, USA) operating in a split mode (10:1). The injector and oven temperature were 200 °C. The detector temperature was 250 °C. The injection volumes and flow rates of EF and PH3 were 60 and 20 μL and 1.5 and 5 mL/min, respectively. The concentrations of EF and PH3 were calculated based on peak areas against external standards.
The concentration of EF was measured using an Agilent GC 7890A equipped with a flame ionization detector (FID) after separation on an Rtx-5 column (15 m × 250 μm × 1 μm, RESTEK, Bellefonte, PA, USA) operating in the split mode (10:1). The PH3 concentration was determined using an Agilent GC 7890A that was equipped with a flame photometric detector (FPD) and HP-PLOT/Q (30 m × 530 μm × 40 μm, Agilent, Santa Clara, CA, USA) operating in a split mode (10:1). The injector and oven temperature were 200 °C. The detector temperature was 250 °C. The injection volumes and flow rates of EF and PH3 were 60 and 20 μL and 1.5 and 5 mL/min, respectively. The concentrations of EF and PH3 were calculated based on peak areas against external standards.
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