Abstract：
BACKGROUND: Acetone, isoprene, and other volatile organic compounds (VOCs) in exhaled breath have been shown to be biomarkers for many medical conditions. Researchers use different techniques for VOC detection, including solid phase microextraction (SPME), to preconcentrate volatile analytes prior to instrumental analysis by gas chromatography-mass spectrometry (GC-MS). These techniques include a previously developed method to detect VOCs in breath directly using SPME, but it is uncommon for studies to quantify exhaled volatiles because it can be time consuming due to the need of many external/internal standards, and there is no standardized or widely accepted method. The objective of this study was to develop an accessible method to quantify acetone and isoprene in breath by SPME GC-MS.
RESULTS: A system was developed to mimic human exhalation and expose VOCs to a SPME fiber in the gas phase at known concentrations. VOCs were bubbled/diluted with dry air at a fixed flow rate, duration, and volume that was comparable to a previously developed breath sampling method. Identification of acetone and isoprene through GC-MS was verified using standards and observing overlaps in chromatographic retention/mass spectral fragmentation. Calibration curves were developed for these two analytes, which showed a high degree of linear correlation. Acetone and isoprene displayed limits of detection/quantification equal to 12 ppb/37 ppb and 73 ppb/222 ppb respectively. Quantification results in healthy breath samples (n = 15) showed acetone concentrations spanned between 71 ppb and 294 ppb, and isoprene varied between 170 ppb and 990 ppb. Both concentration ranges for acetone and isoprene in this study overlap with those reported in existing literature.
CONCLUSIONS: Results indicate the development of a system to quantify acetone and isoprene in breath that can be adapted to diverse sampling methods and instrumental analyses beyond SPME GC-MS.
RESULTS: A system was developed to mimic human exhalation and expose VOCs to a SPME fiber in the gas phase at known concentrations. VOCs were bubbled/diluted with dry air at a fixed flow rate, duration, and volume that was comparable to a previously developed breath sampling method. Identification of acetone and isoprene through GC-MS was verified using standards and observing overlaps in chromatographic retention/mass spectral fragmentation. Calibration curves were developed for these two analytes, which showed a high degree of linear correlation. Acetone and isoprene displayed limits of detection/quantification equal to 12 ppb/37 ppb and 73 ppb/222 ppb respectively. Quantification results in healthy breath samples (n = 15) showed acetone concentrations spanned between 71 ppb and 294 ppb, and isoprene varied between 170 ppb and 990 ppb. Both concentration ranges for acetone and isoprene in this study overlap with those reported in existing literature.
CONCLUSIONS: Results indicate the development of a system to quantify acetone and isoprene in breath that can be adapted to diverse sampling methods and instrumental analyses beyond SPME GC-MS.
摘要：
背景：丙酮，异戊二烯,呼出气中的其他挥发性有机化合物（VOC）已被证明是许多医疗条件的生物标志物。研究人员使用不同的技术进行VOC检测，包括固相微萃取(SPME)，在通过气相色谱-质谱（GC-MS）进行仪器分析之前，对挥发性分析物进行预浓缩。这些技术包括以前开发的直接使用SPME检测呼吸中VOC的方法，但是量化呼出挥发物的研究并不常见，因为由于需要许多外部/内部标准，这可能是耗时的，没有标准化或广泛接受的方法。这项研究的目的是开发一种通过SPMEGC-MS定量呼吸中丙酮和异戊二烯的方法。
结果：开发了一种系统来模拟人体呼气，并将VOC以已知浓度暴露于气相中的SPME纤维。VOC用干燥空气以固定流速鼓泡/稀释，持续时间,和体积与以前开发的呼吸采样方法相当。使用标准品和观察色谱保留/质谱断裂中的重叠来验证通过GC-MS对丙酮和异戊二烯的鉴定。为这两种分析物开发校准曲线，表现出高度的线性相关。丙酮和异戊二烯显示的检测/定量限分别等于12ppb/37ppb和73ppb/222ppb。健康呼吸样本的定量结果（n=15）显示丙酮浓度在71ppb和294ppb之间，和异戊二烯在170ppb和990ppb之间变化。本研究中丙酮和异戊二烯的浓度范围与现有文献中报道的那些重叠。
结论：结果表明开发了一种量化呼吸中丙酮和异戊二烯的系统，该系统可以适应SPMEGC-MS以外的多种采样方法和仪器分析。
结果：开发了一种系统来模拟人体呼气，并将VOC以已知浓度暴露于气相中的SPME纤维。VOC用干燥空气以固定流速鼓泡/稀释，持续时间,和体积与以前开发的呼吸采样方法相当。使用标准品和观察色谱保留/质谱断裂中的重叠来验证通过GC-MS对丙酮和异戊二烯的鉴定。为这两种分析物开发校准曲线，表现出高度的线性相关。丙酮和异戊二烯显示的检测/定量限分别等于12ppb/37ppb和73ppb/222ppb。健康呼吸样本的定量结果（n=15）显示丙酮浓度在71ppb和294ppb之间，和异戊二烯在170ppb和990ppb之间变化。本研究中丙酮和异戊二烯的浓度范围与现有文献中报道的那些重叠。
结论：结果表明开发了一种量化呼吸中丙酮和异戊二烯的系统，该系统可以适应SPMEGC-MS以外的多种采样方法和仪器分析。
