Hybrid GC platform: a micro gas chromatography system with a simple configuration for low-concentration VOC analysis

A compact hybrid gas chromatography (GC) platform was developed by integrating a previously reported hybrid μ-GC column chip (hybrid chip) and a commercial photoionization detector. The hybrid chip enabled both gas preconcentration and separation in a single device, allowing for a highly compact and simple platform design with a volume of 0.62 L. With a sample volume of 40.8 mL and an analysis time of 20 minutes, it achieved detection limits of 19.3, 22.8, 30.4, and 24.4 ppb for benzene, toluene, ethylbenzene, and <i>ortho</i>-xylene, respectively. The linear ranges were 0.25-1 ppm for benzene and toluene, 0.25-1.5 ppm for ethylbenzene, and 0.25-2 ppm for <i>ortho</i>-xylene. The peak capacity ranged from 5.34 to 8.81, with full width at half height between 0.22 and 0.5 min. Importantly, the detection limit for benzene was below US workplace air concentration limits set by the American Conference on Governmental Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), demonstrating the platform's potential for indoor air monitoring. Furthermore, portability was enhanced through the integration with a battery and carrier gas filter pack. The platform consumed 2.65 W during analysis (20 minutes), and assuming one cycle consists of 20 minutes of analysis and 10 minutes of stand-by operation, the system could theoretically operate for 70 cycles (35 hours) on a single charge. Field testing with classroom and laboratory air samples confirmed the potential applicability of the platform. In addition, partial qualitative separations were achieved for alkanes, alcohols, aldehydes, and ketones, suggesting broader utility in fields beyond indoor air monitoring.