การพัฒนาอุปกรณ์เก็บตัวอย่างแบบแพสซีฟและการตรวจวัดสารอินทรีย์ระเหยง่ายในอากาศ

Abstract

In this study, a passive sampler was successfully developed to trap styrene as volatile organic compounds (VOCs) contaminated in air. The adsorbent was produced from the mixture of graphene oxide and agar powder. The agar was introduced to the sampled as a support material, due to its advantages of naturally derived, biodegradable, low cost,and easy-to-find in the marketplace. The styrene was then analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The experimental results showed that the optimum condition for the adsorbent synthesis was 3 g agar powder with 200 mg graphene oxide per 50 mL deionized water. The mixture was heated and stirred until the homogeneous solution was formed. It was then molded in the small plastic tube by freezing it overnight, before being thawed and dried in the hot air oven at 140 °C for 1.5 h. The absorbent material was obtained as black solid xerogel. The following settings were found to be appropriate for styrene analysis using the gas chromatography-mass spectrometry (GC-MS) technique: 120 ºC injector temperature, helium gas flow rate of 1 mL min-1 , 50 ºC initial column temperature for 1 min, 10 ºC min-1 ramp rate, and 120 ºC final temperature for 1 min. The analytical performance showed a wide linear range of calibration graphs at 0.01 to 200 ppm and 0.005 to 200 ppmv for styrene as liquid and gas state, respectively. The good correlation coefficient (R2 ) was greater than 0.99 throughout all experiments. The limit of detection and quantitation in liquid form was as low as 0.01±0.00 and 0.02±0.00 ppm, and in gas form as 0.001±0.000 and 0.003±0.000 ppmv . The developed method presented great performances of accuracy with a relative error percentage in the acceptable range of less than 10. The performance of the designed passive devices was compared with commercially available devices by applying to the prefabricated swimming pool factory. The samplers were suspended at the area for 3 days with high styrene concentration and 7 days at low ones. Styrene in collected samplers was then desorbed at 140 °C for 20 min and evaluated by using gas chromatography-mass spectrometry. The results showed that both types of sampling devices provided 2% and 12.26% differences for areas of low and high concentration, respectively. The cost of produced passive is 145 baht per analysis, and it can be stored in a desiccator for 3 weeks.