Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction

Abstract

Quanti cation of unsymmetrical dimethylhydrazine (UDMH) transformation products (TPs) in solid samples is an important stage in monitoring of environmental pollution caused by heavy rockets launches. The new method for simultaneous quanti cation of UDMH TPs in sand samples using vacuum-assisted headspace solid-phase microextraction (Vac-HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) is proposed. Compared to regular HSSPME, Vac-HSSPME yielded 1.3-4.8 times higher responses for NDMA, MTA and PAl. Increasing air-evacuation time from 20 to 120 s at 23 ºC resulted in decreased responses of analytes by 25-46%. Freezing of samples (-30 ºC) had negligible effect on responses of analytes at air-evacuation time 20 s. The best combination of responses of analytes and their RSDs was achieved after air-evacuation of a sample (m = 1.00 g) for 20 s at 23 ºC, incubation for 30 min and 30-min extraction at 40°C by Car/PDMS ber. Vac-HSSPME provided linear calibration plots in studied ranges of concentrations with coe cients of determination ranging from 0.9912 to 0.9938. The limits of detection for spiked sand samples varied from 0.035 to 3.6 ng g − 1 .Spike recoveries of target analytes from sand samples were 84-97% with RSDs 1-11%. The developed method was successfully tested in the experiment on studying losses of analytes from open vials with model sand spiked with UDMH TPs. The developed method can be recommended for analysis of trace concentrations of UDMH TPs when studying their transformation, migration and distribution in contaminated sand.

Optimization of headspace solid-phase microextraction of volatile organic compounds from dry soil samples by porous coatings using COMSOL Multiphysics

“…At Kfh = 150,000, Ksh = 100,000 and 1000,000, t0.95 linearly decreases from 69.8-71.5 min to 52.3-54.0 min with the increase in ms from 1 to 10 g. At Kfh = 150,000 and Ksh = 10,000, t0.95 linearly decreases from 74.0 to 59.8 min with the increase in ms from 2 to 10 g. At Kfh = 8,300, t0.95 values are not higher than 6 min meaning that equilibrium extraction can be conducted at any ms with low time expenses (Figure 3B). The trends are similar to those at Kfh = 150,000, except at Ksh = 100: t0.95 increases when increasing ms from 1 to 5 g followed by the decrease when ms is increased to 10 g. At Kfh = 150,000 and Ksh = 1000, t0.95 increases when increasing ms from 1 to 5 g followed by a slight decrease when ms is increased to 10 g. faster [31][32][33][34]. This is mainly caused by the decreased diffusion coefficients in headspace under vacuum conditions [35].…”

Latest Improvements and Expanding Applications of Solid-Phase Microextraction

“…This method has showed the advantages of simplicity, rapidity, lower cost, and better accuracy and precision in comparison to the traditional HS-SPME. 85 A simple syringe can replace a heavy electrical vacuum pump for the discharge of air, and the pocket-sized and user-friendly low-pressure headspace solidphase microextraction (LP-HS-SPME) device has been fabricated (Figure 2C), which is reliably portable. This LP-HS-SPME device coupled with GC-FID has been employed for the determination of PAHs in solid samples.…”

“…After the sample vial is evacuated by a vacuum pump, the unsymmetrical dimethylhydrazine transformation products in sand can be extracted from the headspace (Figure B). This method has showed the advantages of simplicity, rapidity, lower cost, and better accuracy and precision in comparison to the traditional HS-SPME . A simple syringe can replace a heavy electrical vacuum pump for the discharge of air, and the pocket-sized and user-friendly low-pressure headspace solid-phase microextraction (LP-HS-SPME) device has been fabricated (Figure C), which is reliably portable.…”