Purge-and-Membrane Mass Spectrometry, A Screening Method for Analysis of VOCs from Soil Samples

Abstract

Purge-and-membrane mass spectrometry (PAM-MS) is a combination of dynamic headspace sampling and membrane extraction. A new and simple purge-and-membrane sampler is introduced and its basic testing results for the analysis of VOCs in soil samples are reported. Soil moisture had no effect on desorption times in the case of sand, but the desorption times increased when the content of organic matter in the soil sample (garden soil) increased. The longest desorption times were measured with dry garden soil samples. For both types of samples, minor differences in desorption peak areas were observed between 10 and 20% moisture. Detection limits of the VOCs varied in the range 2-150 microg/kg, depending on the soil type. Good linearity (correlation coefficient > 0.990) was observed in the range 0.5-50 mg/kg. Aging of the spiked soil samples had only a slight effect on desorption peak areas for samples stored at 5 degrees C up to two weeks, but after six months of storing, differences were observed between dry sand and moistened garden soil. In both cases, peak areas were diminished. On average, 46% of compounds could be desorbed from the aged sand and 86% from the aged garden soil. The modified vapor fortification method was used in preparing standard soil samples, which were analyzed by static headspace gas chromatography (HSGC) and PAM-MS. Some authentic soil samples were also analyzed using both of these techniques. Many of the vapor fortification samples and the authentic samples were also analyzed in another laboratory by HSGC. The agreement between the methods and the laboratories was generally good.

Environmental applications of membrane introduction mass spectrometry

“…Sheet silicone membranes are often coupled with soil sampling devices that can be heated or purged. Purge-and-membrane mass spectrometry (PAM-MS) 49,169,170 and headspace MIMS (HS-MIMS) 171 are two ex situ techniques that combine the major advantages of headspace methods and membrane pervaporation for the direct determination of VOCs in soil samples.…”

Advances and challenges in the identification of volatiles that mediate interactions among plants and arthropods

“…So far, research on belowground allelochemicals mainly used extracts of root exudates, [142][143][144] but other methods to analyse VOCs from soil samples are also available. 130,[145][146][147][148][149][150] As in aerial VOC analyses, comparing various sampling methods can lead to different quantities of VOCs. 148 It is therefore pertinent to include more than one method in the belowground collections.…”

State of the Art in the Determination of MTBE in Natural Waters and Soils

“…Purge-and-membrane mass spectrometry (PAM-MS), which combines dynamic headspace sampling and membrane inlet mass spectrometry (141)(142)(143)(144) has proved to be very promising for the analysis of VOCs in soil samples. Ojala et al (145) described a detailed evaluation of the suitability of the PAM-MS method for analysis of VOCs from soil samples and compares the method with HS-GC. In this study, the effect of soil type and moisture was evaluated using sand, garden soil and their mixtures, as well as moistures contents of 0,10, and 20%.…”