Determination of ethylene by field asymmetric ion mobility spectrometry
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ORIGINAL RESEARCH
Determination of ethylene by field asymmetric ion mobility spectrometry Nattapong Chantipmanee 1 & Peter C. Hauser 1 Received: 19 May 2020 / Revised: 13 July 2020 / Accepted: 14 July 2020 # The Author(s) 2020
Abstract The determination of ethylene with a field asymmetric ion mobility spectrometer, which can easily be constructed in-house, is described. The device makes use of a Krypton lamp for ionization. A rectangular pulse of 500 Vpp at 1 MHz was employed as separation waveform in the drift tube rather than the commonly used less efficient bisinusoidal waveform. The calibration curve for the range from 670 ppb(V/V) to 67 ppm(V/V) was found to be highly linear with a correlation coefficient of r = 0.9999. The limit of detection was determined as 200 ppb(V/V). The reproducibility was 4% (relative standard deviation). The device was found to be suitable for the determination of ethylene given off by fruit; 6 types of climacteric fruit were tested, namely apples, bananas, kiwi fruit, nectarines, pears and plums. Keywords Ethylene . Fruit ripening . Field asymmetric ion mobility spectrometry . Differential ion mobility spectrometry
Introduction Ethylene is an important hormone in plant life (also known as phytohormone) with particular relevance in the ripening of climacteric fruit [1–5]. Therefore in the storage and transportion of many fruits (e.g. kiwi fruit) ambient ethylene levels need to be kept low, and some fruits (e.g. bananas) are artificially ripened by exposure to ethylene before sale. In the management of the postharvest physiology of fruit thus the monitoring of ethylene is important. As for some fruit levels as low as 10 ppb(V/V) (μL/m3) are relevant in ripening [1], its analytical determination can be challenging. The approaches reported for the determination of ethylene in horticulture have been reviewed in recent years by Cristescu et al. [6], Caprioli and Quercia [1], and Hu et al. [2]. The most commonly used method is gaschromatography (GC) with mass-spectrometric detection, which gives high selectivity and sensitivity [7]. On the other hand, the method is relatively complex and expensive. Portable GC instruments are available, but these instruments do not always have the required sensitivity [6]. Optical
* Peter C. Hauser [email protected] 1
Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
detection by direct or indirect absorbance measurements in the infrared range (~10.5 μm) is another possibility. The most simple configurations are based on direct absorbance measurements using broadband thermal emittors, but these devices tend to lack the necessary selectivity and sensitivity for horticultural applications. Photoacoustic instruments based on laser diodes or quantum cascade lasers (QCLs) can attain good selectivity and limits of detection in the low ppb(V/V) range [2, 8]. Such instruments are commercially available, but at a cost of at least € 20′000 [2]. Electrochemical devices based on amperometry are much less expensive
