Hunting for Toxic Industrial Chemicals: Real-Time Detection of Carbon Disulfide Traces by Means of Ion Mobility Spectrometry

Abstract

Sensitive real-time detection of vapors produced by toxic industrial chemicals (TICs) represents a stringent priority nowadays. Carbon disulfide (CS2) is such a chemical, being widely used in manufacturing synthetic textile fibers and as a solvent. CS2 is simultaneously a very reactive, highly flammable, irritant, corrosive, and highly toxic compound, affecting the central nervous system, cardiovascular system, eyes, kidneys, liver, skin, and reproductive system. This study was directed towards quick detection and quantification of CS2 in air, using time-of-flight ion mobility spectrometry (IMS); photoionization detection (PID) was also used as confirmatory technique. Results obtained indicated that IMS can detect CS2 at trace levels in air. The ion mobility spectrometric response was in the negative ion mode and presented one product ion, at a reduced ion mobility (K0) of 2.25 cm2 V−1 s−1. Our study demonstrated that by using a portable, commercial IMS system (model Mini IMS, I.U.T. GmbH Berlin Germany) one can easily measure CS2 at concentrations of 0.1 ppmv (0.3 mg m−3) in the negative ion mode, which is below the lowest threshold value of 1 ppmv given for industrial hygiene. A limit of detection (LOD) of ca. 30 ppbv (0.1 mg m−3) was also estimated.

Fast Sensing of Hydrogen Cyanide (HCN) Vapors Using a Hand-Held Ion Mobility Spectrometer with Nonradioactive Ionization Source

“…The analytical figures of merit related to HCN detection and quantification are very similar, for instance, to those reported by us recently for another toxic industrial compound—carbon disulfide—using a ToF IMS with tritium radioactive ionization source [ 8 ].…”

“…Table 3 summarizes this qualitative information; negative reactant ion peak (RIP) and product ion peak of HCN are displayed. One may easily observe that the HCN product ion has higher reduced ion mobility, compared to the negative RIP, which means that HCN forms a product ion that is smaller and/or more compact than the reactant ion cluster; a similar behavior was noticed previously for chlorine [ 6 ] and for carbon disulfide [ 8 ].…”

“…The logarithmic aspect of the calibration curve observed in Figure 4 is very characteristic for any IMS response obtained using a radioactive ionization source [ 1 ]. Therefore, we may infer the similarity of the quantitative IMS response generated by the hand-held ToF IMS system with nonradioactive ionization source that was used by us (the LCD-3.2E) to the quantitative response produced by any ToF IMS device equipped with a radioactive source [ 4 , 5 , 6 , 7 , 8 ].…”

“…The crucial advantages of IMS lie in its very rapid response, the outstanding sensitivity, and the simple, very robust, and compact instruments. IMS is being utilized today for a broad range of applications—detecting traces of energetic materials, illegal drugs [ 2 , 3 ], precursors of illegal drugs [ 4 , 5 ], chemical warfare agents (CWAs), and toxic industrial chemicals (TICs) [ 6 , 7 , 8 ], plus a continuously expanding number of biomedical and industrial applications [ 9 , 10 ]. Moreover, the IMS technique was found to be useful in other fields too, such as medicine, forensic analyses, industrial hygiene, biology, space research, and investigation of the environment [ 1 ].…”

“…Using an ionization source in air, in ToF IMS, a radioactive ionization source initiates a very complex and fast ion–molecule reaction chemistry that leads initially to the formation of ion clusters called “reactant ions” of type (H 2 O) x H + (predominant), (H 2 O) y NH 4 + , and (H 2 O) z NO + in the positive ion mode, or the (H 2 O) n O 2 − species in the negative mode. Water vapor plays a crucial role in the atmospheric pressure ion–molecule chemistry, so it is necessary to continuously control and maintain its concentration inside the IMS measurement cell at a constant low level [ 7 , 8 ].…”