International Journal for Ion Mobility Spectrometry

International Journal for Ion Mobility Spectrometry

P TY S ECTRO ILI

IONA L SOC T I NA

or ION MO f Y B ET

TRY ME

I N T E R

6(2003)2

Official publication of the International Society for Ion Mobility Spectrometry

T ABLE

OF

C ONTENT

ITMS-MS Analysis of Smokeless Powder

1

Validation of the Volatile Organic Analyzer (VOA) for ISS Operations

5

Monitoring Diborane Vapor with Smiths Detection’s CENTURION

11

Control and Signal Processing for an IMS Sensor

17

A MEMS GC - IMS for the Analysis of Extraterrestrial Environments

23

Toward an Intelligent Ion Mobility Spectrometer (IMS)

29

DETECTION OF DMS USING HAND-HELD IMS

39

Field Dependence of Mobility for Gas Phase Ions of Organophosphorus Compounds at Atmospheric Pressure with Differential Mobility Spectrometry and Effects of Moisture: Insights into a Model of Positive Alpha Dependence

43

USING AN ARRAY OF ION MOBILITY SPECTROMETERS FOR GROUND TRUTH MEASUREMENTS IN FIELD TESTS INVOLVING RELEASES OF CHEMICAL WARFARE AGENT SURROGATES

49

Detection of the mold markers using Ion Mobility Spectrometry

53

Ion Mobility Spectrometry of Peroxide Explosives TATP and HMTD

59

GasolineAnalysisbyGC-UV-IMS

63

IMS ANALYSIS OF VOLATILE METAL CHELATES

67

ITMS-MS ANALYSIS OF SMOKELESS POWDER Jennifer L Neves, Paul E Haigh, , Ching Wu, William J McGann GE Ion Track, 205D Lowell Street, Wilmington, MA 01887, USA

Introduction Ion mobility spectrometers have easily detected commercial explosives such as TNT and RDX for many years. Improvised explosives, such as smokeless powders, have presented detection challenges. As seen in previous work, some of these problem substances have been characterized using a simultaneous dual mode ion trap mobility spectrometer (ITMS) system1. Smokeless powders were identified in positive and negative mode using ITMS, but the identities of the detected ions were not determined. An ITMS detector interfaced to a commercially available quadrupole mass spectrometer (MS) was used to analyze the ions detected for a variety of explosives. Although similar degradation products were seen for many of the substances, other peaks were used to differentiate between the various explosives. The improvised explosives Bluedot smokeless powder and Winchester 748 smokeless powder and the conventional explosives nitroglycerin, TNT, and RDX were analyzed via ITMS-MS.

Experimental A GE Ion Track ITMS detector was coupled to a Finnigan SSQ7000 quadrupole mass spectrometer by way of a Finnigan API1 1. Neves, J.L., Haigh, P., McGann, W.: Expanding the Capabilities of IMS Explosive Trace Detection. IJIMS 5(2002) 3; 119-122

electrospray interface. The ITMS detector was sheared off at the Faraday collector plate and the collector assembly was removed. The electrospray needle assembly block was removed from the API1 interface and the modified ITMS detector was mounted to the API1 assembly in place of the electrospray needle assembly block via a custom machined mounting plate. A GE Ion Track VaporTracer was modified to supply the voltages required to operate the ITMS detector. A standard Itemiser 3 heated desorber was attached to the membrane inlet of the ITMS-MS. Ions that reached the end of the drift region were drawn through a heated capillary (150° C) into the API1 interface, which was differentially pumped to approximately 450 mTorr. A series of lenses and an octapole ion guide conveyed the ions to the ion lenses at the entrance to the quadrupole region. The quadrupole region was maintained at approximately 4.9 x10-6 Torr. In order to produce an ITMS plasmagram for a particular ion, single ion monitoring was used to generate an analog signal from the electron multiplier of the MS. The electron multiplier response was pre-amplified and read on an oscilloscope that was triggered by the ITMS inlet trigger pulse. Twenty nanograms of nitroglycerine and fifteen nanograms of TNT, RDX, and Winchester and Bluedot smokeless powders were introduced into the Itemiser 3 and ITMSMS desorbers.

Table 1: Difference Between Itemiser and ITMS-MS Ion Mobility Substance

Dominant MS peak

Itemiser Appearance

ITMS-MS Appearance

Difference

TNT

226

6.070 ms

8.000 ms

1.93 ms

RDX

257

6.350 ms

8.400 ms

2.05 ms

62

3.890 ms

6.400 ms

2.51 ms

NITRO

Received for review July 8, 2003, Accepted July 25, 2003

2 - ITMS-MS Analysis of Smokeless Powder

Figure 1: MS Signal of TNT

Figure 3: MS Signal of RDX + Cl (close up)

Figure 2: ITMS Analog Signal of TNT by an M+2 peak, which confirms that RDX formed a chlorinated species during ionization. The ITMS-MS plasmagram for RDX is shown in Fig. 2. An MS peak observed at m/z = 62 for nitroglycerine (MW = 227) indicates a NO3 breakdown product. The ingredients listed for Bluedot and Winchester smokeless powders were: nitrocellulose, nitroglycerin, diphenyl-amine, ethyl centralite, rosin and poly-ester. The nitrocellulose and nitroglycerin are the explosive components; the diphenylamine and ethyl centralite are stabilizers and the

Samples were deposited onto sample swabs as methanol solution that was allowed to evaporate.

Results A delay of approximately 2 ms in the ion appearance time was observed on the ITMS-MS with respect to the ion appearance time observed on a standard ITMS detector (Itemiser 3) operating at the same temperature (200° C) (Table 1). This is due to the time of flight between the capillary interface of the ITMS and the MS electron multiplier. An MS peak was observed at m/z = 225.5 for TNT (MW = 227) (Fig. 1). It is assumed that TNT ionized by proton abstraction, which would indicate a calibration offset of m/z 0.5. A peak was observed for RDX (MW = 222) at m/z 257. As seen in figure 3, the RDX MS peak is followed Copyright © 2003 by International Society for Ion Mobility Spectrometry

ITMS-MS Analysis of Smokeless Powder - 3

peak at 3.890 ms and a positive mode peak at 7.447 ms when introduced into an Itemiser 3. The negative mode peak observed for each smokeless powder was identical to that for nitroglycerine. The positive mode MS peak for smokeless powder was observed at m/z = 269 (Fig. 4). The ITMS-MS plasmagram peak observed for the m/z = 269 ion tailed extensively and had a poorly defined maximum (Fig. 5). A 10.0 ng sample of ethyl centralite (MW = 268) was introduced into the Itemiser 3. The same positive mode peak appeared on the Itemiser (Fig 6) as was observed for the smokeless powders, confirming ethyl centralite as the compound in smokeless powder detected in positive mode.

Conclusion The use of ITMS detectors for the detection of common explosives has relied on the use of empirically correlating plasmagram peaks to substances of interest. This work describes the first coupling of an ITMS

detector to a mass spectrometer as a tool for the confirmatory identification of plasmagram ions. The identification of ethyl centralite as the compound detected in positive mode ITMS for smokeless powders could help to discriminate commercial smokeless powder from other explosives that are identified by a nitrate ion breakdown product.

Copyright © 2003 by International Society for Ion Mobility Spectrometry

4 - ITMS-MS Analysis of Smokeless Powder

Copyright © 2003 by International Society for Ion Mobility Spectrometry

VALIDATION OF THE VOLATILE ORGANIC ANALYZER (VOA) FOR ISS OPERATIONS Thomas Limero, Mildred Martin, Eric Reese Wyle Laboratories Inc., Life Sciences Systems and Services

Introduction The Volatile Organic Analyzer (VOA) was installed in the laboratory module (LAB) of the International Space Station (ISS) in September 2001. The envisioned operational plan for VOA was to have the instrument continuously powered with all components maintained at the initial run temperatures, thereby ready to receive a run command. The validation of the VOA for ISS operations involved acquiring 4-6 archival samples during analytical runs of the VOA. After the archival samples were returned to the ground and analyzed, the results would be compared to those obtained from the VOA. In addition the data from a series of 3 consecutive VOA runs would be used to establish the system precision. Given the return frequency of archival samplers, it was anticipated that the validation task would be completed in about 6 months. Unfortunately, a VOA software problem created interface issues with the ISS communication bus and this delayed the start of the validation plan. It took several months of troubleshooting to identify the software problem and devise a new operational scenario that was compatible with the software glitch. The revised plan activated the VOA only when runs were to be performed. Once the runs were completed the VOA was deactivated. The first VOA run coordinated with an archival sample (grab sample container-GSC) did not occur until January 2002. Subsequently, a host of small issues, from the availability of crew time, Shuttle delays, and VOA interactions with ISS systems, stretched the acquisition of all the validation samples to December 2002 and the analysis of the December sample to June 2003. In November 2002 a new software package was installed in the VOA that permitted operations as originally intended.

Figure 1: The VOA (red circle) in the Lab module For the latter half of November and all of December 2002 the VOA was maintained in a warmed state and VOA runs were performed approximately every two days. Previous papers (1, 2, and 3) have provided rationale for a VOA on the ISS and detailed its operational use in April 2002 to supply needed data following a major contingency event (METOX) on the ISS. This paper will discuss and interpret the results from the comparison of the VOA runs to the 8 GSC samples. The results from the first 7 GSC validation samples will be summarized, but much of the discussion will center upon the last sample because of its importance to the overall validation process.

Experimental Volatile organic analyzer The VOA, as seen on orbit in Figure 1, has been described in detail elsewhere (4). The VOA is comprised of four major components that provide its analytical capability. A sample pump pulls a specified amount of ISS atmosphere across preconcentrator traps, which focus the

Received for review July 23, 2003, Accepted August 15, 2003

6 - Validation of the Volatile Organic Analyzer (VOA) for ISS Operations

contaminants and improve detection sensitivity. The gas chromatography (GC) columns separate the mixture of contaminants from the ISS atmosphere so the detector, an ion mobility spectrometer (IMS), can analyze one compound at a time. The VOA onboard computer controls all instrument parameters and reduces the data to provide compound identifications and concentrations to the crew and to ground personnel. The two critical parameters necessary for the VOA to properly identify the contaminants are the GC retention times (seconds) and the normalized ion drift times (ko). Compound quantitation is accomplished by integrating the ion mobility peak and comparing this area to a calibration lookup table. The VOA was calibrated for the target compounds shown in Table 1 in June 2001 prior to its launch to ISS. The calibration procedures and the development of the VOA’s analytical database have been described in other papers (5, 6). Table 1: VOA target compounds Compound Name Methanol 1-butanol Ethanal m,p xylenes o xylene

Compound Name Ethanol 2-methyl 2-propanol Benzene (F22) chlorodifluoromethane 1,1,1, trichloroethane

Toluene

(F113) 1,1,2-trichloro-1,2,2-trifluoroethane

Dichloromethane Propanone 2-butanone 2-propanol

Hexane Isoprene (halon 1301) trifluorobromomethane ethyl acetate

Grab sample containers The GSC shown in Figure 2, and the methods used to analyze them have been previously described (7); therefore, only a brief description will be presented. A sample is acquired on orbit by opening a valve on the GSC permitting the container vacuum to pull in the air sample. The valve is then closed to preserve the sample until analysis. Upon return to the NASA/JSC Toxicology Laboratory, the GSC samples were analyzed by GC/MS for volatile organic compounds according to standard work instructions. The GC/MS method is an adaptation of the U.S. Environmental Protection Agency’s TO-14 method. The analysis of the GSCs by this method is

Figure 1: Grab sample container (GSC) considered to be the reference method for the purpose of this study.

Validation Plan Elements The VOA validation plan was designed to accumulate the data necessary to corroborate the VOA’s on-orbit accuracy and reliability with the VOA groundbased acceptance testing results (8). The pass/fail criteria were based upon the VOA performance during the acceptance testing and the requirements for the VOA to be a valuable monitor on ISS.

Precision Testing the precision of the VOA involved completing 3 consecutive sample runs with no blank runs or inactive periods occurring between these runs. This aspect of the validation is very important in assessing the VOA’s ability to monitor contaminant concentrations during cleanup after an incident. The required relative standard deviation (RSD) was