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MS-200 Application Note - Measuring Chemical Contamination on Protective Suits

Introduction

Protective suits are used throughout fire services and industry to protect personnel from exposure to dangerous chemicals during clean up of spills or general chemical production. After suit exposure, cleaning is required. Eventually, with use and after many wash cycles, the end of the useful lifetime of a suit is reached when it becomes possible for chemicals to permeate the suit. A responsible manufacturer of chemical protection suits in the U.K. approached Kore Technology to learn how the MS-200 could assist their business.

Objectives

  1. Improve characterisation of suits sent to their laboratory with suspected contamination.

  2. Detect compounds of interest down at suitably low concentrations.

  3. Improve evaluation of the effectiveness of standard suit cleaning procedures on site.

Picture of suit next to MS-200

An Appreciative Suit Receives A Clean Bill Of Health From An MS-200

Characterisation of Contaminated Suits

Various suits, many from fire services, had been sent back to the suit manufacturer's laboratory for routine checking. Suits were left inside their storage bags. After taking a measurement of the background air in the laboratory, a sampling tube from an MS-200 was simply inserted into a sealed bags and after approximately 2 minutes a sample of 'suit air' was analysed.

Sensitivity And Detection Limit Of The MS-200 For Commonly Encountered Chemicals

A representative subset of chemicals from a list of commonly encountered chemicals was chosen. To perform a quantitative analysis, gaseous standards in concentrations from approximately 30 to 100 ppm were produced by injecting the liquid sample into a Tedlar® bag filled with a metered amount of nitrogen. Results acquired in a ten second analysis are shown below.

Compound Sensitivity* Detection Limit**
Dimethylformamide 3750 30 ppb
Acetonitrile 2102 600 ppb
n-Heptane 128 000 < 10 ppb
Tetrahydrofuran 10 400 70 ppb
Diethylamine 625 400 ppb
Carbondisulfide 23 500 < 5 ppb
Nitrobenzene 99 000 < 5 ppb
Bromine 7 15 ppm
Dibromomethane 37 500 < 5 ppb
Diethylether 1 400 150 ppb
Pyridine 53 900 < 5 ppb
Diethylenglycol 34 15 ppm
Pentanol 22 300 20 ppb

*Compared to nitrogen having a sensitivity of 1.
**Estimated from the sensitivity and the statistical noise of the background spectrum for the component of concern. Calculated as 3*s of the background noise.

Performance of the MS-200 At A Client Site: In-Situ Analysis To Verify Effectiveness Of The Suit Cleaning Process

For this phase, an MS-200 was taken to a client in the chemical industry. This client has hundreds of suits to protect staff during work which exposes them to potentially harmful chemicals.

In this way, 42 samples were taken from 11 suits within 3 hours of set-up. On the first two suits analysed no contamination above the background sample could be identified. The third suit showed significant mass peaks above the background. As the operator was not aware of the client's procedures, the MS-200 result was analysed 'blind' using the NIST database. A library search suggested that the unknown compound could be "Limonene". It was than confirmed that limonene is the major constituent of the cleaning agent used when decontaminating the suits. The MS-200 mass spectrum sampled can be seen below.

Spectrum

The result of the NIST search was feed back into the MS-200 and a 'mixture analysis' was performed. The MS-200 mixture analysis reported a very good fit for limonene, thus confirming the NIST search result.

Limonene residues were found on 7 out of the 11 suits analysed, at various levels. No other contamination could be identified above levels noted in the table above, confirming the effectiveness of the cleaning process, within the detection sensitivity of the instrument noted above.

Conclusions


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Last updated: 17:06 18/09/2017

© Kore Technology Limited 2005