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on the quality of ambient air is a field of advantage of ... Benzene, Toluene, and Xylene are substances ... a mean flux of 10_2photons/cm2s ... maximum permitted exposure level of pollution at the place of work [MAK]). ... air. (water < 100 ppm) ... ppmv. 0,01. 0.02. 0,03. Drift time. /s. Figure 3: Ion mobility spectra of different ...

N95- 33269

/ © '7?I n c. Determination Ion

J.W.

¢

of Benzene,

Mobility

Leonhardt

Toluene,

Spectrometer

_, H.

z Institut

Bensch

far

and

Device

Xylene

using

j, D. Berge),

Umwelttechnolgien,

ftir

Spektrochemie

und

Dortmund,

means

of an

Photoionization

M. Nolting

2 AUERGESELLSCHAFT/MSA, 3Institut

by

2, J.I.Baumbach

Berlin,

Germany

Berlin,

Germany

angewandte

3

Spektroskopie,

Germany

ABSTRACT

The continuous ion mobility because which

monitoring

of changes

spectrometry.

Benzene,

Toluene,

of their toxicity.

We present

uses photo-ionisation

tubes

this drift tube has a length tube of about for ionisation

180 V/cm a mean

on the quality

and Xylene

an optimised

to produce

of ambient

air is a field of advantage

are substances

drift tube for

ion mobility

the ions to be analysed.

of 45 mm, an electric

field strength

and a shutter-opening-time

established

was established

interest

spectrometers,

The actual

of 400 Fts. With

flux of 10 _2 photons/cm2s

of special

of

version

within

of

the drift

the hydrogen

tube

used

for the experiments

described. We discuss gasoline

the results

SUPER.

in co-operation

The detection

tween

of gasoline

hand-held

KEY

and others

SUPER

the instrument

lytical

takes

by a data evaluation Xylene

device in some

on Benzene, obtained

of 10 ppbv

procedure

are rather

in this case.

produced industrial

Normally,

spectrometer

charge

spectra

and sensitivity

of different

just now is to be tested laboratories

from Ben-

in mixtures found

is be-

concentrations

and the detection

of the system

used developed

transfer

determination

for the resolution

and scientific

in normal

for this case. The interferences

The ion mobility

as an example

Resolution

and Xylene

the simultaneous

developed

weak.

Toluene,

with the ion mobility

place. Nevertheless

are attached

developed.

portable

problems

limits

are in the range

zene ions to Toluene possible

of investigations

limit of

are well demonstrated.

for special

environmental

A ana-

in Germany.

WORDS

Benzene,

gas analysis,

gasoline,

ion mobility

spectrometry,

Toluene,

UV-ionisation,

Xylene

INTRODUCTION

Ion mobility spectrometryis a very sensitivemethodthatcanbeappliedto monitoringof air pollutantsatsub-partsper million concentrations in ambientair andatambientpressure.An applicationtool is the continuosdeterminationof cancerBenzenein air at work placesand environmentalprotection.Theadditionof aromaticsto petrolliesin thepercentrange.The dangerousrisk follow immediately.Thus,a selective, able to detect maximum

the substances

permitted

Benzene,

exposure

the instrument

lene with MAK

In this work,

values

EXPERIMENTAL

in the range

of pollution

be able to detect

400 times

we present

control

level

must

higher

an UV-lamp

in such an environment

The ion

under

Benzene

measurements

out using supported

matic

diagram

rangement

a prototype drift tube.

is given

of the geometrical marised

ion mobility

in Table

UV-lamp

Toluene,

in Figure

1. Details

tion, and standard

power

to establish

are sum-

Benzene

circuit

gas flow

electric water

air

50 ml/min duplex-shutter

open time

500 las 5 109 V/A H 2 - lamp,

flux

MgF-window

1012 photons/cm2s

diameter

30 mm

drift path

were

(25°C)

500 ml/min

mean

a

45 mm

field strength

170 - 230 V/cm

content