Environmental Letters
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Detection and Measurement of Aromatic Hydrocarbons in the Air by a Coated Piezoelectric Crystal Detector K. H. Karmarkar & G. G. Guilbault To cite this article: K. H. Karmarkar & G. G. Guilbault (1975) Detection and Measurement of Aromatic Hydrocarbons in the Air by a Coated Piezoelectric Crystal Detector, Environmental Letters, 10:3, 237-246, DOI: 10.1080/00139307509435825 To link to this article: http://dx.doi.org/10.1080/00139307509435825
Published online: 02 Sep 2009.
Submit your article to this journal
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Citing articles: 13 View citing articles
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Date: 11 November 2015, At: 19:45
ENVIRONMENTAL LETTERS,
10(3), 237-246 (1975)
DETECTION AND MEASUREMENT O F AROMATIC HYDROCARBONS IN T H E AIR BY A COATED PIEZOELECTRIC CRYSTAL DETECTOR
P i e z o e l e c t r i c c r y s t a l s , nujol a n d Ir complex, a r o m a t i c hydrocarbons
Downloaded by [University of Florida] at 19:45 11 November 2015
KEY WORDS:
K. H. K a r m a r k a r and G. G. Guilbault D e p a r t m e n t of C h e m i s t r y University of New O r l e a n s New O r l e a n s , Louisiana 70122
ABSTRACT Nujol with t r a n s - I r C 1 (CO)(PPh3)2 complex, is u s e d a s a coating f o r p i e z o e l e c t r i c c r y s t a l detector.
T h e device p r e f e r e n t i a l l y d e t e c t s
s o m e aromatic h y d r o c a r b o n s in air o v e r a l i p h a t i c ones.
T h e effect of
a t m o s p h e r i c m o i s t u r e is minimal.
INTRODUCTION T h e r e have been s e v e r a l r e s e a r c h r e p o r t s e s t a b l i s h i n g a connection between t h e p r e s e n c e of o r g a n i c compounds i n t h e air and 1 photochemical smog. Bufalini and A l t s h u l l e r have shown t h a t NO is rapidly oxidized in t h e p r e s e n c e of h y d r o c a r b o n s s u c h as 1, 3 , 5 -
trimethylbenzene and u l t r a v i o l e t light t o f o r m t h e toxic NO2. a n d Glasson:
Heuss
by t h e i r s m o g c h a m b e r e x p e r i m e n t s , d e t e r m i n e d t h a t
peroxybenzoyl n i t r a t e was t h e e y e i r r i t a n t f o r m e d by i r r a d i a t i o n of
237 Copyright 0 1976 by Marcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical. including photocopying, microfilming. and recording.or by any information storage and retrieval system. without permission in writing from the publisher.
KAREL4RKAR AND GUILBAULT
238
a mixture of a benzylic hydrocaron, NO2 and ozone.
D'Allera
Heuss, Nebel and
3 observed that the degree of eye i r r i t a t i o n of i r r a d i a t e d auto
exhaust gas increased by the addition of a r o m a t i c s to a special lowa r o m a t i c gasoline.
Sidce benzylic hydrocarbons a r e v e r y common in
gasoline, they a r e naturally a l s o found i n auto exhaust.
Simple, inex-
pensive, yet f a s t methods of detecting and measuring aromatic hydrocarbons i n the a i r a r e a necessity a t the p r e s e n t time.
Downloaded by [University of Florida] at 19:45 11 November 2015
In recent y e a r s coated piezoelectric quartz c r y s t a l s have been developed as sensitive and selective air pollution sensors.
King4'
has developed a sensitive piezoelectric sorption detector f o r monitoring methane and other hydrocarbons i n a i r . and then combusted.
The a i r sample i s first d r i e d
The water f o r m e d upon burning of hydrocarbons
was selectively detected by a piezoelectric sorption detector which responds to water but not hydrocarbons.
Karasek and Gibbins'
and
Karasek and Tiernay' have successfully used coated piezoelectric quartz c r y s t a l s a s g. c. detectors f o r hydrocarbon analysis.
We have developed
coated piezoelectric quartz c r y s t a l s e n s o r s f o r SOz, NOZ and NH i n 3 the p a r t s p e r billion concentrations, 8D 9' l o and also f o r stack gas monitoring.
This paper d e s c r i b e s a new c r y s t a l coating f o r xylenes
and other a r o m a t i c hydrocarbons i n a i r .
A study of i n t e r f e r e n c e s f r o m
other pollutants, is a l s o presented.
EXPERIMENTAL Apparatus Fig. 1 shows the experimental set-up with a piezoelectric c r y s t a l detector in-a flow system.
The cell design i s based on a
design described by the authors e a r l i e r , one f o r a flow system.
and is the most sensitive
A fish tank pump provides ambient a i r at the
r a t e of 20 m l / m i n for the c a r r i e r gas.
The c r y s t a l s used in
C O A T D PIEZOELECTRIC CRYSTAL DETECTOR
239
F+Downloaded by [University of Florida] at 19:45 11 November 2015
r
Fig. 1.
Experimental set-up with a piezoelectric c r y s t a l detector. A : frequency m e t e r ;
B : oscillator;
C: power supply; D: f i s h tank pump;
E : c r y s t a l coating; F : detector cell; c a r battery and P:
v:
12 V d. c. - 115 v a.
12 V C.
power inverter.
this study were 9 MHz AT cut quartz c r y s t a l s with silver-plated electrodes on both s i d e s , and w e r e obtained f r o m International Crystal Manufacturing Co. , Oklahoma.
A low -frequency
OX t r a n s i s t o r oscillator was, built f r o m a n oscillator kit obtained f r o m the Sam; company.
The oscillator was powered by a Heathkit
1-30 V d. c. variable power supply (Model 1P-28). The applied
U R M A R U R AND GUILBAULT
240
voltage was kept constant a t 9 V.
A Systron-Donner frequency m e t e r ,
Model 8050, with a range of 0-30 MHz and a resolution of 0. 1 Hz was used f o r a digital read-out of frequency.
i2 V d. c.
- i15 V a. c.
A micronta (Model 22-130)
power i n v e r t e r connected to a i 2 V c a r battery
was used to operate frequency m e t e r , Heathkit power supply and the The instrument is portable, being s m a l l ,
fish tank pump a t 115 V a. c. and operates on a c a r battery.
Downloaded by [University of Florida] at 19:45 11 November 2015
Reagents A nujol (Plough, Inc., Memphis, Tenn.) mixture of t r a n s chlorocarbonylbis (triphenylphosphine)irridium(I)[trans -1r Cl(CO)(PPh3)2]
(ICNPharmaceuticals, Inc.
, Plainview.
N. Y.) was used a s a coating.
Benzene, o-xylene, p-xylene, toluene, anisole, n-butylbenzene, acetophenone, benzaldehyde, heptane, octane, hexane, cyclohexane, methyl cyclohexane, 1,3,5 -trimethylbenzene. w e r e of technical grade.
SOz,
CO, HZS, NH3, NOZ, propane gas, methane gas, w e r e
obtained f r o m Matheson Gas P r o d u c t s i n l e c t u r e bottles.
Method of Application of Coating
Nujol and the i r r i d i u m complex (1% by w t ) w e r e dissolved i n benzene and the resulting faint yellow solution was applied on the e n t i r e s u r f a c e of the electrode on both s i d e s with a tiny brush.
Benzene
evaporated quickly, leaving a nujol-irridium complex mixture on the crystal.
The amount of this coating corresponded to a d e c r e a s e of
13,000 Hz in the basic frequency (9 M H z ) of the crystal.
T e s t Gas Dilution The t e s t gases and vapors w e r e diluted with l a b air by the syringe method e a r l i e r described by the authors8 and by K a r a s e k and Tiernay.
The bottle containing the organic substance tested was kept
241
C O ~ T E DPIEZOUECTRIC CRYSTAL DETECTOR i n a constant t e m p e r a t u r e w a t e r bath ( r o o m t e m p e r a t u r e ) .
A known
volume of t h e liquid v a p o r was s u c k e d in a 10 rnl s y r i n g e , then t h e s y r i n g e w a s filled t o capacity with l a b air.
T h e d e s i r e d dilution of the
t e s t v a p o r w a s obtained by r e p e a t i n g t h e above p r o c e d u r e f o r the r e q u i r e d n u m b e r of t i m e s .
By knowing t h e v a p o r p r e s s u r e of t h e o r g a n i c liquid at
the t e m p e r a t u r e of t h e bath, the concentration i n p p m of t h e o r g a n i c v a p o r in the s y r i n g e could be calculated.
Inorganic g a s e s t e s t e d w e r e
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f r o m l e c t u r e bottles (Matheson G a s P r o d u c t s ) .
RESULTS AND DISCUSSION Vaska l 2
a n d Moroni, F r i e d e l and Wenderi3 h a v e r e p o r t e d
that the yellow corr)plex, t r a n s -IrC1(CO)(PPh3)2 reacts instantaneously and forms r e v e r s i b l e addition compounds with SO CO, a n d ethylene. 2* T h e r e a c t i o n w a s r e p o r t e d t o o c c u r e i t h e r in benzene solution o r i n t h e solid state.
We t h e r e f o r e t r i e d t h i s compound a s a coating o n the c r y s t a l
f o r CO and SO2 detection. CO o r SO2.
We did not o b s e r v e any r e a c t i o n with e i t h e r
M o l e c u l a r oxygen r e p o r t e d l y f o r m s a 111 adducti4 with
this complex i n benzene; t h i s adduct then d o e s not r e a c t with SO2.
This
is probably the r e a s o n f o r l a c k of r e a c t i o n with SO2 o r GO. We t h e n u s e d nujol m i n e r a l oil as a s u b s t i t u t e f o r t h e o r g a n i c solvent.
If t h e I r - c o m p l e x r e a c t s with SO2 in benzene, we thought it
m i g h t a l s o r e a c t i n t h e p r e s e n c e of nujol m i n e r a l oil. Nujol, being less volatile, s t a y s o n t h e c r y s t a l s u r f a c e but not benzene.
Hence a benzene
solution of t h e nujol t I r - c o m p l e x (1 % w ) w a s p r e p a r e d and t h e c r y s t a l w a s coated a s d e s c r i b e d e a r l i e r .
T h i s c r y s t a l , u s e d in a flow s y s t e m ,
w a s s t i l l i n s e n s i t i v e to SO2 a n d GO.
However, this c r y s t a l coating w a s
r e a c t i v e to a r o m a t i c hydrocarbons, but not as s e n s i t i v e t o aliphatic a n d o r d i n a r y olefines.
Hence, a r o m a t i c compounds s u c h as xylenes,
benzaldehyde, 1 , 3 , 5 - t r i m e t h y l b e n z e n e , a n i s o l e , n-butyl benzene, could be detected a t low concentration, but compounds s u c h as hexane, heptane,
AND GU1LBALII.T
242
octane, cyclohexane, etc., could be detected only a t high concentrations. Inorganic gases show little reaction. for some a r o m a t i c hydrocarbons.
Figs. 2 a n d 3 show calibration plots
The c r y s t a l coating i s l e s s sensitive
f o r benzene and toluene. Since this detector does not respond to m o i s t u r e in the air, t h e r e i s no need to u s e hydrophobic m e m b r a n e f i l t e r s lo* to reduce the
Downloaded by [University of Florida] at 19:45 11 November 2015
moisture response.
The detector m a y r e m a i n stable for months.
Interferences Table 1 shows the results of a n interference study.
The i n t e r -
fering concentrations a r e those which produce a response roughly equivalent to that f o r 1 ppm p-xylene.
Table i Interference Study Interfering Gonc. PPm
Gas s02
H2S NH3
GO
Gas
Interfering Gonc. PPm
2000
Methane Gas
100,000
2000
Propane Gas
100,000
1000
Hexane
600
No Interf.
Gyclohexane Methylcyclo hexane
600
100
240
Chloroform
400
Heptane
240
T h i s detector was then used to monitor auto exhaust for a r o m a t i c hydrocarbons.
Ten ml samples w e r e sucked directly f r o m the exhausts
of different autos using a 10 ml syringe, and the sample was injected into
243
300
N
I
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LJ200
a z 0
a m100
w Lk:
60
I20 P.P.M.
Fig. 2 .
180 240 IN LAB A I R
Calibration plots f o r p-xylene, toluene, and 1 , 3 , 5 -trimethylbenzene on nujol t Ir complex coating: 0 - p-xylene;
0
- toluene;
-
i,3,5-tri-
methyl benzene Lab air c a r r i e r gas 20 ml/min; 10 ml sample injection
244
300
N
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I
200
100
Fig. 3.
60
I20
P.P.M.
IN LAB
240
180 AIR
Calibration plots f o r o -xylene, benzaldehyde and anisole o n nujol 4- I r complex coating: 0
- o-xylene;
0
- benzaldehyde,
x
- anisole
Lab a i r c a r r i e r gas 20 rnl/min; 10 ml sample injection
245
COATED PIEZOELECTRIC CRYSTAL DETECTOR
the i n s t r u m e n t .
A n Opel Kadette (1970) e x h a u s t gave a value equivalent
to 6 p p m p-xylene and a VW t r u c k (1966) gave a v a l u e of 3.5 p p m p-xylene. The Opel used a p r e m i u m quality gasoline. but t h e VW u s e d a r e g u l a r quality gasoline.
T h e method d e s c r i b e d h e r e s e e m s to be f a s t ,
reproducible and inexpensive.
Work is i n p r o g r e s s f o r finding t h e effect
and t h e o p t i m u m weight p e r c e n t of the i r r i d i u m c o m p l e x i n t h e nujol coating, as well a s t o d e t e r m i n e the n a t u r e of t h e i n t e r a c t i o n with h y d r o -
Downloaded by [University of Florida] at 19:45 11 November 2015
c a r b o n s , and t h e stability and reproducibility of t h i s coating as well as others.
ACKNOWLEDGEMENT T h e a u t h o r s a r e grateful to t h e A r m y R e s e a r c h Office f o r the financial a s s i s t a n c e ( G r a n t No. ARO DAHC04-75-G-0098) i n c a r r y i n g out this r e s e a r c h .
REFERENCES
1.
J. J. Bufalini a n d A. P. A l t s h u l l e r , Envir. Sci. Technol., 469 (1969).
2.
J. M. H e u s s and W. A . - G l a s s o n , Envir. Sci. Technol.,
2,
2,
1109 (1968). 3.
J. M. H e u s s , G. J. Nebel and B. A. D'Alleva, E n v i r , Sci. Technol., 2, 641 (1974).
4.
W. H. King, J r . , R e s e a r c h l D e v e l o p m e n t ,
5.
W. H. King, Jr., Envir. Sci. Technol.,
6.
F. W. K a r a s e k and K. R. Gibbins, J. Chromatogr. S c i . , 2,
E, No. 5, 28 (1969). 2, 1136 (1970).
535 (1971).
2,31 (1974). Chim. A c t a , 71.
7.
F. W. K a r a s e k a n d J. M. T i e r n a y , J. C h r o m a t o g . ,
8.
K. H. K a r m a r k a r and G. G. Guilbault, Anal. 419 (1974).
9.
K. H. K a r m a r k a r and G. G. Guilbault, Anal. Chim. Acta, 75, 111 (1975).
246
AND G U I L B A ~ T
10.
K . H. Karmarkar, L. M. Webber. and G. G. Guilbault, Environ. Letters, g, No. 4 (1975).
11.
K. H. Karmarkar and G. G. Guilbault, Anal. Chim. Acta, (submitted 1.
12.
L. Vaska, Accounts of Chemical Research,
13.
E. C. Moroni, R. A. F r i d e l a n d I . Wender, J. Organometal. C h e m . , 2,2 3 (1970).
14.
E. C. Moroni, private communcation.
L,
335 (1968).
Downloaded by [University of Florida] at 19:45 11 November 2015
Received July 11, 1975 Accepted August 1, 1975
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Detection and Measurement of Aromatic Hydrocarbons in the Air by a Coated Piezoelectric Crystal Detector K. H. Karmarkar & G. G. Guilbault To cite this article: K. H. Karmarkar & G. G. Guilbault (1975) Detection and Measurement of Aromatic Hydrocarbons in the Air by a Coated Piezoelectric Crystal Detector, Environmental Letters, 10:3, 237-246, DOI: 10.1080/00139307509435825 To link to this article: http://dx.doi.org/10.1080/00139307509435825
Published online: 02 Sep 2009.
Submit your article to this journal
Article views: 1
View related articles
Citing articles: 13 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=2esa20 Download by: [University of Florida]
Date: 11 November 2015, At: 19:45
ENVIRONMENTAL LETTERS,
10(3), 237-246 (1975)
DETECTION AND MEASUREMENT O F AROMATIC HYDROCARBONS IN T H E AIR BY A COATED PIEZOELECTRIC CRYSTAL DETECTOR
P i e z o e l e c t r i c c r y s t a l s , nujol a n d Ir complex, a r o m a t i c hydrocarbons
Downloaded by [University of Florida] at 19:45 11 November 2015
KEY WORDS:
K. H. K a r m a r k a r and G. G. Guilbault D e p a r t m e n t of C h e m i s t r y University of New O r l e a n s New O r l e a n s , Louisiana 70122
ABSTRACT Nujol with t r a n s - I r C 1 (CO)(PPh3)2 complex, is u s e d a s a coating f o r p i e z o e l e c t r i c c r y s t a l detector.
T h e device p r e f e r e n t i a l l y d e t e c t s
s o m e aromatic h y d r o c a r b o n s in air o v e r a l i p h a t i c ones.
T h e effect of
a t m o s p h e r i c m o i s t u r e is minimal.
INTRODUCTION T h e r e have been s e v e r a l r e s e a r c h r e p o r t s e s t a b l i s h i n g a connection between t h e p r e s e n c e of o r g a n i c compounds i n t h e air and 1 photochemical smog. Bufalini and A l t s h u l l e r have shown t h a t NO is rapidly oxidized in t h e p r e s e n c e of h y d r o c a r b o n s s u c h as 1, 3 , 5 -
trimethylbenzene and u l t r a v i o l e t light t o f o r m t h e toxic NO2. a n d Glasson:
Heuss
by t h e i r s m o g c h a m b e r e x p e r i m e n t s , d e t e r m i n e d t h a t
peroxybenzoyl n i t r a t e was t h e e y e i r r i t a n t f o r m e d by i r r a d i a t i o n of
237 Copyright 0 1976 by Marcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical. including photocopying, microfilming. and recording.or by any information storage and retrieval system. without permission in writing from the publisher.
KAREL4RKAR AND GUILBAULT
238
a mixture of a benzylic hydrocaron, NO2 and ozone.
D'Allera
Heuss, Nebel and
3 observed that the degree of eye i r r i t a t i o n of i r r a d i a t e d auto
exhaust gas increased by the addition of a r o m a t i c s to a special lowa r o m a t i c gasoline.
Sidce benzylic hydrocarbons a r e v e r y common in
gasoline, they a r e naturally a l s o found i n auto exhaust.
Simple, inex-
pensive, yet f a s t methods of detecting and measuring aromatic hydrocarbons i n the a i r a r e a necessity a t the p r e s e n t time.
Downloaded by [University of Florida] at 19:45 11 November 2015
In recent y e a r s coated piezoelectric quartz c r y s t a l s have been developed as sensitive and selective air pollution sensors.
King4'
has developed a sensitive piezoelectric sorption detector f o r monitoring methane and other hydrocarbons i n a i r . and then combusted.
The a i r sample i s first d r i e d
The water f o r m e d upon burning of hydrocarbons
was selectively detected by a piezoelectric sorption detector which responds to water but not hydrocarbons.
Karasek and Gibbins'
and
Karasek and Tiernay' have successfully used coated piezoelectric quartz c r y s t a l s a s g. c. detectors f o r hydrocarbon analysis.
We have developed
coated piezoelectric quartz c r y s t a l s e n s o r s f o r SOz, NOZ and NH i n 3 the p a r t s p e r billion concentrations, 8D 9' l o and also f o r stack gas monitoring.
This paper d e s c r i b e s a new c r y s t a l coating f o r xylenes
and other a r o m a t i c hydrocarbons i n a i r .
A study of i n t e r f e r e n c e s f r o m
other pollutants, is a l s o presented.
EXPERIMENTAL Apparatus Fig. 1 shows the experimental set-up with a piezoelectric c r y s t a l detector in-a flow system.
The cell design i s based on a
design described by the authors e a r l i e r , one f o r a flow system.
and is the most sensitive
A fish tank pump provides ambient a i r at the
r a t e of 20 m l / m i n for the c a r r i e r gas.
The c r y s t a l s used in
C O A T D PIEZOELECTRIC CRYSTAL DETECTOR
239
F+Downloaded by [University of Florida] at 19:45 11 November 2015
r
Fig. 1.
Experimental set-up with a piezoelectric c r y s t a l detector. A : frequency m e t e r ;
B : oscillator;
C: power supply; D: f i s h tank pump;
E : c r y s t a l coating; F : detector cell; c a r battery and P:
v:
12 V d. c. - 115 v a.
12 V C.
power inverter.
this study were 9 MHz AT cut quartz c r y s t a l s with silver-plated electrodes on both s i d e s , and w e r e obtained f r o m International Crystal Manufacturing Co. , Oklahoma.
A low -frequency
OX t r a n s i s t o r oscillator was, built f r o m a n oscillator kit obtained f r o m the Sam; company.
The oscillator was powered by a Heathkit
1-30 V d. c. variable power supply (Model 1P-28). The applied
U R M A R U R AND GUILBAULT
240
voltage was kept constant a t 9 V.
A Systron-Donner frequency m e t e r ,
Model 8050, with a range of 0-30 MHz and a resolution of 0. 1 Hz was used f o r a digital read-out of frequency.
i2 V d. c.
- i15 V a. c.
A micronta (Model 22-130)
power i n v e r t e r connected to a i 2 V c a r battery
was used to operate frequency m e t e r , Heathkit power supply and the The instrument is portable, being s m a l l ,
fish tank pump a t 115 V a. c. and operates on a c a r battery.
Downloaded by [University of Florida] at 19:45 11 November 2015
Reagents A nujol (Plough, Inc., Memphis, Tenn.) mixture of t r a n s chlorocarbonylbis (triphenylphosphine)irridium(I)[trans -1r Cl(CO)(PPh3)2]
(ICNPharmaceuticals, Inc.
, Plainview.
N. Y.) was used a s a coating.
Benzene, o-xylene, p-xylene, toluene, anisole, n-butylbenzene, acetophenone, benzaldehyde, heptane, octane, hexane, cyclohexane, methyl cyclohexane, 1,3,5 -trimethylbenzene. w e r e of technical grade.
SOz,
CO, HZS, NH3, NOZ, propane gas, methane gas, w e r e
obtained f r o m Matheson Gas P r o d u c t s i n l e c t u r e bottles.
Method of Application of Coating
Nujol and the i r r i d i u m complex (1% by w t ) w e r e dissolved i n benzene and the resulting faint yellow solution was applied on the e n t i r e s u r f a c e of the electrode on both s i d e s with a tiny brush.
Benzene
evaporated quickly, leaving a nujol-irridium complex mixture on the crystal.
The amount of this coating corresponded to a d e c r e a s e of
13,000 Hz in the basic frequency (9 M H z ) of the crystal.
T e s t Gas Dilution The t e s t gases and vapors w e r e diluted with l a b air by the syringe method e a r l i e r described by the authors8 and by K a r a s e k and Tiernay.
The bottle containing the organic substance tested was kept
241
C O ~ T E DPIEZOUECTRIC CRYSTAL DETECTOR i n a constant t e m p e r a t u r e w a t e r bath ( r o o m t e m p e r a t u r e ) .
A known
volume of t h e liquid v a p o r was s u c k e d in a 10 rnl s y r i n g e , then t h e s y r i n g e w a s filled t o capacity with l a b air.
T h e d e s i r e d dilution of the
t e s t v a p o r w a s obtained by r e p e a t i n g t h e above p r o c e d u r e f o r the r e q u i r e d n u m b e r of t i m e s .
By knowing t h e v a p o r p r e s s u r e of t h e o r g a n i c liquid at
the t e m p e r a t u r e of t h e bath, the concentration i n p p m of t h e o r g a n i c v a p o r in the s y r i n g e could be calculated.
Inorganic g a s e s t e s t e d w e r e
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f r o m l e c t u r e bottles (Matheson G a s P r o d u c t s ) .
RESULTS AND DISCUSSION Vaska l 2
a n d Moroni, F r i e d e l and Wenderi3 h a v e r e p o r t e d
that the yellow corr)plex, t r a n s -IrC1(CO)(PPh3)2 reacts instantaneously and forms r e v e r s i b l e addition compounds with SO CO, a n d ethylene. 2* T h e r e a c t i o n w a s r e p o r t e d t o o c c u r e i t h e r in benzene solution o r i n t h e solid state.
We t h e r e f o r e t r i e d t h i s compound a s a coating o n the c r y s t a l
f o r CO and SO2 detection. CO o r SO2.
We did not o b s e r v e any r e a c t i o n with e i t h e r
M o l e c u l a r oxygen r e p o r t e d l y f o r m s a 111 adducti4 with
this complex i n benzene; t h i s adduct then d o e s not r e a c t with SO2.
This
is probably the r e a s o n f o r l a c k of r e a c t i o n with SO2 o r GO. We t h e n u s e d nujol m i n e r a l oil as a s u b s t i t u t e f o r t h e o r g a n i c solvent.
If t h e I r - c o m p l e x r e a c t s with SO2 in benzene, we thought it
m i g h t a l s o r e a c t i n t h e p r e s e n c e of nujol m i n e r a l oil. Nujol, being less volatile, s t a y s o n t h e c r y s t a l s u r f a c e but not benzene.
Hence a benzene
solution of t h e nujol t I r - c o m p l e x (1 % w ) w a s p r e p a r e d and t h e c r y s t a l w a s coated a s d e s c r i b e d e a r l i e r .
T h i s c r y s t a l , u s e d in a flow s y s t e m ,
w a s s t i l l i n s e n s i t i v e to SO2 a n d GO.
However, this c r y s t a l coating w a s
r e a c t i v e to a r o m a t i c hydrocarbons, but not as s e n s i t i v e t o aliphatic a n d o r d i n a r y olefines.
Hence, a r o m a t i c compounds s u c h as xylenes,
benzaldehyde, 1 , 3 , 5 - t r i m e t h y l b e n z e n e , a n i s o l e , n-butyl benzene, could be detected a t low concentration, but compounds s u c h as hexane, heptane,
AND GU1LBALII.T
242
octane, cyclohexane, etc., could be detected only a t high concentrations. Inorganic gases show little reaction. for some a r o m a t i c hydrocarbons.
Figs. 2 a n d 3 show calibration plots
The c r y s t a l coating i s l e s s sensitive
f o r benzene and toluene. Since this detector does not respond to m o i s t u r e in the air, t h e r e i s no need to u s e hydrophobic m e m b r a n e f i l t e r s lo* to reduce the
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moisture response.
The detector m a y r e m a i n stable for months.
Interferences Table 1 shows the results of a n interference study.
The i n t e r -
fering concentrations a r e those which produce a response roughly equivalent to that f o r 1 ppm p-xylene.
Table i Interference Study Interfering Gonc. PPm
Gas s02
H2S NH3
GO
Gas
Interfering Gonc. PPm
2000
Methane Gas
100,000
2000
Propane Gas
100,000
1000
Hexane
600
No Interf.
Gyclohexane Methylcyclo hexane
600
100
240
Chloroform
400
Heptane
240
T h i s detector was then used to monitor auto exhaust for a r o m a t i c hydrocarbons.
Ten ml samples w e r e sucked directly f r o m the exhausts
of different autos using a 10 ml syringe, and the sample was injected into
243
300
N
I
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LJ200
a z 0
a m100
w Lk:
60
I20 P.P.M.
Fig. 2 .
180 240 IN LAB A I R
Calibration plots f o r p-xylene, toluene, and 1 , 3 , 5 -trimethylbenzene on nujol t Ir complex coating: 0 - p-xylene;
0
- toluene;
-
i,3,5-tri-
methyl benzene Lab air c a r r i e r gas 20 ml/min; 10 ml sample injection
244
300
N
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I
200
100
Fig. 3.
60
I20
P.P.M.
IN LAB
240
180 AIR
Calibration plots f o r o -xylene, benzaldehyde and anisole o n nujol 4- I r complex coating: 0
- o-xylene;
0
- benzaldehyde,
x
- anisole
Lab a i r c a r r i e r gas 20 rnl/min; 10 ml sample injection
245
COATED PIEZOELECTRIC CRYSTAL DETECTOR
the i n s t r u m e n t .
A n Opel Kadette (1970) e x h a u s t gave a value equivalent
to 6 p p m p-xylene and a VW t r u c k (1966) gave a v a l u e of 3.5 p p m p-xylene. The Opel used a p r e m i u m quality gasoline. but t h e VW u s e d a r e g u l a r quality gasoline.
T h e method d e s c r i b e d h e r e s e e m s to be f a s t ,
reproducible and inexpensive.
Work is i n p r o g r e s s f o r finding t h e effect
and t h e o p t i m u m weight p e r c e n t of the i r r i d i u m c o m p l e x i n t h e nujol coating, as well a s t o d e t e r m i n e the n a t u r e of t h e i n t e r a c t i o n with h y d r o -
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c a r b o n s , and t h e stability and reproducibility of t h i s coating as well as others.
ACKNOWLEDGEMENT T h e a u t h o r s a r e grateful to t h e A r m y R e s e a r c h Office f o r the financial a s s i s t a n c e ( G r a n t No. ARO DAHC04-75-G-0098) i n c a r r y i n g out this r e s e a r c h .
REFERENCES
1.
J. J. Bufalini a n d A. P. A l t s h u l l e r , Envir. Sci. Technol., 469 (1969).
2.
J. M. H e u s s and W. A . - G l a s s o n , Envir. Sci. Technol.,
2,
2,
1109 (1968). 3.
J. M. H e u s s , G. J. Nebel and B. A. D'Alleva, E n v i r , Sci. Technol., 2, 641 (1974).
4.
W. H. King, J r . , R e s e a r c h l D e v e l o p m e n t ,
5.
W. H. King, Jr., Envir. Sci. Technol.,
6.
F. W. K a r a s e k and K. R. Gibbins, J. Chromatogr. S c i . , 2,
E, No. 5, 28 (1969). 2, 1136 (1970).
535 (1971).
2,31 (1974). Chim. A c t a , 71.
7.
F. W. K a r a s e k a n d J. M. T i e r n a y , J. C h r o m a t o g . ,
8.
K. H. K a r m a r k a r and G. G. Guilbault, Anal. 419 (1974).
9.
K. H. K a r m a r k a r and G. G. Guilbault, Anal. Chim. Acta, 75, 111 (1975).
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AND G U I L B A ~ T
10.
K . H. Karmarkar, L. M. Webber. and G. G. Guilbault, Environ. Letters, g, No. 4 (1975).
11.
K. H. Karmarkar and G. G. Guilbault, Anal. Chim. Acta, (submitted 1.
12.
L. Vaska, Accounts of Chemical Research,
13.
E. C. Moroni, R. A. F r i d e l a n d I . Wender, J. Organometal. C h e m . , 2,2 3 (1970).
14.
E. C. Moroni, private communcation.
L,
335 (1968).
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Received July 11, 1975 Accepted August 1, 1975
