Atmospheric Aerosol - American Chemical Society

12 An Automated Thermal-Optical Method for the Analysis of Carbonaceous Aerosol

Downloaded by UNIV OF ROCHESTER on August 5, 2013 | http://pubs.acs.org Publication Date: October 13, 1981 | doi: 10.1021/bk-1981-0167.ch012

RICHARD L. JOHNSON, JITENDRA J. SHAH, ROBERT A. CARY, and JAMES J. HUNTZICKER Department of Environmental Science, Oregon Graduate Center, 19600 N.W. Walker Road, Beaverton, OR 97006

An instrument employing both thermal and optical measurements has been developed for the analysis of organic and elemental carbonaceous aerosol collected on glass or quartz fiber f i l t e r s . The technique involves v o l a t i l i z a t i o n of organic carbon from the f i l t e r under conditions where the elemental carbon remains. The v o l a t i l i z e d carbon is oxidized to CO , reduced to CH , and measured by a flame ionization detector. Elemental carbon is subsequently oxidized to CO and measured. The reflectance of the f i l t e r is continuously monitored throughout the analysis by a helium-neon laser system. During the organic analysis some of the organic carbon is pyrolytically converted to elemental carbon; this results in a decrease in the f i l t e r reflectance. Correction for the pyrolytic production of elemental carbon is achieved by measuring the amount of elemental carbon oxidation necessary to return the f i l t e r reflectance to i t s i n i t i a l value. The instrument is completely automated and is under the control of a microprocessor system. It has been evaluated with respect to model compounds, typical source mixtures (e.g., auto exhaust aerosol), and ambient samples. 2

4

2

Although carbon has long been recognized as an important constituent of ambient aerosols, the analysis of carbon in i t s many molecular forms has presented formidable obstacles. An approach taken by many investigators (1-12) has been to separate aerosol carbon into organic, elemental, and carbonate classes. However, at the present time only carbonate carbon has an unequivocal anal y t i c a l definition. Speciation between organic and elemental car0097-6156/81/0167-0223$05.00/0 © 1981 American Chemical Society

In Atmospheric Aerosol; Macias, E., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


224

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AEROSOL

bon i s d i f f i c u l t , and, as G r o s j e a n (13) has p o i n t e d o u t , c u r r e n t a n a l y t i c a l d e f i n i t i o n s of elemental carbon are " o p e r a t i o n a l " or method-dependent. I n t h i s p a p e r we r e p o r t on r e c e n t p r o g r e s s a c h i e v e d i n o u r l a b o r a t o r y w i t h r e g a r d t o t h e s e p a r a t e and q u a n t i t a t i v e m e a s u r e ment o f o r g a n i c and e l e m e n t a l c a r b o n i n a e r o s o l s a m p l e s . Our i n i t i a l a p p r o a c h (4) was t o h e a t a segment o f an a e r o s o l - c o n t a i n i n g g l a s s o r q u a r t z f i b e r f i l t e r t o 600°C i n a h e l i u m a t m o s p h e r e . V o l a t i l i z e d o r g a n i c compounds w e r e o x i d i z e d t o CO2 i n an o x i d a t i o n o v e n , r e d u c e d t o CH4, and m e a s u r e d by a f l a m e i o n i z a t i o n d e t e c t o r ( F I D ) . R e s i d u a l c a r b o n , w h i c h was assumed t o be e l e m e n t a l c a r b o n , was o x i d i z e d t o CO2 by t h e a d d i t i o n o f O2 t o t h e c o m b u s t i o n o v e n and m e a s u r e d as a b o v e . I t was d i s c o v e r e d , h o w e v e r , t h a t i f t h e f i l t e r was removed f r o m t h e o v e n a f t e r t h e o r g a n i c a n a l y s i s s t e p — b u t b e f o r e t h e a d d i t i o n o f O2, i t was n o t i c e a b l y d a r k e r t h a n a t t h e b e g i n n i n g o f t h e a n a l y s i s . T h i s was i n d i c a t i v e o f t h e p y r o l y t i c formation of elemental carbon d u r i n g the o r g a n i c a n a l y s i s S i n c e t h a t d i s c o v e r y a major aspect of our r e s e a r c h e f f o r t has b e e n t o d e v e l o p a method t o a c c o u n t f o r t h i s unwanted p y r o l y t i c conversion of o r g a n i c to elemental carbon. T h i s r e p o r t des c r i b e s a combined t h e r m a l - o p t i c a l i n s t r u m e n t i n w h i c h t h e r e f l e c tance o f the f i l t e r sample i s c o n t i n u o u s l y monitored d u r i n g the t h e r m a l a n a l y s i s . Dod et_ a l . (14) h a v e a l s o r e p o r t e d a c o m b u s t i o n t e c h n i q u e combined w i t h o p t i c a l t r a n s m i s s i o n . Experimental The c a r b o n a n a l y z e r c o n s i s t s o f t h r e e p r i n c i p a l p a r t s : the c o m b u s t i o n s y s t e m , t h e l a s e r r e f l e c t a n c e s y s t e m , and t h e m i c r o p r o cessor c o n t r o l . The c o m b u s t i o n s y s t e m i s shown i n F i g u r e s 1 and 2. F o u r f i l t e r d i s k s , e a c h 0.25 cm i n a r e a , a r e mounted v e r t i c a l l y i n a quartz boat which i s l o c a t e d i n the l o a d i n g s e c t i o n of t h e c o m b u s t i o n o v e n . The o v e n i s p u r g e d w i t h a 2% 02-98% He m i x t u r e , and t h e t e m p e r a t u r e o f t h e h e a t i n g z o n e i s s e t t o 350°C. The b o a t i s t h e n i n s e r t e d i n t o t h e h e a t i n g zone i n w h i c h o x i d a t i o n and v o l a t i l i z a t i o n o f o r g a n i c c a r b o n i n t o t h e f l o w i n g 02-He s t r e a m occur. The v o l a t i l i z e d o r g a n i c c a r b o n i s t r a n s p o r t e d t h r o u g h t h e o x i d a t i o n z o n e , w h i c h i s a bed o f g r a n u l a r Mn02 a t 950°C. This r e s u l t s i n t h e o x i d a t i o n o f t h e o r g a n i c c a r b o n t o CO2 w h i c h i s s u b s e q u e n t l y r e d u c e d t o CH^ i n t h e N i / f i r e b r i c k (450°C) m e t h a n a t o r and m e a s u r e d by a f l a m e i o n i z a t i o n d e t e c t o r . The c a r r i e r gas i s t h e n changed t o He, and a f t e r p u r g i n g t o remove O2, t h e h e a t i n g z o n e t e m p e r a t u r e i s r a i s e d t o 600°C. This p r o d u c e s a f u r t h e r v o l a t i l i z a t i o n o f o r g a n i c c a r b o n w h i c h i s measu r e d as above. The p u r p o s e o f t h e t w o - s t e p o r g a n i c a n a l y s i s i s to m i n i m i z e the p r o b l e m o f p y r o l y t i c c o n v e r s i o n o f o r g a n i c t o e l e mental carbon. As d i s c u s s e d b e l o w , h o w e v e r , i t has n o t b e e n p o s s i b l e t o e l i m i n a t e t h i s c o m p l e t e l y , and a s i g n i f i c a n t amount o f p y r o l y t i c c o n v e r s i o n o c c u r s d u r i n g t h e 600°C v o l a t i l i z a t i o n . 2


JOHNSON

ET AL.

Carbonaceous

Loading

Heating

Methanator

Oxidation

ι ι ι

Τ Η

ure


225

Aerosol

Lll™PJrI2l Control

He, He/0 , or C H / H e 2

Ί ι ι ι Micro processor

Cassette Recorder

FID

-Air

— ι —

!

4

ι

2

I

I X-Y Recorder

IValve

Figure

1.

Block

diagram of C analyzer. The valve symbol network of valves and plumbing.

Si photocell

Quartz light pipe

Pin hole

represents

a complex

Sample boat

2 χ 3mm oval mirror

To microprocessor

Figure 2.

Laser reflectance

system.

The light pipe is a 3-mm-diameter

quartz rod.


ATMOSPHERIC AEROSOL

226

The r e m a i n i n g c a r b o n o n t h e f i l t e r i n c l u d e s e l e m e n t a l c a r b o n o r i g i n a l l y on t h e f i l t e r , e l e m e n t a l c a r b o n p r o d u c e d p y r o l y t i c a l l y d u r i n g t h e o r g a n i c a n a l y s i s , and a l s o p o s s i b l y o t h e r forms o f c a r bon w h i c h h a v e h i g h t e m p e r a t u r e s t a b i l i t y . T h i s c a r b o n i s measu r e d b y l o w e r i n g t h e h e a t i n g z o n e t e m p e r a t u r e t o 400°C and c h a n g i n g t h e c a r r i e r g a s t o t h e 02-He m i x t u r e . O x i d a t i o n o f t h e c a r b o n to C 0 i s c a r r i e d o u t s e q u e n t i a l l y a t 4 0 0 , 5 0 0 , and 600°C. T h i s three-step process r e s u l t s i n a r e l a t i v e l y slow o x i d a t i o n o f e l e m e n t a l carbon and i s used i n t h e c o r r e c t i o n f o r p y r o l y t i c c o n v e r s i o n as d e s c r i b e d below. When t h e e l e m e n t a l c a r b o n measurement i s c o m p l e t e , t h e t e m p e r a t u r e o f t h e h e a t i n g zone i s l o w e r e d t o 350°C i n p r e p a r a t i o n f o r t h e n e x t s a m p l e . As t h e c o o l i n g i s t a k i n g p l a c e , a known amount o f CH^ i s i n j e c t e d i n t o t h e o v e n . The résultant F I D r e s p o n s e p r o v i d e s a c a l i b r a t i o n f o r t h a t r u n . The c o r r e c t i o n f o r t h e p y r o l y t i c p r o d u c t i o n o f e l e m e n t a l c a r bon i s a c h i e v e d w i t h t h e l a s e r r e f l e c t a n c e s y s t e m shown i n F i g u r e 2. L i g h t (633 nm) f r o m a He-Ne l a s e r i s r e f l e c t e d o f f t h e 2x3mm o v a l m i r r o r a n d down t h e q u a r t z l i g h t p i p e t o t h e f i l t e r s a m p l e w h i c h i s mounted v e r t i c a l l y w i t h t h e a e r o s o l d e p o s i t f a c i n g t h e l i g h t p i p e . Much o f t h e r e t u r n i n g , d i f f u s e l y r e f l e c t e d l i g h t m i s s e s t h e o v a l m i r r o r and i s c o l l e c t e d by t h e l e n s system and measured b y t h e p h o t o c e l l . L i g h t which i s s p e c u l a r l y r e f l e c t e d by t h e ends o f t h e l i g h t p i p e i s d e f l e c t e d away f r o m t h e p h o t o c e l l by t h e o v a l m i r r o r . Thus t h e p h o t o c e l l s e e s p r i m a r i l y l i g h t w h i c h has b e e n r e f l e c t e d f r o m t h e f i l t e r . The c o r r e c t i o n f o r t h e p y r o l y t i c p r o d u c t i o n o f e l e m e n t a l c a r bon i s a c c o m p l i s h e d b y m e a s u r i n g t h e amount o f e l e m e n t a l c a r b o n oxidation necessary to return the f i l t e r reflectance to i t s i n i t i a l value. T h i s i s f a c i l i t a t e d by t h e t h r e e - s t e p e l e m e n t a l c a r bon o x i d a t i o n w h i c h p r o d u c e s a r e l a t i v e l y s l o w i n i t i a l r i s e i n the r e f l e c t a n c e . A t y p i c a l o u t p u t i s shown i n F i g u r e 3. The p y r o l y s i s c o r r e c t i o n c o r r e s p o n d s t o t h e s h a d e d a r e a w h i c h i s added to p e a k s 1 and 2 t o g i v e t h e c o r r e c t e d v a l u e f o r o r g a n i c c a r b o n . T h i s p r o c e d u r e assumes t h a t t h e mass a b s o r p t i o n c o e f f i c i e n t o f t h e p y r o l y t i c a l l y p r o d u c e d e l e m e n t a l c a r b o n i s t h e same a s t h a t o f t h e o r i g i n a l elemental carbon. Research t o t e s t t h i s assumption i s continuing. The r e f l e c t a n c e s y s t e m a l s o p r o v i d e s a t e s t o f t h e e f f e c t i v e n e s s o f p u r g i n g p r i o r t o t h e 600°C/He v o l a t i l i z a t i o n o f o r g a n i c c a r b o n . R e s i d u a l O2 a t 600°C w i l l o x i d i z e e l e m e n t a l c a r b o n a n d produce an i n c r e a s e i n t h e r e f l e c t a n c e o f t h e f i l t e r . I n t h e ev e n t t h a t such an i n c r e a s e i s o b s e r v e d , t h e sample would be r e run, and i f t h i s b e h a v i o u r p e r s i s t s , t h e s y s t e m w o u l d b e c h e c k e d for leaks or other malfunctions. Thus, t h e r e f l e c t a n c e system p l a y s an important q u a l i t y assurance r o l e i n t h e a n a l y s i s . The c o m p l e t e a n a l y t i c a l s y s t e m i s u n d e r t h e c o n t r o l o f a Mot o r o l a 6802 m i c r o p r o c e s s o r . A l l s w i t c h i n g o f g a s f l o w s , t i m i n g , temperature c o n t r o l , e r r o r d e t e c t i o n , analog to d i g i t a l convers i o n , F I D c u r r e n t measurement, s i g n a l i n t e g r a t i o n a n d m a n i p u l a t i o n , and d a t a s t o r a g e and t r a n s f e r a r e c o n t r o l l e d b y t h i s s y s t e m .


2


JOHNSON E T A L .

1

1


ι

Carbonaceous

TIME

1

Aerosol

227

Γ

Figure 3. Analytical response. Peaks 1, 2, and the shaded portion of 3 correspond to organic C; the unshaded portion of Peak 3 is elemental C. The shaded por tion of Peak 3 constitutes the correction for pyrolytic conversion of organic to ele mental C. Peak 4 is the calibration peak.


ATMOSPHERIC

228

AEROSOL

A b l o c k d i a g r a m o f t h e m i c r o c o m p u t e r s y s t e m i s shown i n F i g u r e 4. D e t a i l s o f t h i s system a r e d i s c u s s e d by Johnson ( 1 5 ) . C a r b o n a t e c a r b o n i s d e t e r m i n e d o n a s e p a r a t e f i l t e r segment by measurement o f t h e CO2 e v o l v e d upon a c i d i f i c a t i o n w i t h 20 μΐ o f 1% Η3Ρ0ί|. B e c a u s e c a r b o n a t e s a l s o r e s p o n d i n t h e o r g a n i c mode d u r i n g t h e r m a l a n a l y s i s , t h e o r g a n i c c a r b o n c o n c e n t r a t i o n must b e c o r r e c t e d by s u b t r a c t i n g t h e carbonate carbon c o n c e n t r a t i o n .


Instrument V a l i d a t i o n B o t h t h e a c c u r a c y and p r e c i s i o n o f a n a l y s i s were i n v e s t i g a t e d by a number o f e x p e r i m e n t s . Known amounts o f p u r e compounds w e r e added t o q u a r t z f i b e r f i l t e r segments w h i c h w e r e a n a l y z e d i n t h e u s u a l manner. The compounds i n c l u d e d t e t r a c o s a n e , t e t r a t r i a c o n tane, coronene, perylene, g l u t a r i c a c i d , o l e i c a c i d , s t e a r i c a c i d , d i o c t y l p h t h a l a t e , and m a n n i t o l . The a v e r a g e p e r c e n t r e c o v e r y was 99±6%, and o n l y m a n n i t o l , a s u g a r , showed a s i g n i f i c a n t amount (6%) o f c o n v e r s i o n o f o r g a n i c t o e l e m e n t a l c a r b o n d u r i n g t h e o r g a n i c a n a l y s i s . A n a l y s i s o f l a m p b l a c k gave 1% a s o r g a n i c c a r b o n and 9 8 % a s e l e m e n t a l c a r b o n f o r a t o t a l r e c o v e r y o f 9 9 % . More c o m p l e x s u b s t a n c e s , h o w e v e r , showed h i g h e r d e g r e e s o f p y r o l y t i c conversion. I n a e r o s o l s a m p l e s c o l l e c t e d f r o m t h e com b u s t i o n o f d i s t i l l a t e a n d r e s i d u a l o i l , 31 and 2 5 % r e s p e c t i v e l y of t h e o r g a n i c carbon underwent p y r o l y t i c c o n v e r s i o n t o e l e m e n t a l carbon. L e s s e r amounts o f c o n v e r s i o n w e r e o b s e r v e d f o r l e a d e d a n d u n l e a d e d a u t o e x h a u s t s a m p l e s , and no c o n v e r s i o n o c c u r r e d i n a d i e s e l t r u c k e x h a u s t s a m p l e . B i o l o g i c a l s a m p l e s a l s o showed l a r g e degrees o f c o n v e r s i o n ; e.g., 45% o f t h e carbon a s s o c i a t e d w i t h wood f i b e r was p y r o l y t i c a l l y c o n v e r t e d t o e l e m e n t a l c a r b o n . H i g h d e g r e e s o f c o n v e r s i o n w e r e a l s o o b s e r v e d i n a m b i e n t sam ples. I n a p p r o x i m a t e l y 200 f i l t e r s f r o m 9 u r b a n s i t e s a n a v e r a g e o f 2 2 % o f t h e o r g a n i c c a r b o n was p y r o l y t i c a l l y c o n v e r t e d t o e l e mental carbon. As a f r a c t i o n o f e l e m e n t a l c a r b o n t h i s c o r r e s p o n ded t o 2 3 % . T h u s , t h e c o r r e c t i o n f o r p y r o l y t i c c o n v e r s i o n i s s i g n i f i c a n t and c a n n o t b e n e g l e c t e d . To e l u c i d a t e t h e n a t u r e o f t h e c a r b o n w h i c h i s p y r o l y t i c a l l y converted t o e l e m e n t a l carbon, s o l v e n t e x t r a c t i o n s t u d i e s were p e r f o r m e d . A f i l t e r segment was p l a c e d i n a s t a i n l e s s s t e e l f i l t e r h o l d e r , and t h e s o l v e n t was f o r c e d t h r o u g h t h e f i l t e r b y a s y r i n g e pump a t t h e r a t e o f 0.5 c m / m i n f o r 60 m i n u t e s . T h i s p r o c e d u r e — r a t h e r t h a n more c o n v e n t i o n a l o n e s ( e . g . , S o x h l e t e x t r a c t i o n ) — was u s e d t o m i n i m i z e t h e w a s h - o f f o f i n s o l u b l e p a r t i c l e s from the f i l t e r . B o t h e x t r a c t e d and u n e x t r a c t e d f i l t e r segments were s u b s e q u e n t l y a n a l y z e d i n t h e c a r b o n a n a l y z e r . A l t h o u g h t h e r e s u l t s v a r i e d f o r d i f f e r e n t s o l v e n t s and d i f f e r e n t f i l t e r s , t h e p r i n c i p a l f i n d i n g was t h a t up t o 8 0 % o f t h e p y r o l y t i c c o n v e r s i o n c o u l d be e l i m i n a t e d by o r g a n i c s o l v e n t e x t r a c t i o n . ( S i m i l a r r e moval e f f i c i e n c i e s were found f o r t o t a l o r g a n i c carbon.) These r e s u l t s c o n f i r m t h e organic o r i g i n o f t h e p y r o l y t i c a l l y produced elemental carbon. Solvent e x t r a c t i o n studies to v e r i f y the s p e c i a t i o n i n t o o r g a n i c and e l e m e n t a l carbon a r e c o n t i n u i n g . 3



12.

JOHNSON

E T AL.

Carbonaceous

229

Aerosol

Video Cassette Tape

X -Y Plotter

Read Only Memory

Timer

Random Access Memory

Temperature Control

Valve Control

Microprocessor

D/A Converter

A/D Converter

Flame Ionization Detector Optical System Photocell Oven Temperature

Mul t i p l e x e r

Signa I [Processingj

Figure

4.

Block

diagram

of microprocessor

system


ATMOSPHERIC


230

Figure 5. MI—1975.

AEROSOL

Organic (-Ο-) and elemental (—Π—) C concentrations in Detroit, The value r is the correlation coefficient between the organic and ele mental C concentrations (r = 0.83).

Figure 6. Mass fraction of organic (-Ο-) and elemental (—•—) C in Detroit, MI—aerosol in 1975. Mass is the total mass concentration of aerosol as measured by a high-volume sampler; r is the correlation coefficient between organic and ele mental mass fractions (r = 0.60).


12.

JOHNSON E T A L .

Carbonaceous

231

Aerosol

The p r e c i s i o n o f t h e p y r o l y t i c c o n v e r s i o n c o r r e c t i o n h a s b e e n a s s e s s e d b y r e p e a t e d a n a l y s i s o f one h i g h v o l u m e f i l t e r . For a f i l t e r w i t h 36 pg/cm o f o r g a n i c c a r b o n a n d 25 u g / c m o f e l e m e n t a l c a r b o n one s t a n d a r d d e v i a t i o n c o r r e s p o n d e d t o ±10% i n b o t h t h e o r g a n i c and e l e m e n t a l modes. The a n a l y t i c a l s e n s i t i v i t y i s l i m i t e d b y u n c e r t a i n t i e s i n t h e response t o blank f i l t e r s . F o r g l a s s f i b e r f i l t e r s (Gelman A/E) t h e b l a n k v a l u e s a r e 2.8±1.4 ygC/cm f o r o r g a n i c c a r b o n a n d 0.2 ygC/cm f o r e l e m e n t a l c a r b o n . F o r P a l l f l e x QAST t h e r e s p e c t i v e v a l u e s a r e 1.0±0.5 and 0.3±0.2 ygC/cm . 2

2

2

2

2


R e s u l t s on A t m o s p h e r i c

Samples

The c a r b o n a n a l y z e r h a s b e e n u s e d t o a n a l y z e f i l t e r s f r o m 42 u r b a n s i t e s a n d 22 n o n - u r b a n s i t e s i n t h e U n i t e d S t a t e s . T h e s e f i l t e r s were o b t a i n e d from t h e N a t i o n a l A i r S u r v e i l l a n c e Network (NASN) f i l t e r b a n k f o r 1975. C a r b o n c o n c e n t r a t i o n s and mass f r a c t i o n s f o r D e t r o i t , M i c h i g a n , a r e shown i n F i g u r e s 5 and 6. Both the o r g a n i c and e l e m e n t a l carbon c o n c e n t r a t i o n s a r e h i g h l y v a r i a b l e , a n d no s e a s o n a l t r e n d s a r e a p p a r e n t . F o r t h i s s i t e element a l carbon c o n s t i t u t e d 38% o f t o t a l a e r o s o l carbon. Typical v a l ues f o r o t h e r s i t e s r a n g e d b e t w e e n 35 a n d 5 5 % . F i l t e r s have a l s o been a n a l y z e d from s i t e s i n t h e v i c i n i t y o f a L u r g i c o a l g a s i f i e r (16) and i n t h e Ohio R i v e r V a l l e y . Both t h e s e r e s u l t s and t h e NASN r e s u l t s w i l l b e d i s c u s s e d i n d e t a i l elsewhere. Summary An i n s t r u m e n t e m p l o y i n g b o t h t h e r m a l and o p t i c a l measurements has b e e n d e v e l o p e d f o r t h e a n a l y s i s o f o r g a n i c a n d e l e m e n t a l c a r bon o n g l a s s o r q u a r t z f i b e r f i l t e r s . During the thermal a n a l y s i s the r e f l e c t a n c e o f t h e f i l t e r i s c o n t i n u o u s l y monitored t o permit a q u a n t i t a t i v e c o r r e c t i o n f o r t h e p y r o l y t i c p r o d u c t i o n o f element a l carbon which occurs d u r i n g the o r g a n i c a n a l y s i s . This correct i o n h a s b e e n shown t o b e s i g n i f i c a n t — t y p i c a l l y 2 2 % o f b o t h o r g a n i c and e l e m e n t a l carbon. The i n s t r u m e n t i s c o m p l e t e l y a u t o mated a n d i s u n d e r t h e c o n t r o l o f a m i c r o p r o c e s s o r s y s t e m . I t has been used t o measure o r g a n i c and e l e m e n t a l carbon c o n c e n t r a t i o n s from b o t h u r b a n and r u r a l s i t e s i n t h e U n i t e d S t a t e s . F o r u r b a n s i t e s t h e c o n c e n t r a t i o n s o f b o t h forms o f carbon a r e h i g h l y v a r i a b l e w i t h o r g a n i c c a r b o n s l i g h t l y more a b u n d a n t . Acknowledgment T h i s w o r k was s u p p o r t e d i n p a r t b y N a t i o n a l S c i e n c e F o u n d a t i o n G r a n t No. PFR-7824554 a n d U. S. E n v i r o n m e n t a l P r o t e c t i o n A g e n c y G r a n t No. R806274.


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Literature Cited 1. Appel, B.R.; Colodny, P.; Wesolowski, J.J. "Analysis of carbonaceous materials i n Southern California aerosols". Environ. Sci. Technol., 1976, 10, 359-363. 2. Appel, B.R., Hoffer, E.M.; Kothny, E.L., Wall, S.M.; Haik, M.; Knights, R.L. "Analysis of carbonaceous material i n Southern California atmospheric aerosols 2". Environ. Sci. Technol., 1979, 13, 98-104. 3. Pierson, W.R.; Russell, P.A. "Aerosol carbon i n the Denver area i n November 1973". Atmos. Environ., 1979, 13, 1623-1628. 4. Johnson, R.L.; Huntzicker, J.J. "Analysis of v o l a t i l i z a b l e and elemental carbon in ambient aerosols", i n "Proceedings: Carbonaceous Particles i n the Atmosphere", T. Novakov, Ed., Lawrence Berkeley Laboratory, Berkeley, California, June 1979, 10-13. 5. Johnson, R.L.; Shah, J.J., Huntzicker, J.J. "Analysis of organic, elemental, and carbonate carbon i n ambient aerosols", i n "Sampling and Analysis of Toxic Organics i n the Atmosphere", American Society for Testing and Materials, STP 721, Philadelphia, PA, 1980, pp. 111-119. 6. Cadle, S.H.; Groblicki, J.P.; Stroup, D.P. "An automated carbon analyzer for particulate samples", presented at the Second Chemical Congress of the North American Continent, Las Vegas, Nevada., August 1980. 7. Grosjean, D.; Heisler, S.; Fung, K.; Mueller, P.; Hidy, G. "Particulate organic carbon in urban a i r : concentrations, size distribution and temporal variations", presented at the American Institute of Chemical Engineers 72nd Annual Meeting, San Francisco, California, November 1979. 8. Daisey, J.M.; Leyko, M.A.; Kleinman, M.T.; Hoffman, E. "The nature of the organic fraction of the New York City Summer Aerosol", Ann. New York Acad. S c i . , 1979, 322, 125-141. 9. McCarthy, R.; Moore, C . E . "Determination of free carbon i n atmospheric dust", Anal. Chem., 1952, 24, 411-412. 10. Kukreja, V.P.; Bove, J.L. "Determination of free carbon collected on high volume glass fiber f i l t e r " , Environ. Sci. Technol., 1976, 10, 187-189. 11. Pimenta, J.A.; Wood, G.R. "Determination of free and total carbon i n suspended a i r particulate matter collected on glass fiber f i l t e r s " , Environ. Sci. Technol., 1980, 14, 556-561. 12. Delumyea, R.G.; Chu, L.-C.; Macias, E.S. "Determination of elemental carbon component of soot i n ambient aerosol samples", Atmos. Environ., 1980, 14, 647-652. 13. Grosjean, D., comments at the Second Chemical Congress of the North American Continent, Las Vegas, Nevada, August 1980. 14. Dod, R.L.; Rosen, H.; Novakov, T. "Optico-thermal analysis of the carbonaceous fraction of aerosol particles", i n "Atmospheric Aerosol Research: Annual Report 1977-78", Lawrence Berkeley Laboratory, Berkeley, California LBL-8696, pp.2-10. 15. Johnson, R.L. "Development and evaluation of a thermal-opti-


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cal method for the analysis of carbonaceous aerosols", M.S. thes i s , Oregon Graduate Center, 1981. 16. Huntzicker, J.J.; Johnson, R.L.; Shah, J.J. "Carbonaceous aerosol i n the v i c i n i t y of a Lurgi gasifier", presented at the Second Chemical Congress of the North American Continent, Las Vegas, Nevada, August 1980.


RECEIVED March10,1981.


Atmospheric Aerosol - American Chemical Society

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