Analysis of complex organic mixtures on airborne particulate matter

Canada. Organic compounds adsorbed on airborne particulate matter are recovered from one half of a 24-h Hi-Vol filter sample by a 2-h soxhlet extracti...
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82

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978

Analysis of Complex Organic Mixtures on Airborne Particulate Matter F. W. Karasek," D. W. Denney, K. W. Chan, and R. E. Clement Guelph- Waterloo Cenfre for Graduate Work in Chemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G 1, Canada

Kovat's retention indices of sample components, the identities of which are confirmed by G C / M S analysis. Quantitative information is derived from response-factored integrated area counts of individual GC peaks.

Organic compounds adsorbed on airborne particulate matter are recovered from one half of a 24-h Hi-Vol filter sample by a 2-h soxhlet extraction using methanol. The extract is concentrated for direct GC analysis using a high performance packed column and a digital chromatograph. Qualitative Information is obtained from calculated Koval's retention indlces, the Identities of which are confirmed by G U M S / computer techniques. Quantitative information is obtained from response-factored integrated GC peak areas. A series of 50 comparative survey analyses from a single site can be achieved in less than 8 h per sample.

EXPERIMENTAL Sample Collection. Samples used in this study were provided by the Ontario Ministry of the Environment, Air Resources Branch (ARB), and were obtained using a Hi-Vol Apparatus as described and recommended by the Air Pollution Measurements Committee (18) and ASTM method 11101-01-70T (19). Glass fiber filters, 20 X 25 cm, were used to collect airborne particulate matter by drawing ambient air through the filter at flow rates of typically 1.4 m3/min (50 cfm). These sampling devices were operated for 24 h resulting in volume through-puts on the order of 2000 m3. In the course of this study, 78 Hi-Vol filter samples were obtained from two Ontario sites. Of these samples 42 were collected in Welland, Ontario, representing an industrial, urban area, and 36 were collected in Simcoe, Ontario, representing a rural environment. Sample Extraction. Preparation of an analytical sample involves soxhlet extraction in an all-glass apparatus of one half of a Hi-Vol filter with 200 mL of high purity methanol ("Distilled in Glass'' Methanol, Burdick & Jackson, Muskegon, Mich.) for 2 h. The 200-mL methanol extract is concentrated at room temperature under vacuum on a rotary evaporator to approximately 10 mL. Any undissolved material is removed by centrifugation. The sample is then further concentrated to 1 mL for analysis using high resolution gas chromatography or gas chromatography/mass spectrometry/computer techniques. The use of methanol as the extracting solvent, extraction time, and removal of nonsoluble material were previously investigated in our laboratory. It was found that methanol was more efficient than cyclohexane and that removal of the nonsoluble material by centrifuging removed no chromatographable organic compounds (23). Gas Chromatography Procedures. A Hewlett-Packard 5830A digital gas chromatograph was used in conjunction with a 10 f t x 2 mm i.d. glass column packed with a special column material prepared in our laboratories. This packing is an ultra-thin, thermally treated layer of Carbowax 20 M deposited as an 0.270 w / w layer on exhaustively acid-washed 100/120 Mesh Chromosorb W. The preparation and properties of this packing have been described by Aue ( 2 4 ) and is referred t o here as Aue Packing (AP). Gas chromatographic conditions were as follows: Temperature program, 100 "C for 4 min programmed at 4"/min to 240 "C for 50 min; He flow rate, 28 mL/min; injection port temperature, 240 "C; FID temperature, 300 "C; hydrogen flow rate, 43 mL/min; air flow rate, 420 mL/min; sample injection, 3 WLof the 1-mL methanol extract. Use of the H P 5830A GC instrumentation produces a digital output of the chromatographic data, primarily retention time and counts of integrated peak areas. The values of retention time and area counts are manually punched on computer cards as data pairs for further processing using an IBM 360/75 computer system and programs designed specifically to manipulate the large quantity of data generated (16). S t a n d a r d Solutions. A standard mixture of 17 n-hydrocarbons from CI3to C32at an average concentration of 20 ng/FL was prepared in cyclohexane. A standard mixture of 12 n-methyl esters from CI6 to C3*at an average concentration of 20 ng/pL was prepared in methanol. A standard mixture of 9 PAH

Of all t h e organic compounds present in the atmosphere, those associated with airborne particulate matter constitute a serious environmental problem. Present as complex organic mixtures containing toxic and carcinogenic compounds, the bulk of these organic compounds is associated with suspended particles of less than 5-km diameter and hence are respirable. In order to characterize local pollution, a procedure which can provide qualitative and quantitative information on all types of compounds is required (2). The method should be practical and rapid enough to be applicable to survey studies. I n most of t h e work aimed a t the analysis of organic compounds associated with airborne particulate matter, samples are collected by high volume filtration (Hi-Vol) techniques and t h e organic compounds generally recovered by soxhlet extraction. T h e extract is a very complex mixture containing 50-150 organic compounds and separation techniques are generally employed t o isolate and enrich the compound class of interest. Since many of t h e P A H compounds are known t o exhibit carcinogenic or mutagenic properties, much of the present literature describes procedures for their isolation and analysis (2-5). T h e PAH fraction has been separated from extracted organics by column chromatography ( 6 4 , distillation, liquid-liquid extraction (7,8), thin-layer chromatography (7,8) and sublimation (7). Recent work by Cautreels a n d Van Cauwenberghe describes a procedure for t h e analysis of all types of compounds involving separation of t h e extract into acidic, basic, and neutral fractions by appropriate liquid-liquid extractions (9, 10). Because of the small amount of organics present on a single 24-h Hi-Vol sample, t h e use of composite extracts from as many as 300 Hi-Vol filters has been reported (6, S11). None have been reported for application t o a single 24-h sample. Over the past several years we have developed a rapid and manageable procedure for t h e analysis of the nearly 100 organic compounds found on suspended airborne particulate matter (12). Pre-separation and derivatization steps are eliminated. T h e procedure involves a rapid, efficient extraction step ( 1 3 ) ,the use of a special high resolution packed column ( 2 4 , 2 5 ) t o produce precise temperature-programmed GC analyses with a digitally controlled gas chromatograph, and computer programs for t h e analysis and display of data (26, 17). Qualitative information is obtained from calculated 0003-2700/78/0350-0082$01 .OO/O

(CZ

1977 American Chemical Society

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978

compounds including biphenyl, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[e]pyrene and benzo[a]pyrene a t an average concentration of 2 1 ng/pL was prepared in methanol. A standard mixture of dialkyl phthalates including dimethyl, diethyl, diallyl, dibutyl, and dioctylphthalate a t a n average concentration of 23 ng/pL was prepared. These standard solutions were used to establish reference Kovat's indices and FID response factors. Response factors in Area Counts/ng were found to be: benzo[a]pyrene, 466; phenanthrene, 465; dioctylphthalate, 306; methyl octadecanoate, 323; methyl tetradecanoate, 538; n-nonadecane, 397; n-heneidecane, 444. Identification by Retention Index. The n-alkane standard solution was chromatographed at least once a day to provide retention values for calculation of Kovat's retention indices. The retention indices (RI) of the individual components of the standard solutions were calculated using the computer program RICALC. RICALC employs Equation 1 for calculation of retention indices under linear temperature programming conditions.

83

2 q hr HI-Vol F I L T E R S A M P L E

!

SOXPLET EXTRACT ON 2 ~ 2 0. 0 m l Methanol

t CHROMATOGRAPHIC

I

1

AN^=

DIGITIZED RETEN-ION TIVES D I G I T I Z E D I N T E G R A T E D PEAK AREAS

I

P U N C H E D ON I E M C 3 M P U T E R CARDS

PROFILE

where Cn and C,v-l are carbon numbers of the standards which bracket the unknown peak in retention time, T,v is the retention time of the unknown and S.v and are the retention times of the CN and Cikr-l hydrocarbons, respectively. The computer program RICALC instructs the computer to punch out data cards which contain data pairs of calculated retention index (RI) and area counts. These data cards can then be used in three other programs: GCPLOT, PROFILE, and STANDANAL. GCPLOT produces a bar graph plot of percent area vs. RI for each GC peak in the chromatogram. PROFILEproduces a bar graph representation of the occurrence and concentration variance of an individual component of a given R I vs. samples, dated in chronological order. STANDANAL was written to analyze standard hydrocarbon data used in RICALC. Standard n-hydrocarbons were run as unknowns to monitor the performance of the analytical GC column and to determine an acceptable deviation in RI values over a period of time. Identification by GC/MS. Qualitative identification by matching RI values with those of reference compounds is subject to errors arising from more than one compound having nearly the same RI value under the analytical conditions. To support identifications, representative samples were analyzed by G C / MS/computer techniques to confirm the compounds associated with the RI values of the major components. GC/MS/computer analysis was conducted using a HP 5982/5933A system equipped with a dual EI/CI source. A 6 ft X 2 mm i.d. glass column packed with 100/120 Mesh AP was used to obtain 'iO-eV E1 spectra and 100-eV methane CI spectra at the standard gas chromatographic conditions. In both cases, mass chromatograms of several diagnostic ions were generated to aid in the interpretation of mass spectra. In addition, reference mass spectra and retention time data were obtained for the standard solutions using both ionization techniques prior to analysis of Hi-Vol samples.

RESULTS AND DISCUSSION All t h e experimental work t o develop t h e analytical procedures and t h e comparative final d a t a reported here was completed using t h e 78 Hi-Vol samples from t h e two monitoring sites provided by t h e Ontario Ministrv of the Environment. T h i s analytical procedure is outlined in Figure 1. Chromatograms of the 78 samples were obtained at t h e standardized GC conditions and a representative chromatogram of the methanol extractable organic compounds from t h e industrial Welland samples is given in Figure 2. T h e retention times and corresponding integrated area counts data pairs, automatically produced for each chromatogram, were manually punched onto IBM data cards and processed by the computer program RICALC which computes t h e Kovat's retention index (RI) of each peak and lists this information in t h e format shown in Figure 3. T h e identity of the Hi-Vol

Figure 1. Schematic flow chart of analytical method. 061374 I - W

L-\.. 'L

I

5 .. .~ ~

IO0

100 120

I60

200

240

ISOTHERMIL

TEMPERATURE ( ' C :

Figure 2. Typical chromatogram of methanol extractable organics on Welland Hi-Vol filter sample

filter sample is indicated in the upper left corner a n d t h e retention time of t h e solvent peak used is indicated in t h e upper right corner. T h e total area response of t h e chromatogram with t h e solvent peak excluded is calculated a n d indicated in t h e lower left corner. T h e entry labelled H C STANDARD in t h e lower right corner is t h e identity of t h e hydrocarbon standard which was used to calculate RI values a n d also indicates t h e d a t e t h e sample was analyzed. T h e RICALC output provides a complete record of t h e chromatographic results for each sample in a condensed format. T h e total area response of the chromatograms indicates the total organic compounds analyzed in t h e extract from t h e Hi-Vol filter using methanol. This response can be converted to pg/m3 using a n average response factor a n d volume throughput of t h e air. An average response factor was calculated from the response factors of seven components of these samples including a phthalate, methyl esters, P A H , a n d ri-alkanes. Using this average response factor, the total organic concentration of the individual samples can be displayed using the program PROFILE as shown in Figure 4. l'his display allows rapid visual assessment of variations in airborne organic concentrations a t t h e sampling site during t h e survey. T h e computer program H I C A L C can also instruct t h e computer t o punch out d a t a cards which contain d a t a pairs of retention index and area response as seen in colurnns 4 and 2 in Figure 3. This information is then used in t h e program GCPLOT which produces a bargraph representation of t h e RICALC data. T h e GCPLOT program calculates t h e percentage area response for each R I value from t h e area response a n d

84

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978

F I1.TPR

0 1 I474 1 - S

RETENTICK T I M E C O R KECTFI)

17.03 17-35 17.79

SOLVFNT

PKAK

.4REA

3191

1455 5914 3233 7786 4823 2343 7990 10720

19. 55 19.83 21.4:: 21.12 22.01 22.37 24.39 24.55 26.69 27.08 27.7 1 21J.01 29.91 20. 99 31.19 32.34 33.03 23.19 33.59 34.03 35.04 36. c14 37.04 37.34 38. ')3 40.51

1.00 2.05 0.Y3 3.79 2.11

756K X232 4406 206-10

4.09 3.09 1.50 5.12 6-87 4.46 4.85 5.28 2. 8 3 13.24

RXHO

5.69

2'371

1.91 1.52 1.74 1.50 I .73 1.52 0.86 1.54 3.14

6950

2369

1930 2347 26"n 23h? 1342 23C.R 4S9Y 1220 1P$h 1.392 11870

10.520 155936

TCTAL A R E 4

ARF4

RETFNTION

I N 1)F x 1565

18.83

'I. T O T A L

0.00

PEAK

0.78

1.21 0.89 7.61 6.75 HC SThh'1)AHIl

1x06 1519 1415 1 q14 1902 1913

1'176 1 C)R9 200 1 701 h 21 01 31 0& 220 1 22IP 2248

I

i

1

Figure 5. GCPLOT comparison of three consecutive Welland samples

230-1 2350 2400 242i 24q I

2i01 2?0!' 2520

5'

2iql

2602 2704 27nq 2 7 25 2 Y 0'3 2890 0222nlSTD

Figure 3. Output of RICALC showing a complete record of sample 0 11 4 7 4 1 4 ORGANIC

Figure 6. GCPLOT comparison of PAH and phthalate standards and sample 0917741-W

CONCENTRATION

3 00,

SIMCOE 1501

I50

1

~I

Figure 4. Profile of the organic concentration extracted from Hi-Vol filter samples

plots percent total area vs. RI for each sample. Using GCPLOT, the chromatographic characteristics of any samples, generally not more t h a n three, are plotted on a single page for rapid visual comparison. Figure 5 is a GCPLOT output for three consecutive Welland samples. T h e sample identity is displayed in t h e upper left corner of the plot and the total area response is displayed in the right corner. By visual inspection, t h e occurrence of compounds in the individual samples can be ascertained and t h e relative concentrations of individual components from sample to sample can be observed. Qualitative identification of components of a mixture can be made by cornparison of calculated RI values to reference R I values obtained using standard solutions. By manually searching t h e KICALC output data, several compounds were identified in a representative Welland and a Simcoe sample. T h e results of such a comparison are listed in Table I. More t h a n 20 major compounds were identified in these two samples. The absence of the high molecular weight PAH's in t h e Simcoe sample is readily apparent from Table I. T h e R I values for t h e STANDARD are average values, and the

Figure 7. values

PROFILE

comparison of three individual Retention Index (RI)

RI values for the Welland and Simcoe samples were obtained on different columns and different batches of Aue Packing. Each batch of Aue Packing and column is standardized using the standard solutions and results indicate reproducibility of calculated RI values between 0.5-0.8% for most compounds. Reproducibility on a given column is generally better. An alternative to comparing the RICALC d a t a is t o utilize GCPLOT.The data for standards and an unknown are plotted on the same page for rapid visual assessment. This technique produces the information shown in Figure 6. In this figure the GCPLOT of the PAH and dialkylphthalate standards were plotted for comparison against a Welland sample. T h e presence of any of these compounds in t h e sample may be quickly inferred by observation. T o monitor concentration variations of given compounds in different samples, the program PROFILE can be used to produce a plot of the relative concentration of the component

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978

Table I.

Retention Indices for Identified Compounds

Table 11.

STANDANAL

85

Analysis of Hydrocarbon

OYl'i-

Compound

741-W

n-Tetradecane n-Pentadecane n-Hexadecane Methyl dodecanoate n-Heptadecane n-Octadecane Methyl tetradecanoate Fluorene Dimethylphthalate n-Nonadecane Diethylphthalate n-Eicosane Methyl hexadecanoate n-Heneicosane Phenanthrene n-Docosane Methyl stearate Dibutylphthalate n-Tricosane n-Tetracosane Methyl eicosanoate n-Pentacosane and fluoranthene Pyrene n-Hexacosane Methyl docosanoate n-Heptacosane n-Octacosane Dioctylphthalate n-Nonacosane n-Triacontane Chrysene and benzanthracene and triphenylene n-Heneitriacontane n-Dotriacontane, anthracenedione Benzofluoranthene Benzo[a]pyrene and benzo [ e ]pyrene

1

Figure 8. Concentration at Welland site

1400 1500 1600 1610 1700 1800 1828 1851 1873 1900 1963 2000 2035 2100 2128 2200 2242 2297 2300 2400 2448 2500

2573 2600 2636 2700 2800 2830 2886 2999 3014

2556 2600 2653 2700 2800 2841 2900 3000 3005

2553 2600 2637 2700 2799 2832 2890 3000 3016

3081 3199

3100 3200

3089

3503 3675

3681

-

I "I

250, 150

1400 1499 1599 1610 1699 1800 1819 1842 1863 1900 1951 2000 2024 2100 2138 2200 2228 2284 2300 2400 2433 2500

PROFILE of

-

1613 1700 1799 1821 1844

-

1899 1956 1996 2022 2100 2117 2200 2228 2287 2300 2400 2433 2500

-

-w'REM

three PAH compounds during 1974

as a function of sample number. Figure 7 is the PROFILE output of three compounds with the RI values 1995,3103, and 3203 as indicated in the upper right of each plot. The number in the upper left of each plot is the area value used to normalize t h e d a t a for each individual RI value. These profile plots can alternatively be displayed as concentration profiles (fig/m3) by using response factors determined for t h e individual RI values. This is illustrated in Figure 8 for three PAH compounds found in the Welland samples. Displays of this type allow an accurate assessment of variations of an individual compound. A significant amount of information can be inferred from these diagrams. Com-

14 15 16 17 18 19 20 21 22 23 24 25 26 28 30 32

4.57 7.53 10.64 13.58 16.35 18.96 21.43 23.80 26.08 28.27 30.40 32.46 34.45 38.20 42.04 47.69

4.75 7.75 10.92 13.89 16.68 19.28 21.72 24.05 26.30 28.47 30.55 32.60 34.60 38.38 42.29 48.10

4.45 7.37 10.47 13.40 16.16 18.77 21.25 23.63 25.91 28.11 30.25 32.31 34.31 38.08 41.7i' 47.21

0.10 0.13 0.16 0.17 0.18 0.18 0.16 0.14 0.13 0.12 0.10 0.09 0.09 0.09 0.16 0.32

0.08 0.11 0.13 0.14 0.15 0.15 0.13 0.12 0.11 0.10 0.09 0.07 0.07 0.08 0.13 0.25

Std

Area response Carbon Av No. area 14 15 16 17 18 19 20 21 22 23 24 25 26 28 30 32

14568 14213 15164 14499 14340 14727 14961 15427 14332 15457 14127 14163 14312 12549 15158 15710

Max

Min

dev

Av dev

18420 17180 18300 17690 17610 18070 18530 19160 17430 22550 16880 17150 17780 14960 17910 17570

12670 12480 13410 12850 12590 12850 12960 13340 12310 12840 12080 12100 12340 10770 13100 13270

1656 1348 1398 1351 1294 1331 1378 1372 1216 2430 1275 1451 1632 1346 1519 1559

1124 925 960 91 1 826 895 829 829 769 1460 923 1071 1226 1024 1181 1274

parison of the profiles of RI 3103 and 3203 indicate a similar pattern but the profile of RI 1995 is remarkably dissimilar. Similarily the B [ a ] P and B [ h ] F concentration profiles are similar h u t exhibit dissimilarities from the concentration profile of anthracene and the profiles in Figure 7. In addition, these plots allow assessments of the source of these compounds in t h a t compounds which display the same profile most probably originate from the same source. The information presented in Figures 7 and 8 indicates that techniques which monitor one or two compounds as indicators of the overall characteristics of the organic matter present on suspended airborne particulates are subjected t o error and should be used with caution ( 1 ) . Since qualitative identification of ihe compounds in these samples is based primarily on calculated retention indices, a statistical analysis of the chromatographic behavior of daily hydrocarbon standards was conducted using t h e program STANDANAL. The chromatographic data from 13 injections of the same hydrocarbon standard obtained on 13 different days were analyzed using this program. 'The area response and absolute retention time of each component were analyzed and t h e results are shown in Table 11. T h e overall average standard deviation of the retention times is less than 1% and the overall average standard deviation of the area counts is approximately 10%. Since the same hydrocarbon standard mixture was used for each of the 13 runs which produced the data in Table 11, the variation in retention times primarily reflects column changes, injection procedure, and changes in chromatographic conditions. Variations in retention times of standards run on different days will not necessarily produce the same variation

86

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978 TIME SPECT

J

I

I

I I

50

I

5I

I

l

l

I 1

100

I

150

I IO l I

200

1

1

1 I

250

151

1

I

300

201

1

I

1 l

1 I

350

400

1

1

25 1 1

1

1

301

1

1

I

I

I

I

4AO 5 0 0 SA0

I

35 I I

I

600

650

I I

700

I

I

4I0 l

I

l I

750

800

1

1

45

I

I I

I

I

50 I I

I

840 900 950

I I

I

I

55 I I

I

I

I

I

1000 1050 1100

SAMPLE 5799 5 0 c M < 450 408741-W

RD. 11-10-76

100 4Mlh 4 / M l N 2 4 0 STARTING MASS 50

TI

252

202 14.6 DIETHYL PHTHALATE

22.4

DIBUTYL PHTHALATE

A . C

149

.

n

33.4 DIOCTYL PHTHALATE

-

.

PALMITATE METHYL STEARATE 74 SPEC T

A

A

-

A

*c-.

A

Figure 9. Total ion chromatogram and four mass chromatograms obtained by GC/MS/computer on a Welland sample

i n calculated retention indices, since t h e hydrocarbon standards are chromatographed to provide calibration data. T o check calculated RI values, the standard hydrocarbon solution was injected and treated as an unknown when samples were being analyzed. Table I11 lists the STANDANAL results of the calculated retention indices of five such unknowns. The overall average percent standard deviation is less than 0.1 70, which represents the best obtainable under ideal conditions on a given column. These STANDANAL results indicate a high degree of reproducibility in calculated retention indices as well as in absolute retention times. Quantitative analysis can be expected to be within 10% a t these concentration levels. Even though the reproducibility of retention indices is very good, t h e possibility of one or more compounds having a similar retention index exists. T o support the assigned identities for the major components, representative samples were analyzed by GC/MS/computer employing electron impact and methane chemical ionization techniques. The use of a computerized system allows the reconstruction of mass chromatograms and the PAH compounds are readily detected by this technique because of stable molecular ions. The m / e 252 and 202 mass chromatograms were used to locate the C2,,HI2and CIBHloPAH isomers. The identities assigned were determined from mass spectral data in conjunction with retention time data. The use of retention time data is essential t o distinguish P A H isomers as their mass spectra are almost identical (6). Dialkylphthalates with t h e exception of dimethylphthalate display an intense m / e 149 fragment in their mass spectra (20) and a mass chromatogram for m / e 149 was used t o locate probable phthalate esters. T h e major peaks in the m / e 149 mass chromatogram were identified from their respective mass spectra and retention time data. Methyl esters of fatty acids exhibit a diagnostic McLafferty rearrangement

Table 111. S T A N D A N A L Analysis of Hydrocarbon Standards Retention Indices Carbon No.

Av ret index

14 15 16 17 18 19 20 21 22 23 24 25 26 28 30 32

1402 1502 1602 1701 1801 1902 2001 2101

2201 2301 2401 2501 2601 2801 3000 3201

Max

Min

1408 1506 1605 1704 1804 1904 2003 2103 2202 2302 2402 2503 2603 2803 3002 3203

1398 1499 1599 1699 1799 1900 1999 2100 2200 2300 2400 2500 2600 2800 2999 3198

Std dev

Av dev

4 3 2 2 2 2 2

3 2 2 1 1

1

1

1 1 1 1 1 1 1 1 1

2

2

1 1 1 1 1 1 1

ion a t m / e 74 and a mass chromatogram for m l e 74 can he used to locate possible methyl esters. Table IV lists the methyl esters identified from their mass spectra and retention time data. T h e presence of the corresponding carboxylic acids in the acidic fraction of airborne particulate matter has been reported by Cautreels and Van Cauwenberghe (9, 10). Derivatization with diazomethane produced t h e corresponding chromatographable methyl esters, which were detected using m l e 74 mass chromatograms. The presence of methyl esters on the particulate matter was not reported and the source of methyl esters in our sample was investigated because of t h e possibility of formation during methanol soxhlet extraction. One half of a Hi-Vol filter sample was extracted with cyclohexane and the other half was extracted with methanol.

ANALYTICAL CHEMISTRY, VOL. 50, NO. 1, JANUARY 1978

Table IV. Methyl Esters Identified in Welland Sample by GC/MS Mol wt

Name

186 214 242 254 256 268 270 284 296 298 326 354 382 410

Methyl caprate Methyl laurate Methyl myristate Methyl pentadecenoate Methyl pentadecanoate Methyl gaidate Methyl palmitate Methyl margarate Methyl oleate Methyl stearate Methyl archidate Methyl behenate Methyl lignocerate Methyl cerotate

Table V. Identities of Numbered Peaks, Sample 5799, 408741-W Peak No.

R.T.

ACKNOWLEDGMENT

154, 214 240 194 242 208 222 256 228 268

Mixture of biphenyl and methyl laurate n-Heptadecane Dimethylphthalate Methyl myristate Methyl ethyl terephthalate Diethylphthalate Methyl pendadeconoate Unknown Unsaturated methyl ester

T h e authors express appreciation to 0. Hutzinger and K. Olie of the University of Amsterdam, T h e Netherlands, for helpful assistance with the GC/MS/computer analyses.

Mixture of phenanthrene/ anthracene and methyl palmitate n-Heneicosane Methyl pentadeconoate Methyl oleate Methyl stearate + dibutylphthalate Unknown

7.6

2 3 4 5 6 7 8 9

10.3 12.2 12.9 13.5 14.6 15.4 15.6 17.5

10

17.9

178, 270

11

12 13 14

19.9 20.1 22.1 22.4

15

24.3

16 17

25.1 26.3 28.3 31.7

296 256 296 278, 298 270, 208 202 202 216 228, 234

20 21 22 23 24 25 26 27

32.3 33.4 33.8 34.1 35.3 40.2 42.1 54.7

V lists the identities of the numbered peaks in total ion (TI) trace of Figure 9 as suggested by the electron impact, methane chemical ionization, and retention time data. The analytical procedure outlined in Figure 1 was developed and its value demonstrated while using the 78 weekly Hi-Vol samples acquired in routine monitoring operations of the Ontario Ministry of the Environment during 1974 a t two sites in Ontario, one industrial and the other rural. Even though not all components of these complex mixtures are totally resolved or identified, analysis of a sample can be completed in less than 8 h and sufficient data are obtainable to monitor trends in the major components and many of t h e minor components. Application of new technology now available should considerably improve the speed, accuracy, and sensitivity of the method. Work on further development of the method using glass capillary GC columns and the bench-top H P 5992 GC/MS/Calculator system is now under way and is expected t o result in performing all analytical and d a t a reduction functions on a single instrument.

Comments

Mol wt

1

18 19

87

226 390 228 228 308 252 252 276

cl

5H29C0,CH3

Fluoranthene Pyrene Methyl fluoranthene MW 234 is possibly benzo[gldibenzothiophene or hexahydrochrysene Benzo [ghilfluoranthene Dioctylphthalate Benzo[a]anthracene Chrysene n-C19H60

Benzo Th 1fluoranthene Benzopyiene PAH, several possible isomers

Since t h e same methyl esters were found in the cyclohexane extract, it was concluded t h a t methyl esters are present on t h e airborne particulate matter samples used in this work. T h e total ion chromatogram of the crude methanol extract and four mass chromatograms are shown in Figure 9. Table

LITERATURE CITED (1) (2)

Scientific and Technical Assessment Report on Particulate Polycyclic Organic Matter (PPOM), U.S. EPA Report €PA 60016-74-001, March 1975, National Environmental Research Center, Research Triangle Park, N.C. A. W. Horton, D. T . Denman, and R. P. Trosset, Cancer Res., 17, 758

(1957). (3) A. W. Horton and G. M. Christian, J . Nafl. CancerInst., 53, 1017 (1974). (4) J. Sice, Toxicol. Appl. Pharmacol., 9. 70 (1966). (5) E. Sawicki, "The Chemical Composition and Potential Genotoxic Aspects

of Polluted Atmospheres", presented at the Workshop for Investigations on the Carcinoaenic Burden bv Air Pollution in Man. Hanover. Germanv.

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RECEIVED for review June 2 2 , 1977. Accepted October 11, 1977. This research was supported by the Ontario Ministry of the Environment, Air Resources Branch.