Chemical Pollutants in Air, Water, Soil, and Solid Wastes Phần 7 pdf

ETHYLBENZENE

Synonym: phenylethane; Formula C

8

H

10

; Structure:
MW 106.18; CAS [100-41-4]; used as a solvent and an intermediate to
produce styrene monomer; colorless liquid; characteristic aromatic odor; boils at
136°C; vapor pressure 7.1 torr at 21°C; freezes at –95°C; density 0.86 g/mL at
20°C; solubility in water 0.015 g/100 g; readily miscible with organic solvents.

ANALYSIS OF AQUEOUS AND NONAQUEOUS SAMPLES

Purge and trap method; ethylbenzene transferred from aqueous to vapor phase
under helium purge; analyte adsorbed on a sorbent trap; thermally desorbed
out from the sorbent trap backflushed with He onto a GC column for separation
from other volatile compounds; determined by PID, FID or a mass spectrometer.
Solid samples mixed with methanol; a portion of methanol extract spiked into a
measured volume of water (25 mL) in the purging vessel; subjected to purge
and trap concentration and analyzed as above.
Alternatively, ethylbenzene thermally desorbed from the solid sample under He
purge (without any solvent treatment) onto the GC column and analyzed on a
suitable detector or by a mass spectrometer as above.
• Characteristic masses for GC/MS identification: 106 and 91.

• Limit of detection: in the range 0.5 mg/L for a 5 mL sample volume, when
detected by PID.
• GC column: a nonpolar fused silica capillary column, such as DB-5, SPB-
5, VOCOL, DB-624, or equivalent; packed column: 1% SP-1000 on Car-
bopack B (60/80 mesh) or equivalent.
CH
2
CH
3

3.33

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

350 HANDBOOK OF ENVIRONMENTAL ANALYSIS

• Recommended surrogate/IS: ethylbenzene-d

5

(m/z 111) and 1,4-difluo-
robenzene (m/z 114, 63,88).
• Samples collected in glass containers without headspace, refrigerated, and
analyzed within 7 days. Samples preserved with 1:1 HCl (0.2 mL
acid/40 mL sample) may be analyzed in 14 days.

AIR ANALYSIS

Air drawn through a sorbent tube packed with coconut shell charcoal (100 mg/50
mg); analyte desorbed into CS

2

(more than 30 min standing); CS

2

extract
analyzed by GC-FID (NIOSH Method 1501, 1984); recommended air flow rate
100 mL/min; sample volume 20 L.
• GC column: packed column 10% OV-275 on 100/120 mesh Chromosorb
W-AW, Porapak P (50/80 mesh), or equivalent.
Alternatively, air collected in a SUMMA passivated stainless steel canister either
by pressurizing the canister using a sample pump or by preevacuating; canister
then connected to an analytical system; air transferred to a cryogenically cooled
trap; cryogen removed and temperature raised; analyte revolatilized; separated
on a GC column; determined by PID, FID, or a mass spectrometer (U.S. EPA
Method TO-14, 1988).
Alternatively, air drawn through a cartridge packed with either Tenax (1 g) or
carbon molecular sieve (0.5 g); cartridge heated at 350°C under helium purge;
analyte transported to the front of a precooled GC column, temperature pro-
grammed; ethylbenzene determined on a PID, FID, or a mass spectrometer;
recommended air flow rate 0.5 L/min; sample volume 50 L.
• No precision and accuracy data available for this method.

(1 ppm ethylbenzene in air = 4.34 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
350
ETHYL CHLORIDE
Synonym: chloroethane; Formula: C
2
H
5
Cl; MW 64.52; CAS [75-00-3];
colorless gas at room temperature with ether-like odor; liquefies at 12.5°C;

slightly soluble in water, miscible with organic solvents.
ANALYSIS OF AQUEOUS SAMPLES
Aqueous samples subjected to purge and trap extraction; volatile analyte thermally
desorbed out from the trap on heating and swept onto a GC column for sepa-
ration; detected by HECD, ECD, or MDS; low retention time.
• Characteristic masses for GC/MS identification: 64 and 66.
• Limit of detection: in the range 0.1 µg/L when detected by HECD for a
5-mL sample aliquot (subject to matrix interference).
• Recommended surrogate/IS: bromochloromethane and 1,2-dichloro-
ethane-d
4
.
• Samples collected in glass/plastic containers without headspace, refriger-
ated, and analyzed within 14 days.
See Halogenated Hydrocarbons, Chapter 2.9, for GC columns and conditions and
a detailed discussion.
AIR ANALYSIS
The following methods are recommended:
Adsorbed over carbon molecular sieve (~400 mg); desorbed at 350°C into a
cryogenically cooled trap; flash evaporated onto a capillary column GC/MS
system; recommended sample volume 10 L; flow rate 100 mL/min.
Collected in SUMMA passivated canister or a liquid argon trap; transferred
onto a precooled GC column; determined by ECD or MSD.
The precision and accuracy of the above methods for this compound are not
established.
(1 ppm ethyl chloride in air = ~2.2 mg/m
3
at NTP)
3.34
© 1997 by CRC Press LLC

ETHYLENE CHLOROHYDRIN

Synonyms: 2-chloroethanol, 2-chloroethyl alcohol; Formula: C

2

H

5

OCI;
Structure: Cl–CH

2

–CH

2

–OH; MW 80.52; CAS [107-07-3]; used as a solvent for
cellulose esters and in making ethylene glycol and ethylene oxide; colorless liquid
with a faint ether odor; boils at 129°C; freezes at –67°C; density 1.197 g/mL at
20°C; soluble in water, alcohol, and ether; highly toxic.

ANALYSIS OF AQUEOUS SAMPLE

Purge and trap concentration; sample purged with He under heating; analyte
desorbed from the trap by heating and backflushing with He; transferred onto

a GC column for separation; determined by GC-FID or a mass spectrometer.
• No precision and accuracy data are available.
• Purging efficiency is low because of high solubility of the analyte in water.
Purging vessel should be heated under He purge.

AIR ANALYSIS

Air drawn through a solid sorbent tube containing petroleum charcoal
(100 mg/50 mg); analyte desorbed with 1 mL 5% 2-propanol in CS

2

(more than
30 min standing) and analyzed by GC-FID (NIOSH Method 2513, 1985);
recommended flow rate 0.1 L/min; sample volume 20 L.
• GC column: 10% FFAP on 80/100 mesh Chromosorb WHP or equivalent.
•Working range: 0.5 to 15 ppm for a 20 L air sample.

(1 ppm ethylene chlorohydrin in air = 3.29 mg/m

3

at NTP)

3.35

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC


ETHYLENE DIBROMIDE

Synonyms: 1,2-dibromoethane, EDB; Formula: BrCH

2

CH

2

Br; MW 187.88;
CAS [106-93-4]; used in fumigant and antiknock gasolines; colorless heavy
liquid; chloroform odor; boils at 131°C; freezes at 10°C; vapor pressure 11 torr
at 20°C; density 2.7 g/mL at 25°C; slightly soluble in water (0.4%); miscible
with alcohol and ether; irritant and toxic.

ANALYSIS OF AQUEOUS AND NONAQUEOUS SAMPLES

Purge and trap method; aqueous samples purged with He; EDB thermally desorbed
from the sorbent trap and swept by an inert gas onto a GC column for separation
from other volatile compounds; analyzed by a halogen-specific detector or a
mass spectrometer.
Solid samples mixed with methanol; methanol extract spiked into water; aqueous
solution subjected to purge and trap extraction and analyzed as above.
• Characteristic masses for GC/MS identification: 107, 109, and 188.
• GC column: a fused silica capillary column such as DB-5, SPB-5, Rtx-5,
or equivalent.
• Limit of detection: the range 0.1

µ

g/L for a 5-mL sample aliquot purged.
• Samples collected in glass containers without headspace, refrigerated, and
analyzed within 7 days.

AIR ANALYSIS

Air drawn through a sorbent tube containing coconut shell charcoal
(100 mg/50 mg); EDB desorbed from the charcoal by treatment with 10 mL
99:1 benzene-methanol (allowed to stand for 1 h); the solvent extract analyzed
by GC-ECD (NIOSH Method 1008, 1987); recommended flow rate
100 mL/min; sample volume 10 L.
• GC column: 3% OV 210 on Gas Chrom Q (80/100 mesh).
• IS: 1,2-dibromopropane or 1,1,2,2-tetrachloroethane.

3.36

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

Air collected in a SUMMA passivated canister under pressure using an additional
pump or at subatmospheric pressure by initially evacuating the canister;
sample transferred into a cryogenically cooled trap attached to a GC column;
the trap heated; EDB separated on the GC column and determined by a mass
spectrometer (U.S. EPA Method TO-14).

(1 ppm EDB in air = 7.68 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
356

ETHYLENE GLYCOL

Synonym: 1,2-ethanediol; Formula: HOCH

2

CH

2

OH; MW 62.07; CAS [107-
21-1]; used as antifreeze in cooling and heating systems and in hydraulic brake

fluids; colorless liquid; sweet taste; hygroscopic; density 1.11 g/mL; boils at
197.5°C; freezes at –13°C; highly soluble in water, lower alcohols, acetone, and
pyridine; toxic.

ANALYSIS OF AQUEOUS AND NONAQUEOUS SAMPLES
(SUGGESTED METHOD)

Aqueous samples directly injected onto a GC column and determined by an FID.
• GC column: a polar column (polar PEG type phase), such as Supelcowax
10, Nukol, or equivalent.
• No precision or accuracy data are available.
10 g soil, sediment, or solid wastes sonicated with 50 mL 2% isopropanol in water;
extract injected onto GC column; determined on FID.
• No precision or accuracy data are available.
• Detection level: in the range 50 mg/kg.

AIR ANALYSIS

Air drawn through a glass fiber filter and then through a sorbent tube containing
silica gel (520 mg/260 mg), ethylene glycol desorbed out from silica gel with
2% isopropanol in water (on 5-min standing); the analyte in eluant determined
by GC-FID (NIOSH Method 5500, 1984); recommended air flow rate
0.2 L/min; sample volume 30 L.
• GC column: packed glass column 3% Carbowax 20M on 80/100 mesh
Chromosorb 101. Any appropriate polar column may be used.
• The working range for a 3 L air sample was found to be 7 to 330 mg/m

3

.

3.37

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

Alternatively, air bubbled through water; aqueous soln. of the analyte oxidized
with periodic acid into formaldehyde; the latter analyzed by chromotropic acid
colorimetric method (Tucker and Deye, 1981).

(1 ppm ethylene glycol in air = 2.54 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
358

ETHYLENE OXIDE

Synonyms: 1,2-epoxyethane, oxirane; Formula: C

2

H

4

O; Structure:
MW 44.06; unstable, ring cleaves readily; CAS [75-21-8]; used as a fumigant
and sterilizing agent, and in the manufacture of many glycol ethers and ethano-
lamines; colorless gas with ether-like odor; liquefies at 10.4°C; density 0.88 g/mL
at 10°C; vapor pressure 1095 torr at 20°C; soluble in water and most organic
solvents; highly flammable, toxic, and severe irritant.

AIR ANALYSIS

Air drawn through a solid sorbent tube containing HBr-coated petroleum charcoal;
bromo derivative of analyte formed desorbed with dimethylformamide (DMF)
and analyzed by GC-ECD (NIOSH Method 1614, 1987); recommended air

flow 100 mL/min; sample volume 10 L.
• Calibration standard solutions: 2-bromoethanol in DMF.
• GC column: 10% SP-1000 on Chromosorb WHP or equivalent.
Alternatively, air bubbled through impingers contain 0.1

N

H

2

SO

4

; ethylene oxide
converted into ethylene glycol; latter measured by GC-FID (Romano and
Renner, 1979).
• Activated charcoal, impregnated with H

2

SO

4

may alternatively, be
employed in air sampling; glycol formed desorbed with water or a suitable
organic solvent analyzed by GC-FID.
Ethylene oxide in air may be measured directly

in situ

by a rapid colorimetric
technique (Pritts et al., 1982). Air is drawn through a multipart detector tube
consisting of three reactor tubes: containing periodic acid, xylene, and conc.
H

2

SO

4

, respectively. Ethylene oxide is oxidized by periodic acid to formaldehyde
H
2
CCH
2
O

3.38

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

which then reacts with xylenes to form diaryl methylene compounds. The latter
products are oxidized by H

2

SO

4

, impregnated on silica gel to red p-quinoidal

compounds. Thus, the color in the detector tube changes from white to reddish
brown and the concentration of the analyte in the range 5 to 1000 ppm may be
monitored from the length of stain formed in the detector tube.

(1 ppm ethylene oxide in air = 1.80 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
360

FORMALDEHYDE

Synonyms: methanal, methylene oxide, oxymethane; Formula: HCHO; MW
30.03; CAS[50-00-0]; constitutes about 50% of all aldehydes present in air;
released in trace quantities from pressed wood products, burning wood, and
synthetic polymers; and automobiles; colorless gas at ambient conditions; pungent
suffocating odor; liquefies at –19.5°C; solidifies at –92°C; density 1.07 (air = 1);
very soluble in water, soluble in organic solvents; readily polymerizes; flammable,
toxic, and carcinogenic (Patnaik, 1992).

WATER ANALYSIS

Aqueous samples analyzed by HPLC using a postcolumn reaction detector; form-
aldehyde separated on a reversed phase C-18 column; derivatized with 3-methyl-
2-benzothiazolinone hydrazone and detected at 640 nm (Igawa et al., 1989).
(The method was developed for cloud and fogwater analysis.)

AIR ANALYSIS

Formaldehyde may be analyzed by several techniques involving GC, colo-
rimetry, polarography, HPLC, and GC/MS.

Air drawn through a solid sorbent tube containing 10% (2-hydroxymethyl) pipe-
ridine on XAD-2 (120 mg/60 mg); oxazolidine derivative of formaldehyde
formed desorbed into toluene under ultrasonic conditions (60 min); analyzed
by GC-FID (NIOSH Method 2541, 1989); recommended air flow 200 mL/min;
sample volume 15 L.
• Calibration standards prepared from formaldehyde (formalin) stock solu-
tions; each standard injected into 120 mg portions coated-adsorbent; deriv-
ative desorbed into toluene and analyzed by GC-FID as above; calibration
curve constructed (plotting area/height response against concentrations) for
quantitation.
• GC column: fused silica capillary column such as DBWax or equivalent.

3.39

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

Alternatively, air passed through a solid sorbent tube containing 2-(benzy-
lamino)ethanol on Chromosorb 102 or XAD-2; the derivative, 2-benzyloxazo-
lidine desorbed with isooctane and analyzed by GC-FID (NIOSH Method 2502,
1984).
• 2-Benzyloxazolidine peak often masked under interferences from decom-
position and/or polymerization products from derivatizing agent; isooctane
solution may be readily analyzed by GC/MS using a DB-5 capillary column
(Patnaik, 1991).
Alternatively, air drawn through a PTFE membrane followed by sodium bisulfite
solution in impingers; impinger solution treated with chromotropic acid and
H

2

SO

4

; color developed due to formation of a derivative of formaldehyde;

absorbance measured by a spectrophotometer at 580 nm; a standard calibration
curve prepared from formaldehyde standard solutions for quantitation (NIOSH
Method 3500, 1989); recommended air flow 500 mL/min; sample volume 50 L.
• Phenols, alcohols, olefins, and aromatics interfere in the test to a small
extent.
Air drawn through a midget bubbler containing 15 mL Girard T reagent; Girard
T derivative of formaldehyde analyzed by polarography; a calibration curve
constructed (plotting concentration formaldehyde/15 mL Girard T solution vs.
diffusion current) for quantitation (NIOSH Method 3501, 1989); recommended
air flow rate 100 mL/min; sample volume 10 L.
• The half-wave potential for the derivative vs. saturated calomel electrode
is –0.99 V.
Alternatively, air drawn through Florisil or silica gel adsorbent coated with acidified
2,4-dinitrophenylhydrazine (DNPH); the DNPH derivative of formaldehyde
desorbed with isooctane, and solvent exchanged to methanol or acetonitrile;
the solution analyzed by reverse phase HPLC (U.S. EPA Method TO-11, 1988);
recommended air flow rate 500 mL/min; sample volume 100 L.
Alternatively, a measured volume of air drawn through an impinger containing
ammonium acetate and 2,4-pentanedione; formaldehyde forms a fluorescence
derivative, 3,5-diacetyl-1,4-dihydrolutidine; fluorescence of the solution mea-
sured by a filter fluorometer (Dong and Dasgupta, 1987).

(1 ppm formaldehyde in air = 1.23 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
362

FREON 113

Synonyms: 1,1,2-trichloro-1,2,2-trifluoroethane, fluorocarbon-113; Formula
C

2

O

3

F

3

; Structure:
MW [37.37]; CAS [76-13-1]; colorless liquid with a characteristic odor; boils at
47.6°C; freezes at –35°C; vapor pressure 284 torr at 20°C; density 1.56 g/mL; insol-
uble in water; miscible with organic solvents; used as a refrigerant and dry cleaning
solvent, and also in extracting oil, grease, and hydrocarbons in chemical analysis.

ANALYSIS OF AQUEOUS SAMPLES

An aliquot of sample is purged with He; the analyte adsorbed over a trap (Tenax
or equivalent); the trap heated under He flow; the analyte desorbed from the
trap and transported onto a GC column for separation from other volatile
compounds and determination by a halogen specific detector (ECD or HECD)
or a mass spectrometer.
• The characteristic ions for GC/MS identifications 101, 151, 103, 153, 85,
and 66.
• Samples collected in glass containers without headspace, refrigerated, and
analyzed within 14 days of collection.

AIR ANALYSIS

Air drawn through coconut shell charcoal (100 mg/50 mg); analyte desorbed into
CS

2

(allowed to stand for 30 min) and analyzed by GC-FID (NIOSH Method
1020, 1987); flow rate 10 to 50 mL/min; sample volume 1 to 2 L.
Cl C C F
Cl
F
Cl
F

3.40

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

364 HANDBOOK OF ENVIRONMENTAL ANALYSIS

Air collected in a cryogenic trap under liquid argon; trap warmed; sample trans-
ferred onto a precooled GC column; temperature programmed; separated on
the column and determined by FID, halogen specific detector, or GC/MS.

(1 ppm freon-113 in air = 7.66 mg/m

3

at NTP)

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
364

HYDROGEN CYANIDE

Formula: HCN; MW 27.03; CAS [74-90-8]; occurs in the root of certain
plants, beet sugar residues, coke oven gas, and tobacco smoke; released during
combustion of wool, polyurethane foam, and nylon; produced when metal cya-
nides react with dilute mineral acids; colorless or pale liquid or a gas; odor of
bitter almond; boils at 25.6°C; solidifies at –13.4°C; density of liquid 0.69 g/mL

at 20˚C and gas 0.95 (air = 1) at 31°C; soluble in water and alcohol, very weakly
acidic; dangerously toxic and highly flammable (Patnaik, 1992).

ANALYSIS OF AQUEOUS SAMPLES

• Aqueous samples distilled directly without any acid treatment; HCN liber-
ated and collected in NaOH solution; cyanide analyzed by colorimetric or
by ion selective electrode method (See Cyanide, Chapter 2.6).
•Avoid acid treatment of samples, as it converts metal cyanides into HCN.
Test papers treated with p-nitrobenzaldehyde and K

2

CO

3

produces reddish-purple
stain due to HCN.
• Method suitable for detecting 10 ppm HCN.
Presence of HCN indicated by color change of 4-(2-pyridylazo) resorcinol-pal-
ladium in carbonate-bicarbonate buffer solution from intense red to yellow
(Carducci et al., 1982).
• The method originally developed for determination of plants, tissue, and
toxicological substances; no precision and accuracy data available for envi-
ronmental samples of aqueous matrices.

AIR ANALYSIS

Air drawn through a solid sorbent tube containing soda lime (600 mb/200 mg);

cyanide complex desorbed into deionized water; solution treated with N-chlo-
rosuccinimide-succinimide oxidizing reagent; after several minutes standing

3.41

© 1997 by CRC Press LLC

© 1997 by CRC Press LLC

366 HANDBOOK OF ENVIRONMENTAL ANALYSIS

barbituric acid-pyridine coupling reagent added; color development measured
at 580 nm by a spectrophotometer; concentration determined from a calibration
standard (NIOSH Method 6010, 1989); recommended flow rate 100 mL/min;
sample volume 50 L.
• Oxidizing agent: To 10 g succinimide in 200 mL water, add 1 g N-chloro-
succinimide; stirred to dissolve; volume adjusted to 1 L; stable for 6 months
if refrigerated.
• Coupling agent: To 6 g barbituric acid in 30 mL water, add 30 mL pyridine
slowly with stirring; adjust volume to 100 mL; stable for 2 months if
refrigerated.
Alternatively, 50 L air bubbled through 10 mL 0.1

N

KOH solution at a rate of
0.5 L/min; the solution analyzed for CN

–

by ion-selective electrode method
(NIOSH Method 7904, 1984).

•

where

W

b

and

B

b

are

µ

g CN

–

in sample bubbler and media blank bubbler,
respectively, and

V

, the air volume (L) sampled (and HCN to CN

–

stoichi-
ometric factor 1.04).
• Metals interfere in the test, forming strong complexes with CN

–

; such
interference is eliminated by special treatment with EDTA.
Alternatively, air bubbled through an impinger containing 15 mL 0.2

N

NaOH
solution; HCN converted into NaCN; content of impinger transferred into a
vial, rinsed with 2 mL 0.2

N

NaOH (total volume 17 mL); sealed and heated
overnight in an oven; NaCN hydrolyzed into sodium formate; contents cooled
and diluted to 50 mL; formate ion analyzed by ion chromatography (Dolzine
et al., 1982).
• Concentration of formate determined from a formate calibration standards
in 0.068

N

NaOH.
•

µ

g HCN in sample =

µ

g/mL formate ion

×

0.60

×

50
(factor for converting formate ion to HCN 0.60, sample solution 50 mL)
• mg HCN/m

3

air =

µ

g HCN in sample/liters of air sampled.
• Separator column: strong base anion exchange resin; suppressor column:
strong acid resin in hydrogen form; eluting solvent 0.005

M

sodium borate.
SCN Fe Fe SCN
–

+⇒
()
+3
3

© 1997 by CRC Press LLC

© 1997 by CRC Press LLC
366

HYDROQUINONE

Synonyms: 1,4-benzenediol, hydroquinol,

p

-dihydroxybenzene; Formula:
C

6

H

6

O

2

; Structure:
MW 110.11; CAS [123-31-9]; crystalline solid; melts at 170°C; boils at
286°C; low solubility in water (7%); dissolves readily in alcohol and ether;
oxidizes slowly in air.

ANALYSIS OF AQUEOUS AND NONAQUEOUS SAMPLES

Aqueous samples serially extracted with methylene chloride; the extract concen-

trated and analyzed by GC/MS.
• The characteristic masses for GC/MS identification: 110 (primary ion), 81,
53, and 55.
• GC column: a fused silica capillary column, such as DB-5 or equivalent.
Soils, sediments, and solid wastes mixed with anhydrous Na

2

SO

4

; sonicated or
Soxhlett extracted with methylene chloride; extract concentrated and analyzed
by GC/MS.

AIR ANALYSIS

A measured volume of air drawn through a 0.8-mm cellulose ester membrane
filter; the particulates of hydroquinone extracted with 1% acetic acid in water;
OH
OH

3.42

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

368 HANDBOOK OF ENVIRONMENTAL ANALYSIS

extract analyzed by HPLC using an UV detector at 290 nm (NIOSH Method
5004, 1984); recommended air flow rate 2 L/min; sample volume 100 L.
• HPLC column: M-Bondapak C-18 or equivalent (e.g., 25 cm

×

4.6 mm ID
Partisil 10-ODS) at ambient temperature, 400 to 600 psi; mobile phase 1%
acetic acid in water, 1 mL/min; calibration standard: same as above.
• Sample stable for 2 weeks at ambient temperature.
• Acetic acid stabilizes the sample, preventing air oxidation.
•Working range is 0.5 to 10 mg/m

3

for a 100 L air sample.
• Hydroquinone could occur in air at ambient temperature as particulates and
not vapor, as its vapor pressure is too low.

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC
368

HYDROGEN SULFIDE

Formula: H

2

S; MW 34.08; CAS [7783-06-4]; ocurs in natural gas and sewer
gas; formed when metal sulfides react with dilute mineral acids; colorless gas
with rotten egg odor; liquefies at –60.2°C; solidifies at 85.5°C; slightly soluble
in water (4000 mg/L at 20°C); aqueous solution unstable, absorbs oxygen and
decomposes to sulfur; highly toxic and flammable.

AIR ANALYSIS

Atmospheric monitoring of H

2

S may be performed by commercially available

photorateometric analyzer.
•Paper tape H

2

S analyzers use paper strips treated with lead acetate; colored
stains of PbS detected by photocells (Kimbell, 1982); color ranges from
light yellow to silvery black; extremely high signal amplification required
to measure stains far too light in color for rapid and continuous measure-
ment of H

2

S at low ppb level.
H

2

S exposure may be monitored by diffusion type colorimetric dosimeters (such
as Vapor Gard); color changes from white to brown-black; dosage exposure
measured from the length of stain in the indicator tube.

(1 ppm H

2

S in air = 1.39 mg/m

3

at NTP)

3.43

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC

ISOPHORONE

Synonyms: 1,1,3-trimethyl-3-cyclohexene-5-one, isoacetophorone; Formula:
C

9

H

14

O; Structure:
MW 138.20; CAS [78-59-1]; used as a solvent for vinyl resins and cellulose
esters; boils at 215°C; solidifies at –8°C; density 0.92 g/mL at 20°C; slightly
soluble in water; readily miscible with alcohol, ether, and acetone.

ANALYSIS OF AQUEOUS AND NONAQUEOUS SAMPLES

Aqueous samples extracted with methylene chloride; extract concentrated and
solvent exchanged to hexane; florisil cleanup (for removal of interferences);
extract analyzed on GC-FID or GC/MS.
Soils, sediments, or solid wastes extracted with methylene chloride by sonication
or Soxhlett extraction; extract concentrated; exchanged to hexane (if florisil
cleanup required); analyzed by GC-FID or GC/MS.
•For florisil cleanup, column eluted with methylene chloride/hexane (1:9)
and then with acetone/methylene chloride (1:9) mixture; analyte eluted into
the latter fraction.
• Column-packed: 1.95% QF-1/1.5% OV-17 on Gas-Chrom Q (80/100 mesh)

or 3% SP-2100 on Supelcoport (100/120 mesh) or equivalent; capillary: fused
silica capillary column, such as PTE-5, SPB-5, DB-5, Rtx-5, or equivalent.
• Characteristic masses for GC/MS identification: 82, 95, and 138.
• Suggested surrogate/IS: aniline d

5

, 4-fluoroaniline, nitrobenzene d

5

, and
1-fluoronaphthalene.
• Samples collected in glass containers, refrigerated, extracted within 7 days
of collection and analyzed within 40 days of extraction.
O
CH
3
CH
3
CH
3

3.44

© 1997 by CRC Press LLC
© 1997 by CRC Press LLC