Hazardous Chemicals Handbook 2 Episode 10 pot

High collection Table 10.21 Considerations when using instruments with catalytic detection Portable instrument should be of explosion-proof design; fixed point systems may rely on remote

Table 10.18(a) Cont’d

TOXIC PARTICULATES 349

Table 10.18(a) Cont’d

* Consult with supplier.

Table 10.18(a) Cont’d

TOXIC PARTICULATES 351

Table 10.18(b) Dräger tubes for long-term measurements – with pump

maximum period of use

(4 hr)Oxides of nitrogen 50/a-L (NO + NO2) 13 –350 ppm

Table 10.20 Examples of chemicals for which paper-tape colorimetric instruments are available

Table 10.19 Selected sources of inaccuracy in use of colour detector tubes

Failure to break both ends of the sealed tube before insertion of the tube into the pump housing

Insertion of the tube incorrectly into the pumphousing (the correct direction is indicated on the tube)

Reuse of previously used tubes It is advisable not to reuse tubes even if previous use indicated zero

Leaks in sample lines, or insufficient time allowed to lapse between pump strokes when extensions are used

Use of tubes beyond expiry of the shelf-life Tubes should be stored under refrigerated conditions but allowed to warm toambient temperature prior to use

III-defined stain format because it is irregular, diffuse or has failed, i.e not at right angles to tube wall (This can be caused

by poor quality of granular support medium used by manufacturer.) It is advisable to read the maximum value indicated.Use of tubes under conditions of temperature, pressure or humidity outside the range of calibration

Blockages or faulty pumps Pumps should be checked periodically as instructed by the manufacturer They can be calibratedusing rotameters or bubble flowmeters Unless pumps possess a limiting orifice they should be calibrated with the airindicator tube in position

Misuse of the pump, e.g incomplete stroke or wrong number of strokes

Mismatch of tubes with type of pump

Interference due to the presence of other contaminants capable of reacting with the tube reagent This can result in over- orunder-estimation of concentrations The former is the more likely and hence errs on the side of safety

Tube blockage caused by airborne dusts, affecting the flow rate

Table 10.18(c) Direct-indicating Dräger diffusion tubes – no pump required

particles of respirable dimensions from non-respirable fractions include horizontal elutriation and centrifugation Equipment for personal monitoring comprises a lapel-mounted filter holder connected

to a portable pump with a flow rate of about 3 litres/min Respirable matter can be separated by use of a small cyclone In order to ensure uniformity of fractionation, smooth and constant flow rates are essential The dust collection and analytical stages are separate operations For background monitoring, miniaturization is unimportant and as a consequence equipment incorporates pumps

of higher flow rates, typically ≤100 1/min This enables sampling times to be short and larger samples to be obtained (e.g for laboratory analysis) Both direct-reading and absolute methods are available.

The main principles of instrument design are summarized in Table 10.23 In filtration, e.g for gravimetric analysis, selection of filter material (Table 10.22) requires careful consideration in terms of application, strength, collection efficiency, compatibility with pump, water uptake, etc Humidity-controlled balance rooms, microbalances and careful handling techniques may be required.

Table 10.22 Examples of filter material for collection of particulates

determine water soluble fraction drop, low impurity levels

or for ashing to determineorganic content

gravimetric assessment high wet strength, good

temperature stability, lowpressure drop

• Mixed celluloses, e.g nitrate, Microscopy (asbestos); metal Low levels of metal impurities;

atomic emission, fluorescenceand infra-red spectrometry)

• Polycarbonate Optical microscopy; organic Transparent grades available,

content, solvent resistant

analysis PAHs

black, quartz, silica water pick-up

• Silver membrane Crystalline materials for X-ray Costly High collection

Table 10.21 Considerations when using instruments with catalytic detection

Portable instrument should be of explosion-proof design; fixed point systems may rely on remote sensing heads

For zero adjustment, place instrument in uncontaminated air or use activated charcoal filters to remove flammable vapoursSources of error include:

Inadequate calibration

Drift due to age

Design not fail-safe (i.e no indication of component failure)

Poisoning of Pellistor by, e.g., silicones, halocarbons, leaded petrol

Too high a sampling rate (causing cooling of the elements)

Sampling lines and couplings not airtight

Condensation of high-boiling-point components in the line between sample head and sensor

Hostile environment

Table 10.23 Particulates monitoring – principles of apparatus

Principle Examples Collection Sampling Collection Analysis Advantages/disadvantages

rate efficiency

Impinger Midget impinger By bubbling Microscopy Aggregates broken up; only particles >1 µm collected In wet

phaseImpactor 1 Konimeter Impaction on 60–100 Built-in Underestimates small particles,

2 Cascade Impaction on 1–37

impactor 4 stages on (depending

glass disc on type)

3 Andersen Impaction in

discsElectrostatic Casella thermal Deposition on 1–85 90–100 Microscopy Poor for large particles Collection

Filtration 1 Fibrous filter 1–50 85–100 Gravimetric or Fibrous filter good for gravimetric analysis

Depends on chemical for a range of particle sizesparticle size (fast and relatively easy)

values stated

encountered chemical where required

Respirable 1 Hexhlet Fibrous filter 1–50 60–100 Gravimetric or Instrument must be kept horizontal for

3 Anderson Selective inlet 16.7 Gravimetric Can be used for unattended operations

sampler 2 dust fractions

(<10 µm and <2.5 µm)

Suitable for unattended automated continuous methods

Photometry 1 Number Light scattered Gives automatic particle sizing but accuracy

Direct reading

Direct reading Suitable for automated operations

Principle Examples Collection Sampling Collection Analysis Advantages/disadvantages

rate efficiency

Table 10.24 Selected British Standards relating to ambient air pollution measurements

Particulate matter

Directional dust gaugesSampling equipment for determination ofgaseous sulphur

Nitrogen dioxide in ambient air Modified Griess–Salzman methodNitrogen oxides in ambient air Chemiluminescence

Sulphur dioxide in ambient air Tetrachloromercurate/pararosalineBlack smoke index in ambient air

BS 3405 Particulate matter including grit and dust

particulates

Electron microscopy

BS ISO 12884 Polycyclic aromatic hydrocarbons Collection of filters with gas

chromatography/massspectrometry

Electron microscopy

BS ISO 16000 Indoor formaldehyde and other carbonyl Active and diffusive sampling

compounds

Official methods

Regulatory and advisory bodies publish methods for ambient air analysis such as those issued by

the British Standards Institute and the US Environment Protection Agency (Tables 10.24 and

10.25, respectively) Methods for assessment of workplace air are published by the Health and

Safety Executive Some of these are generic methods (Table 10.26) whilst others are compound specific (Table 10.27) Examples of other official methods for monitoring workplace air quality are those published by the British Standards Institute (Table 10.28), and the US National Institute

of Occupational Safety and Health (Table 10.29) Table 10.30 provides additional guidance on analytical techniques for a selection of substances.

OFFICIAL METHODS 357

Table 10.25 Selected EPA standard methods for air monitoring (Code of Federal register-protection of the environment section, 40)

Part 60 Appendix A

• Various measurement techniques for sample and velocity 1, 1A, 2, 2A, 2B, 2C

from stationary sources, stacks, ducts, pipes

• Sulphuric acid mist and SO2 from stationary sources 8

• Visual assesssment of fugitive emissions from material sources 22

and smoke from flares

• Volatile content, water, density, volume and weight of surface coatings 24, 24A

Part 61 Appendix B (Hazardous air pollutants)

Sampling strategies

The results of environmental monitoring exercises will be influenced by a variety of variables including the objectives of the study, the sampling regime, the technical methods adopted, the calibre of staff involved, etc Detailed advice about sampling protocols (e.g where and when to sample, the volume and number of samples to collect, the use of replicates, controls, statistical interpretation of data, etc.) and of individual analytical techniques are beyond the scope of this book Some basic considerations include the following, with examples of application for employee exposure and incident investigation.

Sampling

It is crucial to consider the sampling protocol, equipment, calibration, and validation Tightly sealed sample containers of adequate strength, and generally protected from heat and light, are required Extreme care must be taken with sample identification and labelling Sample containers must not become contaminated with the substance under study or by any major interfering chemicals Precautions must also prevent accidental loss of material collected awaiting analysis, e.g during storage or transport For example, water samples can become affected by evaporation, degassing, chemical degradation, photophysical degradation, precipitation, or damage of suspended matter.

Samples must be representative of the environment in relation to study objectives and to permit comparison of data with appropriate standards, i.e average concentrations, time-weighted exposures, peak concentrations, etc Replicate samples may be advisable.

Generation of test atmospheres of organic vapours by the syringe injection technique 3

Generation of test atmospheres of organic vapours by the permeation tube method 4

General methods for sampling and gravimetric analysis of respirable and inhalable dust 14/3

Protocol for assessing the performance of a diffusive sampler 27

Sorbent tube standards preparation by the syringe injection technique 33/2

Protocol for assessing the performance of a pumped sampler for gases and vapours 54

Discrimination between fire types in samples of airborne dust on filters using microscopy 87

SAMPLING STRATEGIES 359

Table 10.27 HSE methods for measuring levels of specific airborne chemicals

liquid chromatography after collection

in an impinger containing water

chromatography

adsorption tube and thermal desorptionwith gas chromatography

diffusive samplers with thermaldesorption and gas chromatographyAromatic amines in air and on Lab method using pumped acid-coated 75

chromatography

anhydrides in air tube sampling and high performance

liquid chromatographyAromatic isocyanates in air Field method using acid hydrolysis, 49

diazotization, coupling andspectrophotometry

compounds of arsenic flow injection analysis hydride

spectrometry

diethyldithiocarbamate in presence ofexcess silver nitrate

contrast microscopy

polarized light microscopy

liquid chromatography

desorption, and gas chromatography

polymer adsorbent tubes, thermaldesorption and gas chromatography

diffusive samplers, thermal desorptionand gas chromatography

electrothermal atomic absorptionspectrometry

sieve sorbent tubes, thermal desorptionand gas chromatography

Lab method using molecular sieve 63samplers, thermal desorption and gas

chromatography

cadmium compounds in air electrothermal atomic absorption

spectrometryCarbon disulphide in air Charcoal adsorbent tubes with solvent 15

desorption and gas chromatography

Chlorinated hydrocarbon Lab method using pumped charcoal 28

solvent vapours in air adsorption tubes, solvent desorption

and gas chromatography

compounds of chromium in air

Chromium (hexavalent) in Colorimetric field method using 1,5- 52/3

Chromium (total and speciated chromium) Colorimetric field method using 1,5- 67

in chromium plated mists diphenyl carbazide after oxidation with

silver (1)-catalysed peroxydisulphate

measurement of particulates and gravimetric analysis

cyclohexane soluble material in air

Cobalt and cobalt compounds in air Lab method using flame atomic 30/2

absorption spectrometryCristobalite in respirable Lab method using X-ray diffraction 76

chromatography with massspectrometry

solvent desorption and gaschromatography

absorbent tubes, solvent desorption andelectron capture gas chromatography

tubers, solvent desorption and gaschromatography

solvent desorption and highperformance liquid chromatography

liquid chromatographyGlycol ether and glycol ether Lab method using charcoal adsorbent 21

acetate vapours in air tubes, solvent desorption and gas

chromatographyGlycol ether and glycol acetate Lab method using Tenax sorbent tubes, 23

chromatography

samplers, solvent desorption and gaschromatography

acid-coated glass-fibre filtersfollowed by solvent desorption or intospecially constructed impingers Finalanalysis by derivatization and highperformance liquid chromatographyHydrocarbons (mixed C3–C10) Lab method using pumped porous 60

polymer and carbon sorbent tubes,thermal desorption and gaschromatography

Hydrocarbons (mixed C5–C10) Lab method using porous polymer 66

diffusive samplers, thermal desorptionand gas chromatography

Table 10.27 Cont’d

SAMPLING STRATEGIES 361

Hydrogen cyanide in air Lab method using an ion-selective 56/2

electrode

spectrometryLab method using X-ray fluorescence 7spectrometry

Mercury vapour in air Diffusive samplers with qualitative on- 59

site colorimetric analysis andquantitative cold vapour atomicabsorption spectrometry in thelaboratory

workplace air

inductively coupled plasma emissionspectrometry

Mineral oil mist from mineral Pumped filters with gravimetric 84

oil-based metalworking fluids determination

measurement of total particulate gravimetric evaluation

and cyclohexane-soluble material

compounds of nickel in air absorption spectrometry or

(except nickel carbonyl) electrothermal atomic absorption

spectrometryOrganic isocyanates in air Lab method with sampling either onto 25/3

coated glass-fibre filters followed bysolvent desorption, or into impingersand analysis using high performanceliquid chromatography

Peroxodisulphate salts in air Lab method using mobile phase ion 79

chromatographyPesticides in air and on surfaces Pumped filters/sorbent tubes with gas 94

chromatography

platinum compounds in air atomic absorption spectrometry or

inductively coupled plasma massspectrometry

Resin acids in rosin (colophony) Lab method using gas chromatography 83

solder flux fume

total particulate and gravimetric estimation

cyclohexane-soluble material

tubes, solvent desorption and gaschromatography

adsorbent tubes, thermal desorptionand gas chromatography

Table 10.27 Cont’d

Lab method using porous polymer 43diffusive samplers, thermal desorption

and gas chromatographyLab method using charcoal diffusive 44samplers

Tetra-alkyl lead compounds in air Personal monitoring with atomic 9

absorption analysis or electrothermalatomization or X-ray fluorescencespectrometry or on-site colorimetry

adsorption tubes, solvent desorptionand gas chromatography

polymer adsorption tubes, thermaldesorption and gas chromatographyLab method using charcoal diffusive 64samplers, solvent desorption and gas

chromatography (using Drager ORSAmonitor)

Lab method using charcoal diffusive 69samplers, solvent desorption and gas

chromatographyTriglycidyl isocyanurate (and Lab method using pumped filter, 85

coating powders containing desorption and liquid chromatography

triglycidyl isocyanurate)

Vinyl chloride in air Lab method using charcoal adsorbent tubes, 24

solvent desorption and gas chromatography

gas chromatographyLab method using diffusive solid 80sorbent tubes, thermal desorption and

gas chromatographyLab method using diffusive samplers, 88solvent desorption and gas chromatography

sorbent tubes, solvent desorption andgas chromatography

Selected strategies for determining employees’ exposure to

airborne chemicals

The scheme in Figure 10.1 illustrates a general approach for devising a monitoring strategy Where doubt exists about the level of exposure, a crude assessment can be made by determining levels under expected worst-case situations, paying attention to variations and possible errors More detailed assessment may be required, depending upon the outcome Sampling times should

be long enough to overcome fluctuations but short enough for results to be meaningfully associated with specific activities and for corrective actions to be identified For monitoring particulates, sampling times may be determined from the following equation:

Minimum volume (m ) = 10 sensitivity of analytical method (mg)

suitable hygiene standard (mg/ m )

3

3

×

Table 10.27 Cont’d

SELECTED STRATEGIES FOR DETERMINING EMPLOYEES’ EXPOSURE TO AIRBORNE CHEMICALS 363

Table 10.28 Selected British Standards for analysis of workplace air quality

chromatographySulphur dioxide

Particulate lead and lead Flame atomic absorption

Chlorinated hydrocarbon Charcoal tube, solvent desorption

Aromatic hydrocarbon vapours Charcoal tube, solvent desorption

and gas chromatography

detection and directconcentration measurement totoxic gases General

requirements and test methods

detection and measurement ofcombustible gases Generalrequirements and test methods

detection and measurement ofoxygen Performancerequirements and test methods

detection of flammable gases

General requirements and testmethods

BS ISO 11041 Particulate arsenic and arsenic Hydride generation and atomic

compounds and arsenic trioxide absorption spectrometry

cadmium compounds atomic absorption spectrometry

particulate matter atomic emission spectrometry

BS ISO 16107 Evaluation of diffusive samplers

over 5 l/min

direct detection andmeasurement of toxic gases andvapours

atomic emission spectrometry

chromatography

Table 10.29 Compounds for which there are analytical methods recommended by NIOSH

Acetonitrile (methyl cyanide)

Acetylene dichloride (1,2-dichloroethylene)

Acetylene tetrabromide (tetrabromoethane)

Biphenyl (diphenyl)Biphenyl-phenyl ether mixutre (phenyl ether-biphenyl vapourmixture)

Bis(chloromethyl)ether2,2-Bis[4-(2,3-epoxypropoxy)phenyl] propaneBismuth

Bisphenol A2,2-Bis(p-chlorophenyl) 1,1,1-trichloroethane (DDT)Boron carbide

Boron oxideBioaerosolBitumen fumeBromotrifluoromethaneBromoxynil

Bromoxynil octanoateButadiene (1,3-butadiene)1-Butanethiol (n-butyl mercaptan)2-Butanone (methy ethyl ketone or MEK)2-Butoxy ethanol (butyl cellosolve)sec-Butyl acetate

tert-Butyl acetateButyl acetate (n-Butyl acetate)sec-Butyl alcohol

tert-Butyl alcoholButyl alcohol (n-butyl alcohol)Butyl cellosolve (2-butoxy ethanol)n-Butyl glycidyl ether

n-Butyl mercaptann-Butylamine1,3-Butylene glycolSELECTED STRATEGIES FOR DETERMINING EMPLOYEES’ EXPOSURE TO AIRBORNE CHEMICALS 365

Chlorinated camphene (toxaphene)

Chlorinated diphenyl oxide

Coal-tar naphtha (naphtha, coal tar)

Coal-tar pitch volatiles

Cobalt

Cobalt and compounds

Cobalt, metal, dust, and fumeCongo red

CopperCopper dust and mistsCopper fumeCrag herbicide ICresol, all isomersCristobaliteCrotonaldehydeCryofluoraneCumemeCyanideCyanuric acidCyanazineCyclohexaneCyclohexanolCyclohexanoneCyclohexeneCyclohexylamineCyclopentadieneDBPC

2,4 D2,4-D acid2,4-D 2-ethylhexyl ester2,4-D 2-butoxyethyl esterDDT (2,2-Bis(p-chlorophenyl)-1,1,1-trichloroethane)DDVP

n-DecaneDemetonDiacetone alcohol (4-hydroxy-4-methyl-2-pentanone)1,2-Diaminoethane (ethylene diamine)

o-Dianisidene-based dyesDiatomaceous earthDiazomethaneDiazonium saltsDibenz(a,h)anthraceneDiborane

Dibromodifluoromethane1,2-Dibromoethane (ethylene dibromide)2-Dibutylaminoethanol (aminoethanol compounds)Dibutyl phosphate

DibutylphthalateDibutyl tin bis (isooctylmercaptoacetate)Dichloromethane

1,1-Dichloro-1-nitroethaneo-Dichlorobenzenep-Dichlorobenzene3,3′-DichlorobenzidineDichlorodifluoromethane (Refrigerant 12)1,1-Dichloroethane (ethylidene chloride)1,2-Dichloroethane (ethylene dichloride)Dichloroethyl ether

1,2-Dichloroethylene (acetylene dichloride)Dichloromethane (methylene chloride)Dichloromonofluoromethane (Refrigerant 21)2,4-Dichlorophenoxyacetic acid and salts1,2-Dichloropropane

Dichlorotetrafluoroethane (Refrigerant 114)

Dichloro-5-triazine-2,4,6-trione, sodium salt

Diethylene glycol ether

Di-(2 ethyl hexyl) phthalate

Dimethyl benzene (xylene)

1,3-Dimethyl butyl acetate (sec-hexyl acetate)

bis (Dimethylthiocarbamoyl) disulphide

Dinitrobenzene (all isomers)

Ethanolamine (aminoethanol compounds)Ether

EthionEthoprop2-Ethoxyethanol2-EthoxyethylacetateEthyl acrylateEthyl alcohol (ethanol)Ethyl benzeneEthyl bromideEthyl butyl ketone (3-heptanone)Ethyl chloride

Ethyl etherEthyl formateEthyl mercaptanEthyl sec-amyl ketone (5-methyl-3-heptanone)Ethyl silicate

O-Ethyl-O-p-nitrophenyl phenyl-phosphonothiolatephosphonate (EPN)

EthylamineEthylene chloride (ethylene dichloride)Ethylene chlorohydrin (2-chloroethanol)Ethylenediamine

Ethylene dibromide (1,2-dibromoethane)Ethylene dichloride (1,2-dichloroethane)Ethylene glycol

Ethylene glycol dinitrateEthylene oxideEthylene thioureaEthyleniminedi-2-Ethylhexylphthalate (di-sec-octyl phthalate)Ethylidene chloride (1,1-dichloroethane)N-Ethylmorpholine

FenamiphosFibrous glassFluorantheneFluoreneFluorideFluoroacetate, sodiumFluorotrichloromethane (Refrigerant 11)Fonofos

FormaldehydeFormetanate.HClFormic acidFurfuralFurfuryl alcoholGalenaGalliumGlutaraldehydeGlycerin mistGlycidol (2,3-epoxy-1-propanol)Glycols

HafniumHeptachlor

Table 10.29 Cont’d

SELECTED STRATEGIES FOR DETERMINING EMPLOYEES’ EXPOSURE TO AIRBORNE CHEMICALS 367

Heptanal

3-Heptanone (ethyl butyl ketone)

2-Heptanone (methyl (n-amyl) ketone)

2-Hexanone (methyl butyl ketone or MBK)

Hexone (methyl isobutyl ketone or MIBK)

sec-Hexyl acetate (1,3-dimethyl butyl acetate)

4-Hydroxy-4-methyl-2-pentanone (diacetone alcohol)

2-Imidazolidinethione (ethylene thiourea)

Isopropyl alcohol (isopropanol)

Isopropyl benzene (cumeme)

Isopropyl glycidyl ether

Magnesium oxide fumeMalathion

Maleic anhydrideManganeseManganese fumeMBK (2-hexanone)MDl (4,4′-methylenebisphenyl isocyanate)MEK (2-butanone)

MercaptansMercuryMesityl oxideMetals in airMethamidophosMethanol (methyl alcohol)Methiocarb

Methomyl2-Methoxyethanol (methyl cellosolve)2-Methoxethyl acetate

MethozychlorMethyl(n-amyl)ketone (2-heptanone)5-Methyl-3-heptanone

Methyl acetateMethyl acetyleneMethyl acetylene propadiene mixtureMethyl acrylate

Methyl alcohol (methanol)4-Methylbenzenesulphonic acidMethylamyl ketone

Methyl arsonic acidMethyl bromideα-Methyl butyl acetate (sec-amyl acetate)Methyl butyl ketone (2-hexanone)Methyl cellosolve (2-methoxyethanol)Methyl cellosolve acetate

Methyl chlorideMethyl chloroform (1,1,1-trichloroethane)Methyl cyanide (acetonitrile)

Methyl ethyl ketone (2-butanone)Methyl ethyl ketone peroxideMethyl formate

Methyl iodideMethyl isoamyl acetateMethyl isobutyl carbinolMethyl isobutyl ketone (hexone)Methyl methacrylate

α-Methyl styreneMethylal (dimethoxymethane)Methlyamine

MethylcyclohexaneMethylcyclohexanolMethylcyclohexanone4,4′-Methylenebis (2-chloroaniline)4,4′-Methylenebisphenyl isocyanate (MDl)Methylene chloride (dichloromethane)4′,4′-Methylenedianiline

Table 10.29 Cont’d