Characterization and Quantification of Volatile Organic Compounds in Emissions from Building Materials for Dynamic Chamber Tests

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Characterization and Quantification of Volatile Organic Compounds in Emissions from Building Materials for Dynamic Chamber Tests

http://irc.nrc-cnrc.gc.ca

Cha ra c t e rizat ion a nd Qua nt ific at ion of

Volat ile Orga nic Com pounds in Em issions

from Building M at e ria ls for Dyna m ic

Cha m be r Te st s

Z h u , J . P . ; Z h a n g , J . S . ; K a n a b u s

-K a m i n s k a , M . ; L u s z t y k , E . ; S h a w ,

C . Y .

I R C - I R - 7 5 3 November 1997

Characterization and Quantification of Volatile Organic Compounds in Emissions from Building Materials for Dynamic Chamber Tests

J.P. 2b.1, J.S. Zhang,

M.

Kanabus-Wnska,

E.

Lusztyk

and C.Y. Shaw Address: M-24, IRC, NRC, Montreal Road, Ottawa, Ontario

KIA

OR6 Canada

Phone: (613)

993-9612;

Fax:

(613) 954-3333; Email: jiping.zhu@nrc.ca

1.

Z

This

document provides a general pracedure far measuring the concentrations of selected model voIatile organic compounds (VOCs) or groups of compounds emitted

from

building mate-rials during dynamic chamkt tests using GUFlD or G U M S method, or both. ModeP compounds are selected based on the W M S prescreening results. The exact experiment conditions should be developed for each testing material or type of

testing materials based an this document. An example of such experiment conditions is given in Appendix 1.

1.2 The general analytical procedure described

in

the document supports the standard practices for the determination and chmcterization of VOC emissions (excIuding formaldehyde) from building materials

in

smdl

or

full environmental

chambers under defined test conditions. Such chamber test methods have been developd

at the Institute for Research in Construction, National Research Council of Canada (1). 1.3 Building materials can

be

divided into two major categories, (1)

dry

materials such as w d - b a s e d panels, floor tiles and carpets, and (2) wet materids such as w d stains, adhesives, wax, paints and caulking materials. Because their emission

characteristics

are

not the same, different environment chamber settings and conditions are resquired for conducting both headspace analysis

and

dynamic chamkr tests.

The

environmental chamber settings and conditions can be found in standard practices mentioned in section 1.2

(1).

This documen1 describes the method of collecting and analyzing VOCs in air sampIes during dynamic chamber tests.

1.4 The method described in t h i s document may also be applied to characterize and quantifjr VOC emissions fmm other materids such as consumer products

in

dynamic chamber tests.

1.5 Values stated in

SL

units are to be regarded as the standard.

1.6 This document does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of the document to establish

appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.

2 Referenced Documents 2.1 ASTM Standards:

D 1356 Terminology Related to Atmospheric Sampling and Analysis

D 3609 Standard Practice for Calibration Tabniques Using Permeation Tubes D 3686 Standard Practice for Sampling Atmospheres to CoIlect Organic Compound Vapors. Activated Charcoal Tube Adsorption Method

D

3686 Standard Practice for Analysis of Organic Compound Vapors Collected

by

the Activated Oarcoal Tube Adsorption Method

D

4307 Standard Practice far Preparation of Liquid Blends for Use as Analytical

Standards

D

5 1 16 Stmdard Guide for Small-Scale Environmental Chamber Determinations of Organic Emissions

from

Indoor MateridsJPmducts

E

260 Recommended Practice fat Generd Gas Chromatography Procedures E 355

S

tandad Practice for Gas Chromatography Terms and relationships

E

456 Standard Terminology Relating to Quality and Statistics

E

697 Standard Practice for Use of Electron-Capture Detectors in Gas Chromatography

2.2 EPA Standards:

TO-17 (1 9 97) Determination of Volatile Organic Compounds in Ambient Air Using Active Sampling Onto Sorbent Tubes. In: Compendium of Methods for the Determination of Toxic Organic Compounds

in

Ambient Air, second edition.

IP-lE3 (1993) =termination of Volatile Organic Compunds (VOCs) in Indoor

Air Using Sdid Adsorbent Tubes.

In:

Methods

for

Determination

of

Indoor Air

Pollutants.

2.3 Qher Documents:

MDHS 3 (1990) Methods for

the

Determination of Hazardous Substances. Health and Safety Executive WSH) Generatian

of

Standard Atmospheres - Syringe Injection Methud.

MDHS 3 (1993) Methuds for the Determination of Hazardous Substances. Health

and

Safety Executive (HSISH) Volatile Organic Compwnds

in

Air. Laboratoty Method Using Pumped Solid Adsorbent Tubes, Thermal Desorption and Gas Chromatography. 3. Terminology

3.

f

V o ~ ~ f r ' l e Organic Compound

(VOC)

-

an organic compound having vapor pressure greater

than

lo-' kPa at 25 'C Compounds with boiling point below 250 ' C at nominal atmosphere pressure may be considered VOCs.

Note

I

-

Organic

compotardr

with boiling point below 50 'Care considered very volatile organic c o r n p o d ( WOC). Depending on adsorbents selected and analytical system conditions, the method described in this &went m y not be applicable to memure these W O C s .

3.2 Model C u m p o t .

-

a typical compound selected from the VOCs of a given testing material

for

dynamic chamber tests, Model compounds are used to describe the emission pmfile of the testing material. Usually

three

to six mode1 compounds are selected for a given testing material.

3.3 T h e m 1 desorpfion

-

a rnahanism in

which

adsorbd chemicals

in

sample tubes are released by heat under inert gas stream.

3.4 Cyfmus

-

a caoling device to mf the inlet of

GC

column to certain

temperature (e.g. -50 O C ) for concentrating VOCs r e 1 4 from t h d desorption unit

prior to GC separadan.

5.5 Tube

-

thermal desorption tubes are used to oollect air sampIes. Tubes are made

of

either glass (glass tube) or stainless steel

stainless

steel h&e). Tubes without adsorbents filled are cdled empty tubes. Tubes fdled with dsorbent(s) me called

adsorbent mbw. Adsorbent tubes may contain single adsorknt such as

Tenax

(single-bed tube) or multiple adsorbents (e.g. glass beads, Tenax and synthetic carbons) (multi-bed tube). Adsorbent tubes are used for collecting air samples (sample rubes) or loading with

cdi bration standard ( s t d r d tubes).

3.6 Chemical standard

-

a pure chemical compound with known quantity dissolved in either an inert gas (such as nitrogen) or a solvent (such as methanol).

3.7 Calibration ssandard

-

a chemical standard or a mixture of chemical standards

with known quantity of each of them

in

either an inert gas (gm standard) or a solvent (liqukf standard). Calibmtion standard is used to calibrate the andybcal system such as

GC/FZD o t m s .

3.8 Calibration curve

-

a clrrve showing the response of a detector (area counts) at Y-axis against the amount of

VOC

loaded in the sample tube at X-axis.

3.9 Detection limit

-

concentration level at which an analyte can

be

reliably

detected with defmed (e.g. 95 %) confidence, see also section 13.4.1.

3.10 Quurttifcution limit

-

concentration leveI at which

an

anal- can be reliably quantified with defined (e.g. 95 %] confidence, see also section 13.4.2.

3.1 I For further definition and terms used in this document, refer to ASTM Dl356

Terminology

Relating to Atmospheric Sampling and halysis, a d ASTM E355 Standard Practice for Gas Chromatography Terms

and

Relationships.

4.1 The method consists

of

two analytical parts. The first part is a pre-screening procedure that defrnes the optimal instrument conditions, identifies mode1 compounds and determines proper sample volumes for subsequent dynamic chamber tests. The second part is a quantitative analysis procedure to measure the VOC concentrations

in

air samples that are collected during the dynamic chamber tests. Sample volumes at various test stages may be further adjusted during the dynamic chamber test.

4.2

In

the p~e-screening, test materials were placed

in

a chemically inert, non- permeable bag and headspace air samples are eolIected at 24 h for wet materials and 48 h for dry matetids. Collected samples are introduced into G C M S through a thermal

desorpfron unit. VOCs are separated in a suitable GC capilIary column with

an

optimized

GC

temperature programming to yield the best separation for a given material.

4.3 VOC components separated in

the

GC

column are detected by the mass

spectrometer that is operated under the fuI1 scan mode (20 to 350 m u ) to obtain full mass spectnrrn for each slepamkd peak. Identification of the peak is carried out by comparing

the mass spectrum of the peak with the spectra in a standard mass spec- library.

4.4 Single response factor of toluene is used for the estimation of concentrations

of

individual VOCs and TVOCs (2). Proper sample volumes for the subsequent dynamic chamber test are dculated based on the estimated concentrations in headspace samples.

4.5 T'lme. to six major compounds ar groups of compounds, or a combination of both, at early, middle, and late retention times

on

the

gas

chromatogram are selected as

model compounds for subsequent dynamic chamber tests. Other factors such

as

toxicity and commonality of compunds may also be considered in selecting model compounds.

The

identification of selected model compounds is verified witb chemical standards,

if

necessary.

4.6 Upon completion of pre-screening, a second material of the same spechen is introduced to the environment chamber for dynamic chamber testing. Air samples are collected onto multi-bed tubes during the test period, and

are

thermally desorbed and analyzed using a TDJGCJFlD or TIT/GCJMS system, or both.

Note 2

-

me same rype of

GC

c o l m a d same

GC

temperature program from prescreening are used for amlyz f ng samples coltected during chumber tests for besr

comparison and peak recognitton. Concentrations of selecred model c ~ m p o ~ in

4.7

The

analytical system is

calibrated

with standards of model compounds at

several concentration levels.

A

linear calibration range of at least three order af magnitude, for example

h m

50 ng to 5000 og per tube for GC(FID system, is

established and the response factor is used f i r quantification.

4.8 Concentrations of individual model compounds are quantified using the

Esponse factors of the corresponding individual standards. TVOC concentration is estimated using response factor of toluene standard and a e p i d as TVOC (toluene- equivalent) (2).

5. Significance

of

Use

5.1 Selection of low emission building materials helps to improve indoor air quality It is therefore imptant to characterize the emission profiles for each materid or group

of

materials.

5.2 Small and full enviranmental chamber tests

m

designed to characterize such emission pmflles. However, methods published for such tests are usually focused on chamber design and conditions, and operating procedures for conducting chamber tests. Detailed chemical analysis procedures associated with such tests are rarely available

in

the literature.

5.3 'Fhe method described

in

this document provides a general procedure for chemical mdysis that can be used in such chamber tests, independently

from

the testing materials and chamber conditions. This d m m e n t is therefore an essential support to the dynamic chamber tests and should be used with documents describing chamber tests (see section 1.2).

6. Interference

6.1 Building materials may

contain

very complex mixture of VOCs emitted during chamber tests. It is sometimes not possible to separate all

COV

components

in the

emission. Organic components that co-elute or patidly co-elute on gas chromatogram can cause difficulties in peak identification. Interference may be minimized by selecting a

different stationary phase

GC

column or changing the GC temperature programming or both.

6.2 Co-elution or partial co-elution of other components with the model compunds will interfere with the quantification of the model compounds, especidty when GCJFID is used for quantitative andysis. Temperature programming may be further optimized to elinhate such interference.

G U M S

is a preferred choice to eliminate such interference through proper selection of quantification ions.

6.3 Surface coatings of

GC

columns

may

breakdown at high oven temperature and =lease some components causing high basdine in

GC

chromatogsam. Released components from GC co'lumn may dter the mass spectrum of the peak.

h

such case,

IRCNRC CMEIA Q R e p o ~ 1.4 (NmII997)

baseline subtracted spectrum should

be

used for identification. High baseline may also increase the noise Ievel in

GC

chromatogram.

6.4 Artifacts from sample tubes resulted from reaction or degradation, or both, of the adsorbcnts may interfere with analysis. To minimize the artifacts, adsorbent tubes should be, if possible, we11 cl~aned within 48 hours of sample collection. Any cleaned tubes stored over seven days shall not be used without x-cleaning.

6.5 Compounds with similar chemical stmcture (e.g. isomers) have very similar mass spectrum. This may cause confusion in peak identification. In such case, analyst

may also d a y

on

retention time

and

standards to verify identification.

6.6 S a m

VOC

components may not be themally stable under the experiment conditions. Such components m y

be

destroyed or react with other components during thema1 desorption process causing low response of these components and forming artifacts as well.

Caze

shouId be given if such instability is suspected or anticipated.

6.7 Some volatile compounds such as solvents used

in

buiIding materials and finishing may not be effectively retained in the sample bbe, especially when sampling volume is large. The breakthrough v d u m e of VOCs on the selected adsorbents should be calculated and the sampling volume shouId not exceed half the breakthrough volume. For calculation of breakthrough volume, user is r e f e d to EPA TO-17 method.

"I, Apparatus

7.1 Headspace vial

-

a glass vial that can be sealed with Teflon@ h e d cap. The vial should be Iarge enough to create a head space that is at least 10 times the sampling volume so the impact of sample withdraw is kept minimum,

7.2 Environmental tesf chamber

-

a container used for dynamic chamber tests.

The chamber should have controlled environment conditions (temperature, relative himidity, air change rate etc.).

7.3

Air sample colSection unit

-

An assembly that is used to cal~ect chamber air onto an adsorbent tube using a mechanical pump down stream.

The

flow rate is

controIIed by a flow controller that is connected between the adsorbent tube and the Pump-

7.4 T h e m 1 desorpfion unit

-

a device that releases and transfers the VOCs in the sample tube to the

GC

caTumn inlet by heat under an inert gas stream (e.g. helium). Note 3 - Diflerent types of t h e m 2 desolptwn units are cammercialIy available- They can be divided info two groups, one with multiple &sorption stages [usmily two or threeJ in which the size of inner craps are progressively reduced, the other one with

IRCINRC CMEAQ Report 1.4 (Nm/I997)

7.5

Trcbe

conditioner

-

a device to condition or clean the t h e d desorption tubes by heat under an inert gas stream.

7.6 Fhme ionization defector ( F D J

-

a detector which can generate response

for

wbon-conzaiaing compounds. FED is considered a universal, non-selective detector for organic compounds.

7.7

Mas spectromter ( .

-

mass spectrometer consists three major

130rnpnent.s:

an

ion s a m that ionizes the molecules entering the source, a separator that separates ions according to their mass/charge Y nits, and a detector that records the mass of fragments

in

mass/charge (mlz) unit form.

8- Reagent

and

Materials

8.1 S~~

-

Only compounds with known purity (>98%) may

be

used for preparing chemical stand&. Gas standards should be used whenever possible. Liquid standards may be prepared in

the

laboratory,

8.2 Solvent

-

Solvent is used for preparing standards. Preferred solvent to use is methanol of chromatographic quality.

8.3 Tubes used for t h d desorption should

be

compatible with the thermal

desorption unit. Both single-bed and multi-bed tubes may be used depends

an

the VOCs of interest.

9. Ahorbents

and

tubes

9.1 Adsohnt

tubes

prepacked by manufac;lures should be conditioned

in

a tube mndttjoner at a temperature

just

below (I 0

-

25

"C)

the

maximum

recommended

tempemture of the least stable adsorbent

in

the tube for at least two hours with a pure, inert carries gas

of

at least

60

&min.

The carrier gas flow should

be

in

a direeticrn opposite to that

used

during sampling.

9.2

If

an

adsorbent tube is packed in the laboratory, cwh adsorbent should ideally be preconditioned separately under a flow of inert gas

by

heating it at a temperature at

least 2.5

"C

below the published maximum for that adsorbent for 16 hours befom packing

the tube.

To

prevent recontamination of the adsorbents, they should be kept

in

a clean atmosphere (under inert gas stream for example) during cooling to morn temperature, storage, and loading into the tubes.

Note 4

-

Imtsuctians of precondition and d i t i i o n for &orbents and pre-pmked tubes

provided by manufactures should be followed

if

such instructions are avuilabZe.

9.3 Prior to sampling (within 72 hours if possible), tubes should be cleaned in a tube conditioner for at least 20 rnin under conditions described in section 9.1. Wherever possible, analyticd desorption temperature should be kept below those used for cleaning.

9.4 For each batch of conditioned sample tubes, at least

one

tube should be checked under the same thema1 desosption conditions of the sampIe tubes.

lf

VQC

concentration in the blank is unacceptable (concentration of compound of interest in the

blank is greater than thne times the method detection limit or 111 '0 the concentration anticipated in samples), all tubes should be rexleaned according to section 9.3.

9.5 Once a sample has been analyzed, the tube may

be

=-us& to collect a further sample within 48 hours provided if the tube is tightIy sealed after mdysis. However* it is advisable to check the t u k (section 9.4) if the

tubes

are left far an extended period ('longer than 48 hours) before

re-use

or high concentrations were present

in

the previous sampIe.

Nore

5

-Always seal tubes wifh PXFE lined cap

d

store the tubes in an airtight

container when tubes are not being used.

10.

Calibration standads and Analytical system calibration 10.1 Preparation of calibration standards

10.1.1 Gas standards are purchased if they are commercially available or customer made by a manufacturer for special applications.

10.1.2 Liquid standards shouId be prepared in the laboratory as follows: (1) prepare

an

individual stock solution

by

weighing a known mount of chemical standard into a f 0 ml vial containing 10.0 rnl methanol which had been introduced using a volumetric pipette, and close the vial with Teflon lined cap immediately, (2) prepare a series of calibration standards by adding a known volume of stock solution using a syringe into a 10-mI volumetric flask half-filled with methanol, (33 fill the flask with methanol to the marker.

10.2 Preparation of standard tubes for calibration

10.2.1 Standard purchased in a pressurized gas tank is loaded onto multi-bed tubes through a 6port vdve (Figure 1). 6-port valve is mnntxted with a Imp. Gas is first introduced into the loop (e.g. 5-mL loop). The valve is switched afterwards and the gas sfmdard in the loop is quantitafively purged onto the tube under inert gas stream at a

flow sate of 100 rd/min. The total gas used for purge the standard is 500 ml(5 minutes). 10.2.2 Liquid standards are Ioaded onto the single-bed tube by the following procedure (Figure I): (a) use a syringe to draw accurately 1.0 pL of air, then 1.0 to 5.0 pL of Liquid solution depending

on

the quantity 0f standard, and finally another 1.0 pL of air, (b) insert the syringe through a septum that is part of a T-joint, (3) slowly introduce

the sdution in the syringe into a sample tube under inert gas stream (at a flow rate of

100

d m i n ) . This can be accomplished by slowly pressing the syringe plunger over a p e r i d of 10 (for 1 pL injection) to 30 (for 5

pL

injection) seconds to allow vaporization of

JRCmrRC CMEfAQ Report 1.4 (Nw/J997)

methanol

and

solute compounds in the gas stream,

The

inert gas is wnthared until the majority of methanoI is removed from the tube. The volume of inert gas needed depends on the types of adsorbents and the amount used in the tube, and should

be

predetermined. Note 6 - Mefhnol can rtor be removed dectively from multi-bed tubes containing strong adsarbents such as Ambersorb XE-340 in the rube. It is better to use single-bed tube with

medicrm strong adrorbent swh as

Terurx

or Cabotxap B/C SO prepare standard tuba for calibration. Met?uaml can be removed egedively with I

L

inert gas purge on such tubes.

20.3 Calibration of analytical system

10.3.1

An

initid calibration

for

GCIFII) andlor GUMS-SIM system should be conducted for each dynamic chamber test.

The

system is calibrated with &el

compounds and toluene at different concentrations (minimum five concentration levels over a range of at Eeast three order of magnitude). Linear caIibration m g e should cover anticipated concentrations of these compounds during dynamic chamber tests. The lowest concentration level should be at quantification limit level or anticipated Iowest

concentration in the samples whichever is higher, and the highest level should cover the expected maximum concentrations in the samples.

10.3.1.1

If

the testing objective is to measure the emission factors of target

individual compound, the ' I D - G U M S or TD-GCIFID system shall be calibrated for each individual compound with standards of the same componnd.

10.3.1-2

If

the testing objective is to m e w r e

TVOC

concentration, the

TD-

G C F D system or ?I)-GC/MS system shall

be

calibrated by using toluene as the

mfesence standard. The result shdl be reported as the concentration of toluene equivalent TVUC-by-GC/FJD or TVOC-by-GUMS, depending

on

which

system is used. GUMS systern

In

this case s h d be operated in full scan mode (20 to 350 m u )

and

peak areas of the total ion currency must be used.

10.3.1 -3

If

the testing objective is to measure both h concentrations of W O C and individual target compounds, the 'FD- system or TD-.GCIMS system shdl be

calibrated for both toluene and individual target compounds.

10.3.2

K

GGrFlD system is used for the quanfification, single point calibration checking shall be conducted on each day the system is used.

K

the result of such single p i n t checking deviates less Phan

f

10% from the initial calibration line, the initial calibration line shall be used to cealuIate the mass concentmtions. Othemise, problem shdl be identified and the system fully recalibrated

as

in

the

initial calibration.

10.3.3

If

G U M S system is used for the quantification, daily calibration shdl be conducted at two concentration levels (i.e., a two-point calibration) as a minimum. The low point should be where the linearity of the calibration curve starts or 10 times the

method detection limit, whichever is higher. The high point should be where the linearity of the cdibratiofi curve ends or the anticipated highest concentration in the samples,

whichever is lower. Results of this

daily

calibration shall be used to calculate the

concentrations if they deviate less than 10% from the previous day

and

less than 25%

from the initid calibration. Qthewise, problem shall be identified and the system fuIEy re-calibrated as in the initial calibration.

Note

7

-

Diferent culibrarion practices are specified for G W I D (section 10.3.2) and

GCMS (section 10.3-3) system b~cause a G W S system is utcally subjea to more day to

duy

variutions than a G W I D system

El.

GtYMS analysis for preliminary screening

1 1.1 Collection of gas samples from wet materials

1 1.1.1 Add about 5 to 10

aF

of wet material

in

a head s p w vial. Close tbe vial with a

PTFE

lined cap immediately aftemards. The vial should provide a head space at Peast 10 times the withdraw volume.

1 I.

1.2

Let the vial standing for at l e s t 2 hours at

room

temperature, or at an higher temperature if low VOC concentration in head space is expected.

B.

1.1.3 Use a gas tight syringe of proper

size

to draw 1 to 5 ml of gas

fmm

the

head space through a cap septum, depending an anticipated concentration.

Note 8

-

To avoid overlwding GCMS system, if is advisable to collect and analyze a smaller sample, and increase s m p l e size accordingly $the first sample size is too small.

11.1.4 Inject the gas sample unto an adsorbent tube. under inert gas stteam

in

the

s m e way as injection of liquid standard (section 10.2.2). Continue introduce 50D mZ,

inert gas through the tube after the gas sample is injected,

1

1.1.5

Thermally desorbe the sample t u b into GCJIdS system for analysis through a thema1 desorption unit.

1 1.2 Collection of gas samples from

dry

materials

1 1.2-1 Set

up

the sample container.

The

container should be large enough to

accommodate the large size of

dry

testing material. Cham- used for dynamic chamber tests or Tedlar bags with sample coIlectian fittings a r ~ suitable for this purpose.

1 1.2.2 Place the dry testing material in the container.

In

case

of

particle board or other large piece material, the material should

be

precut into a

size

that can be fit into the container. The material should not be cut into too small pieces to avoid alteration to the

1 1.2.3 Close the container and purge the container with

innen

carrier gas of two container volume and

then

let it stand for at least 24 hours, depending

on

the anticipated concentsation, to dIow

VOC

emissions accumulate in the container.

1 1.2.4 Force the gas

in

the

container

to a multi-bed &be using a pump at a proper flaw rate for a total of

I

to 5 Liter. A larger

volume may be

collected if low VOC

emission is expected.

11.2.5 Thecmally desorbe the sample tube into G U N I S system for analysis through a tke& desarption unit.

1 1.3 GCMS analysis for identification of

VOC

components

1 1.3.1 Tune the G U M S system

an

a daily basis. Aut-tune results must meet manufacturer's specifications,

1

1.3.2

Set

MS

in fill scan mode (20 to

350

mu)

and run

an

empty tube under standard

GC

oven temperature to check the G C / M S system background.

1 1.3.3 Run a sample tube under standard

GC

oven temperamre.

Note

9

- A standard

GC

oven imperature program fur

GC

w e n withod cryu-cooling settirrg is as follows: ser #ha initial iernperarure at 50

"

C@r holding it for 3 min,

increase the temperature to 250 a Qd5

*

Onin and holding it for 5 min fo a total of 48

min. A standard GC oven temperature program for GC oven with cryo-couling setting is mfolbws: set the initial temperature at -50

"

CqFer holding it for 3 mi- increase #he temperature to 250" Cat 10

"

Chin and holding it for 10 min $0 a total of43 min.

1 1.3.4 Run next two to five sample tubes using modified GC oven temperature pmgrarns to yield optimal separation of GC peaks. The total run time for

GC

separation should be wiithin 60 minutes, if possible.

1

1.3.5

Once the optimal

GC

temperature p r o m is found, analyze a standard tube loaded with 5 ml

of

toluene gas standard at (1 ppm) to generate a single response factor of

MS

detector. One level calibration

is

sufficient to estimate toluene-quivalent

TVOC

for samples.

Note 10

-

Toluene-equivnle~ TVOC

in

rhh case is fur the purpose ofcakukthg

sampling VQ Eum for srrbsequens dynamic chamber tests. Initial calibration shotcld be

perjonned for quantitative analysis of samples from dynamic chamber rests.

11.3.6 Cornpate the mass spectmrn of each peak with a standard mass spectrum library such

as

NBS

andfor Wiley libmy. Subtract the mass spectrum of the peak by mass spectrum of the baseline 5 scans prior to or after the peak before cornparing the

spectrum with library if high baseline is observed. Select the three mostly matched compound names for each peak from library.

1 1 -3.7

If

retention index is available, the identified compound

from

one of the three mostly matched compounds must be within

the

retention index window. Retention index window can be pre-established in the laboratory for the

G G M S

system.

1 1.4 Selection of model compounds

1 1.4.1 Select

three

to six major peaks from identified peaks at early, middle and late elution times as the model m p u n d s . Beaks that are not identifiable should not be selected as model compounds.

Nose 11

-

In some cases, peaks of individual components are combined into severaP

&maim of peak. ?Xis is a result of complex mixture of many structurally similar compounds in the sample. In such case, select three to six such peaks to represent three groups of c o r n p a d .

Note 12

-

It is not uncommon t h t the emission prqfils in the early and bter stages are

quite djjgesmf because the early emission contains a larger portion of more vohtile compounds. When selecting d lcompo&, GCppeaks at later elution range m y be selected e v m they are relatively smaller than those at earlier elution range in hehead space

anazysi~.

1 1.4.2 Analyst should work together with pmfessionaIs in dynamic chamber tests for the selection of model compounds.

If

possibb, VOCs with potential serious health concerns should be first considered as mode3 compounds.

1 1.4.3 Confirm the identity af selected model compounds with individual standards

by

analyzing a standard tube loaded with individual standards.

Nore 13

-

At this slage, m l y s t should define all experiment conditions fur a given testing mn~en'ol and save them under a spec@c rnethdfile which can be wedfor subsequenf dynamic chamber testing.

12,

Quantitative analysis of samples fmm dynamic chamber b t s

Note 14

-

Both GCFID and GUMS system can be usedfor quantitative analysis of samples from

dyrramic

chamber tests. The procedure described irt section 12 applies $0

both system mless otherwise specified

12.1 Prepare calibration standards containing made1 compounds and toluene (section 10.1) and standard tubes (section 20.23.

12.3

h a d

the analytical method file (created during p m c d n g ) . Each testing material should have a designated method file. Same t pof

GC

column and sinmilar

GC

oven temperature used for prescmning should be used for best peak recognition.

12.4 Analyze one empty tube to check the system background. 12.5

Run

the calibration stmWs (section 10.3)

Note 15

-

It is dvisabie 10 add clean subes (section 9.4) between sumpies to make sure

there Is no cross contamination.

12,6 Check all the integration results and manually c o m t integration lines if necessary.

12.7 Calculate the mass of compound in the tube (section 10.3).

12.8 Calculate the concentrations of a model compound

in

the chamber gas using the following equation:

Coa~enttation~ (ugfm3) = Massm (ngkarnple) I sample volume Q

53. Performance Criteria and Quality Assurance

13.1

Different building materials may have very different patterns and concentrations of VOC emissions. Therefore, analytical system (sample collection, introduction to GC, separation and selection of compounds e ~ . ) must

be

optimized for each testing materid.

13.2 Standard Operating Procedures (SOPS) should therefore be generated describing and documenting the procedures and experiment oonditions for each testing material or each type of testing materials. Specific stepwise instructions should be provided 3n the SOPS and should be readily available for the laboratory personnel responsible for wnducting the analysis.

13.3 Tdentification of peaks is completed

by

comparhg their mass spectra and relative retention indices to a standard Zibrarqr. Each laboratory

should

have the access to

the standard mass spectrum library and establish relative retention index for as many VQCs as possible.

In

addition, all peaks selected as model compounds must be verified with individual chemical standards.

13.4 The analytical system must meet performance criteria that are given in Table 1.

The

definition of each criterion is describd as follows.

13.4.1 Detection limit

(DL)

is defined as 3.14 (the Student's t vdue for 99 percent

replicate measurements at a concentration level that is one to five times the expected detection limit.

13.4.2 Quantification limit (QL) is defined as h e level at which the system can produce reliable quantitative results.

me

relative standard deviation at quantZcation limit must

be

less than 30 %.

For

practical reasons,

the

quantification

limit

in

this document is defind as three times the

DL.

13.4.3 Tube blank is the

VOC

residue detected in

an

adsorbent tube without sample being collscted, It is independent from sample volume. Chamber blank is the VOC concentrations in chamber air under exact dynamic testing experiment conditions (including specimen holder) without sample specimen. Chamber blank is therefore dependent on air volume collected.

13.4,4 The maximum difference between the duplicate pair samples (%Diff) is defined as the difference between the two samples divided by the mean values of the duplicate.

13.4.5 Accuracy is defined as difference between spiked and obsetved values divided by true value.

For

practical reasons, a spiked vdue is consided a 0

be

the true value.

[ I Observed vdwe

-

True vduel ]

Accuracy, % = f 1

-

) x 1 0 %

True value

13.

Reference

(I) This metbod is primarily used to support chamber tests

for

VCX

emissions Wrn building materids such as hose described

in

documents entitled "Standard 'Practice

for Determination of Volatile Organic Compounds (excIuding formaldehyde) Emissions from Wad-based Panels Using Small Environmental Chambers Under Defined Test Conditions" and "Standard Practice for Determination of Volatile Organic Compounds (excluding formaldehyde) Emissions fmrn Surface Coating Materials Using Small Environmental Chambers Under Defined Test Conditions" which is being developed at IRC,

NRCC.

(2) Tsuchiya,

Y.,

&mabus-Wnska, J.M. (1 9963 "Identification and Quantification of Volatile Organic Compounds Using Systematic Single-Ton Chromatograms'"

h:

Volatile Organic Compounds in the Environment, ASTM STP 1261,

W.

Wang, J. Schnoor and J. Doi, eds., American Society for Testing and MateriaIs, pp. 127-138.

Table 1. Generat Criteria for analytical system performance based

on

maximum sample volume

of 20

L

Criterion Performance Criteria

Detection Limit (GCIFID) 1 ndsample tube (1 n g L for 1

L

sample) Detection Limit (GUMS-full, scan) 1 nglsample tube (1 agL far 1

L

sample) Detection Limit ( W S - 5 l h . I ) 0.1 nglsmple tube (0.1 n g L for 1

L

sample)

Qumt Limit (GUMS-FD)

3

nglsamp3e tube

Quant Limit (GCMS-full scan) 0.3 nglsample tube Qumt Limit (GClMS-SM) 0.3 nglsample

tube

T u k blank 10& of the lowest VOC amaunt

in

sample tubas Chamber blank 1 0 ~ of the lowest

V W

concentration in

&sorption Efficiency

;

90 % for model compounds

Precision of duplicate sample BDiff S 10 %

for

model compounds Accuracy at 10

times

the

DL

leveI within +/- 10 % of the true value

Calibration mge (GCYFD) min. ld (e.g. 3.0, lO,50,300,30M)ng) Calibration range (GUMS-full min. lo3 (e.g. 3.0, 10,50,30a, 3000 ng) ~alibration m g e (GC/MS-SXMJ I).

ld

(e.g. 0.3, 1.0.5.0.30.300 ng)

I R m R C CMEIAQ rep^ 1.4 (NmII997)

Valve

figure 1: Standard tube preparation schema Gas standard pu~chascd in prcssurizcd tank is introduced to the thermal desorption tube through 6-port valve while liquid standard or smdard taken into a syringe is introduced through a Tee tube (e.g. made of Swagelok) via a septum,

JRGshRC CMEIAQ Report 1.4 {NovfI997)

Appendix 1: Experiment Conditions for

Analysis of Emissions f m P m l i e l e b d Samples Method: WOOD1

1. Model compounds:

hexanal, octaml, nonanaE,fLtruEdehyde, l o n g i f o h 2. Thermal desorpaion:

b) Sample tube:

6mm

OD

x 15 m (glass be&/Ted/Ambeersorb

XE-340)

c) Desorption:

Sample tube desorption: 240 O C

(9

ntin.

60

mUmln)

First trap desorption: 240 'C (20 mumin) Second trap desarption: 240 "C (1 mVrnin)

d) Transfer line temperature: 200 "C

3. GC Oven Temperature:

a) Initial temperature: 50

"C

b) Initial temperature hold: 7,5 mfPUn

c) Temperature

ramp

1 : 2 O C / i r r i n to 110 OC d) Temperature hold: 0 nth

e) Temperature ramp 2: 15 "Urnin to 240 OC

f) Final temperature hold: 5 min

a) mass range: 20 - 350 m u .

b) Ion source temperature: 200

"C

c) Electron impact voltage: 70 eV