# Standard Operating Procedure for Generating a Quantitative Multi-Metals Reference Aerosol with the CES QAG

Prepared by : Cooper Environmenta l Services, LLC 10180 SW Ni m bus Blvd Suite J6 Portland, Oregon 97223



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# Standard Operating Procedure for Generating a Quantitative Multi-Metals Reference Aerosol with the CES QAG

June 9, 2005



# DRAFT

Submitted to: The Environmental Protection Agency Research Triangle Park, NC

Prepared by: J.A. Cooper, B.E. Johnsen, K. Petterson, C. A. Yanca, M. Nakanishi, D. Barth Cooper Environmental Services 10180 SW Nimbus Blvd Suite J6 Portland, Oregon 97223

# Standard Operating Procedure for Generating a Quantitative Multi-Metals Reference Aerosol with the CES QAG

Prepared by:___________________________________ Date:_________ Catherine A. Yanca, Environmental Scientist Reviewed by: ___________________________________ Date:_________ Krag A. Petterson, Environmental Scientist Reviewed by: ___________________________________ Date:_________ Bruce E. Johnson, QA Manger Approved by: ___________________________________ Date:________ John A. Cooper, Director

### Executive Summary The QAG is a reference aerosol generator that produces a NIST-traceab le aerosol of known analyte concentration. In the QAG, a NIST-tr aceable or equivalent solution containing an analyte or analytes of interest is conveyed to an aspirator wh ere it is combined with a gas and nebulized to for m an aerosol of liquid droplet s. The sm aller droplets continue through the system and are dr ied. T h e resulting salt p a rtic les and/or vapo rs are then e m itted f r om the system as a reference aerosol of known concen tration. Specifically, the QAG is used to generate a N I ST-traceab le reference aerosol that contains a kn own con centration of m e tal. This m e thod can be used to spike controlled a nd uncontrolled em issions as well as laboratory air for th e p u rpose of evaluating the accuracy an d precision of aerosol measurem ent m e thods and/or calibration of m e thods. The QAG’s generated aero sol concentration ( ) is process traceable to NIST through the traceab ility of its co mponents. The gene rated concentration is a function of the concentration of the solution standard ( ), to tal f l o w rate ( F a-QAG i C

s-QAG i C t ), rate of m a ss loss of the solution ( R m ), and rate of vapor loss ( R v ). Process traceability to NI ST is established by using instrum e nts that are NIS T -traceable (e.g., calibra ted with NIS T standards) to m easure these param e ters. One exception is the standard solu tion used to generate the aerosol; solutions with NIST-traceab le accuracies are either prepar ed in the labo ratory o r purchased from an outside vendor. There are five m a jor components of a nebul izer-based QAG, as described below: 1. The standard solution control system is required to transport the analyte-containing solution to the point of nebulization. This sy stem is needed to regulate the flow of the solution f r o m the rese rv oir to the ne buliza tion c up and dete r m ine the solution m a ss loss rate. A peris t altic p u m p is inclu d ed for cycling the NIST-traceab le so lution through the nebulizer cup as we ll as a laptop connected to a balance for m easuring the m a ss loss of the solu tion

. 2. The nebulizer air control system is us ed to establish and m easure the flow, tem p erature, pressure an d sa turation of the air used in the nebulization process (i.e., nebulizer air). This section of the QAG uses filtered and saturated com p ressed air to crea te the in itial so lution drople t aero s ol. 3. An ice bath f o r is neede d to m a intain the tem p erat ure of the nebulizer air at or near 32°F. 4. The nebulizer and vapor size control system is used for creation of the aerosol. It consists of three m a jor com ponents: the nebulizer cup, the nebulizer and nebulizer nozzle and the nebulizer settling

- equ ilib rating ch am ber. The nebulizer cup contains the standard solution. This solu tion is continuously circu l ated from the nebulizer cup to an ex ternal reservoir in order to m i nim i ze the im pact of va por loss on solution concentra tion an d allow f o r determ inatio n of the solution m a ss loss rate. T h e standard soluti on is aerosolized by a nebulizer, located inside the nebulizer cup. The nebulization process creates a dropl et spray containing

Instru m e ntal Meth od f o r a QAG: V1. 0 Page i of via wide range of droplet sizes. The larg est droplets im pact on the walls of the nebulizer cu p and are recycled. The sm aller dro p lets are en trained in the nebuliz er a i r f l ow and pass into th e se ttling

- equilib ration chamber. The f unction of the nebuliz er settling

- equilibr a tion cha m ber is to re move and re cycle a ll d r o p lets g r ea ter than 30 μm in diam e t er as well as to assure droplet -vapor equilibrium at 32°F. Thus, the only drople t s em itted into th e drying cham ber have d i a m eters less than 30 μm and have been equilibrated with water vapor at 32°F. 5. The drying air and drying cham ber with te m p erature and flow control is needed for drying the liquid aerosol into sa lt pa r tic les. Heated C DA (term e d “drying air” ) is introduced into the drying cham ber for this purpose. The final product of the QAG is an aerosol cont aining dried salt particle s of the analyte or analytes. T h e concentration of the analytes in th e aeroso l an d the c oncen tra tion unce r tain ty are calculated fro m the QAG’s recorded para m e ters. The uncertainty of the generated aerosol concentration is determ ined using stan dard propagation of erro r techniques relevant to those param e ters. The uncertainty values fo r th e param e ters are thos e lis t ed as certified uncertainties by the m a nufacturers and/or NIST.

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### Table of Contents
Executive S u mmary ................................................................................................................. i List of Symbols .........................................................................................................................v List of Figu res ......................................................................................................................... vi 1.0 Principle a nd Applicability
........................................................................................ 1 1.1 Principle

................................................................................................................ 1 1.2 Applicability

......................................................................................................... 1 2.0 Range of Emission Characteristics
............................................................................ 1 2.1 Concentration

........................................................................................................ 1 2.2 Flow

...................................................................................................................... 1 2.3 Particle Size

.......................................................................................................... 1 2.4 Tem p erature

.......................................................................................................... 1 2.5 Species

.................................................................................................................. 1 3.0 Definitions
.................................................................................................................... 2 4.0 Operational Specifications
......................................................................................... 4 4.1 Nebulizing Air Flow Rate (Fe)

............................................................................. 4 4.2 Nebulizing Air Pressure (P c )

................................................................................. 4 4.3 Nebulizing Air Tem p erature

................................................................................. 4 4.4 Nebulizer Cup Tem p erature

.................................................................................. 4 4.5 Ice Bath Temperature

............................................................................................ 4 4.6 Drying Air Flow Rate

........................................................................................... 4 4.7 Drying Air Tem p erature

....................................................................................... 4 5.0 NIST-Traceable Specifications
.................................................................................. 4 5.1 Mass Loss

.............................................................................................................. 5 5.2 Flow Rate

.............................................................................................................. 5 5.3 Rate of Vapor Loss

............................................................................................... 5 5.4 Solution

................................................................................................................. 5 6.0 Apparatus
.................................................................................................................... 6 6.1 Quantita tive Aerosol Ge nerato r
............................................................................ 6 6.2 Standard Solution Control System

........................................................................ 6 6.3 Nebulizer Air Control S y stem

.............................................................................. 7 6.4 Ice Bath

................................................................................................................. 8

Instru m e ntal Meth od f o r a QAG: V1. 0 Page iii of vi6.5 Nebulizer and Vapor Size Control S y stem

........................................................... 8 6.6 Drying Air and Drying Cham ber System

............................................................. 9 7.0 Supplies
...................................................................................................................... 10 7.1 Standard Solutions

.............................................................................................. 10 7.2 Com p ressed Air

.................................................................................................. 11 7.3 Ice Bath

............................................................................................................... 11 8.0 Pre-Test Performance Evaluation Procedures
....................................................... 11 8.1 Pre-Test L a boratory P r eparation

......................................................................... 11 8.2 Pre-Test F i eld Preparation

.................................................................................. 12 8.3 Solution Co ncentr ation and Flow Rate Dete rm ination

....................................... 13 8.4 Solution Sa mple

.................................................................................................. 13 9.0 Generation of a Reference Aero sol w i th NIST-Traceable Accuracy
................... 13 9.1 System Preparation

............................................................................................. 13 9.2 Solution Exchange

.............................................................................................. 14 9.3 Flow Rate and Tem p erature Adjustm e nts

........................................................... 14 9.4 Aerosol Generation and Perform a nce Monitoring

.............................................. 14 9.5 Docum e ntation of Perform a nce
.......................................................................... 14 9.6 Shut-down

........................................................................................................... 15 9.7 Post-Test P r ocedures

........................................................................................... 15 10.0 Calculation s ............................................................................................................... 15 10.1 Generated A e rosol Conc entra tion

....................................................................... 15 10.2 Generated A e rosol Conc entra tion Un certainty.

.................................................. 16 10.3 Solution Co ncentr ation and Flow Rate Set Poin ts

.............................................. 17 10.4 Aerosol Em ission Size

........................................................................................ 17 11.0 Documentation of Quality Control and Assura nce ............................................... 18 11.1 Certif ica tion s
....................................................................................................... 18 11.2 Field Data R ecords

.............................................................................................. 18 12.0 Pollution P revention
................................................................................................. 18 13.0 Waste Man agement .................................................................................................. 18 14.0 Figures and Tables
.................................................................................................... 19 15.0 References
.................................................................................................................. 23

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### List of Symbols

QAG a i C − = Concentration of the i th elem ent in the reference aerosol generated by the QAG.
QAG s i C − = Concentration of the i th elem ent in the standard solution used for the QAG.

liq D = Diam eter of the liquid droplets in the aerosol.

salt D = Diam eter of the sa lt pa rticles in the a e rosol.

e F = Flow of exp a nded ne bulizer air in the QAG.

t F = Total com b ined flow of the nebul izer air and drying air in the QAG.

v M = Mass of water vapor in a liter of satu rated air.

c P = Absolute pressure of the com p ressed nebulizer air in the QAG.

e P = Pressure of the expanded nebulizer air in the QAG.

m R = Total rate of solution m a ss loss for the QAG.

v R = Rate of vapor loss of the QAG standard solution.

salt ρ = Density of the analy t e s a lt in the Q AG. ρ liq = The density of the liquid droplet in the QAG.

σ = One standard deviation.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page v of vi

### List of Figures Figure 1: A. Schem a tic of flow through QAG co m ponents. B. Overview of the set-up of the CES QAG.

............................................................................................................. 19 Figure 2: Schem a tic of the CES QAG standard solution control system

. .............................. 19 Figure 3: Schem a tic of the CES QA G nebulize r air con t ro l s y stem

. ...................................... 20 Figure 4: Schem a tic of the CES QAG nebu lizer and droplet si ze con t ro l system

. ................ 20 Figure 5: Schem a tic of the CES QAG drying air and drying cham ber system

. ..................... 21

Instru m e ntal Meth od f o r a QAG: V1. 0 Page vi of vi

### 1.0 Principle and Applicability
1.1 Principle A solution containing an analyte or analytes of inte res t is con v eyed to an aspirator wh ere it is com b ined with a gas and nebulized to for m an aerosol of liquid droplets. The sm aller droplets continue through the system and are dr ied. The resulting salt particles and/or vapors are th en em itted from the system as a referenc e aerosol of NIST-traceable concentration.
1.2 Applicability This m e thod is applicable to spiking cont rolled and uncontrolled em issions as well as laboratory air for the purpose of evaluati ng the accuracy and p r ecis i on of aerosol m easure m ent m e thods and/or calibration of m e thods.



### 2.0 Range of Emission Characteristics
2.1 Concentration The concentration of an analyte in the ge nerator em issions can range between 0.001 and 1000μg/m 3 depending on the solution concentrat ion, nebulizer configur ation and the total flow of air through the Cooper Environm ental Se rvices (CE S ) quantitative aerosol generator (QAG).
2.2 Flow The total flow of e m issions can range from 10 to 1000 slpm . Total flow is dependent on the nebulizer configuration, nebulizer air flow and the flow of dr ying air.
2.3 Particle Size The size of the dried s a lt particle s is determ in ed by the solution concen tration and the liquid droplet size. The QAG s hould be operated such that the estimated physical diam eter of the salt particles is less than 3-4μm (Section 10.4).
2.4 Temperature The output tem p erature of the QAG em issi ons can be set between 200 and 400°F. Tem p eratures downstream of the QAG m u st be above the dew point of the em itted aerosol but can be as high as the required application.
2.5 Species The QAG pr inciples are generally applicable to a wide range of analytes and solvents (organic and inorganic). However, the applicat ion described in this m e thod is for inorganic

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 1 of 23m e tal salts in aqueous solutions. This can in clude soluble salts of elem ents ranging from atom ic number 3 (Li) to 92 (U).



### 3.0 Definitions Aerosol Generator Sys t em : System in which analytes c ontained within a solution are aerosolized, separa ted ba sed on size, dried, and e m itted.
Aerosol: A suspension of solids and/or liquids in a gas at various relativ e concentrations. Analyte: A species (elem e nt, m e tal, etc.) of interest in an analytical m e thod. Analytically NIST Traceable Para meter: A param e ter whose value is traceable to N I ST through a m easurem ent that is NIST traceable 1

. Applicable Concentration Range: The range of concentrations over which a QRAG m u st be able to produce an aerosol of NIST-traceable or equivalen t analy t e con c entration to be used for a given application. Aspiration: The process by which a liquid is drawn from a r e servoir through a narrow tube by creating a vacuum above the tube with fast moving air. Atomiz ation: The process of converting a liqui d into sm all suspended droplets. Certified Concentratio n Range: R a nge of concentrations for which the QAG is certified. Drying Air: Air added to the QAG at the point of the dr ying cham ber that is used to help dry the ae rosoliz e d liqu i d dro p lets into s a lt par tic les. Generated Aerosol Concentration : The concentration of the aerosolized m e tal at the point of e m ission from the QAG. This concentrati on is a function of the solution concentration, tota l f l ow, rate of m a ss loss a nd rate of vapor loss; it can be calculated using Equation 1. Key Component: A piece of equipment or instru m e nt that measures any param e ter used to determ ine the generated aerosol concentration. Linearity: The degree to which two param e ters are linearly related as determ ined by the value of the slope and correlation coefficien t of a least squares regression analysis. Main Flow : Flow of gas through the aerosol genera tor, transport/inte rface, and sam p ling system

. Make Up Flow (Air or Stack Gas): Flow of air and/or stack ga s added af ter the ae ros o l is em itted from the QAG either before or as part of the trans port/interface system

.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 2 of 23Nebuli z ation: A size-lim iting atomization process in wh ich larger droplets are rem oved from the aerosol through im paction o r sedim e ntati on prior to b e ing em itted from a nebulizer. Nebuli z er Air: Air flowing into the nebulizer that is com b ined with the NIST-trac e a ble solution to c r eate the a e r o soliz ed m e tals. NIST: The National Ins titu te of Standa rds and Technology, Gaithersbu r g, MD. Particula t e: A partic le o f solid or liq u id m a tter. Process NI ST Traceable : A parameter whose value is traceable to NIS T through a procedure, the steps of which are each NIST traceable

. Quantita tiv e Aerosol Generator (QAG) : An aerosol generator system that uses analytes of known concentrations in aqueous solution to create aerosol em i ssions of known m e tal concentrations. Quantita tiv e Reference Aerosol Generator (QRAG): An aerosol generator which em its an aerosol of k nown analyte concentration that is N I ST or equiv a lent traceab le. Sampling System: A collection of integrated component s designed to collect a portion of an aerosol that accurately represen ts an analyte con centration. Stability: P e rcen t relative standard de viation of a value m easured over an extended period of tim e. Standard: Som e thing established by authority, cust om , or agreem ent for use as a rule or basis for co mparison in m easurem ent. Standard deviation : A param e ter th at ind i cates the way in which a probability function or a probability density function is cente red around its m ean and that is equal to the square root of the m o m e nt in which the deviation from the m e a n is squared.
Total Flow : The com b ined flow of nebulizer air a nd drying air within the aerosol generation system . Total flow does not include air added to the transport system af ter the ae rosol exits the QAG. Traceability to NIST: A docum ented procedure by which a m easured response is related to a standa rd with an a ccura cy def i ned b y and cer tif ied by the Na tiona l Ins titu te of Standar d s Technology (NIST). Traceability: A property of the result of a m easurem ent or the value of a standard whereby it can be related to stated references, usually na tio nal or inte rn ationa l stand a rds, th roug h an unbroken chain of com p arisons al l having stated uncertainties 2

. Transport/Interface Component: That portion of a test arrangem e nt that connects the QRAG to the point wher e the ae rosol will be ev aluated.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 3 of 23Uncertainty : An indication of the degree of reli ability of a value usually expressed statistica lly (probability) as a m u ltiple of the stan dard deviation of a set of m e asurements. Unless othe r w ise sta t ed, the unce r ta inty in a m ean value of a serie s of m easurem ents will be the standard deviation. In the case of values based on calculations, th e uncertainty in the value is equ a l to the pro p agated uncertainty ba sed on the uncertainties in the param e ters used in the c a lcu l ations.



### 4.0 Operational Specifications The following operational specifications m u st be m e t to ensure the QAG is functioning properly and the generated aerosol co ncen tration can be accu rately d e termined.
4.1 Nebulizing Air Flow Rate (Fe) The flow must be set be tween 10 and 11 liters per m i nute corrected to 32°F.
4.2 Nebulizing Air Pressure (P c ) The pressure m u st fall in the range of 15 to 20 psi-gauge. 4.3 Nebulizing Air Temperature The tem p erature of the nebulizing air m u st be between 32 and 33°F.
4.4 Nebulizer C up Temperature The nebulizer cup tem p erature m u st fall in the range of 30 to 34°F.
4.5 Ice Bath Temperature The ice bath m u st be kept between 32 and 33°F.
4.6 Drying Air Flow Rate The flow rate m u st be between 25 and 75 slpm

. 4.7 Drying Air Temperature The drying air tem p erature m u st be between 220 and 400°F.



### 5.0 NIST-Traceable Sp ecifications
In addition to m eeting the above operati onal specifications (Section 0), the QAG’s param e ters must be confirm e d as NI ST-traceab le. The generated aero sol concentratio n is

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 4 of 23process traceable to NIST through th e tr aceability of the QAG’s key components , . T h e aerosol concentration is a func tion of the concentration of th e solution standard, total flow rate, rate of m a ss loss of the solution, and ra te of vapor loss (Equation 1 and Equation 2). This process traceability to NIST is establ ished b y m eeting th e f o llowing specif i ca tion s : 5.1 Mass Loss The QAG so lution rate of m a ss loss ( R m ) is determ ined by the balance, which m u st be calib rated in the field with NIST-traceable m a ss standards. B a lance readings m u st be ± 1% of the standard value and certification of the m a ss standards must be current. 5.2 Flow Rate The QAG’s flow param e ters, total flow rate ( F

t ) and flow rate of the expanded nebulizer air ( F e , used to calcu late th e rate of vapor loss ( R v ); E quation 2), are m easured by flow m e ters. The flow m e ters m u st be calibrated to ± 2% in the f i eld with a prim ar y flow calibrator such as the DryC al® 3 . The NIST standard certifi cation must be current.
5.3 Rate of Vapor Loss The rate of vapor loss ( R v ) is dependent on the tem p eratur e and pressure of the expanded nebulizing air ( P e ) as well as the pres sure of the com p ressed nebulizing air ( P c ; Equation 2). In addition, the vapor loss rate re quires that the nebulizing air be saturated with water vapor at 32°F. This is assured by m easuring the te m p erature of the nebulizing air with a NISTtrac eable the r m o m e ter to conf irm that it is 32 ± 1°F. The condition of saturation is assured by first passing the nebulizer air through a bubbler at room te mperature and then through a condenser at 32°F. 5.3.1 Temperature The m a ss of water vapor in one lite r of saturated air is a referenced valu e at 32°F 4 . The operato r m u st confirm that the tem p erature of the nebulizing air is m easured using a NIST-standardized therm o m e ter with current certification.
5.3.2 Pressure The operator m u st confirm that the ambient pr essure and the absolute pressure of the com p ressed nebulizing air upstream of the nebulizer are m easured using a NISTtraceable pressure gauge with current certification.
5.4 Solution The analyte solution m u st be prepared using a NIST-trac eable standard of the analyte(s). The operator m u st confirm that the st andard certification has not expired.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 5 of 23

### 6.0 Apparatus
6.1 Quantitative Aerosol Generator Use any aerosol generator to generate a referenc e aerosol that m eets the s p ecifications of this m e thod. A s c hem a tic of the CES QAG is shown in Figure 1. The five m a j o r com pone nts of a nebulizer-based QAG include: 1. A standard solution control com ponent requir ed to regulate the flow of solution from the reservoir to the nebulization cup and de term ination of the solution m a ss loss r a te. 2. A nebulizer air control com ponent that establishes and m easures the flow, tem p erature, pressure an d satu ration of the nebulizer air. 3. An ice bath f o r m a intain ing tem p erature of the ne bulizer air at or near 32°F. 4. A nebulizer and vapor size control and equilibration. 5. A drying air and drying cham ber with tem p erature and flow control.
6.2 Standard Solution Control System This section of the QAG includes a peristaltic pump to cycle the NIST-traceable solution through the nebulizer cup and a laptop connected to a balance for m easuring the m a ss loss of the solution (Figure 2). 6.2.1 Solution Reservoir The solution reservo i r m u st be large enough to h o ld a m i ni mum of 1 liter of solution and sm all enough to fit com p letely and securely on the balance. It m u st be insulated with foam to prevent m o isture from condensi ng on the outside of the reservoir. Note: it is im portant tha t the e x trac tion an d return of solution tubing not touch any part of the reservo i r. 6.2.2 Solution Transport Line Noroprene or equivalent tubi ng is used to transport the solution through the solution system

. 6.2.3 Peristaltic P u mp A two-headed peristaltic pum p is us ed to ci rculate the NIST-traceable solution between the solution reservoir and the nebulizer cup. The solution is pushed into the cham ber at a rate of 15 m l / m in and pulled out of the cham ber at a rate of 17 m l/m in. 6.2.4 Balance The NIST-traceable solu tion and its reservoi r are placed on a balance located next to the nebulizer/drying chamber assembly. The balance is us ed to m easure the m a ss of the solution being condensed by the QAG.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 6 of 236.2.5 Computer A com puter is connected to the balance and is used to record the changing m a ss of the NIST-traceable solution continuously with cu stom software. These data are used to determ ine the rate of reservoir m a ss loss ( R m ), which is the slope of the recorded reservoir m a ss over tim e
. 6.3 Nebulizer A i r Control System This section of the QAG uses com p ressed air to create the initial so lution droplet aerosol (Figure 3). 6.3.1 Nebulizing Air Lines Stainless steel, PFA or equivalent tubing is used to transport the nebulizing air through the saturator, im pinger, and nebulizer. 6.3.2 Filter Units Filte r units a r e used to re move oil an d other pa rticles f r om the nebulizing air.
6.3.3 Pressure Regulator Downstream of the f ilter units, a p r ec ision pr essur e regulator is needed to contro l the pressure of air flowing into the QAG system to a no m i nal pressure of about 18 psi that is regulated to ± 0.5 psi-gauge. 6.3.4 Flow Meter A flow m e te r is required for determ ining the flow rate of the co m p ressed air which is used to calculate the flo w rate of the expanded nebulization air ( F

e ). This flow rate which m u st be set to a pre-determ ined valu e based on the desired concentration of the aerosol em ission (Section 10.3). 6.3.5 Ball Valve
A m a nual two-way ball valve is used to s hut-off the flow of air to the nebulizer.
6.3.6 Ambient Temperature Saturator The am bient tem p erature saturator is a bubbler h a lf-filled with water. The nebulizer air is pushed through a PFA-coated stainless st eel chamber and is bubbled through water to assure saturation with water vapor at r oom temperature. T h e saturator should be checked and refilled at least once a d a y.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 7 of 236.3.7 Condenser Nebulizing air passing through the condens er is cooled to and saturated at approxim a tely 32oF. The c ondenser should be checked a nd emptied at least once a day.
6.3.8 Pressure Gauge A NIST-traceable pressure gauge is used to m easure the p r ess u re of the co mpressed air flowing into the nebulizer ( P c ).
6.4 Ice Bath Downstream of the am bi ent tem p erature satu rator, the nebulizer air is pushed into a container filled with ice and water m a inta ined at approx imately 32 o F. The condens er, nebulizer cup (which contains th e neb u lize r), and nebuliz er se ttling

- equilib ration chamber ar e all h oused within this container. T h e container s hould have a therm o couple and therm o m e ter for monitoring the tem p erature of the ice bath and a drain to rem ove water. 6.5 Nebulizer D r oplet Size Control System This section of the QAG consists of three m a jor co m ponents (Figure 4): 1. Nebulizer and nebulizer nozzle 2. Nebulizer cup 3. Nebulizer settling-equilibrating chamber
6.5.1 Nebulizer and Nebulizer Nozzle A NIST-traceable solution of known m e tal c oncentration is aerosolized by a nebulizer, such as a Co llison n e bulizer 2 , loca ted inside the n e buliz er cup (see Figure XX-2). The cooled and saturated nebulizing air leaves the condenser and is pushed through the nebulizer nozzles. The bottom of the nebulizer nozzle is located about 3/8 of an inch below the su rface of the solution. Th e nebulizin g air is forced across the surface of the capillary tub e causing th e soluti on to be drawn into the high v e locity air stream . This process creates a droplet spray containing a wide range of droplet sizes. T h e largest droplets im pact on the walls of the nebuliz er cup and are rec y cled. The s m aller drople t s ar e entra i ned in the nebulize r air f l ow an d pass into the settling

- e quilib ration cham ber. 6.5.2 Nebulizer C up The nebulizer cup contains the standard solution. This solu tion is continuously circu l ated from the nebulizer cup to the ex ternal reservoir in order to m i nim i ze the im pact of va por loss on solution concentra tion an d allow f o r determ inatio n of the solution m a ss loss rate.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 8 of 23A therm o couple attached to the neb u lizer cup is connected to a NIST-traceable therm o m e ter in order to m easure the tem p er ature of the cup. The tem p erature of the cup m u st be kept at 32°F , which is the effective tem p erature of M v , the te rm f

o r the m a ss of water vapor in one li ter of saturated air.
6.5.3 Nebulizer Settling-Equilibration Chamber The function of the nebulizer settling-equilibration cham ber is to rem ove and recycle all droplets greater than 30 μm in diam et er as well as to assure droplet-vapor equilibrium at 32°F. Thus, the only dropl e t s em itted into th e drying cham ber have diam eters less than 30 μ m and have been equilibrated with water vapor at 32°F.
6.6 Drying Air and Drying Chamber System The drying air is heated and used for drying the li quid aerosol into salt par tic les. In this part of the QAG, clean dry air (CDA) ai r is required (Figure 5). 6.6.1 Drying Air Lines Stainless steel, PFA or equivalent tubing is used to transport the CDA through the tube heaters and into the drying cham ber. 6.6.2 Filter Units Filte r units a r e used to re move oil an d ot her pa rticles f r om the drying a i r. 6.6.3 Pressure Regulator The pressure regulator on the drying air line is us ed to adju st the flow of drying air to the desired f l ow rate. 6.6.4 Drying Air Flow Meter The drying air flow m e ter is used to m eas ure the drying air flow for the purpose of adjusting the pressure regulator. 6.6.5 Tube Heaters The drying air is split in to two lines downs tream of the flow m e ter and each line is passed through a tube heater just before the air enters the drying cham ber. Both heaters are m a intained at 300 ± 20oF. 6.6.6 Drying Air Ring After being heated by the tube heaters, the dry i ng air en ters the drying chamber through a series of holes in the drying air ring. T h e air increases the drying rate of liquid droplets and acts as an air curtain that keeps the droplets from i m pacting the cham ber walls.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 9 of 236.6.7 Drying Chamber The nebulized liquid droplets from the ne bulizer settling-equilibration chamber are com b ined with the drying air in the drying cham ber, which is heated to approxim a tely 250oF. The droplets are dried in the cham ber and the resulting aerosolized m e tals are em itted into the transpor t system

. 6.6.8 Drying Chamber Heaters The drying cham ber is heated by a tape heat er or a blanket heater m a intained at approxim a tely 250oF. 6.6.9 Flow Meter A flow m e te r is required for dete rm ining the tota l f l ow rate ( F

t ). The user can determ ine th e tota l f l ow by eithe r (1 ) m easur ing the drying air flow rate with a flow m e ter and adding this to the nebulizer air flow rate, or (2) m easuring the main flow rate with a flow m e ter and subtracting a ll f l ows except the to tal f l o w
.


### 7.0 Supplies
7.1 Standard Solutions The QAG g e nerates an aerosol with NIST-tra ceable accuracy based on the NIST-traceable accuracy of the standard solution s used. These so lutions are consum ed at a rate of about 5 to 10 m l/hour. An adequate supply of solutions at various concentra tions required by a test plan should be prepared prior to the testing. The primary requirem ents of the s e solutions are that (1) the accu racy of the analyte c oncentrations be NIST-trac e able (2) the s o lutions b e s t able over the p e riod of their u s e and (3) th e calcu lated diam eter of the resul ting dried sa lt p a rticles be less than 4μm (Section 10.4). 7.1.1 NIST-Traceable Accuracy Solutions with NIST-traceable accuracies can be prepared in the laboratory or purchased from an outside vendor. Solution ac curacies are generally expected to be bette r than 0 .5% at the 9 5 % conf iden ce leve l. At these accuracies, uncertainties in standard solution concentrati ons are insignificant contributor s to the uncertainty of the generated aerosol concentration.
7.1.2 Standard Solution Stability The stability of the standard solution over a pe riod of m onths is generally assured if the m e tal analytes are p r epared as nitrates in 1% nitric acid solutions . Other m e tal analyte salts and acids m a y be used, but stability n eeds to be docum e n ted either by laboratory testing or by vendor certification. Particul ar care should be taken when using standard solution s with m u ltiple a n alyte s to as sure ana l yte stability.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 10 of 237.1.3 Solution Volume The volum e of standard solution prepared shoul d generally be at leas t 2 liters or m o re. Although only a fraction of this volum e m i ght be used, the larger volum e is required by the solu tion reservo i r to m i nim i ze solution c oncentration in creases due to evaporation over the tes t period. Un der norm a l operati ng con d itions, the s o lution concentration increase is less than 1% over test periods of about 10 hours, or about 0.1% per hour, which is usually insignificant fo r test periods of a few hours. 7.1.4 Analyte Concentration The concentration of analytes in the s t andard so lu tion is contr o lled so as to be less than the concentration that w ould resu lt in dried sa lt particle s with diam eters greater th an about 4μm ( S ection 10.4). W ith nitrates in nitric acid solutions, th is will generally be the case if the dissolved solids are less than about 500 to 1000 ppm

. A single m e tal analyte concentration of about 100 p p m will resu lt in an aero s ol concen tration of abo u t 100 μg/m 3 if the typical QAG operating conditions ar e used with a total f l ow of about 100 slpm . Thus, the QAG can be used to gene rate aerosols with m u ltiple analytes in range of EPA e m ission standards without ge nerating salt pa rticles greater than about 4μm in diam eter that might otherwise ha ve sign if icant tran sport issues. 7.2 Compressed Air The QAG re quires at least 40 psi and 80 slpm (a pproxim a tely 2 cfm ) of in strum e nt air. Between 10- 12 lpm are needed to m a intain the flow of nebulizing air and between 25 and 75 slpm are needed for the drying air flow, de pending on the desired em ission concentration. The selected com p ressed air source should be suffi cient to m e et the flow requirem e nts for the desired tests runs.
7.3 Ice Bath The QAG re quires ice sufficient for filling th e ice bath container and m a intaining the tem p erature of the nebulizer air at 32°F for the duration of the test.



### 8.0 Pre-Test Performa nce Evaluation Procedures
8.1 Pre-Test Laboratory Preparation The following system checks and preparations mu st be conducted in th e laboratory prior to shipping and assem b ling the QAG at a test site. 8.1.1 Certification Check Conf irm that all requ ired NIST-t raceable certificates are valid.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 11 of 238.1.2 Operations Check Confir m that the general operation of the QAG meets the m a n u facturer’s specification s
. 8.1.3 Analyte Solution Preparation Prepare a su fficient am ount of analyte soluti on for the length of the test; for exam ple, two liters of solution is su fficient for a 12-hour run.
8.2 Pre-Test F i eld Preparation The following procedures m u st be conducted af ter receiving the QAG at the test site and prior to operating it in the field. 8.2.1 Physical Integrity Check Check the QAG’s physical com ponents to ensure no parts were dam a ged in shipping. 8.2.2 Assembly Assem b le the QAG per m a nu fact urer’s instru ctions.
8.2.3 Operations Check and Calibration Check the QAG’s operations to ensure that it m eets the m a nufacturer’s specifications. Confir m that the pressure gauges used to m easure the am bient air and nebulizing air pressures are NIST-certified and the certi fication s are cu rren t . Confir m that the therm o m e ter used to m easure the tem p eratu r e of the nebulizing ai r is NIST-cer tif ied and the certificate is valid. In addition, calibrate the following com ponents prior to installation and docum e n t all pre-te s t check results and readin gs: Balance Calibrat i on: Calib rate the balance u s in g NIST-trac eable m a sses; conf irm that the readings are ±1 % of th e standard and the NIS T certificate s are cu rren t

. Flow Meter Calibratio n . Calibra te f l ow m e ter with a pr im ary f l ow calib rator such as a DryCal® 3 ; confirm that the reading s are with in 2% of the NIST-traceab le certificate values. 8.2.4 Installation. Install the QAG in the te st facility per test plan requirem e nts. 8.2.5 Pressure an d Leak Check The QAG system uses positive pressure, and th e nebulizer air flow line m u st be leak checked bef o re testing. Cap off the nebu lizer air line just bef o re the nebulizer,

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 12 of 23pressurize th e line, and check for leaks usi ng an appropriate leak indicator. Tighten any sections of the line where leak s are ind i ca ted.
8.2.6 Mass-Loss Evaluation Before running the QAG with NIST-traceab le so lution, th e op erato r m u st conduct a m a ss loss rate evaluation test. Follow the instructions below for starting and running the QAG wi th a NIST-traceable solution, and su bstitute a blank solu tion of 5% nitric acid and distilled water. Run the QAG for 3 to 5 hours using the blank; this also allows the QAG to therm a lly equilibrate. Calculat e the slope and correlation coefficient for the dec r ease in the weig ht of the res e r voir over the run period. The QAG is functioning properly if the sl ope is between 0.1 and 0.2 and the correlation coefficient is better than 0.99. 8.3 Solution Concentration and Flow Rate Determination Using the equation for generated aerosol concen tration (Equation 1), determ ine the necessary solution concentration and flow rates set points for the desired em ission concentrations (see section 10.3). 8.4 Solution Sample Collect and store a 50 m l sam p le of the analy t e solution for possible quality assurance checks at a later time if necessary.



### 9.0 Generation of a Reference Aero sol w i th NIST-Traceable Accura cy 9.1 System Preparation Connect the therm o m e ters for the ice bath and ne b u lizer cup. Fill the ic e b a th container with ice, m a king sure it surrounds the im pinger and ne bulizer cup. If an ice bath is left from a previous run, drain the water and add enough ice to ensure that the tem p erature of the bath rem a ins at 32 ± 1°F during the test run. W h ile the ice bath is stabi lizing, turn on the m a in flow pum p. Adjust the flow to the rate specified in the test plan. Next, turn on the drying air flow and adjust the p r ess u re regu lato r until th e flow reaches the desired rate. Periodically check the drying air flow and readjust as necess ary as it will tend to d r op af ter the initia l adjustm e nt. Turn on the tube heaters and adju st the set point to 300°F. Switch on the drying cham ber heaters to 125°F and start increasing th e tem p eratures by 50°F increm ents to the set point. At this tim e, turn on any heaters asso c i ated with the tra n sport sys t e m . W h en the cooler is full of ice, add wate r to 1” below the top of the cool er wall and insulate any gaps at the top of the cooler with foa m . Continue to increase the temperature o f the heate r s throughout the solution exchange pro cess describ e d below until they reach their set p o ints. Continue to monitor and adjust QAG operati ng param e ters as necessary.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 13 of 239.2 Solution Exchange The 5% nitric acid solution left in the bo ttom of t h e nebulizer cup after the m a ss loss evaluation must be cycled out of the system and replaced with the analyte solution. Using the tube s co nnecting the peris t altic p u m p to the reservoir, pump the dist illed wate r ou t of the nebulizer cup and into an em pty beaker while simultaneously pum p ing 300 m l of the analyte solution fro m another b eaker into th e cham ber. When all of the analyte s o lution h a s been pum p ed thro ugh the chamber, place the rem a inin g analyte solution in an empty reserv oir, swirl gen tly, center the reservoir on the balanc e, and replace the peris t altic pum p tubes. Gently lift the reservoir off the balance, zero the balance, and place the reservoir back down, taking care to ensure that the peristaltic pum p tubes are not touching any part of the reservoir itself. Once the solution is pum ping in and out of the reservoir, turn on the laptop and the balance software. Monitor the m a ss of the re servoir until it begins to fluctuate around a constant m e an. 9.3 Flow Rate and Temperature Adjustm e nts At this point, the flow rates and heaters m u st be checked and adjusted again if necessary. During this process, turn on the sam p le system and bring it into e quilibrium. The QAG system is in equilibrium when the operational spe c if ications a r e m e t (Section 0), the total flow is stable, the flow of drying air is stable, and the heaters are operatin g at their set points.
9.4 Aerosol Generation and Performance Monitoring When the QAG is in equilibrium , turn on the nebulizer flow by slowly opening the m a nual ball valve. Check to m a ke sure the pressure re gu lato r is con t r o lling the f l ow at the f l o w set point (between 10 and 11 slpm ) and adjust if ne cessary. W h en the nebulizer flow is on, the QAG is func tioning as an aerosol ge nerator. Check to ensure th e pressure regulator and flow m e ter are stable at the desired set point. M onitor the perform a nce of the QAG for the next 30 m i nutes, m a king m i nor adjustm e nts if necessar y. During this tim e, the sampling system results should also be m onitored to ensure that system is functioning properly. The QAG should be ch ecked again after 90 m i nutes of running tim e and any necessary m i nor adjustm e nts should be made. Before leaving the QAG for any overnight runs, the operator should pack fresh ice into the cooler.
9.5 Documentation of Performance The QAG’s perform a nce m u st be docu m ented usi ng a data sheet such as Figure 6. Before beginning a test, fill out the top of the data sheet with the appropr iate test inform ation. Take a read ing of the atm o spheric p r essu re with a NIST-traceable pressure gau g e and reco rd this value, which is equiv a len t to th e pr essure of the expanded nebulizer air ( P e ). After the QAG reaches equilibrium , the nebulizer flo w is on, and the system is generating an aeroso l, record the tim e and the f o llowin g param e ter s : the tem p eratur e of the ice ba th, the tem p erature of the nebulizer cup (for M v ), the nebulizer flow rate ( F

e ), the pressure of the nebulizer compressed air ( P c ), the flow rate of the drying air, the pressu re of the drying air, the tem p erature of the drying air (i.e., tube heater tem p eratu r e), th e to tal f l ow rate ( F

t ), room te mperature, room

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 14 of 23hum i dity, and the weight of the solution. Docu ment new readings for these param e ters every 1 hour. Also record b a g s of ice added and tim e as well as an y necessary notes. 9.6 Shut-down To turn the QAG o ff a f ter testing, first close the m a nual ball valve on the nebulizing air line and shut off the flow. Turn off all of the heater s. Next, turn off the drying air flow and shut down the sampling system. Pum p as m u ch of the solution out of the droplet generating cham ber as possible and turn off the peris t altic pum p, balance, and lapt op. Finally, shut off the m a in flow.
9.7 Post-Test Procedures 9.7.1 Balance Check Check the balance calibration follow i ng th e procedure described in Section 8.2.3. 9.7.2 Flow Meter Check Check the flow m e ters calibrations following the procedure described in Section 8.2.3.
9.7.3 Ambient Pressure Reading Take a final reading of the am bient pressu re with a NIST-traceable pressure gauge. 9.7.4 Solution Sample Collect and store an additional 50 m l sam p le of the analyte solution for possible quality assurance ch ecks at a later tim e if necessary.



### 10.0 Calculati o ns 10.1 Generated A e rosol Concentration The following equation is used to calculate th e generated aerosol concentration of the i th elem ent ( ) from the QAG’s record e d param e ters: a-QAG i C


### ) R (R F C C v m t QAG s i QAG a i 

### − = −

− Equation 1

Where:
s-QAG i C = Concentration of the i th elem ent in the QAG’s NIST traceable solution.

Instru m e ntal Meth od f o r a QAG: V1. 0 Sect i on 1 0

. 0 C a l c ul at i ons Page 15 of 23F t = Total flow, i.e., the com b ined flow of nebulizer air and drying air added within the aerosol generation system , determ ined by the flow m e ter located between th e QAG and the transport system

. R m = Measured ra te of rese rvo i r m a ss lo ss, determ ined as the slope of a linea r le ast s quares f it of the res e rvo i r m a ss data o v er the p e rio d of a test or series of tests. R v = Rate of vapor loss is a calcul ated value based on the following equation: 

### ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− =

c e v e v 

### P P 1 M F R Equation 2

Where: F

e = Flow rate of the expanded nebuliz ation air as m easured by th e flow m e ter on the nebulizing air line. M v = Mass of water vapor in a liter of saturated air at 32 °F. This value has been well defined and docum ent e d : M v (32°F) = 4.847 m g /liter P e = Pressure of the expanded gas out side the nebulizer nozzle. Since the droplet generating cham ber and the droplet size selecto r are open to the atm o sphere, P e is the atmospheric p r essure record ed from the field barom e ter reading. P c = Absolute pressure of the com p ressed air upstream of the nebulizer nozzle, calculated by adding the atmospheric pressure to the gauge pressure. 10.2 Generated A e rosol Concentration Uncertainty. The uncertainty of the genera ted aerosol concentration ( ) is determ ined using standard propagation of error techniques a-QAG i C 

### σ 5 relev a nt to the pa ram e ters of Equation 1. The uncertainty values for th e param e ters are thos e lis t ed as c e rtif ied uncer tain tie s by the m a nufacturers and/or NIST . This procedure is co nsistent with those used at NIST 6 , , 7 8

. The uncertainty of the genera ted aerosol concentration ( ) is calculated using the f o llowing eq uation : a-QAG i C

2

v m ) R (R 2

t F 2
s-QAG i C QAG a i C 

## ) R (R

σ F σ C σ C σ v m t s-QAG i a-QAG i 

## ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

= − − Equation 3

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 16 of 23Where: 

# ( ) ( ) 2 R 2 R ) R (R v m v m 

## σ σ σ + =

− Equation 4

and 2

c e P P 1 2

v M 2

e F
v R 

## P P 1 σ
M σ F σ R σ c e

v e

v 

## ⎟ ⎟ ⎟ ⎟ ⎟

⎠ ⎞

⎜ ⎜ ⎜ ⎜ ⎜

⎝ ⎛

⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

= ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− Equation 5

and 2

c P 2

e P

c e

c e P P 

### P P P P

P P 1 c e c e 

### ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

= ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− 

### σ σ σ 1 Equation 6

10.3 Solution Concentration and Flow Rate Set Points To determ ine the required solution concentration and flow rate set points f o r given test run, select a desired concentration of the QAG’s aerosol em issions ( ). Use the expanded for m of Equation 1: a-QAG i C



### ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

− − = −

−

c e v e m t QAG s i QAG a i 

### P P 1 M F R F C C

Plug in the desired concentration ( ), the estim a ted rate of m a ss loss ( R a-QAG i C m ; see also section 8.3), the m a ss of water vapor in a liter of saturate d air at 32 °F ( M v , 32 °F = 4.847 mg/lite r), th e pressu re of the expande d nebuliz ation air ( P e ), and the absolute pressure of the com p ressed nebulizing air ( P c ). Solve for an appropria te combination of solution concentratio n ( ) and flow rates, bearing in m i nd that tota l f l ow ( F s-QAG i C t ) equals the expanded flow of nebulizing air ( F

e ; which m u st be between 10 and 12 lpm ) plus the drying air flow (which can range from 28 to 1990 lpm )

. 10.4 Aerosol Emission Size Use the following equation to determ ine the si ze of the salt partic les emitted by the QAG:

Instru m e ntal Meth od f o r a QAG: V1. 0 Sect i on 1 0

. 0 C a l c ul at i ons Page 17 of 233 salt liq s-QAG i liq salt 

### C D D ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛

= ρ ρ Equation 7

Where: D salt = The diam eter of the salt in μm

. D liq = The diam eter of the liquid dropl ets in μm as specified by the nebulizer manufacturer in μm

. s-QAG i C = The concentration of the analyt e stan dard in the NIST-traceable solution in gram s of analyt e salt per gram of solution ρ salt = The density of the analyte salt in g/m 3

. ρ liq = The density of the liquid droplet in g/m 3

.



### 11.0 Documentation of Quality Control and Assurance 11.1 Certifications Prepare a ch eck list and confirm the certificat ion s of NIST-traceable components. Assem b le the certifications of NIST traceability for each com ponent. 11.2 Field Data Records Create and u s e a data sheet for the calibration the balance and flow m e ters in the field.



### 12.0 Pollution Prevention The excess aerosol generated by the QAG should be trapped in a filter and disposed of accord ing to the approp riate regulatio ns. The unused solution should also be disposed of accord ing to regulation.



### 13.0 Waste Management
The solution standard s should be handled acco rdi ng to th eir Material Safety Data Sheets.

Instru m e ntal Meth od f o r a QAG: V1. 0 Sect i on 1 3

. 0 Wast e M a na ge m e nt Page 18 of 23

### 14.0 Figures a nd Tables

A. B. Figure 1: A. Schematic of flow through QA G components. B. Overview of the set-up of the CES QAG.

Figure 2: S c hematic of the CES QAG standard solution control system.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 19 of 23Figure 3: S c hematic of the CES QAG nebulizer air con t rol system.

Figure 4: S c hematic of the CES QAG nebu lizer and droplet siz e control system.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 20 of 23Figure 5: S c hematic of the CES QAG dr ying air and drying chamber system.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 21 of 23O p er a t or: S ol n . Conc: L o c a ti on: S p ik ing:

Not e s : # Bags Neb. Pr es . (p si ) M ake -Up A i r Pr es su re ( in

. H2 O ) T r anspor t Te m p ( °F ) Ma k e - U p A ir

T e mp ( °F ) Neb. Col d Bath ( °F ) Neb. Ai r ( °F )

A dded I c e Sp i k e S o ln

. M a ss (g) M ake -Up Ai r

F l o w ( sl p m ) Room Te m p ( °F ) Roo m ( RH) Sta ck Gas

Fl ow ( l p m ) Ma i n Fl ow ( sl p m ) Neb. Cup ( °F )

Ti me 

### Da ta Sh ee t QA G M - 3 01 T e s t s Dat e : S t a r t Da te /T ime : S t op Da te/ T ime:

Ti m e o f Rec o rd Ne b

. Fl o w ( l p m )Figure 6: Sample data sheet for the QAG.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 22 of 23

### 15.0 Referen ces
1

. Scott Spec ia lty Gases. S c ott Gas M i xt ures Data: Gas and Li quid Mixture Basics. Plum steadville, PA: Scott Specialty Gases; 2004

. 2

. Bureau International des Poids et Mesures , Intern ationa l Ele c trotechn i ca l Comm ission, International Federation of Clinical Che m istry and Laboratory Medicine, International Organi zation for Standardization, In ternational Union of Pure and Applied Chem istry Intern ational Union of Pure and Applied Physics, International Organization of Legal Metrology [BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OI ML]. International Vocabulary of Basic and General Term s in Metrology (VIM). Geneva, Switzerland: BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OI ML; 1993. Available from : ISO, Ge neva, Switzerland; ISBN 92-67-01075-1.
3

. Sm ithsonian Physical Tables, 9th Rev. E d. W a shington D.C.: Sm ithsonian Institution Press; 1954.
4

. Scace, G.E. and J.T. Hodges. Uncertain ty of the NIST Low Frost-Po int H u m i dity Generator. Gaithersburg, MD: National Inst itute of Standards and Technology; 2004.
5

. McClave, J.T., F.H. Dietrich, II, and T. Sincich. Statistics, 7th Ed. Upper Saddle River, NJ: P r entice Hall; 1997.
6

. Taylor, B.N. and C.E. Kuyatt. Guide lines for Evaluating and Expressing the Uncerta inty of NIST Measurem ent Results. Gaithersburg, MD: National Institute of Standards and Technology [NIST]; 1994. Av ailable from : NIST, Gaithersburg, MD; TN 1297.
7

. Am erican National Stan dards Ins t itu t e/ National Conference of Standards Laboratories [AN S I/ NC SL]

. U.S. Guide to the E xpression of Uncerta inty in Measurem ent

. W a shington, D.C: ANSI/NCSL; 1997. Available from : NCSL International, W a shington, D.C; Z540-2-1996.
8

. May, K.R. The Collison nebulizer: d e scrip tion, p e rform a nce and application. Aerosol Science 1973; 4: 253-243.

Instru m e ntal Meth od f o r a QAG: V1. 0 Page 23 of 23