Collected mass or internally separated mass

Calculate the average mass for each of the three sets of candidate samplers with different sampling times for each partial sampling period, sampling and experimental run from Formula (9):

avermrtl = 1 NS

rtl

mrtls

s=1 NSrtl

∑ (9)

where

mrtls is the average mass collected during partial sampling period l, in run r for sampling time t (here t = 1,2,3 represents sampling times texp, texp/3 and texp/9 respectively);

avermrtl is the mass collected by candidate sampler s during partial sampling period l, in run r for sampling time t; and

NSrtl is the number of candidate samplers used with partial sampling period l in run r for sampling time t.

For each partial sampling period l for each set of sampling times t and runs r, calculate the concentrations corresponding to each sampling period, according to Formula (10):

Crtl = avermrtl

Q0trtl (10)

where

Crtl is the (average) concentration determined with the candidate sampler for partial sampling period l in run r for sampling time t;

avermrtl is the mass collected by candidate sampler s during partial sampling period l, in run r for sampling time t;

Q0 is the nominal flow rate of the candidate sampler; and

trtl is the actual time of partial sampling period l for sampling time t in run r.

For each experiment r, for the third set of candidate samplers (used with the shortest sampling periods), calculate the time-weighted concentrations, twa1−9Cr3, twa1−3Cr3, twa4−6Cr3 andtwa7−9Cr3, respectively, according to Formula (11):

twal1−l2C r3= tr3lCr3l

l=l1

∑l2

tr3l

l=l1

∑l2 (11)

where

Cr3l is the (average) concentration determined with the candidate sampler for partial sampling period l in run r for sampling time t = 3;

twal1−l2Cr3 is the time-weighted concentration average for candidate sampler for run r, sampling time t = 3 extending from partial sampling period l = l1 to partial sampling period l = l2;

tr3l is the actual sampling time of partial sampling period l for sampling time t = 3 in run r.

Calculate the relative concentrations for each experiment r to the concentrations measured with candidate samplers operated for the shortest time. For each run r calculate the following rrtl ratios: for the first set the ratio rr11=Cr11 twa1−9Cr3 and for the second set the three ratios rr21=Cr21 twa1−3Cr3, rr22=Cr22 twa4−6Cr3 and rr23=Cr23 twa7−9Cr3.

7.4.7.2 Collected aerosol mass

Plot each value rrtl (for t = 1 and 2) versus the collected mass of the of the candidate sampler operated at a higher mass loading (the corresponding values avermrtl). Use any curvilinear regression by the least-squares method to determine the effect of collected mass.3) The derived regression function shall be monotonic over the interval for the regression. The parameter values of the derived function and their uncertainties shall be documented.

If the regression is significant, calculate the value of the regression formula at the above determined value of maximum collected mass, YEst-Collected max( mCollected), and a value corresponding to almost zero collected mass, YEst-Collected zero( mCollected). If YEst-Collected zero( mCollected) is not approximately unity within the uncertainty of

the regression model, the results cannot be used, either because the lowest collected masses obtained in the experiment for the shortest sampling times are too high or because the aerosol variability at sampling location was too high. The uncertainty component due to collected mass in the range zeromCollected;maxmCollected is calculated from Formula (12) as:

uCandSampler-CollectedMass= YEst-Collected max( mCollected)−YEst-Collected zero( mCollected)

3 (12)

where

maxmCollected is the expected maximum collected mass;

zeromCollected is a mass corresponding to almost zero collected mass;

uCandSampler-CollectedMass is the standard uncertainty (of measurement) due to mass collected by the candidate sampler; and

YEst-Collected(mCollected) is the prediction from the regression formula for the effect of collected mass ( mCollected) on the sampling efficiency of the candidate sampler.

If the regression is not significant, then in the range of collected aerosol masszeromCollected;maxmCollected, 0

uCandSampler-CollectedMass= (13)

where

uCandSampler-CollectedMass is the standard uncertainty (of measurement) due to mass collected by the candidate sampler.

7.4.7.3 Internally separated aerosol mass

Estimate the average amount of mass deposited inside the candidate sampler, InternSepavermrtl, based on the difference between the total airborne particle (or the inhalable aerosol fraction) concentration and the concentration sampled by the candidate sampler. For each run r, sampling time t, and partial sampling period l, this is calculated from Formula (14) as

InternSepavermrtl=Camb inhale

rtlQ0trtl−avermrtl (14)

where Camb inhale

rtl is the (average) total airborne particle (or inhalable aerosol fraction) concentration for partial sampling period l in run r for sampling time t;

avermrtl is the mass collected by candidate sampler s during partial sampling period l, in run r for sampling time t;

InternSepavermrtl is the average internally separated mass for partial sampling period l, in run r for sampling time t;

Q0 is the nominal flow rate of the candidate sampler; and

trtl is time t for run r, sampling period l, and partial sampling period l.

Plot each value rrtl (for t = 1 and 2) versus the internally separated mass of the of candidate sampler operated at a higher mass loading (the corresponding value InternSepavermrtl). Use any curvilinear regression by the

least-squares method to determine the effect of internally separated mass.4) The derived regression function shall be monotonic over the interval for the regression. The parameter values of the derived function and their uncertainties shall be documented.

From the best model including all significant parameters, calculate the value of the regression formula at the above determined value of maximum internally separated mass, YEst-InternSep max( mInternSep), and a value corresponding to almost zero internally separated mass,YEst-InternSep zero( mInternSep). If YEst-InternSep zero( mInternSep) is

not approximately unity within the uncertainty of the regression model, the results cannot be used, either because the obtained lowest internally separated masses obtained in the experiment for the shortest sampling times are too high or because the aerosol variability at sampling location was too high. The uncertainty component due to the internally separated mass in the range zeromInternSep;maxmInternSep is calculated from Formula (15) as:

uCandSampler-InternSepMass= YEst-InternSep max( mInternSep)−YEst-InternSep zero( mInternSep)

3 (15)

where

maxmInternSep is the expected maximum internally separated mass;

zeromInternSep is a mass corresponding to almost zero internally separated mass;

uCandSampler-InternSepMass is the standard uncertainty (of measurement) due to internally separated mass by the candidate sampler; and

YEst-InternSep(mInternSep) is the regression formula for the effect of internally separated mass ( mInternSep) on the internal penetration of the candidate sampler.

If the regression is not significant, then in the range of collected aerosol masszeromInternSep;maxmInternSep, 0

uCandSampler-InternSepMass = (16)

where

uCandSampler-InternSepMass is the standard uncertainty (of measurement) due to mass collected by the candidate sampler.