NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

NIOSH Manual of Analytical Methods (NMAM) 5th Edition 

BACKUP DATA REPORT 

NIOSH Method No. 0501/5100

Title: Total particulates not otherwise regulated

Analyte: Nuisance dust, PNOS

Author/developer: Sean O’Connor, Paula Fey O’Connor, 

H. Amy Feng and Kevin Ashley

Date: 2/27/2015

Disclaimer: Mention of any company or product does not constitute endorsement by the National 

Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. In addition, 

citations to websites external to NIOSH do not constitute NIOSH endorsement of the sponsoring 

organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of 

these websites. All web addresses referenced in this document were accessible as of the publication 

date. 
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BACKUP DATA REPORT FOR NIOSH 0501/5100

Sean O’Connor, Paula Fey O’Connor, H. Amy Feng and Kevin Ashley, CDC/NIOSH/DART 

Background

The previous issues of NIOSH Methods for gravimetric analysis, NIOSH 0500 and 5000, specified the use 

of polyvinyl chloride (PVC) filters housed in closed-face filter cassettes (CFCs) for collection of airborne 

particles for subsequent gravimetric analysis.1 As described in these earlier versions of the NIOSH 

methods, the PVC filter is weighed before and after sample collection, with the reported weight of 

sampled particulate matter being the difference between pre- and post-weighing. However, airborne 

particles collected using CFCs can deposit elsewhere than on the PVC filter, and thus would not be 

included in gravimetric analysis of the filter alone.2 An alternative technique for ensuring that internal 

non-filter deposits are included in the analysis is to collect airborne particles within an internal capsule, 

housed within the CFC, which is weighed in its entirety before and after sample collection. PVC 

capsules for gravimetric analysis of airborne particulate matter have been commercially available for 

several years. The filter capsules are designed to be inserted into 37-mm plastic CFC samplers on top of 

cellulose support pads, as illustrated in Figure 1. The evaluation described in this report was 

undertaken in order to provide necessary performance data for validation of the new NIOSH 0501 & 

5100 methods, which is based on the use of PVC internal capsules. The validation protocol followed 

here is analogous to that which was carried out to validate the previous filters-only procedures for 0500 

and 5000.1

Procedure

Polyvinyl chloride (PVC) Accu-caps® with 5-μm pore size PVC filters (Lot #11136-7DBPASK-104, SKC, 

Eighty-Four, PA) were allowed to equilibrate to room temperature and humidity in the laboratory under 

a dust cover box for at least two hours (most were equilibrated for 24 hours). Once equilibrated, the 

Accu-caps were weighed on a Mettler Toledo high-precision analytical balance (Model XP205DR, 

Greifensee, Switzerland) before spiking with certified reference material (CRM) dust; balance calibration 

was checked before each use with ASTM Class 1 weights. A 210Po static control device (NRD, Grand 

Island, NY, USA) was used to eliminate electrostatic effects during weighing. The pre-spiked weight of 

each PVC Accu-cap was recorded to the nearest 0.1 mg. The Accu-caps were then were placed into 

two-piece SKC plastic cassettes (Lot #2039-7D6PASK-010) and were then sealed in the cassettes. For 

spiking with CRM, each cassette was connected to a personal sampling pump (Aircheck Sampler, Model 

#224-PCXR7, SKC) set to a calibrated flow rate of 2.5 ± 0.1 L/min. 

The certified reference materials (CRMs) used were Standard Reference Material (SRM) 1648, Urban 

Particulate Matter (National Institute of Standards and Technology, Gaithersburg, MD) and Arizona 

Road Dust – Air Cleaner Test Dust (General Motors AC Spark Plug Division, Flint, MI). On glycine 

weighing paper, five different levels of CRM (4 mg, 2 mg, 1 mg, 0.5 mg, 0.1 mg), with 3 samples 

(minimum) at each level, were weighed to the nearest 0.1 mg. The test materials were loaded into 

separate Accu-caps via 23-mm plastic micro funnels (Poly Micro Funnel, The Science Company, Denver, 

CO), which were inserted into the inlets of the cassettes housing the Accu-caps. Once the weighed test 

material was poured into the funnel, the sampling pump was activated so that the particulate material 

was drawn completely out of the funnel and into the PVC Accu-cap housed within the cassette. The 

1 NIOSH Manual of Analytical Methods, 4th ed. NIOSH: Cincinnati, OH (2003).

2 Ashley K, Harper M, “Closed-face filter cassette (CFC) sampling – Guidance on procedures for 

inclusion of material adhering to internal sampler surfaces,” J. Occup. Environ. Hyg. 10: D29-D33 (2013).
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pump was used to pull air through the system for approximately one minute, which enabled complete 

transfer of CRM from the funnel into the Accu-caps. 

The cassettes were removed from the pump and then the PVC Accu-caps were removed from the 

cassettes using a cassette opener and were then weighed individually. The mass of the spiked Accucaps for all replicate levels were weighed using the same balance and were recorded as mass for Day 

1. Collection efficiency was calculated by dividing the collected mass of the test material by the total

material weight before transfer to the Accu-cap. For each of the sets of CRM samples (i.e., SRM 1648 and

Arizona Road Dust – Air Cleaner Test Dust), 6 lab blanks were weighed and sealed, recording their Day 1

masses as well.

Once the Day 1 masses were recorded for all replicate samples and lab blanks, the PVC Accu-caps 

(sealed in their labeled testing cassettes) were stored in cardboard boxes (organized by sample set) for 

a 4-week storage study. On 7-day intervals, the Accu-caps were weighed and the results recorded for 

comparison to their Day 1 mass. Percent change in mass was calculated by subtracting the Day1 mass 

from the Day 7 (and then Day 14, 21, and 28) masses, dividing by the Day 1 mass and multiplying by 

100%.

Pressure drop experiments3 were carried out (by Dr. T. Lee, NIOSH/HELD) in order to further characterize 

the PVC Accu-caps. Five different Accu-caps were placed in 37-mm plastic cassettes and the absence of 

leakage was verified before measurement. The pressure drop from a 5-μm pore PVC filter was measured 

for comparison.

Results

Storage stability

Storage stability data are presented in Tables 1 and 2 (for NIST SRM 1648 and Arizona Road Dust sample 

sets, respectively). In each table, sample mass (i.e., mass of internal capsule plus mass of added dust) 

is indicated by descending order for each spiking level (4 mg; 2 mg; 1 mg; etc.). Laboratory blank data 

are also included and are indicated in the tables. Percent changes in weights were generally less than 

5 percent for SRM 1648 (Table 1) at the 1, 2, and 4mg sample loadings but are quite a bit higher at the 

0.5 and 0.1 mg levels. SRM 1648 seemed to have greater variability especially at the levels near the 

LOD/LOQ. For the Arizona Road Dust SRM samples the percent changes were lower at the 0.5, 1, 2, and 

4 levels. The percent changes for the 4, 2 and 1mg sample was ≈1. The 0.5 mg level was higher at ≈8 

percent for Arizona Road Dust (Table 2) for time periods up to 28 days.

Limits of detection and quantitation

The estimated method detection limit (MDL) and limit of quantitation (LOQ) of the gravimetric 

procedure was obtained from PVC Accu-cap blank data based on Day 1 to 7 weight changes (n=12). 

The overall mean weight change was -0.000013 g and the standard deviation was 0.000016. Thus the 

estimated MDL is obtained by three times this value or 0.000048 g, ≈0.05 mg (50 μg). The estimated 

LOQ is ten times the standard deviation of blank results, i.e., ≈0.16 mg (160 μg).

Analytical recovery

Measured recoveries of spiked Accu-caps are shown in Table 3 for capsules spiked with ≈1 mg, ≈2 

mg and ≈4 mg of SRM 1648 and Arizona Road Dust. Recoveries were computed as the ratio of the 

amount of material weighed after spiking to the amount of material weighed prior to spiking. (These 

gravimetric measurements attempted to account for CRM losses onto weighing paper during spiking; 

recovery calculations of course subtracted the weights of Accu-caps obtained before spiking was 

carried out.) Measured recoveries for these spiked PVC Accu-caps ranged from ≈92% to ≈102%. (See 

Table 3)

3 Breuer, D., “Flow resistance of samplers for personal monitoring in work areas and requirements 

for sampling pump performance,” J. Occup. Environ. Hyg. 9: D25-D32 (2012).
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Pressure drop tests

At sampling pump flow rates of 2 and 4 L/min, the average pressure drop values for PVC Accu-caps 

were 0.134 (±0.008) and 0.270 (±0.026) psi, respectively. For the PVC filter, these values were 0.154 and 

0.302 psi for flow rates of 2 and 4 L/min, respectively.

Observations

Sample stability and analytical range

The data presented in Tables 1 and 2 illustrate the long-term weight stability of blank and spiked 

PVC Accu-caps for up to at least 28 days. For loadings of ≈1mg and greater, measured weights 

are all within 100% ± 5% for NIST SRM 1648 and Arizona Road Dust (Air Cleaner Test Dust). 

Arizona Road Dust is observed to be more weight stable than NIST SRM 1648 (Tables 1-2), and 

this is attributed to trace moisture loss / off-gassing from the latter material, especially during 

the first week of storage. Despite this, the excellent weight stability of the PVC internal capsule 

material is clearly seen. The weight stability demonstrated by the PVC capsules is greatly 

superior to that of plastic cassettes, which have been shown to adsorb or desorb significant 

amounts of moisture (as much as 1-2 mg over a several-day period), depending on humidity 

conditions9 

Analytical Range

At loading (spiking) levels of ≈1 mg and greater, recoveries of SRM 1648 and Arizona Road Dust from 

PVC Accu-caps (spiked as described above) were >90% (Table 3). However, for spiking levels of ≈0.5 mg 

and below, the measured recoveries were inconsistent, varying from <40% to >500% (data not shown). 

To investigate whether there was any appreciable background dust being collected during spiking, 

air was drawn through a completely separate set of blank Accu-caps. But these experiments did not 

show any statistically significant differences between the blank capsules, indicating that there was no 

measureable dust collected. It should also be noted that the MDL for all sample loadings was above the 

expected level for the gravimetric method using the Accu-cap samplers. Causes of high imprecision at 

spiking levels of ≈0.5 mg are ascribed to inherent difficulties in accurately weighing and transferring 

masses of CRMs below 1 mg.

Pressure drop tests

Measured pressure drops for PVC Accu-caps and the PVC filter were comparable. No collapse or other 

physical failures of the Accu-caps were observed when using sampling pump flow rates of up to 5 L/

min. At sampling pump flow rates of 2 and 4 L/min, the average pressure drop values for PVC Accu-caps 

were 0.924 (±0.055) kPa and 1.86 (±0.18) kPa, respectively. For PVC filters, these values were 1.06 kPa 

and 2.08 kPa for flow rates of 2 and 4 L/min, respectively. (Similar pressure drop results for PVC filters 

have been reported elsewhere.3) 

Special precautions

Because of the generally delicate nature of the PVC Accu-caps, there should be as little pressure on the 

plastic top as possible (even little pressure created a sizable indentation on the top of the Accu-caps). 

Deformation of the Accu-caps could lead to a misalignment of the collection holes of the Accu-cap 

with the cassette inlet ports, which in turn could result in incomplete aerosol collection and poor 

collection rates. Accu-caps having misaligned inlet holes were not used in this evaluation. During 

sample preparation, when removing the PVC Accu-caps from the cassettes in which they were housed, 

the Accu-caps tended to adhere to the top-half section of the cassette. In the method, it is suggested 

that the filters be removed by using a scalpel blade or something similar, but for the Accu-caps, this is 

not always effective. When the Accu-caps did become stuck, they required more than a little applied 

pressure to remove them from the cassettes. To remove them, it was often necessary to use a forceps 

and, with gloved fingers, physically grab the outer plastic edge of the Accu-cap and pull as hard as 
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practicable. Because of the effort that was required to remove the Accu-caps from the cassettes, 

misplacement or slippage of the forceps can occur, often resulting in tears of the filters of the Accucaps. Accu-caps that were damaged during removal from cassettes were not used in this evaluation.

It was observed that some Accu-caps were prone to sticking inside the cassettes, and this was ascribed 

to their non-uniformity in manufacture. From batch to batch, or even Accu-cap to Accu-cap, the 

appearance and construction of the different Accu-cap capsule inserts can vary significantly. For 

example, the fringe plastic on one Accu-cap can be noticeably wider than that of a different Accu-cap. 

The top shell of one Accu-cap can also be considerably different from that of another capsule (in terms 

of thickness of the capsule dome and/or position of the inlet hole). About one in twenty capsules was 

found to have fabrication deficiencies. It is apparent that these problems are due to the manufacturing 

technique used to make the capsules, thus the manner in which these imperfections are avoided 

during fabrication should be addressed and corrective action taken. Damaged Accu-caps should not be 

analyzed.

It is strongly recommended to use long insert plugs that will ensure complete sealing of the PVC 

internal capsules after sample collection. This will help to prevent collected particulate matter from 

being lost through the inlet hole of each capsule during transport and handling. The use of short inlet 

plugs that have historically been used with cassette sampling should be avoided.

Independent results

Laboratory data

In order to test the internal capsule weighing procedure in an independent laboratory, PVC Accu-cap 

gravimetric measurements were carried out at the NIOSH contract lab, Bureau Veritas North America 

(BVNA, Novi, MI). Analysts at BVNA carried out LOD/LOQ and stability studies (NIOSH Project Seq. No. 

11481-CA & -CB). From seven Accu-cap blanks, the standard deviation was 0.0000189 g, which yielded 

estimated values for the LOD and LOQ of 0.057 mg (≈60 μg) and 189 mg (≈190 μg), respectively. For 

seven Accu-cap blanks that were stored for six months, the average deviation of the individual blank 

measurement from the average blank was 0.02 mg, with a maximum deviation of 0.05 mg. The absolute 

value of the average percent deviation over this time period was less than 0.01%. These figures of merit 

are comparable to those obtained independently in the NIOSH/DART laboratory.

A subsequent “User Check” study was done wherein the PVC Accu-cap of Tables 1 and 2 (SRM 1648 and 

Arizona Road Dust spikes as well as media blanks) were sent to BVNA for weighing by an independent 

laboratory. The results from BVNA are listed vs. the final weights obtained at the NIOSH laboratory in 

Table 4. With the exception of one statistical outlier, all independently reported results are within 10% 

of the weights obtained by NIOSH.

Field data

To test the gravimetric method using internal capsules in the field, results from PVC Accu-caps and 

Institute of Occupational Health (IOM) samplers were compared in air samples obtained at metal 

foundries in France. Side-by-side static (area) samples for gravimetric analysis were obtained using 

the Institut de recherché Robert-Sauvé en santé et en sécurité du travail (IRSST) Method 48-1,4 which 

specifies PVC Accu-caps, and the Health and Safety Executive (HSE) MDHS Method 14/3,5 which relies on 

IOM samplers. The purpose of the field experiments was to evaluate the use of internal capsules housed 

within CFCs against the established ‘reference’ sampler for inhalable aerosols, the IOM sampler.6 The 

IRSST method specifies a flow rate of 1.5 L/min and a minimum sample volume of 180 L, while the 

4 IRSST. “Poussière totale,” Méthode 48-1; in Méthodes analytiques. IRSST: Montréal, Canada 

(1998).

5 HSE, “General methods for sampling and gravimetric analysis of respirable and inhalable dust,” 

MDHS Method 14/3. HSE Books: Sudbury, UK (2000).

6 Woebkenberg, M.L., Bartley, D.L., “Inhalable aerosol samplers,” Appl. Occup. Environ. Hyg. 13: 

274-278 (1998).
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HSE method specifies a flow rate of 3.5 L/min and a minimum sampling time of 4 h. Results from these 

experiments are presented in Table 5, and demonstrate the comparability of the Accu-cap gravimetric 

method and the IOM sampling method.

Figure 1. (a) Photograph of a 37-mm diameter plastic close-face cassette sampler (left) and an internal 

filter capsule (right); (b) Schematic of the CFC sampler showing placement of the filter capsule (shaded 

portion) and cellulose back-up pad within the 

cassette.

(b)

Accuracy

The results of Table 2, for spiking levels of 1 to 4 mg/sample, were used to estimate overall method 

accuracy, in accordance with NIOSH guidelines.7

 From these data an overall pooled recovery of 94.3% 

is obtained, thereby yielding a bias estimate of -0.057. The CVTotal was calculated to be 0.059. Also, 

a pooled estimate of precision (as overall relative standard deviation) of 0.031 was obtained from 

these results. Using the nomogram relating accuracy to precision and bias,7,8

 an accuracy estimate 

of ±15.4% is obtained. Given that the NIOSH accuracy criterion is ±25%, these analytical figures of 

merit demonstrate that the performance criteria for accuracy for acceptance as a NIOSH method are 

satisfied for gravimetric measurement using PVC capsule inserts. The statistical calculations are shown 

in Appendix 1.

7 Kennedy, E.R., Fischbach, T.J., Song, R., Eller, P.M., Shulman, S.A., “Guidelines for Air Sampling and 

Analytical Method Development and Evaluation.” CDC/NIOSH, Cincinnati, OH, 1995; DHHS (NIOSH) Publ. 

No. 95-117.

8 Kennedy, E.R., Fischbach, T.J., Song, R., Eller, P.M., Shulman, S.A., “Development and Evaluation of 

Methods”, Chap. E., in NIOSH Manual of Analytical Methods, 4th ed. CDC/NIOSH, Cincinnati, 1994.

9 Smith, J. P.; Bartley, D. L.; Kennedy, E. R.: Laboratory investigation of the mass stability of sampling 

cassettes from inhalable aerosol samplers. Am. Ind. Hyg. Assoc. J. (1998) 59, 582-585.
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Table 1. Storage stability data for polyvinyl chloride (PVC) Accu-caps spiked with National Institute 

of Standards and Technology Standard Reference Material (NIST SRM) 1648, Urban Particulate Matter; 

percent change (%Δ) values are with respect to Day 0 masses (in grams). The sample weights are 

corrected for capsule weight and error in mean blank tare weight.

SRM 

1648

≈4 mg

Day 0

wt. (g)

Day 7 wt. 

(g)

% Δ Day 14 

wt. (g)

% Δ Day 21 

wt. (g)

% Δ Day 28 wt. 

(g)

% Δ

Sample 1 0.00386 0.00378 -2.07 0.00375 -2.85 0.00376 -2.59 0.00376 -2.59

Sample 1 0.00386 0.00378 -2.07 0.00375 -2.85 0.00376 -2.59 0.00376 -2.59

Sample 2 0.00383 0.00376 -1.83 0.00375 -2.09 0.00371 -3.13 0.00374 -2.34

Sample 3 0.00385 0.00379 -1.56 0.00378 -1.82 0.00379 -1.56 0.00377 -2.08

%Δ mean -1.82

± 0.26

-2.25

± 0.54

-2.43 

± 0.80

-2.34

± 0.26

≈ 2 mg

Sample 1 0.00169 0.00166 -1.78 0.00165 -2.37 0.00166 -1.78 0.00165 -2.37

Sample 2 0.00130 0.00126 -3.08 0.00125 -3.84 0.00124 -4.62 0.00124 -4.62

Sample 3 0.00170 0.00165 -2.94 0.00165 -2.94 0.00167 -1.76 0.00165 -2.94

%Δ mean -2.60± -3.05± -2.72 ± -3.31 ± 

≈ 1 mg

Sample 1 0.00090 0.00088 -2.2 0.00088 -2.2 0.00088 -2.2 0.00088 -2.2

Sample 2 0.00110 0.00111 +0.91 0.00110 -0- 0.00111 +0.91 0.00111 +0.91

Sample 3 0.00117 0.00114 -2.56 0.00113 -3.42 0.00115 -1.71 0.00113 -3.42

%Δ mean -1.28 ± -1.87 ± -1.00 ± -1.57 ± 

≈0.5 mg

Sample 1 0.00035 0.00020 -43 0.00017 -51 0.00020 -43 0.00020 -43

Sample 2 0.00035 0.00031 -11 0.00023 -34 0.00023 -34 0.00024 -31

Sample 3 0.00049 0.00040 -18 0.00039 -20 0.00039 -20 0.00040 -18

Sample 4 0.00045 0.00029 -36 0.00026 -42 0.00025 -44 0.00026 -42

%Δ mean -27± 15 -37± 13 -35± 11 -34± 12

≈0.1 mg

Sample 1 0.00005 -0.00006 -220 -0.00008 -250 -0.00006 -220 -0.00006 -220

Sample 2 0.00016 0.00018 +13 0.00017 +6.3 0.00017 +6.3 0.00017 +6.5

Sample 3 0.00024 0.00024 -0- 0.00022 -8.3 0.00024 -0- 0.00024 -0-

Sample 4 0.00018 0.00019 +5.6 0.00019 +5.6 0.00019 +5.6 0.00020 +11

%Δ mean -50± 110 -64± 130 -52± 110 -51± 

Media 

Sample 1 0.28025 0.28021 -0.0143 0.28023 -0.0071 0.28021 -0.0143 0.28019 -0.0214

Sample 2 0.29180 0.29179 -0.0034 0.29177 -0.0103 0.29177 -0.0103 0.29177 -0.0103

Sample 3 0.28421 0.28421 -0- 0.28419 -0.0070 0.28419 -0.0070 0.28419 -0.0070

Sample 4 0.30742 0.30744 +0.0065 0.30744 +0.0065 0.30744 +0.0065 0.30745 +0.0098

Sample 5 0.31681 0.31676 -0.0158 0.31677 -0.0126 0.31676 -0.0158 0.31677 -0.0126

Sample 6 0.32797 0.32791 -0.0183 0.32791 -0.0183 0.32792 -0.0152 0.32792 -0.0152

%Δ mean -0.0092 ± -0.0081± -0.0094± -0.0095± 
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Table 2. Storage stability data for PVC Accu-caps spiked with Arizona Road Dust – Air Cleaner Test 

Dust; percent change (%Δ) values are with respect to Day 0 masses (in grams). The sample weights are 

corrected for capsule weight and error in mean blank tare weight.

AZ Rd. dust 

≈4 mg

Day 0 wt. 

(g)

Day 7 wt. 

(g)

%Δ Day 14 wt. 

(g)

%Δ Day 21 wt. 

(g)

%Δ Day 28 wt. 

(g)

%Δ

Sample 1 0,00418 0,00421 +0,72 0,00420 +0,48 0,00420 +0,48 0,00420 +0,48

Sample 2 0,00394 0,00396 +0,51 0,00397 +0,76 0,00397 +0,76 0,00396 +0,51

Sample 3 0,00374 0,00373 -0,27 0,00373 -0,27 0,00373 -0,27 0,00375 +0,27

%Δ mean +

std. dev.

+0,32 ±

0,52

+0,32 ± 

0,53

+0,32 ± 

0,53

+0,42 ± 

0,13

≈2 mg

Sample 1 0,00221 0,00219 -0,90 0,00220 -0,45 0,00219 -0,90 0,00219 -0,90

Sample 2 0,00185 0,00186 +0,54 0,00186 +0,54 0,00186 +0,54 0,00186 +0,54

Sample 3 0,00185 0,00189 +2,16 0,00189 +2,16 0,00190 +2,70 0,00190 +2,70

Sample 4 0,00187 0,00190 +1,60 0,00186 -0,53 0,00188 +0,53 0,00188 +0,53

%Δ mean +

std. dev.

+0,85 ± 

1,34

+0,43 ± 

1,25

+0,72 ± 

1,49

+0,72 ± 

1,49

 ≈1 mg

Sample 1 0,00100 0,00103 +3,0 0,00103 +3,0 0,00103 +3,0 0,00103 +3,0

Sample 2 0,00114 0,00116 +1,8 0,00118 +3,5 0,00117 +2,6 0,00117 +2,6

Sample 3 0,00098 0,00099 +1,0 0,00098 -0- 0,00100 +2,0 0,00099 +1,0

Sample 4 0,00097 0,00096 -1,0 0,00095 -2,1 0,00097 -0- 0,00097 -0-

%Δ mean +

std. dev.

+1,2 ± 

1,7

+1,1 ± 

2,6

+1,9 ± 

1,3

+1,7 ± 

1,4

≈0,5 mg

Sample 1 0,00036 0,00037 +2,8 0,00037 +2,8 0,00037 +2,8 0,00039 +8,3

Sample 2 0,00041 0,00044 +7,3 0,00044 +7,3 0,00044 +7,3 0,00044 +7,3

Sample 3 0,00044 0,00047 +6,8 0,00046 +4,5 0,00048 +9,1 0,00048 +9,1

Sample 4 0,00051 0,00054 +5,9 0,00053 +3,9 0,00055 +7,8 0,00055 +7,8

%Δ mean +

std. dev.

+5,7± 2,0 +4,6 ± 

1,9

+6,8 ± 

2,8

+8,1 ± 

0,8

 ≈0,1 mg

Sample 1 0,00032 0,00033 +3,1 0,00034 +6,3 0,00019 -41 0,00019 -41

Sample 2 0,00008 0,00013 +63 0,00014 +75 0,00014 +75 0,00014 +75

Sample 3 0,00010 0,00011 +10 0,00012 +20 0,00012 +20 0,00014 +40

Sample 4 0,00008 0,00012 +50 0,00010 +25 0,00011 +38 0,00011 +38

%Δ mean +

std. dev.

+32 ± 29 +32 ± 30 +23 ± 

48

+28 ± 49

media blank

Sample 1 0,32999 0,33000 +0,0030 0,33002 +0,0091 0,33000 +0,0030 0,33002 +0,0091

Sample 2 0,23152 0,23150 -0,0086 0,23153 +0,0043 0,23150 -0,0086 0,23151 -0,0043

Sample 3 0,26775 0,26772 -0,0112 0,26775 -0- 0,26774 -0,0037 0,26775 -0-

Sample 4 0,30638 0,30637 -0,0033 0,30639 +0,0033 0,30638 -0- 0,30639 +0,0033

Sample 5 0,32830 0,32830 -0- 0,32834 +0,0122 0,32831 +0,0030 0,32832 +0,0061

Sample 6 0,32176 0,32172 -0,0124 0,32177 +0,0031 0,32176 -0- 0,32177 +0,0031
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AZ Rd. dust 

≈4 mg

Day 0 wt. 

(g)

Day 7 wt. 

(g)

%Δ Day 14 wt. 

(g)

%Δ Day 21 wt. 

(g)

%Δ Day 28 wt. 

(g)

%Δ

%Δ mean +

std. dev.

-0,0054 

± 0,0063

+0,0053 

± 0,0045

-0,0011 

± 

0,0045

+0,0029 

± 0,0048

Table 3. Computed recoveries from spiked PVC Accu-caps for certified reference material 

(CRM) masses of ≈1, ≈2 and ≈4 mg per sample.

Spiking Level CRM Mean Recovery ± Std. Dev., %

≈4 mg NIST SRM 1648 96.1 ± 1.6 (n=7)

Arizona Road Dust 96.7 ± 2.8 (n=4)

≈2 mg NIST SRM 1648 93.1 ± 6.2 (n=6*)

Arizona Road Dust 97.4 ± 1.3 (n=4)

≈1 mg NIST SRM 1648 91.6 ± 9.0 (n=7)

Arizona Road Dust 102 ± 3.2 (n=4)

*One statistical outlier omitted (Q-test, p=0.05)
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Table 4. Sample weights for Arizona Road Dust and PVC capsules obtained by NIOSH vs. 

independent gravimetric laboratory results reported by Bureau Veritas North America (BVNA).

Sample NIOSH wt. (g) BVNA wt. (g) Δ (g) % Δ

Arizona Road 

Dust

≈4 mg #1 0.00418 0.00408 -0.00010 -2.4

≈4 mg #2 0.00394 0.00379 -0.00015 -3.8

≈4 mg #3 0.00374 0.00361 -0.00013 -3.5

≈2 mg #1 0.00221 0.00210 -0.00011 -5.0

≈2 mg #2 0.00185 0.00188 +0.00003 +1.6

≈2 mg #3 0.00185 0.00186 +0.00001 +0.54

≈2 mg #4 0.00187 0.00178 -0.00093 -4.8

≈1 mg #1 0.00100 0.00105 +0.00005 +5.0

≈1 mg #2 0.00114 0.00116 +0.00002 +1.7

≈1 mg #3 0.00098 0.00094 -0.00004 -4.1

≈1 mg #4 0.00097 0.00098 +0.00001 +10

≈0.5 mg #1 0.00036 0.00038 +0.00002 +5.6

≈0.5 mg #2 0.00041 0.00042 +0.00001 +2.4

≈0.5 mg #3 0.00044 0.00047 +0.00003 +6.8

≈0.5 mg #4 0.00051 0.00056 +0.00005 +9.8

≈0.1 mg #1 0.00032 0.00031 -0.00001 -0.97

≈0.1 mg #2 0.00008 0.00009 +0.00001 +13

≈0.1 mg #3 0.00010 0.00003 -0.00007 -70

≈0.1 mg #4 0.00008 0.00008 -0-

PVC capsule media 

blanks

#1 0.28019 0.28036 +0.00017 +0.061

#2 0.29177 0.29195 +0.00018 +0.062

#3 0.28419 0.28436 +0.00017 +0.060

#4 0.30745 0.30762 +0.00017 +0.055

#5 0.31677 0.31698 +0.00021 +0.066

#6 0.32792 0.32812 +0.00020 +0.061

#7 0.33002 0.33018 +0.00016 +0.048

#8 0.23151 0.23165 +0.00014 +0.060

#9 0.26775 0.26792 +0.00017 +0.063

#10 0.30639 0.30659 +0.00020 +0.065

#11 0.32832 0.32853 +0.00021 +0.064

#12 0.32177 0.32197 +0.00020 +0.062
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Table 5. Summary of field gravimetric data from paired PVC Accu-cap samplers housed in 

closed-face cassettes (CFCs) (n=15) and Institute of Occupational Medicine IOM samplers (n=12) 

obtained in metal foundries. (Results courtesy of M. Demange, Institut National de Recherche et 

de Sécurité [INRS], Vandoeuvre, France)

Data set Accu-cap (mg/m3) IOM (mg/m3) Ratio (Accu-cap/IOM x 

100%) 

1 9.0 9.7

9.1 10.8

avg. = 9.1 avg. = 10.3 88

2 3.9 5.2

4.0 5.5

avg. = 4.0 avg. = 5.4 74

3 9.3 12.4

8.7 5.8

avg. = 9.0 avg. = 9.1 99

4 10.3 11.0

9.8 11.1

6.6 8.1

9.0

avg. = 9.0 avg. = 10.1 89

5 4.7 5.4

4.8 6.0

4.6 3.8

4.9

5.1

avg. = 4.8 avg. = 5.1 94

 mean overall ratio (Accu-cap / IOM) = 89% (±9%)
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Appendix 1

These statistical calculations were provided by Amy Feng (DART/NIOSH).

The CVTotal was calculated taking into account the 5% pump error. The equation used was : CV_total 

=Sqrt(CV1**2+0.05)**2) =sqrt(0.031**2+0.05**2)=0.059, was then used to calculate the Accuracy of the 

Methods. The updated accuracy is now 0.15466.

Two sets of dust source: AZ and NIST were used for this study. The NIST dust had some problems with 

moisture so that set of data was not included in the statistical analysis. 

1. The bias was defined as the difference between the NIOSH total dust weight on day 1 and BVNA 

adjusted dust weight on day 28. The following steps were taken for the calculation (see Appendix 

Table 1): 

a. Tare28_wt = NIOSH_twt28 - dwt_D0 NIOSH tare weight on day 28 is the difference between 

total weight on day 28 and the dust weight on day 1.

b. BVNA_dwt = BVNA_twt28 - Tare28_wt ; Adjust BVNA total dust weight by subtracting off the 

NIOSH tare weight.

c. Scale = the average blank of NIOSH – the average blank of BVNA on day 28. Calculate scale 

difference between NIOSH and BVNA using the blank samples on Day 28.

d. BVNA_adj=BVNA_dwt-scale; Adjust BVNA dust weight by subtracting off the scale difference.

e. Pt_bias=dwt_D0-BVNA_adj; Point bias is calculated as the difference between NIOSH Day 0 

dust weight and BVNA adjusted dust weight. 

2. The data at level 0.1 was below LOQ so was excluded from the subsequent analysis. Homogeneity 

of bias was tested using the ANOVA procedure. The test result indicated the bias was not 

homogenous. To take a conservative approach, the maximum mean bias value was used for the 

evaluation for the accuracy. Homogeneity of precision was tested using the Bartlett’s test. The 

Bartlett’s test suggested that the precision was poolable across the tested levels; therefore the 

pooled RSD was used for the accuracy evaluation (see Appendix Table 2). The NIOSH method 

Accuracy and 95% upper limit of the Accuracy was estimated and listed in Appendix Table 3.
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Table 1. Data listing

Source = 

AZ level sample

NIOSH_

twt28

BVNA_

twt28

NIOSHdwt_

D0

tare28_

wt

BVNA_

dwt scale BVNA_adj pt_bias 0.1 1 0.25091 0.25108 .00032 0.25059 .00049 .000181667 .000308333 -0.03646

0.1 2 0.28280 0.28299 .00008 0.28272 .00027 .000181667 .000088333 0.10417

0.1 3 0.26069 0.26080 .00010 0.26059 .00021 .000181667 .000028333 -0.71667

0.1 4 0.26153 0.26171 .00008 0.26145 .00026 .000181667 .000078333 -0.02083

0.5 1 0.32152 0.32172 .00036 0.32116 .00056 .000181667 .000378333 0.05093

0.5 2 0.31611 0.31630 .00041 0.31570 .00060 .000181667 .000418333 0.02033

0.5 3 0.31734 0.31755 .00044 0.31690 .00065 .000181667 .000468333 0.06439

0.5 4 0.31176 0.31199 .00051 0.31125 .00074 .000181667 .000558333 0.09477

1.0 1 0.31949 0.31972 .00100 0.31849 .00123 .000181667 .001048333 0.04833

1.0 2 0.27512 0.27532 .00114 0.27398 .00134 .000181667 .001158333 0.01608

1.0 3 0.25899 0.25913 .00098 0.25801 .00112 .000181667 .000938333 -0.04252

1.0 4 0.32531 0.32550 .00097 0.32434 .00116 .000181667 .000978333 0.00859

2.0 1 0.31342 0.31349 .00221 0.31121 .00228 .000181667 .002098333 -0.05053

2.0 2 0.30589 0.30610 .00185 0.30404 .00206 .000181667 .001878333 0.01532

2.0 3 0.25327 0.25346 .00185 0.25142 .00204 .000181667 .001858333 0.00450

2.0 4 0.26232 0.26241 .00187 0.26045 .00196 .000181667 .001778333 -0.04902 4.0 1 0.29227 0.29235 .00418 0.28809 .00426 .000181667 .004078333 -0.02432 4.0 2 0.26984 0.26987 .00394 0.26590 .00397 .000181667 .003788333 -0.03849 4.0 3 0.30441 0.30446 .00374 0.30067 .00379 .000181667 .003608333 -0.03520

 

Table 2. List of data for the Accuracy Estimation

Sourcer = AZ

level pt_bias m_bias est_bias pool_TRSD* 0.5 0.050926 0.057604* 0.057604 0.031388

0.5 0.020325 0.057604 0.057604 0.031388

0.5 0.064394 0.057604 0.057604 0.031388

0.5 0.094771 0.057604 0.057604 0.031388

1.0 0.048333 0.007622 0.057604 0.031388

1.0 0.016082 0.007622 0.057604 0.031388

1.0 -0.042517 0.007622 0.057604 0.031388

1.0 0.008591 0.007622 0.057604 0.031388

2.0 -0.050528 -0.019932 0.057604 0.031388

2.0 0.015315 -0.019932 0.057604 0.031388

2.0 0.004505 -0.019932 0.057604 0.031388

2.0 -0.049020 -0.019932 0.057604 0.031388 4.0 -0.024322 -0.032674 0.057604 0.031388 4.0 -0.038494 -0.032674 0.057604 0.031388 4.0 -0.035205 -0.032674 0.057604 0.031388

*The conservative approach took the maximum mean bias across levels as the bias estimation.

Table 3. NIOSH 0501 Gravimetric Method, estimation of NIOSH Accuracy and 95% upper limit of the 

Accuracy

source n k est_bias est_rsd

CV_total 

accuracy Acc_U95 AZ 4 4 0.057604 0.031388 0.059 0.15466 0.21657

Filename: Gravimetric_AZ_accuracy_based on CVTotal.docx 6/2/2014

Gravimetric_AZ_accuracy dated 4/25/2014.
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