NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

NIOSH Manual of Analytical Methods (NMAM) 5th Edition 

BACKUP DATA REPORT 

NIOSH Method No. 5524 

Title: Metalworking fluids

Analyte: Metalworking fluids

Author/developer:Robert Glaser 

Date: Oct 30, 2013

 

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date. 
BACKUP DATA REPORT

NMAM Method No 5524

Analyte: Metalworking fluids (MWF)

Author/developer Robert Glaser

Oct 30, 2013

Substance: metalworking fluids (MWF) 

Exposure Limits: Exposure to certain MWFs has been related to occupational asthma, 

hypersensitivity pneumonitis (HP), and possibly to cancer. NIOSH recommends that 

exposure to metal working fluids (MWF) be maintained at < 0.4 mg/m3, measured as 

thoracic particulate or < 0.5 mg/ m3 measured as total particulate.

Metal working fluids (MWF) are primarily formulated to remove metal debris from the 

work surfaces of metal parts that are being turned, ground, milled or drilled; they also

provide lubrication and cooling to the work piece and to the work tool. These fluids are 

also used to cool and lubricate in cold metal-forming operations such as stamping, 

punching, hobbing or drawing [1].

There may be as many as 600 compounds in MWF, including mineral oils, emulsifiers, 

water, alkanolamines, polyethoxyethanols, biocides, surfactants, chlorinated paraffins 

and boron compounds. Despite the complexity of their formulations, they are generally 

classified into four categories according to the amount of mineral oil that they contain. 

Straight fluids contain essentially 100 % mineral oils and/or other organic additives but 

no water. Soluble fluids contain large amounts of mineral oil (up to 80%) and 

emulsifying agents to form emulsions when mixed with water. Semi-synthetic fluids 

contain surfactants to dissolve relatively small amounts of mineral oil (5-30%) and are 

soluble in water. Synthetic fluids contain no mineral oil and are soluble in water [2]. 

Chemicals Used for Evaluation: Samples of metalworking fluids for the spiking tests 

were obtained from Cincinnati Milacron Chemical Corporation (Cincinnati Ohio, USA) 

and Solutia Inc., (St Louis, Missouri). The dichloromethane, methanol and toluene used 

in this study were distilled-in-glass (DIG) grade and obtained from various sources by 

contractors performing the performance tests. Distilled/deionized water from in-house 

sources was also used. 
Synopsis

In areas of the USA where there are metalworking facilities in rural areas, agricultural 

debris may be a significant source of interference, especially during planting and 

harvest times. There may also be background dust levels due to in-plant construction. 

Furthermore, urban ambient particulate levels as high as 0.1 mg/m3 have been reported 

by the EPA in US cities [3]. Furthermore, there may be significant levels of metal 

particulate generated during many metalworking processes, in particular, during welding

operations. 

For these reasons, NIOSH adapted ASTM method PS-42-97 [4] for metalworking fluids 

to support the standard. Using this procedure, MWF is extracted and separated from comingled background particulate using a ternary blend of equal parts of dichloromethane, 

methanol and toluene [5,6]. A later extraction using 1:1 methanol:water was added for a 

single fluid (Solutia) that was found to be insoluble in the ternary blend [7]. In this way, 

exposure to MWF only is determined. NIOSH has designated this as NMAM Method 

5524. The analytical procedure is described graphically in Figure 1 below. 

Figure 1. Measurement of MWF using NMAM Method 5524. (1st line) The filter is tared 

(W1). Sampling is conducted as indicated; samples are refrigerated during storage, 

then desiccated prior to weighing (W2). (2nd line) The filter is extracted using the ternary 

(1:1:1 dichloromethane:methanol:toluene) and binary (1:1 methanol:water) blends, 

dried and reweighed (W3). Total weight, WT = W2 –W1; MWF is measured as 

Extractable Weight, WE = W2-W3; and the fraction extracted, FE = WE/WT. 

Sample 8-hr

1.6 L/min (Thoracic) 

2 L/min (Total) 

W1 Refr W2 igerate

upon receipt

at lab

Tare

Desiccate 2-hr Re-weigh

10-mL Ternary blend

10-mL Binary blend

10-mL Ternary blend

then 1-2-mL ternary blend Extract Dry 2hr

W3 

Re-weigh

37-

mm

2-μm 

PTFE 

Filter
Analytical Aspects

Extraction

Using the method described above, the filters are extracted in a specially designed filter 

funnel. The funnel uses no frit, but a photo etched stainless steel screen to support the 

filter. The funnel has been designed with a precisely-machined narrow circular lip at the 

base of an upper heavy stainless steel weight to engage the 37-mm sampling filters. 

When inserted into the funnel base, it mimics the way the inlet sampling cassette 

component engages the perimeter of a filter contained in the outlet sampling cassette 

component. In this way, the same narrow perimeter around the filter (that is unexposed 

to sample flow) is engaged and only the sampling surface of the filter is available for 

extraction. That screen does not plug and even if damaged, is replaceable. A graphic of 

this funnel is shown in Figure 2. 

Figure 2. Filter funnel consists of (A) a 37-mm ID X 28 mm long 

aluminum body with hose barb to connect to a vacuum 

extraction flask. This body retains (B) a 37-mm photo-etched 

stainless steel screen support for the PTFE filter to be extracted. 

A 25-mm long X 50-mm OD (upper section) X 37-mm OD ( lower

section) heavy stainless steel funnel spout (C) holds the PTFE 

filter (not shown) in place against the 37-mm photo-etched 

screen. Completely assembled, the device is ~ 73 mm long. 

Filter Pretreatment 

Recent problems with high background contamination on the filters have necessitated 

use of a pretreatment technique for the filters. This was developed under contract to 

NIOSH and is given as Appendix 1 in the revised method. It is also given in this report 

as Appendix [1]. The cleanup procedure has been used in several recent sequences 

(sequences 11525-CA,-CC, and –CG) for analysis of MWF. LODs and LOQs of 30

μg/sample and 90 μg/sample respectively have been reported [8]. 
Gravimetry 

All gravimetric analyses were carried out using a Mettler Mdl MT 5 six-place balance. 

Filters were conditioned for 2 hours in a controlled humidity/temperature chamber. 

While it is assumed this standard procedure of a 2-hr desiccation would stabilize 

weights and remove water, the efficacy of the step was not measured. They are then 

weighed by first passing them through a 210Po source to neutralize static charges. MWF 

content is determined by further extracting, drying and then re-weighing the filters.

Specificity

This technique is specific to MWF as a group only. The criteria document specifies that 

only exposures to the total mass of MWF are to be considered. Tests (see below) have 

shown that the extraction regimen can remove all four classes of MWF. This permits the 

MWF to be separated from miscellaneous solid particulates such as machining swarf,

welding fumes, agricultural debris, and construction dust, etc. 

Solvent Development 

This method involves determination of the total/extractable weights of MWF samples; 

extractions are performed using a 1:1:1 blend of toluene:dichloromethane:methanol and 

a 1:1 blend of methanol:water. The development of the ternary solvent for nine (9) test 

fluids of MWF is described in reference [5]; the initial evaluation of the ternary blend with 

spiked MWF samples is described in reference [6]. The use of this solvent was 

validated during a survey of 79 US plants for exposures to MWF [8,9]. The fluids 

encountered in this survey are listed in Appendix 2 of this report. Of 122 fluids 

encountered, only one (Solutia) was found to be insoluble in the ternary blend. Solutia 

was found to be soluble in the binary solvent blend of methanol:water. The binary blend 

was therefore added to the extraction regimen. The more comprehensive evaluation of 

this extraction regimen is discussed below under ‘Spiking Experiments.’ 

Samples of all MWF samples encountered were tested for solubility in the ternary 

solvent blend by injecting 50-uL aliquots of the pure MWF into the ternary blend [9]. All 

fluids encountered in that survey are listed in Appendix 2 of this report; all were soluble 

except for Solutia. 
Method Evaluation

The method has been subjected to significant rigorous evaluation [5, 6, 8, 9,10]. 

Validation has included ‘spiking experiments’ with the ternary blend only to extract 4 test

fluids of MWF [6] and with the combination binary/ternary blends to determine accuracy, 

precision, robustness, stability, and limits of detection and quantitation for 5 test fluids of 

MWF (including Solutia) [10]. The results of the analyses of these 5 test fluids using the 

combination ternary and binary blend are presented below. The method was further 

validated according to ASTM standard E 691-99 specifications in a ‘six-laboratory round 

robin evaluation [11].’ These samples were obtained from synthetic atmospheres of an 

aerosolized test MWF in air. These results are discussed below as well. 

Spiking Experiments

The accuracy and precision of the analysis of MWF were initially estimated by spiking 

separate sets of PTFE filters with aerosolized aliquots of the four types of conventional 

MWF (STR 1, SOL 2, SEMI 3, and SYN 4) contained in the ternary blend. An additional 

filter set was spiked with a synthetic fluid (SYN5), dissolved in methanol:water. MWF 

extraction efficiencies were studied over four different concentration levels and results 

are described in detail below. 

LOD/LOQ 

Spiking experiments were carried out by metering known volumes of MWF in the 

ternary or binary solvent blends onto filters. Therefore, blank PTFE filters were spiked 

with identical volumes of the neat ternary blend or binary blends to exactly replicate 

production of the samples. Samples were spiked with the ternary delivery solvent at 3 

levels; volumes ranged from 5-20 μL of the solvent. These spikes were allowed to 

evaporate from each set of blank filters. The LODs and LOQs for total and extractable 

weights were then obtained by carrying these filters through NMAM Method 5524. The 

weights of these blanks are shown in Figs 3A and 3B below. 
-0.01

-0.005

0

0.005

0.01

0.015

0.02

LOW MEDIUM HIGH

Wt (mg)

Level 

Total Wt Blanks 

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

LOW MEDIUM HIGH

Wt (mg)

Level 

Extractable Wt Blanks 

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5

Figure 3A and 3B.

 

3A 

3B 

 

Limits of quantitation were determined to be 73 μg and 80 μg respectively for the totalweight and extracted-weight procedures. Since the volumes of solvent spiked varied by 

fluid, the blanks were assigned separately to each fluid. The masses of each sample 

spiked onto the filters are shown in Fig 4A. Samples were spiked at the following levels: 

straight: 230 - 940 μg, soluble: 260-1130 μg, semisynthetic: 64 – 260 μg, synthetic I: 

110 – 480 μg and synthetic II: 90 - 372 μg. Following spiking, the samples were dried by 

storage for 24 hours. The fraction extracted at each level is shown in Fig 4B. On 

average, fractions extracted (weight recovered/weight spiked) for all fluids for all levels 

tested exceeded 94%. 
Figure 4A and 4B.

4A 

4B 

The precision of the analysis of the total weight samples are shown in Figure 5A; the 

precision of the analysis of the extracted weight samples are shown in Figure 5B. Note 

that the spiking error has been removed from these estimates using techniques 

described in NOTE 1 in reference 6. Pooled estimates of the coefficients of variation of 

analysis over all samples tested were 0.043 for the total weight samples and 0.046 for 

the extracted weight samples. 

0

0.2

0.4

0.6

0.8

1

1.2

LOW MEDIUM HIGH

Wt (mg)

Level 

MWF Spikes 

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5

0

0.15

0.3

0.45

0.6

0.75

0.9

1.05

LOW MEDIUM HIGH

FE 

Level 

Fraction Extracted 

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5
Figure 5A (top) Analytical precision of the method for total weight 

5B (bottom) Analytical precision for extracted weight.

5A 

5B 

Analytical Precision total weight 

0

0.025

0.05

0.075

0.1

0.125

0.15

0.175

LOW MEDIUM HIGH

Level 

CV

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5

Analytical Precision ext weight 

0

0.025

0.05

0.075

0.1

0.125

0.15

0.175

LOW MEDIUM HIGH

Level 

CV

STR 1

SOL 2

SEMI 3

SYN 4

SYN 5

Six–lab performance testing of NMAM Method 5524 using

dynamically-generated samples

 

A performance test of NMAM Method 5524/ASTM Method D-7049-04 for analysis of 

metalworking fluids (MWF) was conducted [11]. These methods involve determination 

of the total and extractable weights of MWF samples; extractions are performed using a 

ternary blend of toluene:dichloromethane:methanol and a binary blend of

methanol:water. Six laboratories participated in this study. Statistical evaluation of the 

data obtained was conducted according to the ASTM E691-99 inter-laboratory method 

comparison standard [12].
 A preliminary analysis of 20 blank samples was made to familiarize the laboratories 

with the procedure(s) and to estimate the methods’ limits of detection/quantitation 

(LODs/LOQs). The results of these analyses are shown in Figs 6A and 6B below for 

each lab. In the preliminary analysis of blanks; the average LOQs were 0.094 mg for the 

total weight analysis and 0.136 mg for the extracted weight analysis. 

Figure 6. Six-lab preliminary blank study: 

 (A top) Total weight (TW) blanks

 (B bottom) Extractable weight (EW) blanks.
Dynamically-Generated Samples

Generator Construction

A generation system that had been built for the production of solid aerosols [13] was 

modified to produce liquid MWF aerosols. A diagram of this system is shown in Figure 

7. High pressure air —21 psi (144.8 kpA) (A) was passed through a Collison nebulizer 

(model C-27, BGI Inc., Waltham, MA) (B) to produce a stream of aerosol. In order to 

mitigate problems with adiabatic cooling and formation of significant levels of 

precipitates of higher molecular weight MWF components during aerosolization, the 

nebulizer was thermally jacketed with a leakproof plastic cylinder connected to a water 

bath that circulated water at constant temperature (46oC) around the nebulizer housing 

during operation. From the nebulizer, the aerosol then passed through a large particle 

dropout zone (C) to a heated copper pipe (D) and was transported into a 1 foot (0.3 m) 

diameter x 8 foot (2.44 m) long cylindrical mixing chamber (E), where it was diluted with 

air, supplied at around 400 cubic foot per hour (11.3 m3

/hr). Flow was disrupted by a 

metal plate at (F) in the mixing chamber. A 1 foot (0.3 m) diameter x 4 inch (10.2 cm) 

thick section of metal aviation honeycomb was provided at point (G) to provide laminar 

air flow. Diluted samples of the airstream were obtained at point (H) using a laser 

particle counter (MDL 217A, Met One Inc., Grants Pass, OR) capable of monitoring the 

number of particles > 500 nm generated. This permitted the same number of particles 

and therefore the same mass (~0.5 mg) to be deposited from run to run. Samples were 

collected at 2 Liter per min at the bottom of the mixing chamber by mounting sampler 

cassettes (I) on an 18-port sampling manifold. Flows through each port in the manifold 

were controlled by critical orifices (J) dedicated to that port. The critical orifices were 

connected to a central manifold which in turn was connected to a series of tandem 

sampling pumps (Gast, Benton Harbor, MI). 
Figure 7. Liquid Aerosol Generator

Dynamically-generated samples of a semi-synthetic MWF aerosol were then collected 

on tared polytetrafluoroethylene (PTFE) filters, distributed to the six participating labs 

and analyzed according to NMAM Method 5524 by all participants. Sample masses 

deposited (∼0.4–0.5 mg) corresponded to amounts expected in an 8-hr shift at the

NIOSH REL of 0.4 mg/m3 (thoracic) and 0.5 mg/m3 (total particulate). All sampling was 

conducted at approximately 2L/min. The generator output was monitored with a 

calibrated laser particle counter. The reported concentrations are shown in Figs 8A and 

8B above. In this study, one laboratory (Lab 1) reported concentrations that were 19% 

lower and less precise (CV = 0.20) than the average results reported by the five other 

labs.

The data from all six labs were evaluated by computation of the ASTM-recommended h 

and k consistency statistics, which are measures respectively of the bias and precision 

of the technique [12]. The calculated h statistic indicated that the nonconsistent 

laboratory (Lab 1) was significantly biased relative to the other five labs; in addition, the 
computed k statistic indicated that this laboratory’s results were significantly less precise 

than the other five labs. This study generally indicated that samples analyzed within 7 

days of collection were quantitatively and precisely recovered.

Figure 8. (A) Concentrations (mg/m3 ± 95% CI) for the total weight analyses from 

the six-lab performance study. Each point for each lab represents the mean of 12 

samples. (B) Concentrations (mg/m3 ± 95% confidence intervals) for the extracted 

weight analyses from the six-lab performance study. 
Fractions Extracted of Dynamically-generated samples

The fractions extracted (FE, or extracted weight/total particulate weight) ±95% 

confidence limits for each lab are plotted in Figure 9. All of the MWF samples were 

quantitatively extracted by all labs, including Lab 1, which reported particulate masses 

for a few samples that were 58–72% of those reported by the other labs. For all six labs, 

the average fraction extracted was > 94% (CV = 0.025). The extraction data is much 

more precise (coefficient of variation [CV] = 0.025) than the reported concentration data 

shown in Figure 8. 

The fractions extracted data were tested using an analysis of variance technique, and 

there were no statistical differences in the fractions extracted among the six labs. The 

precision estimates for the remaining five labs (excluding Lab 1) were not different 

statistically (alpha = 0.005) for either the total or extractable weights. Pooled estimates 

of the total coefficients of variation of analysis were 0.13 for the total weight samples 

and 0.13 for the extracted weight samples. An overall method bias of -5% was 

determined by comparing the overall mean concentration reported by the participants to 

that determined by the particle counter.

Figure 9. Fractions Extracted of Test MWF reported by six participating 

laboratories in round robin test. 
Further Stability testing

From the above data obtained with the dynamically-generated samples, it is important 

to note that the regimen involved unrefrigerated overnight shipment and refrigerated 

storage for periods up to 7days prior to analysis. Despite this, the samples still retained 

84–90% of the initial mass loading after storage for 7 days. Similar experiments have 

been conducted in our laboratories under even less stringent storage conditions. Figure 

10 shows a decay curve for nine filters loaded with ∼0.4 mg of dynamically-generated 

MWF aerosol. The samples were stored in an open face position (supported in lower 

cassette halves with no upper halves in place) in a temperature- (∼26◦C) and humiditycontrolled (35–45% RH) environmental chamber. This figure shows that the average 

weight decreased by <20% after 2 weeks storage; that is, the sample recovery still met 

minimum NIOSH requirements for storage under these suboptimal conditions. 

However, this is but one of several MWF formulations; there are hundreds if not 

thousands of formulations of MWF. It is prudent to refrigerate MWF samples during 

shipment in order to mitigate loss of semi-volatile components or possibly bacterial 

decomposition of samples stored for extended periods during shipment.
Figure 10. Percent remaining of ~0.4-mg aerosol samples of the test semisynthetic MWF stored in an open-face cassette at ambient conditions for periods 

ranging from 1–14 days. Data follows equation: Percent remaining = −1.167 × day 

+97.7. 

Conclusions

These studies provide confidence in the ruggedness of the NMAM Method 5524 

sampling and analytical procedure and also support for consideration by ASTM as a 

fully validated standard. Aerosolized samples of a test soluble MWF sampled at 

concentrations corresponding to either of the NIOSH thoracic and total particulate RELs

could generally be shipped unrefrigerated, stored refrigerated up to 7 days, and then 

analyzed quantitatively and precisely for MWF using the NIOSH/ASTM procedures.

However, there are many other formulations of MWF than those evaluated here. It is 

therefore prudent to ship and store MWF samples under refrigeration to mitigate 

possible sample loss in such fluids. 
REFERENCES

1. National Institute for Occupational Safety and Health (NIOSH): Criteria for a 

Recommended Standard: Occupational Exposure to Metalworking Fluids. DHHS 

(NIOSH) Pub. No. 98-102. Cincinnati, Ohio: NIOSH, 1998.

2. Darcy, J: Exposure to Metalworking Fluids, Metalworking Fluids Symposium 

Dearborn, MI, 2008. 

3. National Air Quality and Emissions Trends Report 198. U.S. Environmental 

Protection Agency, Office of Air Quality, Planning and Standards Technical Support 

Division. Research Triangle Park, N.C. EPA-450-91-0, 1993. 

4. ASTM International: Provisional Standard Test Method for Metal Removal Fluid 

Aerosol in Workplace Atmospheres (ASTM PS42-97). West Conshohocken, Pa.: ASTM, 

1997. 

5. Glaser, R.A.: Data supporting a provisional American Society for Testing and 

Materials (ASTM) method for metalworking fluids, Part 1: A solvent blend with wideranging ability to dissolve metalworking fluids. J. Test. Eval. 27:171–174 (1999). 

6. Glaser, R.A., S. Shulman, and P Klinger: Data supporting a provisional American 

Society for Testing and Materials (ASTM) method for metalworking fluids, Part 2: 

Preliminary report of evaluation of a ternary solvent blend in a provisional ASTM method 

for metalworking fluids (P-42-97). J. Test. Eval. 27:131–136 (1999).

7. Bureau Veritas North America Novi, MI, Sequences 11525-CA, -CC, and –CG, 2013. 

8. Piacitelli, G.M.,W.K. Sieber,D.M. O’Brien, R.T. Hughes, R.A. Glaser, and J.D. 

Catalano: Metalworking fluid exposures in small machine shops: An overview. Am. Ind. 

Hyg. Assoc. J. 62:356–370 (2001).

9. Glaser, R.A., S. Shulman, R.Kurimo, and G. Piacitelli: Data supporting a Provisional 

ASTM method for metalworking fluids, Part 3. Evaluation of an ASTM method for 

metalworking fluids in a survey of metalworking facilities. J. Test. Eval. 30:439–451 

(2002).

10. Glaser, R.A., R. Kurimo, C. Neumeister and S. Shulman: Data supporting ASTM 

method D 7049-04 for metalworking fluids. J. Test. Eval. 33:323–330 (2005).

11. Glaser, R.A., R. Kurimo, & S. Shulman: Performance Testing of NIOSH Method 

5524/ASTM Method D-7049-04, for Determination of Metalworking Fluids. J. Occup. 

Environ Hyg. 4(8):583-595 (2007).

12. ASTM International: Standard Practice for Conducting an Interlaboratory Study to 

Determine the Precision of a Test Method (ASTM E 691-99). West Conshohocken, Pa.: 

ASTM, 2006.

13. Carsey, T.: LISA: A new aerosol generation system for sampler evaluation.

Am. Ind. Hyg. Assoc. J. 48:710–717 (1987).
Appendix 1: Procedure to remove PTFE filter contaminants 

that are soluble in and extracted with the ternary blend. 

Use this procedure to prevent high blanks from being obtained following extraction of PTFE 

filters. The filters are rinsed with ternary solvent (1:1:1 dichloromethane:methanol:toluene) 

described in NMAM Method 5524. The filters are air-dried and protected from airborne 

contamination prior to weighing and assembly into cassettes for field sampling. 

A. EQUIPMENT, SUPPLIES, REAGENTS AND STANDARDS 

1. 250 mL glass beaker(s)

2. 500 mL of ternary solvent 1:1:1 ratio of methanol, toluene and dichloromethane in a 

stoppered container

3. A fume hood 

4. Watch glasses to fit the beakers 

5. Glass stir rod

6. One box of 2 micron PTFE filters to be cleaned (or as many as required); recommend 

cleaning no more than 1 package of 50 filters per 100 mL of solvent

7. Stainless steel forceps to manipulate the filters

8. Large lint-free towellettes 

9. Clean stainless steel metal trays or screen approximately 18" x 24"

10. Nitrile gloves

11. Clean wide mouth glass container, e.g., ointment jar with Teflon® cap or French square 

bottle

B. PROCEDURE 

Perform all of the following tasks inside a fume hood! 

1. Wear nitrile gloves throughout this procedure to protect yourself from the solvent and to 

protect the filters from skin oil during handling. 

2. Pour approximately 100 mL of ternary solvent into a 250 mL glass beaker. 

3. Remove the PTFE filters from the package and remove the plastic spacers from 

between the filters. Place the filters individually (sample side up) into the beaker filled 

with ternary solvent. Be careful that the filters stay separated from each other and do 

not clump together.

4. Carefully stir the filters with the glass stir rod; do not allow the filters to turn over. Cover 

the beaker with the watch glass. Allow the filters to extract in the solvent in the beaker 

for 10 minutes.

5. Decant the ternary solvent out of the beaker and into a waste bottle. Use the stirring rod 

to compress and retain the filters in the beaker as the solvent is slowly decanted off.

6. Refill the beaker with 100 mL of fresh ternary solvent after decanting following step 2.5. 

Repeat steps 2.4 and 2.5 two times for a total of three solvent washes. 

7. After the three rinses are complete, drain off as much solvent as possible. Remove the 

filters from the beaker using forceps and place them onto a clean stainless steel metal 

tray or screen that has been covered with a large lint-free paper towel. Place them onto 
the tray sampling side up. Allow the filters to dry overnight. It is recommended that the 

filters contact the stainless steel screen directly. Make sure that lint-free paper towels 

are used. 

Warning: Keep the hood sash approximately half way open. If the sash is pushed 

lower, the higher air flow may blow the filters off the drying tray or screen. 

Place a sign on the sash indicating that it is to be left at this height 

overnight and not to be moved. 

8. Place the dried filters in a clean French square glass bottle or a wide–mouthed Teflon® 

capped ointment jar. Label the container "PTFE Filters rinsed with MWF solution," 

giving the date, initials, and number of filters. Do not store filters in plastic containers. 

Filters are now ready to be used for sampling. Since the filters are not separated by 

spacers, use care to remove them from the storage container for use. 

Cleanup Procedure Evaluation

The cleanup procedure described in Appendix 1 has been incorporated into NMAM Method

5524 in order to deal with reported spurious weight gains and losses before and after analysis of 

the PTFE filters used with this method. It is believed that trace levels of dust or extractable 

material are entrained in these filters during the manufacturing process. This cleanup 

procedure has been evaluated using 60 filters from three different batches of PTFE filters (20 

filters/batch) [1]. Prior to cleaning, the filters were weighed (untreated filters), then washed with 

the ternary blend according to the procedure in Appendix 1, dried, and then reweighed (treated 

filters). 

Results: The differences in each of the 3 batches were compared by subtracting the treated 

filter weights from their untreated filter weights. For all 60 samples, the overall mean 

difference in weights (+/-the standard error of the mean) was 0.2 μg (+/-1.4 μg). For each of the 

3 batches, the differences in weight were: 5 μg (+/-2.5 μg), 2 μg (+/-2.0 μg), and -3 μg (+/-2.7 

μg) for batches 1, 2 and 3, respectively. The weight differences were not statistically significant

from zero overall or by batch using a paired t-test (p = 0.05) and allowing for multiple 

comparisons. 

To determine if the washing procedure affected the filter’s performance for analysis of 

metalworking fluids, each of the filters was analyzed according to the procedure of NMAM 

Method 5524, which includes extraction with the binary and ternary solvent blends. The 

differences in the post-analysis weights of the filters and their treated or untreated weights 

were computed. The average difference in the weights of the 60 untreated filters and their postanalysis weights (reported as mean +/- standard error of the mean) was: 34 μg (+/-1.9 μg). For 

each of the 3 batches, the differences in the untreated and post-analysis weights were: 30 μg 

(+/-3.9 μg), 38 μg (+/-2.0 μg) and 34 μg (+/-3.3 μg) for batches 1, 2 and 3, respectively. These 

differences are statistically significantly different from zero, both overall and individually by 

batch, using a paired t-test (p=0.05) and allowing for multiple comparisons. 

The average differences in the weights of the 60 treated filters and their post-analysis weights 

were: 34 μg (+/-1.4 μg). Again the differences in weight are reported as mean +/-standard error 
of the mean. For each of the 3 batches, the differences in the post-analysis minus treated 

weights were: 35 μg (+/-3.4 μg), 36 μg (+/-2.0 μg) and 31 μg (+/-1.8 μg) for batches 1, 2 and 3, 

respectively. These differences are statistically significantly different from zero, both overall and 

individually by batch, using a paired t-test (p=0.05) and allowing for multiple comparisons. 

In summary, the weight differences were statistically different from zero by batch and overall 

using a paired t-test for both the post-analysis minus treated weights and for the postanalysis untreated weights (p = 0.05). However, the untreated/treated-weight differences were 

not statistically different using the same tests. 

These experiments indicate that cleaning the filters lowered the overall LOQ of the analytical 

method. The LOQ determined from the differences in weights between the untreated and 

analyzed filters was 140 μg. This was substantially higher than the LOQ of 110 μg determined 

from the differences in weights between the treated and analyzed filters.

1. NIOSH [2014]. CEMB Analytical Services Report: Sequence 11600-CA. Novi, Michigan: 

Bureau Veritas North America, unpublished. 
APPENDIX 2: List of metalworking fluids that have been found to be soluble in 

the ternary blend. The individual fluids have been identified by type and 

manufacturer. 

Manufacturer Tradename Type Soluble

All Power KOOLMIST 77 Semi-synthetic Yes

American Lubricants All Purpose Cutting Oil Straight Yes

Americhem Corp AM Cutting 2506 Oil Straight Yes

Angler Industries Draw LT-1R Synthetic Yes

Angler OIL Cut 121-M straight oil Straight Yes

Aqueous Cleaning Tech Inc. ACT 486 Cutting Coolant Soluble Yes

ACT 734 Synthetic Coolant Synthetic Yes

Associated Chemists ACITemplex 5950 Semi-synthetic Yes

ACI 4926 Carbide Grinding Fluid Synthetic Yes

ACI 4920 Grinding Fluid Synthetic Yes

ACITemplex 4966 Semi-synthetic Yes

ACITemplex 4929 Low Foam Grinding Fluid Synthetic Yes

ACI 4931 Mach and Tap Fluid Straight Yes

Blaser Swisslube BLASOCUT 4000 STRONG Soluble Yes

Blasocut 2000 Universal Soluble Yes

Castrol Castrol MeqqemCob Synthetic Yes

Clearedge 6519 Semi-synthetic Yes

Clearedge 6584 Semi-synthetic Yes

Drawfree 811 (Previously Iloform) Soluble Yes

N100 Pale oil (Brass Oil) Straight Yes

Safety Cool 407 Soluble Yes

Safety Cool 800 Semi-synthetic Yes

Syntilo 9951 Synthetic Yes

Syntilo 9954 Synthetic Yes

Chemtrol Inc. CT-345-J Semi-synthetic Yes

Chevron Chevron Met Working Fluid #503 Straight Yes

Citgo Petroleum Citgo Cutting Oil 205 Soluble Yes

Citgo Cutting Oil 425 Straight Yes

Citicool 22 Synthetic Yes

Citcool 33 Synthetic Yes

CLC Lubricants CLC Cut PX2 NS Straight Yes

CLC ChemFinish 605 Straight Yes

CLC ChemCut MX-CG Straight Yes

Coolant 2224 Plus Synthetic Yes

ChemFinish 605 Straight Yes

Commonwealth Oil Comminac 32 MAX Straight Yes
Manufacturer Tradename Type Soluble

Cutting & Grinding Fluids Inc. CG 650 D Soluble Yes

CG 5352 R Straight Yes

CG 5352 RR Straight Yes

KoolKut 692 Soluble Yes

DA Stuart Co Dascool LN 231-78 Semi-synthetic Yes

Dascool 2223 Semi-synthetic Yes

Superkool 25 straight Straight Yes

Surgrind 86 Synthetic Yes

Die-Casting ID Corp ID DUA Chem 202 Semi-synthetic Yes

Diversy Corp LUBRICOOLANT AC Soluble Yes

LUBRICOOLANT 4D Soluble Yes

DoALL Co. DoAll 80 Straight Yes

KoolAll 940 Semi-synthetic Yes

KoolAll 948 Semi-synthetic Yes

ELF Lubricants North America

Inc. 

Elfdraw S 13 Synthetic Yes

Enterprise Oil Co Duracut 130 Straight Yes

ETNA Products Master Draw B 942/I Soluble Yes

Fuchs Lubricants FuchsVelvesol 96 Soluble Yes

Lus-Co-Cut 570ST Straight Yes

Lus-Co-Cut 514 CMP Straight oil Straight Yes

Lus-Co-Cut 400 Straight oil Straight Yes

Renodraw 419NC Soluble Yes

Renocut 471 Straight oil Straight Yes

Shamrock LF Soluble Yes

Ultracool 430 Synthetic Yes

Hangsterfer's Lab Co Hangsterfer's Hard Cut # 531 Straight Yes

Houghton Intl Cut Max 570 Straight Yes

Cut MaxTPO-46 Straight Yes

Hocut 787 H Soluble Yes

Intercon Enterprises JokischW2-OP Semi-synthetic Yes

ITW Fluid Prod Group Accu-Lube LB-2000 Straight Yes

Accu-Lube LB 3000 Straight Yes

Rustlick PB-10 Soluble Soluble Yes

Rustlick WS 5050 Soluble Yes

Lillyblad DB BROMUS B water soluble Soluble Yes

DB Water Soluble oil D Soluble Yes

Lyondell Petrochemical Transkut HD 200 Straight Yes
Manufacturer Tradename Type Soluble

Master Chemical Trim E 190 Soluble Yes

Trim CE/CE Soluble Yes

Trim O M287 Straight Yes

TRIMSOL Soluble Yes

Trim Microsol 265 Soluble Yes

TRIMSOL Silicone Free Soluble Yes

Metalworking Lubricants METKUT 20546-TX-40 Straight Yes

Milacron Cimstarr 60-LF Semi-synthetic Yes

Cimstar 3700 Semi-synthetic Yes

Cimtech 100 Synthetic Yes

CimstarQualStar Semi-synthetic Yes

Cimtap II Yes

Cimperial 1010 Soluble Yes

Cimperial 1011 Soluble Yes

Cimstar 55 Semi-synthetic Yes

Cimstar 540 Semi-synthetic Yes

Cimtech 400 Synthetic Yes

C10TX Soluble Yes

Mobil Oil Corp Mobil Mobilmet Omicron Straight Yes

Mobil Mobilmet Nu oil Straight Yes

MobilVascul 18F Straight Yes

MobilmetAlpha Straight Oil Straight Yes

Mobilmet Omega Straight Yes

Vacmul 281 Straight Yes

Mobil Hydraulic AW 68 Straight Oil Straight Yes

Mobilmet Upsilon Straight Yes

Vacmul 3A Honing Oil/EDM Straight Yes

Monroe Fluid Tech Co Prime Cut Soluble Oil Soluble Yes

Motor Oil Inc. Thredkut 99 cutting oil Straight Yes

Kleercut CF Straight Yes

National Oil Products National Oil Products 3115 cutting oil Straight Yes

National Oil Products Supreme Soluble HD Soluble Yes

OakiteProducts Inc OakiteControlant 650 NS Synthetic Yes

Ocean State Oil Hycut 4 Straight Oil Straight Yes

Neil Cut 570 Cutting Straight Oil Straight Yes

Perkins Products Perkut 296-H Straight Yes

Perkool 5005- EP Semi-synthetic Yes
Relton Corp ReltonA-9 Aluminum Cutting Fluid Soluble Yes

Rex Oil & Chemical Co Titan Cutting Straight Oil Straight Yes

Magic Cutting Oil Straight Yes

Richards Apex Prod. formerly

GWhitefieldRichards Co 

Near-a-Lard # 62 Straight Yes

Manufacturer Tradename Type Soluble

Rock Valley Oil &Chemical Co Rockpin Straight Oil Straight Yes

Solar Chem Co Solar Cut Synthetic Yes 

Solutia Glacier Synthetic No

Spartan Chem Co COOLSPAR Synthetic Yes

StecoCorp TAP Magic Aluminum Semi-synthetic Yes

Tapmagic Extra Cutting Fluid Straight Yes

Stirling Industries Division Tufcut 316 Straight Yes

RaecutA-1 Straight Yes

16228 HONING OIL Straight Yes

Sunnen Products Sunnen Honnig Oil MB 30-55 Straight Yes

Tapmatic Corp LPSTapmaticPlus 2 Synthetic Yes

Texaco Texaco Sulfur Oil (Sultex) Straight Yes

Texaco Sultex F Straight Yes

Texaco 2731 Almag Special Straight Yes

Texaco 01659 rando HD 68 brass st oil Straight Yes

Trico Mfg TriCool Synthetic Yes

Union Butterfield Union Butterfield Tapping & Cutting Oil Straight Yes

Unocal Refining Unocal KooperKut 11HD Straight Yes

US Oil Co Inc. Blanking Oil 250 Straight Yes

Alkut 810 Straight Yes

US Drawlube 1517 Straight Yes

Vanishing Oil 300 Straight Yes

Gem Soluble CP Soluble Yes

US Cut 6040 Straight Yes

Spindle Oil ISO 10 Al St Oil Straight Yes

321-SS Cutting Straight Oil Straight Yes

ValeniteInc ValCoolTurntech Semi-synthetic Yes

ValcoolVNT 800 Soluble Yes

Varoum Chemical Gauge Sterling Brass Cutting Oil Straight Yes

Metacut MS Steel Cutting Oil Straight Yes

GM 465 Straight Yes

Viking Chemical Co Cut Rite 305 CFX Straight Yes
Vulcan Oil & Chem Ultrasol Soluble Oil Soluble Yes

J-Cut 931 Cutting Oil Straight Yes

Poseidon R&O HD Straight Yes

WS Dodge Oil Co Pale Oil (all Viscosity grades) Straight Yes

Manufacturer Tradename Type Soluble

Combo base 82 Additive Straight Yes

Deosol 202 Soluble Yes

Pale Straight Oil 55 Straight Yes

Superkut Cutting Oil 72/200 Straight Yes

ZEP Products ZEP Lubeze 14 Straight Yes