Page:NIOSH Manual of Analytical Methods - 5524.pdf/2

 METALWORKING FLUIDS (MWF) ALL CATEGORIES: METHOD 5524, Issue 2, dated 29 December 2014 - Page 2 of 10

INTERFERENCES:  None identified. However, any material that is collected on the filter and is soluble in the extraction solvents may interfere (positively) with the analysis. OTHER METHODS:  This method is similar to NMAM Method 0500 for Particulates Not Otherwise Regulated [7] and replaces NMAM Method 5026 as a general technique for analysis of MWF. NMAM Method 5026, which employs infrared analysis, may be used solely for the analysis of (straight) MWF that produce mineral oil mists; that method is not recommended for use with water-based fluids [8]. ASTM D7049 is another method that may be used to analyze metalworking fluids [9]. REAGENTS:

EQUIPMENT:

1.	Dichloromethane, distilled-in-glass (DIG) (See Note)‡ 2.	Methanol, distilled-in-glass (See Note)‡ 3.	Toluene, distilled-in-glass (See Note)‡ 4.	Water, filtered, double deionized (18 MΩ∙cm resistivity) 5.	Calcium sulfate, desiccant 6.	Ternary solvent blend‡: Mix equal volumes of dichloromethane, methanol and toluene in a clean dust-free container. Use a bottle with a screw cap (e.g., a clean, empty solvent bottle): Mix the solvents by gentle swirling, not by violent shaking. 7.	Binary solvent blend‡: Mix equal volumes of methanol and water in a clean dust-free container. Use a bottle with a screw cap (e.g., a clean, empty solvent bottle): Mix the solvents by gentle swirling, not by violent shaking. NOTE:	Lower grade solvents have not been evaluated for this method. If it is desired to use ACS or liquid chromatographic grade solvents, in the interest of economy, the user must demonstrate that these solvents perform equally to the DIG grade ( blanks < those obtained with the DIG grade). ‡

See SPECIAL PRECAUTIONS

1.	Sampler: 37-mm PTFE, 2-µm pore size membrane filter (see Appendix 1 for PTFE filter cleanup procedure) and PTFE supporting pad in 37-mm cassette filter holder. Use a 2-piece (closed face) cassette for sampling ‘total’ aerosol. For sampling the thoracic fraction, use a 3-piece cassette with thoracic cyclone that samples at 1.6 L/min at the thoracic cutpoint. See Evaluation of Method. Also, see page 5524-1 for discussion of alternative thoracic sampling. 2.	Personal sampling pump, 1.6 to 2 L/min, with flexible connecting tubing 3.	Cassette shrink bands, cellulose, 37-mm size 4.	Microbalance, capable of weighing to 0.001mg 5.	Static neutralizer: e.g., 210Po; replace nine months after the production date 6.	Forceps (preferably nylon or chrome-plated steel) 7.	Extraction funnel, See Figure 1 for specifications p. 5524-10 8.	Desiccator 9.	Wash Bottle, PTFE 10.	Vials, 20-mL and 10-mL, glass, with leak-proof PTFE-lined caps 11.	Syringe, gas-tight with large bore needle, e.g., 16-gauge needle 12.	Graduated cylinder, glass, 20 mL 13. Paper towels 14.	Metal screen for drying filters following extraction, approximately 550 cm2 or other convenient size. Grid size approximately 12 to 18 mm. Pre-wash screen with ternary blend solvent and allow to dry.

SPECIAL PRECAUTIONS: Dichloromethane is an inhalation hazard and is a suspect carcinogen. Handle all solvents in a fume hood. The solvents are flammable and have associated adverse health effects. Avoid breathing vapors. Avoid skin contact. Use extreme caution when blending the solvents together. The heat of mixing can cause pressure to develop as the solvents are blended, e.g., blowing a stopper from a glass-stoppered container. Use clean containers sealed with PTFE-lined screwcaps.

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition