Page:NIOSH Manual of Analytical Methods - 6402.pdf/2

 PHOSPHORUS TRICHLORIDE: METHOD 6402, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1.

2.

3.

4.

5.

6.

7.

EQUIPMENT:

Potassium dihydrogen phosphate stock solution, 100 µg H 3PO 4/mL. Dissolve 0.1389 g KH 2PO 4 in distilled H 2O and dilute to 1 L. Calibration stock solution, 10 µg/mL H3PO 4. Dilute 100 mL KH 2PO 4 stock solution to 1 L with distilled water. Sulfuric acid, 10 N. Slowly add 279 mL conc. H 2SO 4 to 500 mL distilled water. Dilute to 1 L when cool. Sodium molybdate solution. Dilute 25.0 g Na 2MoO 4·2H 4O to 1 L with 10 N surfuric acid. Bromine water, saturated.* Add sufficient liquid Br 2 to saturate distilled water with stirring. Hydrazine sulfate solution, 1.5 g/L. Dissolve 1.5 g N 2H6SO 4 in distilled water to make 1 L solution. Hydrazine sulfate, saturated. Add sufficient hydrazine sulfate to distilled water with stirring to saturate.

1.

2. 3.

4. 5. 6. 7. 8.

Sampler: glass midget bubbler* with non-rubber (e.g., PTFE) stopper and fritted glass inlet (Corning EC or 170- to 220-µm max pore); 5-cm glass tube with glass wool plug for protection of pump from splashover. Personal sampling pump, 0.05 to 0.2 L/min, with flexible connecting tubing. Spectrophotometer, reading at 830 nm, with matched glass cuvettes, 1-cm path length. Waterbath, boiling. Pipets, 0.1-, 1-, 2-, 3-, 5- and 25-mL.* Volumetric flasks, 50-mL and 1-L.* Beakers, 50-mL.* Cold water bath.

Boil all glassware contaminated by phosphate detergent in 1:1 HCl. Rinse thoroughly with distilled water.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Liquid bromine causes severe eye and skin burns. Bromine vapor is a severe irritant of the eyes and respiratory tract. Permanent breathing difficulty may result [3].

SAMPLING: 1. 2.

3.

4.

Calibrate each personal sampling pump with a representative sampler in line. Add 15 mL distilled water to the bubbler. Sample at an accurately known flow rate between 0.05 and 0.2 L/min for a total sample size of 11 to 100 L. NOTE: The bubbler must be kept in a vertical position during sampling. If the bubbler solution spills into the trap, discard the sample. Remove the bubbler stem and tap gently against the inside wall of the bubbler to recover as much of the sample solution as possible. Rinse the stem with several mL distilled water, collecting the rinse in the bubbler. Seal the bubbler bottom with a stopper. Alternatively, connect the inlet of the bubbler top to the outlet with PTFE tubing and seal the top to the bottom with tape.

SAMPLE PREPARATION: 5.

6. 7.

Transfer contents of the bubbler quantitatively to a 50-mL volumetric flask. Dilute to mark with distilled water and mix. NOTE: Start reagent blanks at this step. Pipet 25 mL of the diluted sample into a 50-mL beaker. Pipet 3 mL saturated bromine water into the beaker. Let stand 60 sec for oxidation to occur. NOTE: The purpose of the bromine water is to oxidize PCl 3, present in water as H 3PO 3, to H3PO 4.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94