Page:NIOSH Manual of Analytical Methods - 7908.pdf/2

 NON-VOLATILE ACIDS (Sulfuric Acid and Phosphoric Acid): METHOD 7908, Issue 1, dated 20 May 2014 - Page 2 of 5

REAGENTS:

EQUIPMENT:

1.	Water, deionized (DI), ≥18 MΩ-cm resistivity 2.	Sodium carbonate (Na2CO3), anhydrous, American Chemical Society (ACS) analytical grade 3.	Sodium hydrogen carbonate (NaHCO3), ACS analytical grade 4.	Extraction & eluent stock solution: 0.27 M Na2CO3 / 0.03 M NaHCO3; dissolve 2.86 g Na2CO3 and 0.25 g NaHCO3 in 25 mL of deionized water and swirl to mix. Then bring to 100 mL in a volumetric flask, stopper and mix thoroughly. 5.	Extraction & eluent solution: 0.0027 M Na2CO3 / 0.0003 M NaHCO3; transfer 10 mL of 0.27 M Na2CO3 / 0.03 M NaHCO3 stock solution to a 1 L volumetric flask, dilute to the mark with deionized water, stopper and mix thoroughly. 6.	Sulfate (SO42-) ion and phosphate (PO43-) ion standard solutions, each 1000 mg/L 7.	Calibration stock solution, 100 mg/L (as the anion): Place 10 mL aliquots of sulfate and phosphate standard solution into a 100 mL volumetric flask, dilute to the mark and mix thoroughly.
 * See Special Precautions

1.	Sampler: filter, 37-mm diameter quartz fiber; or polytetrafluoroethylene (PTFE), 0.45 µm pore size, in cassette filter holder manufactured from acid-resistant (chemically inert) material NOTE:	Quartz fiber filters should be binderless and heat-treated. 2.	Personal sampling pump, 1 to 5 L/min, with flexible connecting tubing 3.	Ion chromatograph, with pre-column (50 mm by 4.0 mm), anion-exchange column (200 mm by 4.0 mm), suppressor column (4 mm) and conductivity detector; and connected to data processing unit 4.	Ultrasonic bath 5.	Vessels, 10-mL, plastic (e.g., polypropylene), with screw caps 6.	Volumetric flasks, 25- to 1000 mL 7.	Pipets, 50 to 10000 µL 8.	Beakers, 25 to 100 mL 9.	Water purification system, to prepare greater than or equal to18 MΩ-cm resistivity deionized water 10.	Bottles, polyethylene, 100 mL 11. Syringes, plastic, 5 mL 12. Syringe filter cartridges, with 0.8-µm pore size polytetrafluoroethylene (PTFE) membrane filters 13.	Micro-syringes, 50 µL, with 60 mm x 0.6 mm needles 14.	Tweezers, PTFE-coated 15.	Auto-sampler vials, 2 mL capacity 16.	Analytical balance, with capability of weighing to nearest 0.01 mg

SPECIAL PRECAUTIONS: Wear gloves, lab coat, and safety glasses while handling acids. All work should be performed with adequate ventilation for personnel and equipment. It is imperative that acid be added to water in order to avoid a violent exothermic reaction. There is risk of fire and explosion when phosphoric acid has contact with bases, combustible substances, oxidizing agents, reducing agents or water. Avoid physical contact since both sulfuric and phosphoric acid are both corrosive and irritants to eyes, skin, and the respiratory system. These are caustic materials and can react with metals to form flammable hydrogen gas. Do NOT mix with solutions containing bleach or ammonia [9,10]. SAMPLING, SAMPLE TRANSPORT AND STORAGE: 1.	Calibrate each personal sampling pump with a representative sampler in-line. 2.	Sample at an accurately known flow rate between 1 and 5 L/min for a total sample size of 15 to 1000 Liters. Avoid sampler overloading. 3.	Immediately after sampling, remove the filter from the cassette with PTFE-coated tweezers and place it in a 10-mL screw-cap plastic vessel. With about 2 mL extraction

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition