Page:NIOSH Manual of Analytical Methods - 5031.pdf/2

 ASPARTAME: METHOD 5031, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5. 6. 7. 8.

Aspartame,™ 96% pure. Water, deionized. Acetonitrile, distilled in glass. Methanol, distilled in glass. 1-Heptanesulfonic acid sodium salt. Monobasic potassium phosphate. Phosphoric acid, reagent grade. Eluent A: Add 2.062 g 1-heptanesulfonic acid sodium salt and 0.45 g monobasic potassium phosphate to 1.0 L deionized water and adjust pH to 2.5 with dilute phosphoric acid.* 9. Eluent B: Add 2.062 g 1-heptanesulfonic acid sodium salt to 1.0 L of 3:2 (v/v) acetonitrilewater, and adjust pH to 3.0 with dilute phosphoric acid. 10. Calibration stock solution: 5 mg/mL. Add 0.05 g Aspartame and dilute with 10 mL eluent B.

1. Sampler: 1-µm, 37-mm PTFE filter (Millipore FALP or equivalent) with a cellulose backup pad in a 37-mm polystyrene 2-piece cassette. 2. Personal sampling pump capable of 1 to 3 L/min, with flexible connecting tubing. 3. High-performance liquid chromatograph (HPLC) with UV detector, 220-nm, integrator and C 18 column (page 5031-1). 4. Syringe filters, 13-mm: 0.45 µm, PTFE. 5. Syringe, 10-mL, disposable. 6. Vials, glass, scintillation, 20-mL with PTFE-lined caps. 7. Syringes, microliter, readable to 0.1 µL. 8. Pipets, various sizes. 9. Tweezers. 10. Ultrasonic water bath. 11. pH meter.

See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Phosphoric acid is extremely corrosive. Work with care in a hood using protective gloves.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Remove the front and rear plugs immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately controlled flow rate between 1 and 3 L/min for a sample volume of 70 to 1200 L. At the completion of sampling, replace both plugs and pack the sampler securely for shipment. Include appropriate number of blanks in the shipment.

SAMPLE PREPARATION: 5. 6. 7.

Remove the PTFE filter with tweezers and transfer to a 20-mL scintillation vial. Discard the back-up pad. Add 2.0 mL eluent B. Agitate the samples for 1 hour in an ultrasonic water bath. Filter the sample solution using a disposable syringe fitted with a 0.45-µm PTFE filter into a clean vial.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solutions to eluent B, using serial dilutions as needed to obtain concentrations in the range of 1 to 400 µg /mL. b. Analyze with samples and blanks (steps 11 through 13). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94