EQUIPMENT

1. Dionex DX-100 Ion Chromatograph
2. Dionex Autosampler
3. Disposable plastic PolyVials (0.5 mL)
4. Filter caps

REAGENTS

1. Sodium Carbonate: Na₂CO₃
2. Sodium Bicarbonate: NaHCO₃
3. Sulfuric acid: H₂SO₄

GAS

1. Nitrogen (pneumatic)

SOLUTIONS

1. Eluent concentrates:
   1. 0.5 M sodium carbonate - weigh 26.49 g Na₂CO₃ into a 500 mL volumetric flask containing 400 mL of deionized water. Dissolve and dilute to volume with deionized water and mix well.
   2. 0.5 M sodium bicarbonate - weigh 21.00g NaHCO₃ into a 500 mL volumetric flask containing 400 mL deionized water. Dissolve and dilute to volume with deionized water and mix well.
2. Eluent:
   1. Pipet 7.0 mL of 0.5 M sodium carbonate into a 1 liter volumetric flask.
   2. Pipet 2.0 mL of 0.5 M sodium bicarbonate into the 1 liter volumetric flask.
   3. Fill to volume with degassed, deionized water and mix by gentle inversion.
3. Regenerant:
   1. 0.025 N H₂SO₄ - Add 14 drops of sulfuric acid to a 1 liter volumetric flask containing 400 mL of deionized water. Dilute to volume with deionized water and mix well.

STANDARDS

1. Stock solution - SPEX-ION Standard (catalog #ICMIX1) - 100 ppm F, 200 ppm Cl, 400 ppm NO₃, 400 ppm SO₄, 600 ppm HPO₄.
2. Instrument Calibration Standards - Pipet the designated volumes of stock solution into 100 mL volumetric flasks. Dilute to volume with deionized water and mix well.

   Standard #	Stock Solution mL	Final Concentration ppm
   		F	Cl	NO3-N	PO4	SO4
   1	5	5	10	4.52	29.69	20
   2	3	3	6	2.71	17.81	12
   3	1	1	2	.903	5.94	4

QUALITY CONTROL SAMPLE

1. Stock Solution - SPEX-ION Standard (catalog #ICMIX2) - 20 ppm F, 30 ppm Cl, 100 ppm NO₃, 150 ppm HPO₄, 150 ppm SO₄.
2. Quality Control Sample - Pipet 10 mL of stock solution into a 100 mL volumetric flask. Dilute to volume with deionized water and mix well.

   Quality Control Sample
   Final Concentration ppm
   F	Cl	NO3-N	PO4	SO4
   2	3	2.26	14.8	15

INSTRUMENT WARM-UP

1. Turn on the Nitrogen gas.
2. Turn on the Computer, Monitor, Printer, Autosampler, Dionex DX-100, Dionex Advanced Computer Interface, Pump, and Eluent Nitrogen Pressure.
3. Check the regenerant and eluent reservoirs to see if they have enough liquid to complete the analysis and fill if necessary.
4. Set the Eluent switch to Eluent A.
5. Set the regenerant pressure to 15 psi.
6. Set the Eluent Nitrogen Pressure to 5 psi.
7. On the front panel of the DX-100 press HIGH LIMIT, then press the RANGE up switch to select 10 S, then press PUMP.
8. Let the instrument warm up for 30 minutes before beginning analysis.

PROCEDURE

1. Using the mouse double click on the SCHEDULE icon.
   1. Click on FILE, then OPEN, then anions.sch, then OK. A blank schedule will appear.
2. Fill out the schedule in the following manner:
   1. In position #1 under SAMPLE NAME type AUTOCAL1R
   2. In position #2 under SAMPLE NAME type AUTOCAL2R.
   3. In position #3 under SAMPLE NAME type AUTOCAL3R
   4. Use the remaining positions under SAMPLE NAME to identify client and quality control sample
   5. Under the DATA FILE column, type CALDATA for positions 1,2, and 3.
   6. Type RAWDATA under the DATA FILE column for all other position.
   7. Type anions.met under the METHOD column for all positions used in the schedule.
   8. Click on FILE, then SAVE AS, then anions.sch, then OK.
   9. Click on FILE, then EXIT.
3. Fill the autosampler trays with calibrants, quality control samples and client samples in the same order as done on the schedule and place in the autosampler.
4. Double click on the RUN icon.
   1. Click on LOAD, then METHOD, then anions.met.
   2. Click on LOAD, then SCHEDULE, then anions.sch.
   3. Click on RUN, then START.
   4. Press the CONTROL switch on the front panel of the DX-100.
5. After analysis of the calibration standards is complete, click on the space at the bottom of the screen above the background. The main menu will appear in the foreground.
   1. Double click on the CalPlot icon, then click on FILE, then OPEN METHOD, then anions.met, then OK.
   2. Use the horizontal arrow keys and check the curves for each component. r² values should be greater than 0.990.
   3. Click on FILE, and then EXIT.
   4. Click on the bar at the top of the screen that reads "A1 -450 Model 1 - RUN". The run menu will appear on the screen.
6. After analysis is complete check the chromatograms generated.
   1. Unusually high concentrations of an element will read 0 on the concentration print out, but will be readily visible on the chromatogram. Dilute these samples and rerun them.
   2. Check the baseline for each chromatogram, adjust if necessary and recalculate the results, following the procedure specified in the instrument instruction manual.
7. Shutdown.
   1. Click on the gray square adjacent to the file bar, then CLOSE, then OK.
   2. Open the door of the DX-100 and press the eluent switch from Eluent A to Eluent B ( Eluent B is deionized water). Rinse the IC column for 30 minutes with the deionized water.
   3. Turn off the Nitrogen gas.
   4. Release the regenerant pressure and the pressure on the eluent reservoir.
   5. Turn off all the items mentioned in step 2 of the Warm Up section.

QUALITY CONTROL

1. Analyze the quality control sample twice with each set of client samples, once before and once after client samples. Results for all elements should be within 5% of the known values. Record the values of the quality control sample on the quality control sheet provided.

NOTES

1. Because of the stability of this instrument it is not necessary to run the calibration samples with each set of client samples. It is acceptable to use the data obtained on the two quality control samples in order to determine the viability of the data generated, as long as the quality control samples meet the quality control criteria set forth above. In this case client sample data is generated from the previous calibration curve.
2. Analysis time is approximately 19 minutes per sample.

REFERENCES

1. Small, H., T. Stevens and W. Bauman.1975. Novel ion exchange chromatographic method using conductimetric detection. Anal. Chem. 47:1801.
2. Weiss, J. 1986. Handbook of Ion Chromatography. E. L. Johnson, ed. Dionex Corp.
3. Pfaff, J. D., C. A. Brockhoff and J. W. O'Dell. 1994. The Determination of Inorganic Anions in Water by Ion Chromatography. Method 300.0A. U. S. Environmental Protection Agency. Environmental Monitoring Systems Lab.