ASTM D5827 Standard Test Method for Analysis of Engine Coolant for Chloride and Other Anions by Ion Chromatography
6. Apparatus
6.1 Analytical Balance, capable of weighing accurately to 0.0001 g.
6.2 Ion Chromatograph - Analytical system with all required accessories including syringes, columns, suppressor, gasses, and detector. Column life and performance are enhanced by the use of a two-eluant channel gradient pump, if available.
6.3 Guard Column, for protection of the analytical column from strongly retained constituents. Better separations are obtained with additional plates.
6.4 Anion Separator Column, capable of producing analyte separation equivalent to or better than that shown in Fig. 1.
6.5 Anion Suppressor Device - Micro membrane suppressor or equivalent. A cation exchange column in the hydrogen form has been used successfully, but it will periodically need to be regenerated as required, being indicated by a high background conductivity and low analyte response.
6.6 Conductivity Detector, low volume (<2 µL) and flow, temperature compensated, capable of at least 0 to 1000 µS/cm on a linear scale.
6.7 Integrator or Chromatography Data System Software, capable of obtaining approximately the same detection limits as are listed in Table 1.
6.8 Drying Oven, controlled at 105, 150, and 600 +/- 5°C.
6.9 Desiccator.
7. Reagents
7.1 Purity of Reagents - Reagent grade or higher purity chemicals shall be used for the preparation of all samples, standards, eluants, and regenerator solutions. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specification are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type II of Specification D1193. It is recommended that all water be filtered through a 0.2-µm filter. For eluant preparation, degas the water by sparging with helium or vacuum degassing and sonication.
7.3 Eluant Buffer Stock Solution - Sodium bicarbonate (NaHCO3) 1.5 mM and sodium carbonate (Na2CO3) 1.2 mM. Dissolve 2.5203 +/- 0.0005 g of NaHCO3 and 2.5438 +/- 0.0005 g of Na2CO3 in reagent water in a 1000-mL Type A volumetric flask and dilute to 1 L. Dilute 100.0 mL of this stock solution to 2000 mL in a 2-L Type A volumetric flask with degassed reagent water. The pH of the stock solution is 10.1 to 10.3 (based on pKa calculation). The eluant solution used may be different if other system or analytical columns are used.
7.4 Stock Bromide Solution - Dry approximately 2 g of sodium bromide (NaBr) for 6 h at 150°C and cool in a desiccator. Weigh and dissolve 1.2877 g of the dried salt in reagent water and dilute to 1 L (1.00 mL = 1.00 mg bromide).
7.5 Stock Chloride Solution - Dry approximately 2 g of sodium chloride (NaCl) for 1 h at 600°C and cool in a desiccator. Weigh and dissolve 1.6485 g and dilute to 1 L with reagent water (1.00 mL = 1.00 mg Cl−).
7.6 Stock Formate Solution - Dry approximately 2 g of sodium formate (NaHCO2) at 105°C for 6 h and cool in a desiccator. Weigh and dissolve 1.4775 g of the salt in reagent water and dilute to 1 L (1.00 mL = 1.00 mg formic acid).
7.7 Stock Glycolic Acid Solution - Weigh and dissolve 1.0000 g of the solid acid in reagent water and dilute to 1 L (1.00 mL = 1.00 mg glycolate).
7.8 Stock Nitrate Solution - Dry approximately 2 g of sodium nitrate (NaNO3) for 24 h at 105°C and cool in a desiccator. Weigh and dissolve 1.3707 g and dilute to 1 L with reagent water (1.00 mL = 1.00 mg NO3−).
7.9 Stock Nitrite Solution - Dry approximately 2 g of sodium nitrite (NaNO2) for 24 h in a desiccator containing concentrated sulfuric acid (relative density of 1.84). Weigh and dissolve 1.4998 g and dilute to 1 L with reagent water (1.00 mL = 1.00 mg NO2−). Refrigerate and prepare weekly because nitrite is oxidized easily.
7.10 Stock Oxalic Acid Solution - Weigh and dissolve 1.4002 g of oxalic acid dihydrate (C2H2O4·2H2O) in reagent water and dilute to 1 L (1.00 mL = 1.00 mg oxalic acid).
7.11 Stock Phosphate Solution - Weigh and dissolve 1.4330 g of potassium dihydrogen phosphate (KH2PO4) and dilute to 1 L with reagent water (1.00 mL = 1.00 mg PO4(−3)).
7.12 Stock Sulfate Solution - Dry approximately 2 g of anhydrous sodium sulfate (Na2SO4) for 1 h at 105°C and cool in a desiccator. Weigh and dissolve 1.4790 g and dilute to 1 L with reagent water (1.00 mL = 1.00 mg SO4(−2)).
7.13 Suppressor Solution for Membrane Suppressor - 0.025 N H2SO4. Carefully add 13.7 mL of reagent sulfuric acid (relative density of 1.84) to approximately 500 mL reagent water in a 1-L volumetric flask. Dilute to 1000 mL with reagent water. Dilute 100 mL of this concentrate to 2000 mL with reagent water for the final working suppressor solution.
7.14 Stability - Standard stock solutions are stable for at least one month when stored at 4°C. Fresh nitrite and phosphate standards must be prepared weekly.
