HJ 501-2009Water quality - Determination of total organic carbon - Combustion oxidation nondispersive infrared absorption method (English PDF)

2.1 Total organic carbon, TOC

The sample is acidified and aerated; the inorganic carbon in it is converted into carbon dioxide and removed; the sample is injected into the high-temperature combustion tube to directly measure the total organic carbon. Since the purgeable organic carbon (POC) may lose in acidified aeration, the measured total organic carbon value shall be non-purgeable organic carbon (NPOC).

5.1 Carbon dioxide-free water

boil the distilled water in a beaker (10% of evaporation); use it later after cooling. Pure water or ultra-pure water that is prepared by a pure water machine can also be used. Carbon dioxide-free water shall be prepared when necessary; the measured TOC mass concentration shall not exceed 0.5 mg/L.

5.2 Sulfuric acid (H2SO4)

rho(H2SO4) = 1.84 g/ml.

5.3 Potassium hydrogen phthalate (KHC8H4O4)

excellent grade.

5.4 Anhydrous sodium carbonate (Na2CO3)

excellent grade.

5.5 Sodium bicarbonate (NaHCO3)

excellent grade.

5.6 Sodium hydroxide solution

rho(NaOH) = 10 g/L.

5.7 Organic carbon standard stock solution

rho(organic carbon, C) = 400 mg/L.

Accurately weigh 0.850 2 g of potassium hydrogen phthalate (dry to constant weight at 110 ~ 120°C in advance); place it in a beaker; add water (5.1) to dissolve; transfer the solution to a 1 000 ml volumetric flask; use water (5.1) to dilute to the mark and mix. It can be stored for two months at 4°C.

5.8 Inorganic carbon standard stock solution

rho(inorganic carbon, C) = 400 mg/L.

Accurately weigh 1.763 4 g of anhydrous sodium carbonate (dry to constant weight at 105°C in advance) and 1.400 0 g of sodium bicarbonate (dry in a dryer

In a set of seven 100 ml volumetric flasks, add 0.00, 2.00, 5.00, 10.00, 20.00,

40.00, 100.00 ml of solution for the differential subtraction standard (5.9); use water (5.1) to dilute to the mark and mix. Formulate into standard series solutions with a total carbon mass concentration of 0.0, 4.0, 10.0, 20.0, 40.0,

80.0, 200.0 mg/L and an inorganic carbon mass concentration of 0.0, 2.0, 5.0,

10.0, 20.0, 40.0, 100.0 mg/L; measure the response value according to the steps in (8.4). Correspond the standard serious solution mass concentration to the response value of the instrument to draw the total carbon and inorganic carbon calibration curves respectively.

8.2.2 Drawing of the direct calibration curve

In a set of seven 100 ml volumetric flasks, add 0.00, 2.00, 5.00, 10.00, 20.00,

40.00, 100.00 ml of solution for the direct method (5.10); use water (5.1) to dilute to the mark and mix. Formulate into standard series solutions with an organic carbon mass concentration of 0.0, 2.0, 5.0, 10.0, 20.0, 40.0, 100.0 mg/L;

measure the response value according to the steps in (8.4). Correspond the standard serious solution mass concentration to the response value of the instrument to draw the organic carbon calibration curve.

The above calibration curve concentration range can be adjusted according to the instrument and the type of the measured sample.

8.3 Blank test

Use the carbon dioxide free water (5.1) to replace the sample; measure the response value according to the procedure in (8.4). The TOC content of carbon dioxide-free water (5.1) shall be measured first in each test; the measured value shall not exceed 0.5 mg/L.

8.4 Sample determination

8.4.1 Differential subtraction method

For the acidified sample, use sodium hydroxide solution (5.6) to neutralize to neutrality before the determination; take a certain volume to inject into the TOC analyzer for determination; record the corresponding response value.

8.4.2 Direct method

Take a certain volume to acidify it to pH <= 2; inject the sample into the TOC analyzer; remove the inorganic carbon by aeration; introduce it into a high- temperature oxidation furnace; record the corresponding response value.

9.1 Differential subtraction method

GB 5085.1-2007 | GB/T 11892-1989 | HJ 505-2009 | […]