US 12,235,255 B2
Method of determining chemical oxygen demand (COD) for high chloride samples
Isabel Hünig, Dusseldorf (DE); Carsten Schulz, Dormagen (DE); Helga Guthmann, Grevenbroich (DE); and Ralf Kloos, Schwerte (DE)
Assigned to HACH LANGE GMBH, Berlin (DE)
Appl. No. 17/253,503
Filed by HACH LANGE GMBH, Berlin (DE)
PCT Filed Jun. 19, 2019, PCT No. PCT/EP2019/066212
§ 371(c)(1), (2) Date Dec. 17, 2020,
PCT Pub. No. WO2020/007611, PCT Pub. Date Jan. 9, 2020.
Claims priority of application No. 18181661 (EP), filed on Jul. 4, 2018.
Prior Publication US 2021/0270794 A1, Sep. 2, 2021
Int. Cl. G01N 33/18 (2006.01); G01N 21/31 (2006.01)
CPC G01N 33/1806 (2013.01) [G01N 21/31 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of determining chemical oxygen demand (COD) for a sample comprising a high concentration of chloride, the method comprising:
obtaining the sample;
determining a concentration of chloride in the sample to obtain a known concentration of chloride in the sample, wherein the known concentration of chloride is in a range from about 5,000 mg/L to about 20,000 mg/L;
dosing an amount of the sample, an acid and an oxidizing agent into a cuvette to obtain an analyte, wherein the dosing comprises pre-dosed reagents of the acid and the oxidizing agent in the cuvette;
heating the cuvette containing the analyte;
photometrically determining a preliminary chemical oxygen demand (COD) of the analyte in the cuvette in an analytic device; and
correcting the preliminary chemical oxygen demand (COD) using a chloride correction, to obtain the chemical oxygen demand (COD) and based upon a previously determined calibration value of the cuvette.