Water quality -- Determination of nitrate -- Part 3: Spectrometric method using sulfosalicylic acid

رقم المستند: NL ISO 7890 3 : 2009
القطاع: Food Technology
TC: No
ICS: 13.060.50
1.1 Substance determined This part of ISO 7890 specifies a method for the determination of nitrate ion in water. 1.2 Type of Sample The method is suitable for application to raw and potable water samples. 1.3 Range Up to a nitrate nitrogen concentration, @N of 0,2 mg/l using the maximum test Portion volume of 25 ml. The range tan be ex- tended upwards by taking smaller test portions. 1.4 Limit of detectionl) Using cells of Optical path length 40 mm and a 25 ml test por- tion volume the limit of detection lies within the range QN = 0,003 to 0,013 mg/l. 1.5 Sensitivityl) A nitrate nitrogen concentration of @N = 0,2 mg/l gives an ab- sorbance of about 068 unit, using a 25 ml test Portion and cells of Optical path length 40 mm. 1.6 Interferences A range of substances often encountered in water samples has been tested for possible interference with this method. Full details are given in annex A. The main potential interferents are chloride, or-thophosphate, magnesium and manganese(ll), as shown in annex A. Other tests have shown that this method will tolerate a Sample colour of up to 150 mg/l Pt providing the test Portion absorp- tion correction procedure is followed. (See 6.5.