1)—— Drawing the working curve of total nitrogen requires measuring the absorbance of the prepared standard solution, and measuring its absorbance at 220nm and 275nm respectively. The following is my personal measured data;

Nitrate nitrogen standard solution/ml

0 0.5 1 2 3 5 7 8

Nitrate nitrogen content /ug 0 5 10 20 30 50 70 80

Absorbance value A220

0.332

0.384

0.443

0.553

0.64 1

0.85 1

1.036

1. 15 absorbance value B275

0.002

0.006

0.009

0.008

0.002

0.007

-0.00 1.0062) —— The following curve can be obtained by checking and calculating the absorbance:

Y=98.332X+0.0855 (R2=0.9998)

3)—— The nuclear calibration process is as follows:

The corrected absorbance value a is corrected by 0.328.

0.372

0.425

0.537

0.637

0.837

1.0381.138 correction absorbance value calibration

0 0.044 0.097

0.209

0.309

0.509

0.7 1 0.8 1