scinco Mega-800 - CHAPTER 6 Dna;Protein Analysis; The Principle of Protein;Dna Analysis; Principle of Using Absorbance of UV Light to Determine Protein; Principle of Using Absorbance of UV Light to Determine DNA

53 Mega-800 SCINCO
Fig. 5.19 Calibration curve
H. Measurement
Pipet 10ml filter solution into a 25ml colorimetric tube with a stopper. Then perform
measurement (refer to 5.6 measurement). Calculate the nitrite concentration by the
measured absorbance value and the standard curve.
I. Result analysis
After measurement, the nitrite content is calculated as 35.63mg/kg by the following
formula.
1000
1000
1
2



V
V
m
A
X
…………………………… （5-2）
X
——nitrite content，
kgmg /
；
m
——sample weight，
g
；
A
——nitrite weight of the filter solution in use，
g 
;
2
V
——the total filter solution volume，
mL
；
1
V
——the volume of filter solution in use，
mL
.
Chapter 6. DNA/Protein Analysis
This mode allows the user to perform DNA/Protein analysis. The two pre-set methods and a custom
defined method are available.
6.1 The principle of Protein/DNA analysis
6.1.1 Principle of using absorbance of UV light to determine protein:
As the biological micromolecule, protein absorbed UV light by its species, such as tryptophan,
phenlalanine, tyrosine and peptide bond etc. The conjugated doublebond included in the tryptophan,
phenlalanine, and tyrosine absorbed UV light. The absorbance values are related to the concentration
of the three kinds of amino acid. Peptide bond also absorbs UV light, so the absorbance value of
protein solution at 238nm is in direct ratio with the peptide bond, which is then in direct ratio to the
protein concentration.
6.1.2 Principle of using absorbance of UV light to determine DNA:
As the biological micromolecule, DNA absorbed UV light by its species, such as purine, and
pyrimidine, which absorb the UV light together with nucleoside, nucleotide and DNA&RNA. They have
the maxium absorbance value at 260nm.