TITLE: Spectrophotometry method for the detection of Biochemical parameters
AUTHORS: Xiaohua Du, Xia Liu, Mawolo James Blackar, Yingjie Zhou, Haifeng Wang, Fayang Liu, Zhiqing He

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block"><span style = "font-weight:bold;">Definition of key terms</span></div><div class = "text-block"><span>Spectrophotometry is an experimental technique that is used to measure the concentration of solutes in a specific solution by calculating the amount of light absorbed by those solutes.</span><a href="https://www.wikihow.com/Do-Spectrophotometric-Analysis#_note-1" style = "text-decoration:underline;color:blue;cursor:pointer;"><span style = ":;">[1]</span></a><span> This technique is powerful because certain compounds will absorb different wavelengths of light at different intensities. By analyzing the light that passes through the solution, you can identify particular dissolved substances in solution and how concentrated those substances are. A automatic analyser (7180) is the device used to analyze solutions in a laboratory research setting.</span></div><div class = "text-block"><span style = "font-weight:bold;">Desecription of Automatic analyser</span></div><div class = "text-block">The Automatic analyser (7180) is a medium-sized biochemistry automatic analyzer.The minimum required amount of reaction solution is smaller due to a new optical design, and running cost is lower and working efficiency higher because the operating unit is usable in the same way as a general-purpose personal computer. Further, this analyzer features a wide range of applications including routine, stat and special analyses.</div><div class = "text-block"><span style = "font-weight:bold;">Benefit of Spectrophotometry method</span></div><div class = "text-block">The usage of Automatic analyser (Hitachi Ltd 7180 Serial, Tokyo, Japan) enabled us to obtained more samples result in less time and this prevented other factors from influencing our tested results.</div></div>

[STEPS]
?. [PART I: Sample preparation]
Turn on the automatic analyser: Turn the automatic analyser on to warm up to give an accurate reading.While the automatic analyser was warming up, prepare the samples to be run.
The warm up process will take   before the samples can be run.
?. [PART I: Sample preparation]
Load the proper volume of the sample into the cuvette: The automatic analyser contains a volume of 1 milliliter (mL) and test tubes with a volume of 5 mL.
Use different pipettes for each sample to prevent contamination. [3]
?. [PART I: Sample preparation]
Prepare of a control solution: Known as a blank, the control solution has chemical solvent in which the solute to be analyzed is dissolved in. The blank should have the same volume as the solution to be analyzed and kept in the same kind of container.
?. [PART I: Sample preparation]
Wipe the outside of the cuvette: Before placing the cuvette into the automatic analyser, make sure that the cuvette is cleaned to avoid interference from dirt or dust particles.
We used a lint free cloth, and remove water droplets or dust that were on the outside of the cuvette.[4]
?. [PART II: Running the experiment]
Select and set the wavelength of light to analyze the sample with: Use a single wavelength of light (monochromatic color) to make the testing more effective. The color of the light to choose is the one known to be absorbed by one of the chemicals thought to be in the test solute. Set the desired wavelength according to the specifications of your spectrophotometer.
?. [PART II: Running the experiment]
Calibrate the machine with the blank: Place the blank into the cuvette holder and shuted the lid. Record the values, while the blank still in the machine, move the needle to zero using the adjustment knob.
On an analog automatic analyser, there was a screen with a needle that moves based on the intensity of light detection. When the blank got in, we saw the needle moved to the right.
When we removed the blank, the calibration was still in place. During measuring the rest of our samples, the absorbance from the blank was automatically subtracted out.A single blank was use per session so that each sample is calibrated to the same blank.
?. [PART II: Running the experiment]
Remove the blank and test calibration: Remove the blank and the needle should stay at 0 (zero). Put the blank back into the machine to ensured the needle readout doesn’t change.
If the machine is properly calibrated with your blank, everything should stay at 0.
?. [PART II: Running the experiment]
Measurement of the absorbance of experimental sample: Removed the blank and place the experimental sample into the machine. Slide the cuvette into the designated groove and ensure it stond upright. Wait about  until the needle is steady or until the digital numbers changed. Recorded the values of % transmittance and/or absorbance.
The absorbance is also known as the optical density (OD). The more light that is transmitted, the less light the sample absorbs. Generally, we wanted to record the absorbance values which will usually be given as a decimal, for example, 0.43.
?. [PART II: Running the experiment]
Repeat the test with successive wavelengths of light: The samples have multiple unknown compounds that vary in their absorbance depending on wavelength. To eliminate uncertainty, repeat your readings at 25 nm intervals across the spectrum. This allow you to detect other chemicals suspected to be in the solute.
?. [PART III: Analyzing the Absorbance Data]
Calculation of the transmittance and absorbance of the sample: Transmittance is how much of the light that passed through the sample reached the automatic analyser. Absorbance is how much of the light has been absorbed by one of the chemicals in the solute. Many modernautomatic analyser have an output of transmittance and absorbance, when you recordthe intensity, calculate these values.[5]The absorbance (A) is expressed as the negative of the base-10 logarithm (exponent) of the transmittance value: A = -log10T.[6] For a T value of 0.1, the value of A is 1 (0.1 is 10 to the -1 power), meaning 10% of the      light is transmitted and 90% is absorbed. For a T value of 0.01, the value of A is 2 (0.01 is 10 to the -2 power), meaning 1% of the light is transmitted.
?. [PART III: Analyzing the Absorbance Data]
Plotting the absorbance values versus the wavelengths on a graph. Plot the absorbance value on the vertical y-axis against the wavelength of light used for a given test plotted on the horizontal x-axis. Plotting the maximum absorbance values for each wavelength of light tested, produces the sample's absorbance spectrum and identifies the compounds making up the test substance and their proportions.
An absorbance spectrum usually has peaks at certain wavelengths that can allow you to identify specific compounds.
?. [PART III: Analyzing the Absorbance Data]
Comparing our absorbance spectrum plot to known plots of specific compounds: Compounds have unique absorbance spectrum and always produced a peak at the same wavelength every time they are measured. Comparing your plots of unknown compounds to those of known compounds, identify the solutes that compose of your solution.
This method can also to identify contaminants in sample. If you are expecting 1 clear peak at a specific wavelength and you get 2 peaks at separate wavelengths, you know something is not right in your sample.