52 Mega-800 SCINCO
zinc sulfate. If it doesn’t produce white deposition, add sodium hydroxide 2-5ml to mix
up.put the sample into water bath, heat 10mins. And then cool it to the room temperature.
Add water to the mark. Filter the sample solution with filter paper after half an hour. Get rid
of the primary filter solution 20ml, and collect later filter solution.
C. Switch on the instrument
Turn on the MEGA-800 UV-VIS Spectrophotometer. After 30mins warm-up, press in
the case of instrument main menu to gain access to quantitation mode.
D. Parameters setting
Please refer to ―5.2 Parameters setting‖, set the measurement mode to ―Standars method‖
and working wavelength to 550nm.
E. Standard preparation
Pipet the prepared sodium nitrite standard 0.10ml, 0.20ml, 0.40ml, 0.6.ml, 0.80ml, and
1.00ml (equal to sodium nitrite 2.5µg, 5µg, 10µg, 15µg, 20µg and 25µg) into 25ml
colorimetric tubes with stoppers respectively. And then add 4.5ml ammonium chloride
buffer, 2.5ml 60% acetic acid solution, and 5.0ml chromogenic agent into the tubes
respectively. Dilute them with water to the mark. Put the prepared standard samples into
the dark for 25 minutes. Put the different concentration standards into 1cm quartz cells
respectively. And then number the cells 1-6.
F. Standard setup
In the case of parameters setting page of quantitative measurement, press key to
gain access to the menu of parameters setting page of standards method. Press
key to change the standard number into 6. Put the quartz cell with distilled water into the
sample cell, and press to perform autozero.
In the case of parameters setting page of standards method, press key to input
serial number, sample concentration, and press to skip absorbance entry. Tnen,
put the numbered sodium nitrite into the cell No.1, press key and key.
The Abs value displayed is the current sodium nitrite Abs.
G. Construct the calibration curve
In the case of parameters setting page of standards method, press key to construct
a calibration curve, as shown in Fig. 5.19. If the instrument displays ―Data Range Error,
Retry‖, press key to return to the parameters setting page of standards method to
reset the standard samples.
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