Method for determining lactose content in cow's milk with electrochemical biosensor
A biosensor, lactose content technology, applied in the direction of material electrochemical variables, measuring devices, scientific instruments, etc.
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Embodiment 1
[0022] (1) Enzyme immobilization method
[0023] The change of lactose concentration is measured in the instrument because it is a dual-enzyme biosensor for measuring lactose concentration with the activity of glucose oxidase (GOD) and β-galactosidase. This instrument uses chitosan cross-linked glutaraldehyde to immobilize Enzymes have uniform stability and are less affected by external factors.
[0024] Deposit an appropriate amount of mixed solution A (mixed solution A: take 2.5 μL of glucose oxidase GOD, 2.5 mg of BSA and 5 μL of glycerol, and 40 μL of phosphate buffer solution with a pH of 7.5.) deposition (soak the glassy carbon electrode in mixed solution A After 30min in the glassy carbon electrode, the electrode ( figure 1 The two electrodes 1 is a platinum electrode, and the electrode 2 is a glassy carbon electrode) placed in glutaraldehyde vapor for 1 hour, so that it forms a network with the enzyme and chitosan. Afterwards, take an equal amount of mixed solution B...
Embodiment 2
[0053] Operation method:
[0054] The whole experimental process was carried out at constant temperature.
[0055] 1. Preparations
[0056] (1) Platinum electrode 1 and glassy carbon electrode 2 were treated according to the enzyme immobilization method described in Example 1.
[0057] (2) Prepare the blank solution (for example, distilled water, or any other substance solution) and place it in the sample cup; the outer cover of the sample cup has two ports, one port is inserted into the anode of the biosensor (platinum electrode 1), and the other port is inserted into the biosensor. The cathode of the sensor (glassy carbon electrode 2), and the two electrodes are respectively connected to the positive pole (platinum electrode 1 is connected to the positive pole) and negative pole (the glassy carbon electrode 2 is connected to the negative pole) of the microcurrent measuring instrument ( Figure 4 As shown in J4), the liquid level of the blank solution should not be lower th...
Embodiment 3
[0065] refer to image 3 , is the circuit diagram of the potentiostat of the present invention, which is used to provide power for the microcurrent measuring instrument. Operational amplifiers U1A and U1B form a differential input single-ended output amplifier circuit with a gain of 100. This circuit uses a wideband dual-channel JFET operational amplifier LF353. The sampling resistor R and other peripheral resistors are high-precision (the error is ±1%) ) metal film resistors.
[0066] refer to Figure 4 , is the circuit schematic diagram of the microcurrent measuring instrument of the present invention: ICI7135 is a 4-bit double-integral A / D conversion chip, which can convert and output ±20000 digital quantities, has BCD code output controlled by STB gate, and is very convenient to interface with the microcomputer. ICL7135 has the advantages of high precision (equivalent to 14-bit A / D conversion) and low price. Its conversion speed is related to the clock frequency. Each c...
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