Below is a brief explanation of some of the main factors that need to be considered for PCR machines:
1. Types of sample tubes:
There are mainly two types now, 0.2ml and 0.5ml. The number of personnel using 0.5ml PCR tubes is very small. Firstly, there are relatively few thin-walled tubes for 0.5ml PCR. Secondly, if you want a larger volume of PCR product, you can divide it into several 0.2ml PCR tubes. Unless a larger volume of PCR product is frequently required, a 0.5ml PCR instrument may not be considered.
2. Sample size:
There are many types, such as 96 and 48 wells for 0.2ml, 60 and 30 wells for 0.5ml, 384 wells, etc. Of course, there are also some other combinations, such as the combination of 48 wells for 0.2ml and 30 wells for 0.5ml.
3. Temperature gradient function:
The temperature between different columns or rows can be different. This function may not be very useful for inspectors of fixed PCR programs, but it can be said to be necessary for researchers who frequently perform different gene amplifications.
4. Calculate temperature control and module temperature control:
Module temperature control is a temperature control method used in early PCR instruments, where the set temperature is the temperature of the heating module. During the temperature change process, when the target temperature is almost reached, the PCR instrument reduces the rate of temperature rise and fall, allowing the temperature of the module to gradually approach the target temperature without overshoot.
Calculated temperature control, also known as tube temperature control, considers the temperature in the PCR reaction tube. In order to increase the temperature in the reaction tube to the target temperature, the module temperature is first flushed, and then adjusted to the appropriate temperature when the temperature in the reaction tube approaches the target temperature. The adjustment method is a combination of theoretical calculations and experiments, and is related to the volume of the reaction solution in the reaction tube. Therefore, calculating the temperature control mode requires the experimenter to input the volume of the reaction solution. Calculating temperature control mode has become a widely adopted method.
5. Power off protection function:
This is also a very useful function, mainly in small and medium-sized cities, where short-term power outages, fuse melting, and air switch tripping often occur. Without this function, the experiment cannot be automatically carried out after turning on, which often affects the work.
6. Hot lid function:
The hot lid function is available from all manufacturers, if not, no one would want it. Hot covers are also divided into adjustable hot covers and non adjustable hot covers. There is also a torque adjustable heat cover in the adjustable heat cover, which mainly solves the problem of excessive or insufficient force when pressing the heat cover.
7. Software functions:
In terms of instrument software functionality, PCR programs can certainly be set up, but the issue of convenience is not significant. Once used, it becomes more convenient, and the difference is not significant. Some display screens are larger and can draw a temperature change curve, but most of them are simulated and not very meaningful, just good-looking. There are also functions such as temperature and time adjustment for each cycle, which most instruments seem to have. If there is a need in this regard, attention should be paid.
8. Service life:
The service life of the instrument, if maintenance costs are not considered, is mainly related to the service life of the semiconductor refrigeration chip.
9. Power stability:
This is a very important factor, but it is also a factor that users may overlook. Because most instrument malfunctions are caused by power issues or power problems. Due to the fact that the PCR instrument is a variable temperature instrument and is often used continuously for a long time, some users use it for about 20 hours per day. The reasons for power supply problems are multifaceted. Firstly, there is moisture and dust. In the north, there is a lot of dust, while in the south, there is heavy moisture. Sometimes the dust is so large that some PCR machines cannot see electronic components after being turned on, and the circuit board has poor heat dissipation, causing the power supply to burn out. Sometimes the humidity is so high that water can flow out of the instrument, causing a short circuit on the circuit board and burning out the power supply.
10. Repair cost and warranty time:
This is a very practical issue, most PCR machines only come with a one-year warranty, and some may increase the warranty period at the request of the user. The warranty cost for general instruments is 8-12% of the instrument price per year, so the warranty is just money. Generally speaking, the maintenance cost of instruments is relatively high, firstly due to the high cost of accessories themselves, and secondly due to transportation costs and tariffs. In addition, instrument manufacturers generally do not allow the repair of original components for profit and quality considerations. In fact, the cost of repairing foreign components may be higher than the cost of replacing circuit boards. Therefore, only personnel are responsible for repairing components, with lower labor costs and higher levels of expertise.
11. Accuracy and reliability of temperature:
Accuracy and sex are both defined by standards. The degree of similarity between repeated observations of the same indicator or trait in a survey or experiment. In terms of PCR equipment, accuracy refers to the difference between the set temperature and the actual temperature, while performance refers to the difference in temperature between different wells. Generally speaking, the accuracy and performance of the temperature of the heating module are better.
12. Heating and cooling rate:
This is a concern for many buyers as it may affect the PCR reaction time. But there are some differences in understanding on this issue. Generally, instruments are labeled with high temperature rise and fall rates, while what users understand is the ratio of temperature difference to the time taken for temperature rise and fall. This is the reason why some users find that the temperature rise and fall rate cannot reach the rate indicated by the instrument. What users care about is what is meaningful to them. Excessive heating and cooling rates are of little significance to users, as they can easily cause temperature overshoot and require a long time to adjust.
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