What factors affect the accuracy of direct reading spectrometers

The direct reading spectrometer is essentially an atomic emission spectrometer. The reason why it is called direct reading is that compared to spectrographs and early emission spectrometers, before the 1970s, computers did not use it. All the photoelectric converted current signals were read using digital tubes, and then curves were drawn on logarithmic conversion paper to calculate the content value. After the application of computer technology in spectrometers, all data processing was completed by computers, which can directly convert the content. Therefore, a more vivid term is called direct reading, abbreviated as direct reading.

The impact of measurement steps and mode selection on the accuracy of direct reading spectroscopic analyzer analysis:

1. Usage environment: The laboratory where the spectrometer is placed should be shockproof, clean, ventilated and dry (such as the environment requirements for the QL-5800A direct reading spectrometer produced by Nanjing Qilin: temperature between 23 positive and negative 5, moderate between 15-70%). Generally, the relative humidity of the direct reading spectrometer should be less than 80%, and the indoor temperature should be maintained between 0-50 degrees Celsius. The indoor temperature change within the same calibration cycle should not exceed 5 degrees Celsius.

2. On site power supply voltage requirements: The power supply voltage of QL-5800A direct reading spectrometer must be 220V, and 380V voltage must not be used, because the HX-750 model only has overcurrent protection without overvoltage protection, and the voltage change of 220V is less than 10%, the frequency change of 50Hz is less than 2%, and it must be well grounded.

3. Check if the argon cylinder contains argon gas, which must be high-purity argon with a purity of 99.99% or higher. The purity and flow rate of argon gas have a significant impact on the analysis and measurement values. Check if the argon gas is correctly connected to the host and pressure gauge, open the argon valve, and check if the argon gas pressure is above 10 bar.

4. After starting up, check whether the conditions such as air pressure and temperature meet the requirements for normal use of the instrument. The general host pressure is displayed between 5 and 5.5, and the temperature is between 38 plus and minus 1. When everything is normal, other operations can start.

5. The time from the start of the machine to the measurable point is about 10 minutes. During the waiting process, the sample can be polished first. Sample polishing is also important for measurement. If the polishing is not accurate, the carbon content measured is low. If the polishing is coarse, the carbon content measured is high. For the rough polishing of the sample, it is good to use 40 # sand for fine grinding. The same point cannot be excited twice, otherwise there will be deviation in the results. The surface texture of the sample is clear, without shrinkage holes or sand holes, and can be measured and analyzed. The polished surface of the sample should not be touched by hands, which is a common error in human operation. It is necessary to strictly follow the safety operating procedures.