Starting from the principle of relative measurement of photoelectric direct reading spectrometer , the maintenance principle of the instrument is discussed. Because direct reading spectrometer analysis technology is a relative measurement analysis technique, We use a direct reading spectrometer to determine the elemental content of the measured sample, which is actually determined by measuring the intensity of the emission spectral line of the element to be tested. This is actually to say that there should be a functional relationship between the content of the element and the intensity of the emission spectrum of the element. As long as the function relationship is determined, then only the "light intensity value" is obtained by the instrument, and the content of the sample to be tested can be obtained by this function relationship. In direct reading spectrometers, we call this functional relationship a curve. Everyone should have the common sense that the higher the content of an element in a sample, the greater the intensity of the emission spectral line representing the element, when other conditions are met. Even if the content of the sample is constant, there are other factors that can affect the intensity of the line. We can imagine that if the excitation energy of the sample is increased for the same sample, what effect does it have on the intensity of the line? What happens when the alloy and cast iron are tested under the same conditions?
Then, a rough summary below, the influencing factors of "light intensity value" can be generally divided into the following three aspects:
1. The content of this element in the sample.
2. The material of the sample to be tested.
3 , the working state of the instrument. Â Â Â Â Â Â
What I want to say here is that the relative measurement we are talking about here uses the relationship between the spectral intensity, the element content, the sample structure (material) and the working state of the instrument, assuming that the working state of the instrument remains basically the same. In the case of change, the working state of the instrument and the material of the sample, the influence parameters on the light intensity are regarded as constant constants, and the constants are sought to obtain the constants, so that the content of the elements can be directly determined by the light intensity value. That is to say, our curve equation, in addition to the "content" and "light intensity" two variables, the specific number of other constant parameters, determined by the instrument working state and sample material. Â Â Â Â Â The process of drawing the curves is actually the process of calculating these constant parameters. The method is to use a plurality of sets of known "content" samples to obtain a plurality of sets of light intensity corresponding to the known "content", and then use the mathematical method to calculate the undetermined coefficient. Under normal circumstances, in the measurement range of the curve, regardless of the influence of self-absorption, etc., we approximate the relationship between "light intensity value" and "content" by a quadratic function. Then, through the standard sample, the constant parameters of the curve equation obtained actually have two meanings:
1. Record the working state of the instrument when it stimulates the standard sample.
2 , recorded the material of the standard sample (tissue structure) In fact, the above content can get two conclusions: Â
1 The sample to be tested with a fixed material must pass the curve produced by a specific set of standard samples to measure the correct result. Â
2 When the current working state of the instrument is exactly the same as your drawing curve (normalized curve), the measurement results will not produce an escapement other than accidental error. Â Then the curve drift that we usually say is actually the change of the working state of the instrument, of course, including the working state of each component in the signal line, the state of the laboratory environment and so on. When they change, in reality, the relationship between spectral intensity and elemental content has quietly changed, and the curve recorded in our computer, because it records the previous working state, will become no longer applicable ( Outdated). Â Â Â Â Â Â Â
From the above, our maintenance of the instrument, to its roots and purpose, is to ensure that when you are doing daily samples, and when the curve is made, the working state of the instrument remains the same.
 The word "consistent" has become the core idea of ​​our daily maintenance.      Â
First of all, it is necessary to maintain the laboratory environment as much as possible, and it can always be in a favorable working environment. It should be noted that: temperature, humidity, indoor dust, etc. It is recommended that the laboratory be equipped with air conditioning, dehumidifier, and temperature. Humidity meter. Â Â Â Â Â
Second, during the use of the instrument, the state of some components will vary with the use, such as: electrodes, spark table inside, lens, vacuum pump oil, photomultiplier tube. Then we want to ensure the stability of their working conditions, we need to do regular maintenance. Clean the electrode, clean the spark table, wipe the lens, replace the pump oil, stabilize the high-voltage power supply of the photomultiplier tube. Â Â Â
Third, during the use of the instrument, try to keep the sample of the sample to be tested (measured object), and the pre-processing is scientific and reliable.
Fourth, in the various modules of the instrument, there are many controllable parameters used to adjust the working state of the instrument. When doing daily analytical samples, it should be noted that these parameters must be consistent with the curve. Such as: the excitation state control parameters of the sample, The negative high voltage value of the photoelectric conversion efficiency of each channel photomultiplier tube. Â Â Â Â
Fifth, in the process of using the instrument, some consumables must be used, for example, high-purity argon gas, some instruments also need to use high-purity nitrogen, the grinding wheel for sample pre-treatment, sandpaper, etc. try to ensure the same manufacturer, model Similarly, if argon is not guaranteed, an argon purifier can be purchased. Do the above five points, just try to maintain the working state of the instrument, and can only be suppressed by various means. When this inevitable drift reaches a certain level, it will have a greater impact on our quantitative analysis. Go to the slit scan (stroke), redraw the curve, or use standardization, sample control, etc. to rediscover the new instrument work point.
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