verifySecond hand UV spectrophotometerThe true performance mainly needs to be achieved through a series of rigorous technical indicator testing and performance verification steps. Here is a detailed verification process:

1、 Preparation before verification

1. Environmental conditions: Ensure that the calibration environment meets the requirements of the instrument. Generally, the indoor temperature should be between 10 ℃ and 30 ℃, the relative humidity should be ≤ 65%, the workbench should not be exposed to direct sunlight, there should be no corrosive or other gas interference affecting the measurement indoors, and there should be no strong electric or magnetic fields or strong vibrations around that affect the calibration.

2. Standard substances: Prepare certified standard substances for verification to ensure the traceability of measurement results.

3. Calibration tools and supplies: Prepare a balance for weighing (weighing 100g with a division value of 0.1mg), holmium oxide glass (meeting the specifications of the sample room with a thickness of 2mm~2.5mm), potassium dichromate (reference), sulfuric acid (analytical grade), sodium iodide (analytical grade), sodium nitrite (analytical grade), etc.

2、 Technical indicator testing

1. Wavelength calibration and verification

Wavelength accuracy: Calibration is performed by observing absorption peaks at specific wavelengths using low-pressure mercury or deuterium lamps as light sources. Usually, holmium oxide glass calibration plates are used for measurement. The instrument wavelength is set within a specified range, the slit is less than a certain value (such as 1nm), air is used as blank, the transmittance is adjusted to 100%, and the measurement is repeated multiple times. The average value is taken and compared with the specified value to calculate the accuracy of the wavelength. The allowable deviation usually does not exceed ± 1nm.

Wavelength repeatability: The same holmium oxide glass calibration plate is used for measurement, and the same wavelength is measured multiple times in a row. The difference between the maximum and minimum values of the measured values is calculated as wavelength repeatability. The allowable deviation usually does not exceed 0.5nm.

2. Absorbance calibration and validation

Accuracy of absorbance: Prepare a series of standard solutions with known concentrations, such as potassium dichromate standard solution, and place each standard solution into the sample cell one by one to measure its absorbance. Compare the measured absorbance value with the theoretical value and calculate the relative error. The relative deviation of the allowable absorption accuracy absorption coefficient usually does not exceed ± 1.0%.

Transmittance accuracy and transmittance density repeatability: Take a certain bandwidth value (such as 2nm), use a standard quartz absorption cell to fill blank solution and potassium dichromate standard solution with a known mass fraction, and measure the transmittance continuously at multiple wavelengths. Compare with the standard value to calculate the accuracy of transmittance and the repeatability of transmittance density. Transmittance repeatability is usually evaluated by calculating the standard deviation of multiple measurements.

3. Baseline calibration and verification

Baseline flatness: willSecond hand UV spectrophotometerThe wavelength range is set within the specified range (such as 800~200nm), the slit is set at a certain value (such as 1nm), the sample and reference light paths are both air, and the transmittance is adjusted to 100%. Scan the baseline of the instrument at an appropriate scanning speed to check for changes in transmittance. The baseline allowed to be drawn may have slight fluctuations when replacing the light source or filter.

4. Stray light detection

Measure the transmittance of a specific concentration solution (such as 10% sodium iodide solution or 5% sodium nitrite solution) using water as a blank at a designated wavelength (such as 220nm or 380nm). Record the measured values and compare them with the specified values to evaluate the performance of stray light. Stray light should usually be below a certain value (such as 0.8%).

5. Resolution verification

Use a specific solution (such as a toluene/hexane mixed solution) and observe at a specified wavelength (such as 269nm) to see if bimodal peaks can be resolved. The wavelength difference (Δλ) between the two peaks should be less than a certain value (such as 1nm) to evaluate the resolution of the instrument.

6. Stability and noise testing

Stability test: Observe the drift of absorbance at a specified wavelength (such as 500nm) for a continuous period of time (such as 30 minutes). The allowable drift usually does not exceed a certain value (such as 0.002A).

Noise test: Measure peak to peak noise at 0A, with a permissible noise level typically not exceeding ± 0.001A (bandwidth 2nm).

3、 Verification result processing

1. Recording and evaluation: Detailed recording of the results of various verifications, including standard substance batch numbers, environmental temperature and humidity, measured values, deviations, etc. Evaluate whether the performance of the instrument meets the requirements based on the recorded results.

2. Report and Review: Write a verification report, including verification methods, results, conclusions, and other information. Submit the report to relevant departments for review and approval to ensure the accuracy and compliance of the verification process.

4、 Precautions

1. Regular calibration: It is recommended to conduct comprehensive calibration and verification at least once a year. For instruments that are frequently used or in poor environments, the calibration frequency can be appropriately increased.

2. Professional operation: The verification process should be carried out by trained personnel to ensure the accuracy and reliability of the results.

Through the above steps, comprehensive verification can be carried outSecond hand UV spectrophotometerThe true performance ensures that it can provide accurate and reliable data during use.