Spectrophotometer Verification Procedure Details

　　UV-2450 Introduction

　　V-2450 is a UV-visible spectrophotometer that has won high praise from users. It has excellent performance and is easy to operate. When combined with the powerful operating software UVProbe, it can have powerful functions. The optical system with a small spot makes the measurement of trace amounts more convenient.

　　UV-2450 UV-Visible Spectrophotometer Features

　　1. High level of ultra-low stray light

　　UV-2550 uses excellent DDM (double blazed diffraction grating, double monochromator) technology to achieve ultra-low stray light (less than 0.0003%) and high light flux. Although UV-2450 uses a single monochromator, the stray light is also less than 0.015%. Low stray light can directly measure high-concentration samples without dilution.

　　2. Universal software UVProbe

　　UV-2450/2550 is controlled by the new generation of bilingual operating software UVProbe, which includes four modules: spectral measurement, photometric measurement, kinetic measurement and report processing. It can realize everything from basic measurement to research and analysis. UVProbe realizes the real QA/QC function and fully supports GLP and GMP. In addition, software such as film thickness measurement and color analysis can be loaded.

　　3. Rich accessories and wide range of applications

　　Life sciences: can test trace samples obtained from living organisms. Integrating sphere test: can test turbid samples and powdered samples. Reflection accessories: can measure relative and absolute reflectance of optical materials.

　　UV 2450 Ultraviolet Visible Spectrophotometer Verification Procedure

　　The working band of this instrument is 190~900nm, which is divided into two sections: 190~340nm and 340nm~900nm for separate calibration.

　　1. Measurement performance requirements

　　1.1 Maximum allowable wavelength error: Section A: ±0.5, Section B: ±1.0

　　1.2 Wavelength repeatability: Section A: ≤0.2, Section B: ≤0.5

　　1.3 Noise and drift: 0% transmittance: ≤0.1; 100% transmittance: ≤0.2; drift: ≤0.2

　　1.4 Maximum allowable error of transmittance: Section A: ±0.5, Section B: ±0.5

　　1.5 Transmittance repeatability: Section A: ≤0.2, Section B: ≤0.2

　　1.6 Stray light: A section: 220nm, ≤0.2; B section: 360nm, ≤0.2, 420nm, ≤0.5

　　1.7 Absorption cell matching: Quartz: 220nm, 0.5; Glass: 440nm, 0.5

　　2. General technical requirements

　　2.1 Marking: name, model, serial number, manufacturer's name, date of manufacture, working power supply voltage and frequency.

　　2.2 Appearance:

　　2.2.1 All fasteners of the instrument should be well tightened, and all adjustment knobs, buttons and switches should work normally.

　　The cable plugs all fit tightly and are well grounded.

　　2.2.2 The instrument should be able to be placed stably on the workbench and the sample rack should be positioned correctly.

　　2.2.3 The indicator scale lines should be uniform and clean, the digital display should be clear and complete, and the adjustable parts should not have any sticking, sudden jumps or significant backlash.

　　2.3 Absorption cell: The absorption cell shall not have any cracks, and the light-transmitting surface shall be clean without scratches and spots.

　　3. Verification conditions

　　3.1 Wavelength standard materials

　　3.1.1 Mercury lamp

　　3.1.2 Titanium oxide, neodymium praseodymium and erbium praseodymium filters with wavelength standard values ​​at three spectral bandwidths of 1, 2 and 5 nm 3.1.3 Titanium oxide solution, 40 g/L

　　3.1.4 Interference filter: wavelength peak standard uncertainty ≤ 1nm, spectral bandwidth < 15nm3.2 Transmittance standard material

　　3.2.1 0.001 mol/L perchloric acid standard solution of potassium dichromate with a mass fraction of 0.06000/1000 3.2.2 Ultraviolet light transmittance filter

　　3.2.3 Spectral neutral filters, with nominal transmittance values ​​of 10%, 20%, and 30% 3.3 Stray light standard substances

　　3.3.1 Cut-off filter, the use wavelength is 220, 360, 420nm, the half-height wavelength is 260, 400, 470nm, the cut-off wavelength is not less than 225, 365, 430nm, the absorbance of the cut-off area is not less than 3, and the average transmittance of the light-transmitting area is not less than 80%.

　　3.3.2 Sodium iodide standard solution, concentration is 10.0g/L 3.2.3 Sodium nitrite standard solution, concentration is 50.0g/L

　　3.4 Standard quartz absorption cell: specification is 10.0mm, and its transmittance matching error is no more than 0.2%

　　4. Verification environment

　　4.1 Temperature: 10-35℃

　　4.2Relative humidity: no more than 85%

　　4.3 Power supply: voltage 220±22V, frequency 50±1Hz

　　4.4 The instrument should not be exposed to direct strong light, strong magnetic field, electric field interference, strong airflow and corrosive gas.

　　5. Verification items

　　5.1 General technical requirements

　　5.2 Wavelength differential error and repeatability

　　5.3 Noise and Drift

　　5.4 Transmittance indication error and repeatability

　　5.5 Stray Light

　　5.6 Absorption pool matching

　　6. Verification method

　　6.1 General Technical Requirements Inspection: Visual, Manual Inspection

　　6.2 Maximum allowable wavelength error and wavelength repeatability

　　6.2.1 Standard substances

　　6.2.2 Verification steps

　　According to the selected calibration wavelength, set the instrument's wavelength scanning range (if the wavelength scanning range is wide, segmented scanning is allowed), common spectral bandwidth, slow scanning, and sampling interval less than the instrument's wavelength repeatability index. Use transmittance or absorbance measurement method, use air as blank to perform baseline calibration of the instrument according to the set scanning parameters, use light shield to perform dark current calibration, then place the standard substance perpendicular to the sample light path, set the appropriate recording range, scan continuously for 3 times, and detect the transmittance valley value or absorbance peak wavelength λi respectively. Result calculation: Calculate the wavelength indication error for each measured wavelength according to the following formula:

　　∆λ=λ-λn

　　Where:

　　λ——the average value of 3 measurements

　　λn——Standard value of wavelength

　　The wavelength repeatability is calculated as follows:

　　λ=λmax-λmin

　　Where: λmax, λmin are the maximum and minimum values ​​of the wavelengths measured three times respectively

　　6.2.3 Noise and Drift

　　Select 250nm and 500nm as the noise measurement wavelength; 500nm is the drift measurement wavelength.

　　Set the instrument scanning parameters as follows: time scanning mode (or fixed wavelength scanning), spectral bandwidth 2nm (the instrument with fixed spectral bandwidth remains unchanged), sampling time interval 1s, photometric measurement mode is transmittance, recording range is 99%~101% (not set for non-scanning instruments), treat the reference beam and sample beam as air blanks at each measurement wavelength, adjust the instrument transmittance to 100%, scan for 2 minutes, and measure the difference between the maximum and minimum values ​​on the spectrum (non-scanning instruments record the maximum and minimum values ​​within 2 minutes), which is the instrument transmittance 0% noise. When switching wavelengths, allow the visible light to stabilize for 5 minutes.

　　Automatically scan the instrument, test the transmittance 0% and 100% noise according to the above requirements, set the wavelength at 500nm, scan for 30min, and read the difference between the maximum and minimum values ​​of the center line of the envelope of the scanning graph, which is the transmittance 100 line drift of the instrument.

　　6.2.4 Maximum allowable error and repeatability of transmittance

　　6.2.4.1 Using standard substances and standard absorption cells, measure the transmittance three times at 235, 257, 313, and 350 nm respectively.

　　6.2.4.2 Use spectral center filters with nominal transmittance values ​​of 10%, 20%, and 30% to measure the transmittance at 440nm, 546nm, and 635nm, respectively, with air as the reference. 6.2.4.3 Calculation of results

　　The transmittance error is calculated as follows:

　　∆T=T-Tn

　　Where: T——average value of 3 measurements

　　Tn——Transmittance standard value

　　The transmittance repeatability is calculated as follows:

　　T=Tmax-Tmin

　　Where: Tmax, Tmin——maximum and minimum values ​​of transmittance measured 3 times

　　6.2.5 Stray light

　　Select a standard substance and measure its transmittance at the corresponding wavelength. The transmittance value is the stray light of the instrument at that wavelength.

　　For segment A, use sodium iodide standard solution (or cutoff filter) at 220nm, nitrite standard solution (or cutoff filter) at 360nm (tungsten lamp), 10nm standard quartz absorption cell, and distilled water as reference to measure its transmittance value.

　　The B-section prism instrument uses a cut-off filter at a wavelength of 420nm and air as a reference to measure its transmittance value.

　　6.2.6 Absorption pool compatibility

　　In the absorption cells of the same optical path attached to the instrument, distilled water is filled at 220nm (quartz absorption cell) and 440nm (glass absorption cell), the transmittance of one absorption cell is adjusted to 100%, and the transmittance values ​​of the other cells are measured. The difference is the matching of the absorption cells.

　　For instruments with a transmittance range of only 0-100%, 95% can be used instead of 100%.

　　6.3 Processing of test results

　　The instrument qualification level is indicated by the lowest level in the calibration results; if one of the test items does not meet the requirements, it is judged as unqualified, and a calibration result notice is issued, indicating the unqualified item.

　　6.4 Verification cycle

　　The calibration cycle generally does not exceed 1 year. During this period, if the instrument is repaired or there is doubt about the results, it should be calibrated in time.