Spectrophotometer Guide: Principles, Usage, Troubleshooting, and Maintenance — PE UV Spectrophotometer, UV Spectrophotometer, Atomic Absorption Spectrophotometer, UV-Vis Spectrophotometer

Spectrophotometer Guide: Principles, Usage, Troubleshooting, and Maintenance — PE UV Spectrophotometer, UV Spectrophotometer, Atomic Absorption Spectrophotometer, UV-Vis Spectrophotometer

I. Overview

The spectrophotometer, also known as the PE UV spectrophotometer, UV spectrophotometer, atomic absorption spectrophotometer, and UV-Vis spectrophotometer, is a precise spectral analysis instrument. It analyzes the composition and content of substances by measuring their absorption or transmission of light at specific wavelengths. Widely applied in chemistry, biology, medicine, environmental science, and other fields, it is an indispensable analytical tool in laboratories.

II. Principles

The fundamental principle of the spectrophotometer is based on the Lambert-Beer Law. When a monochromatic light passes through a uniform, non-scattering medium, the absorbance A is proportional to the concentration c of the absorbing substance in the medium and the thickness l of the medium. The relationship is expressed as A = kcl, where k is a proportional constant related to the properties of the absorbing substance and the wavelength of the incident light.

The core components of a spectrophotometer include the light source, monochromator, sample chamber, detector, and data processing system. The light source provides broad-spectrum light radiation, while the monochromator decomposes this light into monochromatic light and allows specific wavelengths to pass through. The sample chamber holds the sample to be tested; when monochromatic light passes through the sample, part of the light is absorbed, and the remaining light passes through the sample into the detector. The detector converts the light signal into an electrical signal, which is then analyzed and processed by the data processing system to obtain parameters such as the sample’s absorbance or transmittance.

III. Usage Method

1. Preheat the Instrument: Turn on the power switch and preheat the instrument for 20-30 minutes to stabilize its performance.
2. Select Wavelength: According to experimental requirements, rotate the wavelength adjuster to indicate the desired monochromatic light wavelength.
3. Set Sensitivity: Choose an appropriate sensitivity setting based on the absorption of light by the colored solution and keep it fixed.
4. Adjust “0” Point: Rotate the “0” potentiometer so that the pointer on the readout indicates “0” transmittance.
5. Adjust T=100%: Place a cuvette containing distilled water (or blank solution) in the cuvette holder, cover the dark box, and rotate the light adjuster to achieve T=100% transmittance.
6. Measurement: Place the cuvette with the sample to be tested in the cuvette holder, gently pull the lever to allow the solution into the light path, and read the absorbance value.
7. Shutdown: After the experiment, cut off the power and clean the cuvettes and instrument components.

IV. Common Faults and Repair Methods

1. Unstable Digital Display
   • Causes: Environmental vibration, high air flow near the light source, external strong light interference, insufficient preheating time, desiccant failure in the photoelectric tube.
   • Solutions: Improve the working environment, extend preheating time, replace or bake the desiccant, and send for repair if necessary.
2. Instrument Cannot Be Zeroed
   • Causes: Incomplete closure of the light gate, “100%” knob turned to the maximum, instrument dampness, circuit failure.
   • Solutions: Repair the light gate components, readjust the “100%” knob, use a hairdryer to dry the instrument and replace the desiccant, repair the circuit.
3. Instrument Cannot Adjust to “100%”
   • Causes: Insufficient light energy, cuvette holder not in position, aging of the photoelectric conversion part, circuit failure.
   • Solutions: Increase the sensitivity multiplier, adjust the cuvette holder, replace the photoelectric conversion components, repair the circuit.
4. Light Source Lamp Failure
   • Causes: Broken filament, weak output light spot energy.
   • Solutions: Replace with a bulb of the same specifications, adjust the position of the light source lamp to align the filament with the light output hole.
5. Monochromator Failure
   • Causes: Tight wavelength adjuster, unreadable wavelength dial, no change in emitted light.
   • Solutions: Repair the fit between the axis and sleeve, grind the rubber friction wheel, calibrate the wavelength adjustment screw, replace the protective glass.

V. Maintenance

1. Environmental Control: Maintain constant laboratory temperature and humidity, reduce vibration and strong light interference.
2. Cleaning and Maintenance: Regularly clean the instrument casing and internal components, keep optical elements clean and dry.
3. Regular Inspection: Calibrate and verify the instrument regularly to ensure the accuracy and reliability of measurements.
4. Usage Precautions: Avoid contaminating the cuvette surface, handle with care, clean and dry correctly.

VI. Brands and Models of Spectrophotometers Repaired by Longi Electromechanical

1. Agilent Technologies
   • Cary Series: Cary 60 UV-Vis, Cary 100 UV-Vis, Cary 300 UV-Vis, Cary 4000 UV-Vis, Cary 5000 UV-Vis, Cary 7000 UMS
2. Thermo Fisher Scientific
   • Evolution Series: Evolution 60S, Evolution 220, Evolution 260 Bio, Evolution 350
   • NanoDrop Series: NanoDrop One/OneC, NanoDrop 2000/2000C
3. Shimadzu
   • UV Series: UV-1800, UV-2600, UV-2700, UV-3600 Plus
   • BioSpec Series: BioSpec-nano
4. PerkinElmer
   • LAMBDA Series: LAMBDA 25/35/45 UV/Vis, LAMBDA 365 UV/Vis, LAMBDA 650 UV/Vis/NIR, LAMBDA 850 UV/Vis/NIR, LAMBDA 1050+ UV/Vis/NIR
5. JASCO
   • V-700 Series: V-730 UV-Vis, V-750 UV-Vis/NIR, V-760 UV-Vis/NIR, V-770 UV-Vis/NIR, V-780 UV-Vis/NIR
6. Hitachi
   • UV-Vis/NIR Spectrophotometers: U-5100, UH4150, UH5300, U-2900/2910, U-3900/3900H, UH5700, UH4150
   • Fluorescence Spectrophotometers: F-7000, F-7100
   • Atomic Absorption Spectrophotometers (AAS): ZA3000 Series
7. Bruker
   • TENSOR Series: TENSOR II FT-IR
8. BioTek (Agilent)
   • Epoch Series: Epoch 2 Microplate Spectrophotometer
   • Synergy Series: Synergy H1 Hybrid Reader
9. Horiba
   • Duetta: Fluorescence and Absorbance Spectrometer
   • FluoroMax Series: FluoroMax-4, FluoroMax Plus
10. Beckman Coulter
    • DU Series: DU 730, DU 800
11. Hach
    • DR Series: DR3900, DR6000
12. Analytik Jena
    • Specord Series: Specord 50 PLUS, Specord 200 PLUS, Specord 250 PLUS
13. Ocean Insight
    • Flame Series: Flame-S UV-Vis
    • Maya Series: Maya2000 Pro
14. Lambda Scientific
    • LS Series: LS-1055 UV-Vis, LS-1155 UV-Vis/NIR
15. Edinburgh Instruments
    • FS5: Fluorescence Spectrometer
    • FLS1000: Photoluminescence Spectrometer
16. datacolor: Spectro700UV, 200R, 200M
17. Beijing Purkinje: TAS-990AFG, Flame-Graphite Furnace Integrated Atomic Absorption Spectrophotometer

Longi Electromechanical Company specializes in the repair of spectrophotometers (PE UV spectrophotometers, UV spectrophotometers, atomic absorption spectrophotometers, UV-Vis spectrophotometers) with nearly 30 years of experience. We can quickly repair various instruments and also offer recycling and sales of various vacuum gauges. Welcome to consult.