In a basic biology lab class, a spectrophotometer appears pretty robust and easy to use. That’s still the case for the most part, despite the increasing sophistication of the instruments—some covering wavelengths from the near-infrared (NIR) through ultraviolet (UV). To get the most accurate results. In this article, we will explore ways to avoid problems altogether—and get high-accuracy results—when using a spectrophotometer. Despite the breadth in spectrophotometers, many best-use practices apply across all of them.
The correct choice of spectrophotometer depends on the wavelengths of interest and the amount of accuracy needed. Lower-end instruments are robust and user-friendly but usually only allow for readings at one wavelength at a time. A simple manual adjustment is required for measurement at various wavelengths. These units are easily moved and used in various locations. A computer-controlled higher-end instrument gives the ability to scan over a range of wavelengths.
Like all instruments, spectrophotometers work best when properly maintained and used as directed. Then, be methodical, work consistently and take the time needed to properly prepare and place a sample. Make sure that the spectrophotometer’s lamp is up to temperature, and the device is in proper working order. By the following form, you will get the best guide.
Problem | Possible | Solution |
Instrument Inoperative | Power cord not connected to outlet | Plug instrument in. |
Instrument Inoperative | Dead Power outlet | Change to a different outlet |
Instrument Inoperative | Internal fuse blown or defective electronic component | Call an authorized service engineer. |
Instrument Inoperative | Improper power setting | Set to the main power |
Instrument cannot set 100%T (0.000A) | Light beam blocked | Check sample holder. See if holder is properly positioned and nothing is blocking light path. |
Instrument cannot set 100%T (0.000A) | Lamp is misaligned. | Check to see if light is positioned properly on entrance slit to color spectrophotometry. |
Instrument cannot set 100%T (0.000A) | Defective electronic component. | Call an authorized service engineer. |
Incorrect Transmittance to Absorbance correlation | Bubbles or particles in solution. | Check sample preparation and analytical procedure. |
Instrument cannot set 100%T (0.000A) | Defective electronic component. | Call an authorized service engineer. |
LCD Digital Display does not change regardless of sample concentration | Concentration reading “frozen”. | Sample Solution too Dark , dilute it and Restart measurement procedure. |
LCD Digital Display does not change regardless of sample concentration | Wrong wavelength setting. | Check sample procedure and wavelength setting. |
LCD Digital Display does not change regardless of sample concentration | Insufficient sample volume. | Fill cuvette with more sample. |
LCD Digital Display does not change regardless of sample concentration | Stray sample preparation vapors. | Prepare the sample away from the instrument. Use proper ventilation. |
LCD Digital Display does not change regardless of sample concentration | Bubbles or particles in solution. | Check sample preparation and analytical procedure. |
LCD Digital Display does not change regardless of sample concentration | Defective electronic component or loose wiring. | Call an authorized service engineer. |
Instrument drift and noise | Lamp not adjusted properly.(misalignment) | Check lamp has been properly installed or has moved during transit. |
Instrument drift and noise | Lamp old or defective. | Replace with a new lamp. |
Instrument drift and noise | Defective or dirty detector or defective electronic component. | Call an authorized service engineer. |
Incorrect readings obtained | Insufficient sample volume | Fill cuvette with more sample. |
Incorrect readings obtained | Stray sample preparation vapors. | Prepare sample away from instrument. Use proper ventilation. |
Incorrect readings obtained | Bubbles or particles in solution. | Check sample preparation and analytical procedure. |
Incorrect readings obtained | Instrument out of electronic calibration. | Call an authorized service engineer. |