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The Go Direct^® Visible Spectrophotometer (GDX-SPEC-VIS) and the Go Direct^® SpectroVis^® Plus Spectrophotometer (GDX-SVISPL) are both CCD array spectrometers. Both units can measure absorbance, percent transmittance, and emissions from 380 nm to 950 nm. The Go Direct^® SpectroVis^® Plus Spectrophotometer (GDX-SVISPL) also measure fluorescence with excitation wavelengths centered at 405 nm and 500 nm.

The GDX-SPEC-VIS is more expensive than the GDX-SVISPL for a number of reasons. The GDX-SPEC-VIS comes in a machined aluminum housing. The light source is capable of being detached from the detector, making emissions data easier and more accurate as well as eliminating thermal noise from the detector.  In addition, the light source in the GDX-SPEC-VIS is a very expensive collimated light source; the optics inside are more expensive and of higher quality to allow for greater accuracy. These features make it more appropriate for upper division courses where accuracy and temperature control are more desirable.

The GDX-SVISPL is an excellent affordable spectrometer that is designed exclusively for entry level spectroscopy education. The GDX-SVISPL is housed in a plastic case. The light source is not collimated nor can it be removed from the detector. The cuvette cannot be locked in place using set screws which, if students hold onto the cuvette during data collection, can cause changes in their spectral results. The GDX-SVISPL has lower wavelength accuracy and optical resolution (particularly in the blue region of the spectrum) as compared to the GDX-SPEC-VIS. The photometric accuracy is also poorer compared with the GDX-SPEC-VIS. The fiber optic (Vernier Spectrophotometer Optical Fiber (VSP-FIBER)) sits in the cuvette holder and is made out of plastic, so it is less accurate at emissions measurements.

If you are trying to decide between these two devices, it is very important to consider your application. If you are only doing absorbance measurements (identifying unknowns, Beer’s law experiments, etc.), you will most likely not notice any difference in the two devices. The exception to this is if you need highly accurate absorbance values and wavelength values – see each units specifications https://www.vernier.com/products/sensors/spectrometers/visible-range/) before making your decision.
If you compare the two for emissions measurements (e.g., determining the spectral lines of hydrogen) you will notice a difference. The GDX-SPEC-VIS is superior in measuring emissions because it requires higher quality optics and finer resolution to obtain accurate data.

Both spectrometers can connect via bluetooth and usb. Both will work with LabQuest or Spectral Analysis. The GDX-SPEC-VIS does not work with Logger Pro, while the GDX-SVISPL does.

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