If this is a one-time measurement, then it is better to find a laboratory with radiometric equipment. If you plan periodically carry out such studies, then you need a calibration lamp with known spectral radiation in UV/Vis/NIR. For example, Avantes AvaLight-DH-BAL-CAL. You need calibrate the spectrometer with this lamp and perform measurements. If you need full luminous flux, then you need integrating sphere and a calibrated light source in couple with the spectrometer.

If you have access to a spectrometer, measure the emission spectrum to see if there is any peaks in the range your are looking for. regarding percentage measurement of UV or VIS light in the emission spectrum, the easiest thing is to area under each peak and compare that to the total area of the spectrum.

Things to note: 1- your spectrograph must be wavelength and intensity calibrated beforehand.

Thanks Dr. Gadirov and Dr Maryam.