The apparatus disclosed herein features: (a) a handheld, portable spectrometer that includes a radiation source configured to direct incident radiation to a sample, a detector configured to receive signal radiation from the sample, and a housing enclosing the radiation source and the detector; (b) an extended member attachable to the housing and having an interior channel to define a path for directing radiation from the source to the sample and for receiving radiation from the sample at the detector; (c) and a vial receptacle configured to hold a different sample and positioned to receive radiation from the source, where the detector is positioned to receive radiation from the different sample and the housing is configured to support the vial receptacle and attach to the extended member at the same time.