Abstract: To enable a spectrometer (10) to be used for taking analysis readings from plastics articles (24) of varying shapes and degree of preparation, the spectrometer (10) is enclosed within a housing which has an interface device (14) attached to the sensing window (58). The interface device (14) is sensitive to the positioning of a sample (24) in position to carry out sample preparation tasks as the sample is brought into the analysis position opposite the sensing window (58). The interface device (14) comprises a front wall (16) with a sample aperture (18) against which the sample (24) can be placed so that a surface of the sample (24) is exposed through the aperture (18), means (48) for cleaning a sample surface (24) placed against the front wall (16), means (52) for extracting debris resulting from the sample cleaning, and means (30, 32) for guiding the front wall (16) towards the sensing window (58) to enable the spectrometer (10) to take a reading from the sample surface (24).