Abstract: An improved tristimulus sample cup of the type that generally includes an optically transparent bottom portion, a side wall portion and an open mouth. Such cups have a cavity for holding the sample, the cavity being defined by the bottom and side portions of the cup. The side wall portion has a surface which is exposed to the cavity. The improvement of the present invention relates to the optical properties of this surface of the side wall portion of the cup which is exposed to the cavity, i.e., that it have a diffuse reflectance at 580 nanometers of preferably more than eighty percent. In addition, if the sample cup is equipped with a plunger positioned in the mouth of the cup, the plunger having a surface exposed to the cavity, then the plunger surface exposed to the cavity should also have a diffuse reflectance at 580 nanometers of preferably more than eighty percent. A highly preferred cup of the present invention is made with a flat optical glass bottom, sides of white TEFLON .

Abstract: A method for determining the wavelength accuracy of a variable wavelength liquid chromatography detector in the low UV range comprising filling the cell of the detector with a test solution and varying the indicated wavelength of detection to find the indicated wavelength of maximum absorbance in a wavelength region around a reference wavelength of the test solution and then calculating the difference between the indicated wavelength of maximum absorbance and the reference wavelength to determine the accuracy of the indicated wavelength of the detector. The test solution contains terbium III ions in a solvent such as n-propanol so that the absorbance maximum of the test solution does not shift more than about 0.5 nm for a spectral bandpass ranging from 2 to 6 nm.

Abstract: A packaged test solution for determining the wavelength accuracy of variable wavelength liquid chromatography spectrophotometric detectors at one or more reference wavelengths consisting of 254.6, 378.9, 522.3, and 652.5 nanometers. The packaged solution comprises a hermetically sealed container of an effective concentration of erbium III ions such as a sealed container of a 0.2 molar solution of erbium III perchlorate in water. The test solution has the required intense absorption bands at the reference wavelengths which additionally do not vary by more than about 0.3 nanometers with the varying bandpass characteristics of such detectors.