To measure wavelength accuracy, the filter reduces the light beam of the spectrophotometer to a greater extent at certain wavelengths (peaks). Ideally, any reference materials used to determine wavelength accuracy should have narrow, well-defined peaks at a variety of wavelengths in the UV and visible range.
You can use the following reference materials to check your wavelength accuracy:
For all reference materials for checking the wavelength accuracy, a change of the slit width of the spectrophotometer leads to slight shifts of the absorption maxima. Due to the narrowbandness of the peaks, the height of the measured maxima varies greatly with a change of the slit width. Therefore, reference materials for checking wavelength accuracy generally can not be used for checking photometric accuracy.
Control charts, such as e.g. target cards are used to graphically display measured values. Here, the value specified in the Hellma Analytics calibration certificate is used as the target value. All measured values must be within the range of the measurement uncertainty, otherwise there is an out-of-control situation.