Description
| Traceability | All Starna liquid wavelength references are NIST traceable and supplied with UKAS ISO/IEC 17025 accredited certificate of calibration. |
| Description | Liquid references permanently sealed by heat fusion into far UV quartz cells. This ensures the optical configuration method used for quality control is identical to that for normal analysis. They also have narrower bandwidths than glass filters, providing more accurate location of the peaks. |
| Primary Usage | These solutions can be used to confirm that the wavelength scale of your instrument is within the manufacturer's tolerances for any given wavelength. Four references cover wavelengths from UV to Far UV. |
| Spectral Bandwidth | Because the absorption bands are asymmetric, wavelength values will be dependent on spectral bandwidth. For this reason the certified wavelength values given below are approximate. The certificate supplied with each reference gives actual wavelength values measured at 0.1, 0.25, 0.5, 1, 2, and 3 nm. Values at other SBWs can be supplied on request. |
Holmium Oxide (Holmium Oxide in Perchloric Acid) (RM-HL):
| Certified Wavelengths | 241, 250, 278, 288, 334, 346, 361, 385, 417, 451, 468, 485, 537, 641 nm |
Holmium oxide (4% m/v) in 10% v/v 1.2 perchloric acid, permanently sealed by heat fusion into a 10 mm far UV quartz cuvette. When prepared in perchloric acid, holmium oxide gives a spectral scan containing a series of 14 sharp and well-defined peaks covering the wavelength range from 240 to 650 nm.
It is the most widely used reference for validating the wavelength scale of UV/Vis spectrophotometers.
Didymium Oxide (Didymium Oxide in Perchloric Acid) (RM-DL):
| Certified Wavelengths | 298, 329, 354, 444, 469, 482, 512, 522, 575, 732, 740, 794, 799, 864 nm |
Didymium is a mixture of two Rare Earth elements, neodymium and praseodymium. It is popular as a visible wavelength standard in the form of doped glass. This Starna liquid reference extends the range of the reference into the UV region, and gives 14 sharp peaks over the range 290 to 870 nm.
Far UV Reference (Rare Earth Oxide in Sulfuric Acid) (RM-RE):
| Certified Wavelengths | 201, 212, 223, 240, 253 nm |
The validation of the wavelength scale in the Far UV is difficult because of the lack of suitable reference materials. This material, developed by Starna, allows wavelength scale validation down to 200 nm. The Rare Earth oxide is dissolved in very dilute sulfuric acid and provides five peaks for wavelength qualification over the range 200 – 270 nm.
Samarium Oxide (Samarium Oxide in Perchloric Acid) (RM-SL):
| Certified Wavelengths | 235, 279, 290, 305, 318, 332, 344, 362, 374, 391, 401, 415, 464, 479 nm |
Samarium oxide is a particularly suitable reference material for checking the wavelength scale of a spectrophotometer over the commonly used range of 200 to 500 nm, as it has peaks throughout this region. Many of the peaks are very narrow, not only providing accurate location of the peak wavelengths, but a useful indication of the spectral bandwidth of the instrument.
Suggestions for Use:
Scan the filter over its usable range and identify the peaks whose wavelength values are given in the calibration certificate, having regard to the bandwidth of the instrument. Compare the measured values to the certificate values. Taking the expanded uncertainty budget† of the references into consideration, then the wavelength values should fall within the expected parameters† of your instrument if it is working correctly.
The results may be used to build up a data log of the instrument’s wavelength accuracy over time. This may be used for certification purposes and for troubleshooting should the correlation change. The data will also be useful to a service technician to diagnose and correct any problems that may develop with your instrument.
† Expected Parameters and Expanded Uncertainty Budget
The expanded uncertainty budget (k=2) is the tolerance that we could expect to measure in the assigned value on any one of our reference spectrophotometers during the 2 year period of certification.
When used to verify the performance of any given spectrophotometer this certificate tolerance must be added in a simple linear manner to the stated appropriate specification accuracy of the instrument on the test, see following example:
| Wavelength | Absorbance | |
| Certificate | ±0.10 nm | ±0.0049 A |
| Instrument | ±0.30 nm | ±0.0050 A |
| Total | ±0.40 nm | ±0.0099 A |
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