Permanently sealed, reusable and recertifiable

Use these reference sets to assure that your spectrophotometer is performing to the best of its capabilities

Each set is supplied with a certificate of analysis and NIST Traceability. All certificates are supplied by our ISO 9001, ISO 17025

Table of NIST Traceability

Ultraviolet References

Visible References

Potassium Dichromate - UV - Absorbance/Linearity

Description: Potassium Dichromate from NIST (SRM 935a), sealed in quartz cells
Primary Usage: Testing absorbance scale and linearity in the UV region
Useable Range: 235nm to 350nm, instruments with spectral bandpass of less than 2 nm
Physical Configuration: UV quartz cells that have been permanently heat sealed

Product Description:

The following chart is a listing of approximate absorbance values for each concentration based on the wavelength at which the potassium dichromate cells are to be read:

Concentration 235nm 257nm 313nm 350nm
Potassium Dichromate solvated in dilute perchloric acid has been found to be the best method for testing the absorbance scale and linearity of spectrophotometers in the UV. Starna purchases the potassium dichromate crystals directly from NIST (SRM 935a). We then make up the solutions as per the instructions from NIST and permanently heat fuse seal the solutions in UV quartz spectrophotometer cells.

The filled cells are tested and certified against the expected values from NIST and a certificate is provided with each set of cells which has the certified absorbance values for each cell and the confidence limit. The certificate supplied is suitable for use with inspecting agencies when used in the context of a standard operating procedure for quality control that is established in your laboratory. Each set is supplied with a sealed blank cell that was used for the certified measurement.

Suggestions for Use:

Suggested procedure:
Measure the absorbance of the potassium dichromate cells at the four wavelengths specified by NIST (with the NIST traceable set, measure against the supplied blank).
These are: 235, 257, 313, 350 nm.

Absorbance Scale Accuracy:
If you are using the NIST traceable set, compare the absorbance values to the certificate supplied. If using the non-traceable set, measure the cells over time and calculate the expected absor­bance values for your instrument.

Linearity:
To evaluate linearity, plot a graph of concentration against absor­bance for each of the four wavelengths.
If you determine that your instrument is not giving you the cor­rect values, consult your service technician for advice on how to determine and correct any problem which this reference may detect.

RM-0204060810 set:
This NIST traceable set of one blank and five increasing concentrations of potassium dichro­mate is our most useful and widely purchased set. It consists of 6 cells with the following mate­rials:

Holmium Oxide - UV/Vis - Wavelength Reference

Description: Holmium oxide (4%) in perchloric acid (10%)
Primary Usage: Assessment of wavelength scale accuracy in both UV and Visible
Useable Range: 240nm to 650nm
Physical Configuration: Filled far UV quartz cell that has been permanently heat sealed

Product Description:

Holmium has been used as a wavelength standard for many years and now we have extended the use by creat­ing a filled and sealed far UV quartz cell which allows it to be used into the UV spectra. Holmium offers sharp, stable peaks over the range of 219 to 650nm. Holmium perchlorate is used to assure that the wavelength scale of your instrument is within the manufacturers tolerances to the actual wavelength being measured. The use of the filled quartz cell assures that the optical configuration for your quality control is exactly the same as for a normal analysis.

Suggestions for Use:

Holmium presents a wide range of crisply resolvable peaks which are easily used to correlate the wavelength indicator on your spectrophotometer to the known peak. The first procedure should be to scan the cell over the usable range to assure that all peaks can be resolved. Adjust the slit width and scan rate to produce a usable spectra. Check each peak to assure that the reading on your spectrophotometer is within the manufacturers toler­ances of the wavelength readout. If not, get a service technician to adjust or recheck your instrument. Holmium is measured against an air blank.

Periodically check the spectra, at a minimum in the area where you are doing your analysis. Periodic use of the Holmium cell will build a log of your instrument's spectral accuracy for use with certification and troubleshooting should the correlation change over time.

Didymium - Visible - Wavelength reference

Description: Didymium in perchloric acid, sealed in quartz cells
Primary Usage: Assessment of wavelength scale accuracy in the Visible spectrum
Useable Range: 290nm to 870nm
Physical Configuration: Filled far UV quartz cell that has been permanently heat sealed

Product Description:

Didymium has been used as a visible wavelength standard in the form of a glass filter. We now offer a quartz cell filled and permanently sealed with a didymium perchlo­ric solution that will evaluate more effectively the optical performance of your instrument. Didymium offers sharp, stable peaks over the range of 290 to 870nm. The primary use of Didymium is to assure that the wavelength scale of your instrument is within the manufacturers tolerances to the actual wavelength being measured. The use of the filled quartz cell assures that the optical configuration for your quality control is exactly the same as for a normal analysis.

Suggestions for Use:

Didymium presents a wide range of crisply resolvable peaks which are easily used to correlate the wavelength indicator on your spectrophotometer to the known peak. The first procedure should be to scan the cell over the useable range to assure that all peaks can be resolved. Adjust the slit width and scan rate to produce a usable spectra. Check each peak to assure that the reading on your spectrophotometer is within the manufacturer’s toler­ances of the wavelength readout. If not, get a service technician to adjust or recheck your instrument. Didymium is measured against an air blank.

Periodically check the spectra, at a minimum in the area where you are doing your analysis. Periodic use of the Didymium cell will build a log of your instrument’s spectral accuracy for use with certification and troubleshooting should the correlation change over time.

Samarium Perchlorate - UV/Vis - Wavelength

Description: Samarium Perchlorate sealed in quartz cells
Primary Usage: Assessment of wavelength accuracy in both UV and Visible
Useable Range: 230nm to 560nm
Physical Configuration: Far UV quartz cell that has been permanently sealed by heat fusion

Product Description:

Samarium Perchlorate is a particularly good reference for establishing wavelength calibration because it has useful peaks from 230 to 560nm, many of which have a spectral bandwidth of less than 5nm permitting precise location of the peaks. This is a great advantage over using glass fil­ters which may have spectral bandwidths of over 30nm. In addition to offering wavelength calibration, the Samarium Perchlorate can be used for checking instrument spectral bandwidth. By using peaks in the 230-240 or the 410-420 region, the ability to resolve complex peaks can betested.

Suggestions for Use:

Samarium presents a wide range of narrow resolvable peaks which are easily used to correlate the wavelength indicator on your spectrophotometer to the known peak. The first procedure should be to scan the cell over the usable range to ensure that all peaks can be resolved. Adjust the slit width and scan rate to produce a usable spectra. Check each peak to assure that the reading on your spectrophotometer is within the manufacturer’s tolerances of the wavelength readout. If not, get a service technician to adjust or recheck your instrument.

Periodically check the spectra, at a minimum in the area where you are doing your analysis. Periodic use of the Samarium cell will build a log of your instrument’s spectral accuracy for use with certification and troubleshooting should the correlation change over time.

Stray Light Reference Materials

Description: Materials with sharp cutoffs in transmission at specified wavelengths
Primary Usage: Detection of stray light in the UV
Useable Range: 200nm to 260nm, depending on the material
Physical Configuration: Far UV quartz cells that have been permanently sealed by heat fusion

Product Description:

Stray light can be described as an indication by the instrument of transmitted light when in reality there is no light being transmit­ted through the sample. The presence of more stray light than specified in your instrument operators manual may cause errors in your analysis. Stray light can be a problem in any wavelength range of the instrument but the problem increases the further into the UV that you will be measuring. The stray light reference materials are useful in determining the amount of stray light in your instrument because each material stops transmitting light below a specified wavelength. Hence, below the specified “cut­off” wavelength, any indication of light transmisson must be stray light. The testing for stray light is important even if the spectro­photometer is not used below 260nm, because it is an excellent indication of the overall system health of the instrument optics, grating and deuterium lamp.

Stray light determinations are run against a water blank. This blank is supplied with all NIST traceable stray light references. The Certificate of Traceability supplied with stray light reference is measured against the water blank supplied with that reference cell.

Suggestions for Use:

The procedure for using the stray light references is similar for all materials. Set your spectrophotometerʼs wavelength 20nm above the cutoff for the stray light reference that you are using (for Potassium Iodide you would start at 280nm). Insert the stray light reference cell in the measurement cell holder and the stray light blank cell in the blank cell holder of your instrument. Scan down into the UV to the lowest wavelength that your instru­ment manual specifies. Any light transmitted below the cutoff wavelength will be stray light. If the amount of stray light is greater than the specification given in your instrument manual, call a service technician to investigate and correct the problem. Periodically rescan with the same instrument configuration and compare the results. Over time you will have a data trail for your instrument which will make the detection and correction of any problems relating to stray light much more reliable.

Benzene Vapor for Spectral Resolution

Description: 0.1ml Benzene in a vapor state sealed in a quartz cell
Primary Usage: Test the resolution at various bandwidths of grating based instruments in the UV range
Useable Range: 270nm to 230nm
Physical Configuration: Far UV quartz cell that has been permanently sealed by heat fusion

Product Description:

The ability of your spectrophotom­eter to resolve absorption lines is the basis of its theory of opera­tion. If absorption lines cannot be resolved adequately, then interfer­ing lines will be integrated with the correct line, thus giving an inaccu­rate measurement. Benzene vapor is an effective material for the detection of a grating based spec­trophotometer’s resolving power, as it has a great number of close but distinct absorption lines. Benzene vapor will not work well wit a pho­todiode array spectrophotometer as it does not measure a continuum and the peaks will not be resolved well enough to be usable.

Suggestions for Use:

Set your spectrophotometer to a slit width and a scan rate and note the settings. Scan from 260 to 250nm which is the area of the largest peaks. Compare the peaks to the two charts and determine what changes need to be made to the setting of your spectrophotometer to improve the resolution of the scan. Continue to alter both the slit and scan rate until you have opti­mized the resolution. Make a note of the settings in your quality procedures.

Each time that the scan is repeated you can compare the new scan with previous scans to check for any variance. If your instrument needs service because of a drop in resolution, the historical data will greatly assist the service technician.

Ultraviolet Bandwidth- Toluene in Hexane

Description: Quartz cell filled with Toluene in Hexane and permanently sealed
Primary Usage: Determination of bandwidth and resolution in the UV region
Useable Range: 267.0nm and 268.7nm
Physical Configuration: Far UV quartz cells that have been permanently sealed by heat fusion

Product Description:

The Spectral Bandwidth (SBW) of a spectrophotometer is the basis of establishing its ability to resolve absorbtion lines separated by small differences in wavelength. If a substance that you need to measure has an absorbtion line at 257.4nm and there is an interfering line at 260.0nm you need to have established whether your spectrophotometer can resolve the two lines separately or “mixes” the two absorbtion lines into a single line which will give erroneous results.
Toluene in Hexane is used as a reference for the calculation of SBW. The ratio of the absorbtion of the solution when read at two peak wavelengths (~268.7 and ~267.0nm) relates directly to the SBW of the instrument being assessed. Regular use of this technique will assure that the resolution of your instrument is within the required range for your work.

The Toluene in Hexane reference consists of two far UV quartz spectrophotometer cells with the solution permanently sealed by heat fusion in the cells. One cell is 0.02% Toluene in Hexane, the other is a Hexane only blank. The Toluene in Hexane cell is traceable to SRM 935a which is an absorbtion reference material.

Neutral Density Filters

Description: Neutral Density Filter Set
Primary Usage: Routine verification of photometric scale
Useable Range: 440nm to 635nm
Physical Configuration: Glass Filters mounted in anodized aluminum holder

Product Description:

Our neutral density filter sets are based on and traceable to the NIST sets SRM 930e and SRM 1930. These sets are used to test the photometric scale in both Transmission and Absorbance in the visible wavelength range. The filters are made from Schott NG-type glass which blocks a known percentage of the light passing through it. We calibrate the glass type and thickness of the filters to produce known transmission and absorbtion values. The approximate values are shown on the chart below. Each NIST trace­able filter is individually tested and certified to transmission values and confidence intervals.

The neutral density filters are mounted in a black anodised aluminum holder, 12.5 x 12.5 x 45 mm, which is fully com­patible with all standard spectrophotometer cell holders. The filters have been shown to be effective in instruments with an effective bandwidth of 2.2nm to 6.5nm.

Suggestions for Use:

Set your spectrophotometer in either absorbance or trans­mission at 440.0 nm. Using the empty filter holder (blank) zero the instrument. Insert each filter in turn and note the value. Set your instrument to each successive wave­length and repeat the procedure. The value that you read should be close to the measured certificate value listed for that filter. Using the readings from your instrument you can assure that the readings are of the correct value (photometric accuracy). You can also plot the readings on graph paper and plot the figures to check the linearity of your scale. Repeat the tests at a fixed period of time. If you note any discrepancy in the readings, call your service technician and they can use the data that you have col­lected from using the filters to diagnose and correct any problems with your instrument.

Sets for Simplified Instrument Verifications

To make your verification task easier, our reference materials have been assembled into sets which allow you to meet specific verification requirements. In addition, you can save money by purchasing a group of references in a set instead of purchasing several references individually.

Ultraviolet Reference Sets: