Home Page Downloads How to Purchase Technical Assistance Starna Banner
Nicotinic Acid Reference
For assessing the Far UV absorbance scale of your spectrophotometer
Description Nicotinic acid in 0.1M hydrochloric acid sealed in a quartz cell
Primary Usage Validate the Far UV absorbance scale of spectrophotometers
Useable Range 213nm and 261nm, spectral bandpass of 2nm or less
Physical Configuration Far UV quartz cells that have been permanently sealed by heat fusion
NIST Traceability Each set is supplied with a Certificate of Analysis and NIST Traceability
ISO Accredited Accredited by UKAS ISO 17025, ISO Guide34 and ISO 9001

Product Description

View/Download Comprehensive Data Sheet for Nicotinic Acid Reference

The use of nicotinic acid solvated in dilute hydrochloric acid is a well documented method for the validation of the absorbance scale and linearity of a spectrophotometer in the Far UV region. When prepared in 0.1M hydrochloric acid, nicotinic acid gives a spectral scan containing characteristic peaks at approx. 210nm and 260nm. Within the concentration range 5-25 mg/l, if the absorbance scale of a narrow SBW (2 nm) spectrophotometer is linear, the apparent absorbances of a series of concentrations will be a linear function of concentration, at a specified SBW.

The filled cells are tested and certified against the calculated values. 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 the quality control that is established in your laboratory. Each set is supplied with a sealed blank cell that was used for the certified measurment. Below is a table with approximate absorbance values for the Nicotinic Acid reference set:

Concentration 213nm 261nm
6 mg/L 0.240 0.281
12 mg/L 0.477 0.556
18 mg/L 0.730 0.849
24 mg/L 0.988 1.149

Suggestions for Use

Measure the absorbance of the nicotinic acid cells at the two certified wavelengths. These wavelengths are: 213 and 261nm. The absorbance scale is verified by assuring that the absorbance readings on your instrument are within your instruments tolerance to the readings on the certificate supplied with the reference set. To evaluate linearity, plot a graph of concentration against absorbance for each of the four wavelengths.

Scan of Nicotinic Acid

Linearity Plot of Nicotinic Acid

Interpertation of Results

Consult your spectrophotometer's reference manual for the specification of your instrument's absorbance scale tolerance. This figure will be listed as a plus and minus (+/-) number in absorbance units. Add your instrument's absorbance tolerance to the confidence limit on the certificate supplied with the Nicotinic Acid set for your expected absorbance range. Compare the absorbance values measured on your instrument with the expected values calculated from your instrument manual and the NIST traceable certificate. If the readings are within the expected range for your instrument then your absorbance scale is correct. If not, consult your service techincian and have the instrument evaluated. Quite often if the results of your absorbance measurments are low, it shows that your lamp needs to be replaced.

Quality program

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

How to Order

Catalog Number Description
RM-1A2A3A4A Nicotinic Acid UV Reference set, 4 concentrations
RM-1A Nicotinic Acid UV Reference set, 6 mg/L
RM-2A Nicotinic Acid UV Reference set, 12 mg/L
RM-3A Nicotinic Acid UV Reference set, 18 mg/L
RM-4A Nicotinic Acid UV Reference set, 24 mg/L

Download MSDS Sheet for Nicotinic Acid Reference