Effect of Integration Time on Precision of Absorbances Measured with a Diode Array UV-VIS Spectrophotometer.
Abstract
Modern UV-VIS spectrophotometers such as the HP8450A equipped with a diode array controlled by a minicomputer can scan a spectrum from 200 to 800 nm in one second, or the instrument can time-average scans over a period of time denoted the 'integration time.' In order to see whether the precision was significantly enhanced by time-averaging, replicate measurements were made with holmium oxide, and a dyestuff with peak absorbance near unity, as well as a diluted sample of the dye with peak absorbance near 0.01 absorbance unit. Measurements were made at 1-, 2-, 5-, 10-, 20-, and 40-second integration times. Bartlett's chi-squared statistic was used to test whether the variances were significantly different. The results showed that the variances were independent of integration time for all samples tested. The sample standard deviation was 0.001 absorbance unit for samples with peak absorbances near 1.0. For the diluted dye, the sample standard deviation was 2 x 10 to the minus 4th power absorbance unit.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1984
- Accession Number
- ADA146952
Entities
People
- J. R. Ward
- J. W. Hovanec
- R. P. Seiders