Inconsistent absorbance of reference wavelength
Posted: Thu Apr 10, 2008 2:46 am
Hi everyone,
We are using HPLC 8453 UV- visible Spectrophotometer which is a single-beam to monitor the pH of seawater over days. We use three wavelengths 730nm, 578nm and 434nm to measure and record the absorbances, in which 730nm is the reference wavelength. But the absorbance of reference wavelength is not consistent over time (hours or days), usually we got the increasing trend or fluctuation curve (under the condition of no CO2 exchange with the sample and no biological activity within the sample). The lamp of spectrophotometer is Ok because we got all tests passed (self test, lamp intensity, lamp stablity) executed by operating the software.
Could anyone explain to me the cause of the inconsistency of non- absorbing wavelength (730nm) over time ?
Many thanks in advance,
We are using HPLC 8453 UV- visible Spectrophotometer which is a single-beam to monitor the pH of seawater over days. We use three wavelengths 730nm, 578nm and 434nm to measure and record the absorbances, in which 730nm is the reference wavelength. But the absorbance of reference wavelength is not consistent over time (hours or days), usually we got the increasing trend or fluctuation curve (under the condition of no CO2 exchange with the sample and no biological activity within the sample). The lamp of spectrophotometer is Ok because we got all tests passed (self test, lamp intensity, lamp stablity) executed by operating the software.
Could anyone explain to me the cause of the inconsistency of non- absorbing wavelength (730nm) over time ?
Many thanks in advance,