(UV) Tips and Tricks - How soon can samples be measured after switching the UV-VIS spectrophotometer power ON?

There are many components within a UV-Vis Spectrometer and much more in a UV-Vis-NIR version.  Electronic components take a while to establish stability and performance, especially source lamps.  It can often be tempting to turn on the Spectrometer and immediately start a measurement when an urgent samples needs analysis, but careful consideration has to be made about the instrument optics when judging the required stability time before proceeding.

There are three types of initial configuration of a spectrometer emission section where the lamps are housed and beams are monitored for stability.  The following lists their designs:

Single-Beam UV-VIS Spectrophotometers (UVmini-1240)

In single-beam UV-VIS spectrophotometers, any variations in the light source brightness directly affects measurement data. (The basic configuration of single-beam spectrophotometers is illustrated in Fig. 1.) Therefore, wait until the brightness of the light source stabilizes sufficiently before measuring, usually about one hour after switching the power ON.

Double-Beam Monitoring UV-VIS Spectrophotometers (UV-1280)

In UV-VIS spectrophotometers with double-beam monitoring, variations in light source brightness tend not to affect measurement data, because, unlike single-beam systems, double-beam systems use a separate detector to monitor the light level from the light source. (Fig. 2 illustrates the basic configuration of double-beam monitoring UV-VIS spectrophotometers). However, the brighter the light source, the lower the noise level in measurement data. Consequently, it is preferable to wait a while after switching the light source ON before measuring. In addition, considering instrument temperature changes and electrical circuit stabilization time after switching the light source ON, wait about 30 minutes after switching the power ON before measuring samples.

Double-Beam UV-VIS Spectrophotometers (UV-1900i, UV-2600i, UV-2700i, UV-3600i Plus, and SolidSpec-3700)

Double-beam UV-VIS spectrophotometers are designed to prevent variations in light source brightness from affecting measurement data by monitoring the light level of the reference light. (Fig. 3 illustrates the basic configuration of double-beam UV-VIS spectrophotometers).
Furthermore, double-beam monitoring also can reduce the effects from absorption by solvents. However, just like the other configurations, the brighter the light source, the lower the noise level in measurement data. Consequently, it is preferable to wait a while after switching the light source ON before measuring. Considering instrument temperature changes and electrical circuit stabilization time after switching the light source ON, wait about 30 minutes after switching the power ON before measuring samples.