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Absorbance Measurements (Cuvette Centre-Mount Sample Holder)

The following procedure can be used for obtaining absorbance measurements with a

centre-mounted cuvette. In the centre-mount configuration, normally reflected light exits

the sphere through the transmission port and is not counted.

1. Darken the room and drive the instrument to 500 nm

2. Fill a clean cuvette with the pure solvent used as the sample preparation.

Note

If the intended sample is turbid, use an empty cuvette for the baseline scan. Load

the blank cuvette into the holder and load the sample holder assembly into the

centre-mount port. Position the alignment pins on the centre-mount device to match

the holes in the sphere.

3. While viewing the front cuvette surface through the reference port, check that the

sample beam strikes the centre of the cuvette. This step may require use of a piece of

translucent paper. If the beam is off centre or will not fit on the sample, re-adjust the

sample beam optics using M3 to achieve the correct alignment. If any adjustments are

made to the optics, make sure the sample beam does not clip the transmission port.

Figure 50. The beam falling on the cuvette centre mount.

4. Examine the path of the reference beam inside the integrating sphere. The beam

should strike the reference port without clipping any part of the cuvette or sample holder.

5. Collect a Baseline scan

, or use a zeroline baseline, using the blocked beam method.

6. Remove the sample holder and replace the blank cuvette with the sample cuvette.

Load the sample holder assembly back into the sphere.

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Mantis 5000 Dokumentacja Strona 65