Bio-Rad SmartSpec Plus Spectrophotometer - Manual (Page 57)

11.3 Cuvette Selection Guide
Catalog Minimum Maximum Cuvette
Number Volume Volume Type Pathlength
170-2502 1,000 µl 3,500 µl Standard cuvette, quartz 10 mm
170-2503 500 µl 1,400 µl Semi-microvolume cuvette, quartz 10 mm
170-2504 200 µl 700 µl Microvolume cuvette, quartz 10 mm
170-2505 80 µl 100 µl Sub-microvolume cuvette, quartz 10 mm
11.4 Selecting the Appropriate Cuvette
The SmartSpec Plus has 1 mm, 2 mm, 5 mm and 10 mm pathlengths. For most
absorbance measurements you will be using 10 mm pathlength cuvettes. Cuvettes of shorter
pathlength allow the measurement of concentrated samples without dilution. If you put a
solution in a 10 mm pathlength cuvette and get a reading of 2.0 AU, you can use a 5 mm
pathlength cuvette to get an absorbance of 1.0 AU for the same solution. SmartSpec Plus
corrects for pathlengths shorter than 10 mm when converting absorbances into concentration.
The following table gives you the absorbance at A260 and corresponding concentration
for the different pathlength cuvettes.
Pathlength A260 = 0.1 AU A260 = 1.5 AU **
10 mm 5 µg/ml * 75 µg/ml
5 mm 10 µg/ml 150 µg/ml
2 mm 25 µg/ml 375 µg/ml
1 mm 50 µg/ml 750 µg/ml
* DNA concentration based on 1 O.D. = 50 µg/ml for dsDNA
** Working range of the SmartSpec Plus is 0.1–1.5 AU per Good Laboratory Practice.
Cuvettes that can fit the SmartSpec Plus should have 8.5 mm 'Z' dimension and either 1,
2, 5 or 10 mm pathlength and 12.5 mm width. In general there are two types of 'Z' dimensions:
15 mm and 8.5 mm. This is only applicable for sub microvolume cuvettes i.e., for volumes
100 µl or lower. In most cases you will use 10 mm pathlength cuvettes.
The SmartSpec Plus has 8.5 mm 'Z' dimension. This is 8.5 mm from the bottom of the
cuvette and it is the distance required for the light path to hit the sample. See Figure below.
54
"Z" dimension