Lamotte SMART3 Colorimeter User Manual download pdf (Page 19)

 SAMPLE DILUTION TECHNIQUES & VOLUMETRIC

MEASUREMENTS

If a test result using the SMART3 Colorimeter gives an over range message

then the the sample must be diluted. The test should be repeated on the diluted

sample to obtain a reading which is in the concentration range for the test.

(Note: This is not true for colorimetric determination of pH.)

Example:

Measure 5 mL of the water sample into a graduated cylinder. Add

demineralized water until the cylinder is ﬁ lled to the 10 mL line. The sample

has been diluted by one-half, and the dilution factor is therefore 2. Perform

the test procedure, then multiply the resulting concentration by 2 to obtain

the test result.

The following table gives quick reference guidelines on dilutions of various

proportions. All dilutions are based on a 10 mL volume, so several dilutions will

require small volumes of the water sample. Graduated pipets should be used for

all dilutions.

Size of Sample

Deionized Water to

Bring Volume to 10 mL Multiplication Factor

10 mL 0 mL 1

5 mL 5 mL 2

2.5 mL 7.5 mL 4

1 mL 9 mL 10

0.5 mL 9.5 mL 20

If the above glassware is not available, dilutions can be made with the

colorimeter tube. Fill the tube to the 10 mL line with the sample then transfer

it to another container. Add 10 mL volumes of demineralized water to the

container and mix. Transfer back 10 mL of the diluted sample to the tube and

follow the test procedure. Continue diluting and testing until a reading, which

is in the concentration range for the test, is obtained. Be sure to multiply the

concentration found by the dilution factor (the number of total 10 mL volumes

used).

Example:

10 mL of sample is diluted with three 10 mL volumes of demineralized water;

the dilution factor is four.

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Lamotte SMART3 Colorimeter User Manual Page 19