Page 500 - Applied Pharmacognosy

• The intensity of the blue color is measured in a
spectrophotometer at 820 nm.

• Naturally occurring phosphates are present in most samples

and are not removed during clean- up procedures.

• Extracts of uncontaminated materials contain about 0.05 –

0.1 ppm of phosphorus.

• This amount should be subtracted from the results obtained

on testing phosphate residues.

• No contamination of organophosphate pesticides can be

assumed in the range of 0.05 – 0.1 ppm.

•