Rizal - do you have an actual pigment (that is, an insoluble colored material)?  If so, you won't be able to use a spectrophotometer at all.  When we've worked on a similar problem before, we have set up a standardized light box with a mount to hold a camera and a very black, nonreflective surface to place the plate on prior to photography.  Next to ever petri dish, we place a calibrated color card (on amazon, http://www.amazon.com/Reference-Balance-Exposure-Temperature-Calibration/dp/B012HMB1N8?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00)  .  That card will provide a constant color balance reference across any images you take.  If you standardize the light intensity and direction in the light box, and standardize the camera stand and camera exposure settings, you will be able to capture digital images that can be adjusted in photoshop or even ImageJ  to allow a quantitative comparison from one experiment to the next.

Good luck,  John

www.akadeum.com

You have to find out yourself at what wavelength it will be best results, Sometimes during process several intermediates also important so better to you several wave lengths, we use several for crystal violet degradation assay.

Article Bioegradation of hexamethyl-p-rosaniline chloride (crystal v...

Rizal - do you have an actual pigment (that is, an insoluble colored material)?  If so, you won't be able to use a spectrophotometer at all.  When we've worked on a similar problem before, we have set up a standardized light box with a mount to hold a camera and a very black, nonreflective surface to place the plate on prior to photography.  Next to ever petri dish, we place a calibrated color card (on amazon, http://www.amazon.com/Reference-Balance-Exposure-Temperature-Calibration/dp/B012HMB1N8?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00)  .  That card will provide a constant color balance reference across any images you take.  If you standardize the light intensity and direction in the light box, and standardize the camera stand and camera exposure settings, you will be able to capture digital images that can be adjusted in photoshop or even ImageJ  to allow a quantitative comparison from one experiment to the next.

Good luck,  John

www.akadeum.com

hi,

Please find the type of bacteria. Mostly Serratia sps., are found to produce red color pigment Prodigiosin. If that is so, The maximal wave length  should be identified and You can record the readings using that wave length.

Cheers,

Krithika.

dear Mr Singh. 

i will search for another source (journal) to know from which wavelenght should i take, thank you for your answer :)

dear Mr Younger,

it was an bacterial pigment think it's not soluble in growth media.

thank you for your answer, that was really opening my mind. i could use that colored card so i can see difference color quantitatively. i think it was good method, wort to try.

many thanks :)

dear mrs Krishnamoorthy,

actually that is the problem, none of any paper has researching about exact wavelenght to measure pigment from this archaea.

but thank you for your answer :)

hi,

its quite interesting. You can standardise the maximal wave length by subjecting the inoculated media to minimal to the maximum nm (uv-visible). Then find for the maximal value at  a particular wavelength and standardize it. Either You can do it after extracting the pigment using high polar solvents.Hope this will help you 

Cheers,

Krithika

why not try the wavelength of red in the spectrum? i guess thats about 600-700 nm