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| PREPARATION 1. Water samples are removed from the locked refrigerator. 2. A typed laboratory identification tag containing the project name, site location number and collection date is taped to each sample bottle. 3. An aliquot is withdrawn from the bottle using a disposable polyethylene pipette and placed into a KIMAX®51 borosilicate glass test tube which is then sealed with a polypropylene cap. 4. The sample trays are then placed in a constant temperature bath, covered to prevent photochemical decay and allowed to equilibrate to the analysis temperature 5. The test tube is then placed in the Shimadzu RF 5301PC spectrofluorophotometer for analysis by synchronous scanning. ANALYSIS The analysis for water samples is performed by synchronous scanning on the synchronously scanning spectrofluorophotometer. The synchronous scanning technique is similar to the analysis for eluted charcoal samples with the scanning parameters adjusted to compensate for shifts in the excitation and emission maximum wavelengths as well as differences in the Stoke's shift caused by the differences in pH and polarity of water as compared to elutant. The emission spectra from the synchronous scan is displayed on the monitor and plotted on a laser printer. The printout has the sample identifier, job name, date collected and scanning parameters at the bottom of the page. If the scan indicates positive results for fluorescent dye, a second printout is made utilizing spectrum integration and calibration curves stored in the computer to determine the concentration of the dye in question. If the emission spectra from two or more dyes overlap, then the spectra for each dye is separated by use of a non-linear curve-fitting computer program specifically designed for spectral separation. Spectrum integration is then used to determine the concentration of each individual dye present in the sample. For a sample where the concentration is approaching the quenching threshold, serial dilutions will be made until it can be scanned without quenching occurring. |
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