The Atrazine RaPID Assay, kit has been successfully applied to the determination of atrazine in fertilizer samples using the ollowing guidelines:
1. Weigh fertilizer into diluent.
a) For each gram of fertilizer, use 10 mL of diluent. It is recommended that at least 1 g or up to 50 g of fertilizer be used to obtain a representative sample.
b) As diluent use either a 50%(v/v) methanol: 50%(v/v) kit Diluent/Zero Standard solution (order Part # A00051) or 100% methanol. Extraction with 100% methanol gave somewhat lower recoveries than the 50:50 solution of methanol and kit diluent. When preparing the 50:50 methanol/diluent solution some precipitate may form but should redissolve.
2. Mix the fertilizer suspension for a least 2 hours on a shaker or at least 30 minutes in a sonicator.
3. Dilute the fertilizer 1:10 in kit Diluent/Zero Standard. Greater dilutions maybe used to determine higher concentrations of atrazine.
4. Following the instructions for the Atrazine RaPID Assay kit assay the diluted extracted fertilizer samples. Either the standard 200 uL sample procedure or the 100 uL extended range procedure (order Part # A00050 ) maybe used. The extended range procedure is generally preferred.
5. Calculate final results by multiplying the value obtained from the Atrazine RaPID Assay by the dilution. For example, if
6. g of fertilizer is extracted in 10 mL of diluent,
the extract is diluted 1:500 in diluent,
and gives a result of 2.5 ppb in the Atrazine assay,
then the total dilution would be 1:5000 and
the final result 12.5 ppm (10 X 500 X 2.5 ppb).
This method has been tested with a limited number of fertilizers and should be validated with fertilizer samples in the user's laboratory.