General, chemical type or category of compound to be separated.
The type of resin that is packed inside the column tube.
United States Pharmacopeia HPLC column designation.
Size (in micrometers) of the polymer or silica bead packed inside the column tube.
Inside diameter (in millimeters) of the column tube.
Length of the column tube (in millimeters).
Polymeric cation exchange packing for separation of glyphosate and its metabolite in drinking water
The PRP-X400 column provides a fast separation for glyphosate and its metabolites.
Use at Room Temperature
The PRP-X400 column does not have to be heated to 65° C, so you don't need to purchase a column heater for this method.
No Methanol Required
PRP-X400 columns do not require the use of methanol in the mobile phase.
PRP-X400 columns cost much less than other glyphosate columns.
Use the PRP-X400 Column for EPA Method #547
The PRP-X400 is a 7 µm poly(styrene-divinylbenzene) sulfonate cation exchange support (2.5 meq/gm) column. It separates glyphosate and aminomethylphosphonic acid according to charge in less than 10 minutes. This separation requires post-column oxidation and derivatization (see Figure 1).
Mobile Phase Preparation
To prepare 0.005 M monobasic potassium phosphate (KH2PO4) pH 1.9, dissolve 0.68 gm of monobasic potassium phosphate in 1 Liter of deionized water. Adjust the pH to 1.9 using concentrated phosphoric acid. Prior to using this preparation, filter it through a 0.45 µm nylon filter and degas.
Post column reaction (oxidation) with calcium hypochlorite followed by derivatization with o-phthalaldehyde solution provides sensitive (6 ppb or lower) and selective (primary and secondary) amine detection. To achieve low-level detection (6 ppb) of glyphosate and its metabolite, follow the instructions listed under Separation Conditions.
Column Mobile Phase
Post Column Conditions - Oxidation Solution
Post Column Conditions - Derivatization Solution
Oxidation Solution Preparation (15 ppm calcium hypochlorite)
Stock Concentrate Solution Preparation - To prepare the 1500 ppm concentrate solution, add 0.23 gm of tech grade calcium hypochlorite to 100 mL of deionized water. With a 2 µm nylon filter, remove any insoluble calcium carbonate (as it produces a cloudy solution). Store the solution in the freezer. The shelf life is several freeze/thaw cycles.
Working Oxidation Solution Preparation
Dissolve 1.36 gm monobasic potassium phosphate, 11.60 gm sodium chloride, and 0.40 gm sodium hydroxide (or use 0.50 mL 50% w/w sodium hydroxide solution) in 950 mL deionized water. Add 10 mL of 1500 ppm calcium hypochlorite stock concentrate solution, and dilute to 1 Liter. Filter through a 0.45 µm nylon filter. Prepare this solution fresh daily. Use and store this solution in an inert atmosphere (helium or nitrogen). Degas before use.
Derivatization Solution Preparation (o-phthalaldehyde)
Dissolve 19.1 gm of disodium tetraborate decahydrate in 950 mL of deionized water. Heat the solution to approximately 50° C for about one hour to dissolve the disodium tetraborate decahydrate (or prepare the solution one day in advance and allow the borate to dissolve). Cool the solution to room temperature, and adjust the pH to 10.9 with 1 N sodium hydroxide. Now dissolve 0.80 gm phthalic dicarboxyaldehyde (Aldrich Part # P3,940-0) in 10 mL methanol. Add all 10 mL to the disodium tetraborate decahydrate solution. Then add 50 µL of 2-mercaptoethanol. (Caution: Use adequate ventilation and /or a hood when handling 2-mercaptoethanol, as the fumes are noxious.) Dilute the concentrate to 1 Liter with deionized water, mixing well. Filter the mixed solution through a 0.45 µm nylon filter, and degas before using. Store the solution in an inert atmosphere (helium or nitrogen). Refrigerate the unused solution. Shelf life is one or two weeks.
Reaction coils can be made in the laboratory (see Separation Conditions) or entire post-column derivatization systems are available for purchase.