CHLORINATED AND ORGANONITROGEN HERBICIDES (HAND WASH): METHOD 9200 - Page 9 of 11
TABLE 5. NOTES ON ANALYTICAL CHARACTERISTICS OF CHLORINATED AND ORGANONITROGEN HERBICIDES Compound (alphabetically)
A.
B. SAMPLE
C. GAS
AND PHYSICAL
PREPARATION
CHROMATOGRAPHIC
1
Alachlor
3
1
2
Atrazine
3
2,3
3
Cyanazine
3
2,4
4
2,4-D, acid
1
5
2.4-D, BE
1
2
6
2,4-D, EH
1
2
7
Metolachlor
3
1
8
Simazine
3
2,3
5
CHEMICAL AND PHYSICAL 1.
B.
A. CHEMICAL
Esters may hydrolyze to the free acid. Free acid may also be present in formulations.
SAMPLE PREPARATION 1.
Methylation via diazomethane is possible in isopropanol having up to 1% water present. The isopropanol must be anhydrous, and at least 99% pure.
2.
The esters are not affected by the diazomethane reagent provided the solutions are quenched within one hour with silicic acid. Recoveries for all esters diminish otherwise. This makes possible the speciation of 2,4-D esters and of the free acid in one analysis.
3. C.
Analytes were not affected by the diazomethane reagent.
GAS CHROMATOGRAPHIC 1.
Very good peak shape.
2.
Analyte has tendency to tail on most column phases. Columns and injection ports must be clean and in good condition.
3.
The s-triazines, simazine, Atrazine, and propazine, elute very close in that order on the
4.
Cyanazine is very polar and tends to tail and to elute very late on very polar columns. It
non-polar columns DB-1 and DB-5. The order is reversed on most polar columns. has very unpredictable behavior and peak areas either diminish or increase noticeably in subsequent injections. This behavior appears to be associated with the cyano group. 5.
2,4-D BE behaves similarly to cyanazine, chromatographically (see C.4.), though to a much lesser extent.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
