Page:NIOSH Manual of Analytical Methods - 9201.pdf/9

 CHLORINATED AND ORGANONITROGEN HERBICIDES (PATCH): METHOD 9201, Issue 1, dated 15 January 1998 - 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

1,3

2,4

4

2,4-D, acid

2 (methyl ester)

5

2.4-D, BE

1

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.

Generally high recoveries from PUF patches compared to liquid standards for reasons unknown.

2.

The esters are not affected by the diazomethane reagent provided the solutions are quenched within one hour with silicic acid. Otherwise, recoveries for all esters will diminish. 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 closely in that order on the

4.

Cyanazine is very polar and tends to tail and to elute very late on highly polar columns. It

non-polar columns DB1and DB-5. The order is reversed on most polar columns. has extremely unpredictable behavior. 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.), although to a much lesser extent.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition