Page:NIOSH Manual of Analytical Methods - 5601.pdf/9

 ORGANONITROGEN PESTICIDES: METHOD 5601, Issue 1, dated 15 January 1998 - Page 9 of 21 TABLE 3. RECOMMENDED LIQUID CHROMATOGRAPHIC COLUMNS AND CONDITIONS PARAMETER

HPLC COLUMN AND CONDITIONS

Column: Solvent:

C18 Acetonitrile

C18 Methanol

Cyano Acetonitrile

Cyano Methanol

Primary Analysis

Confirmation

Confirmation

Confirmation

NOVA-PAK C18

NOVA-PAK C18

Supelcosil LC-CN

Supelcosil LC-CN

octadecyl

octadecyl

cyanopropyl

cyanopropyl

Length (mm)

300

150

250

250

ID (mm)

3.9

3.9

4.6

4.6

4

4

5

5

2.7

2.7

5.2

5.2

water

water

water

water

2% 1-propanol

none

none

none

TEA-PO4

none

TEA-PO4

TEA-PO4

0.02 M

none

0.02 M

0.02 M

acetonitrile

methanol

acetonitrile

methanol

2% 1-propanol

none

none

none

0

0

0

0

3-95% B

10-80% B

3-60% B

3-95% B

30

30

30

30

linear

linear

linear

linear

5

5

5

5

1.00

1.00

1.00

1.00

ambient(~24)

ambient(~24)

ambient(~24)

ambient(~24)

0.6-0.8

3.5-3.8

0.6-0.8

0.6-0.8

5

30

5

5

acetonitrile

1:3 acetonitrile:H2O

acetonitrile

acetonitrile

Application: Column parameters: Column Stationary phase

Particle size (µm) A

Ligand density

Mobile Phase A: Solvent B

Organic modifier C

Buffer

Concentration (Molarity) Mobile Phase B: SolventD Organic modifier Mobile Phase Program: Initial hold time (min) Program rate Program time (min) Program type Final hold time (min) Flow rate (mL/min) Column temperature ( C) Dwell volume (mL) Injection volume (µL) Injection solvent

A B

C

D

Ligand density (micromole/m2) is a better description of surface coverage than % carbon loading [22,23]. Choice of alcohol modifier is not critical. Percentages may be varied to adjust retention times andpeak shapes for early eluting analytes. Reequilibration time may be shorter with 1-propanol [24-26]. Buffer is very essential for basic analytes such as Formetanate, Carbendazim, and Benomyl [12,27,28]. Formentate is cationic at about pH 7, and its actual elution time is sensitive to small changes in pH and ionic strength of the buffer in mobile phase A. Acetonitrile is the better choice when monitoring compounds at UV absorptions below 210 nm [20,29].

NIOSH Manual of Analytical Methods, Fourth Edition