Page:NIOSH Manual of Analytical Methods - 5600.pdf/15

 ORGANOPHOSPHORUS PESTICIDES: METHOD 5600, Issue 1, dated 15 August 1994 - Page 15 of 20

Table 6.

(1) Recommended Gas Chromatographic Columns and Conditions

Parameter

Wide Bore Fused Silica Capillary Column

Stationary Phase (2) Polarity Length (meters) I.D. (millimeters) Film thickness (mm) (3) Injection (vol., mode) (4)(5) Oven Temperatures Initial (°C) Final (°C) Max. Recommended (°C) Program (°C/min.) Carrier Gas (Helium) Head pressure (p.s.i.) (1) (2)

(3) (4) (5)

(6)

DB-1 non-polar 30 0.32 0.25 1 µL, SPL

(5)

DB-5 weakly polar 30 0.32 1.0 1 µL, DIR

DB-1701 mod. polar 30 0.32 1.0 1 µL, DIR

DB-210 mod. polar 30 0.32 0.25 1 µL, SPL

100 275 325 3.0

125 275 325 4.0

125 275 280 4.0

100 250 240/260 3.0

15

15

15

15

Actual conditions may vary depending on column and analytical objectives. The conditions given above are those corresponding to the RT data in Table 7. DB-1, 100% methyl silicone; DB-5, 5% phenyl, 95% methyl silicone; DB-1701, 14% cyanopropylphenyl, 86% methyl silicone; DB-210, 50% trifluoropropyl, 50% methyl silicone. Other phase types may also work well. Thinner films give faster separations at lower temperatures promoting analyte stability. Use 2-mm i.d. injection port lines for 0.5-µL injection and 4-mm i.d. injection port liners for 1-to-2-µL injections with 0.32-mm i.d. capillary columns. SPL = splitless mode, initial oven temperature 5-10 °C < BP of desorption solvent; DIR = direct mode, initial oven temperature 5-10 °C > BP of desorption solvent. In both modes, split-vent off time should be 60 sec for 1-2 µL injections with 4-mm ID injection port liners, and 20-30 sec for 0.5-µL injections with 2-mm ID injection port liners. Use 2-mm ID injection port liners for 0.5-µL injection and 4-mm ID injection port liners for 1-2 µL injections with 0.32-mm ID capillary columns. J & W Scientific Catalog, p. 21. [10]

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94