Page:NIOSH Manual of Analytical Methods - 5525.pdf/15

 ISOCYANAT ES, TOTA L (MAP): METHO D 5525, Issue 1, dated 15 March 2003 - Page 15 of 17

APPENDIX A: PREPARATION OF PHO SPHATE-FORMATE BU FFER AND MO BILE PHASE 100 mM PHO SPHATE - 100 mM FOR MATE BUFFER Add 46.12 g 85% Phosphoric Acid (~27 mL) and 15.08 m L Form ic Acid to 3700 m L deionized hi-pure water. The initial pH should be ~1.56. Titrate with Triethylamine (TEA) to a pH of 6.0 using a standardized pH m eter. This will take between 115 and 120 mL of TEA. After the pH adjustment to pH 6.0, add additional deionized hi-pure water to bring the final volume to 4.0 L. Sp lit into two 2L-po rtions. The first portion is adju sted to pH 1.6 with concentrated HCl, monitoring the pH by pH m eter. T his shou ld take be twee n 30 and 35 m L of c onc entra ted H Cl. The second portion remains at pH 6.0, but must have a volume of hi-pure water added that is equal to the volume of H Cl ad ded to the first portion. This will ensure that the concentration of salts in the two different pH buffers are the same resulting in less baseline change during the gradient run. Store all buffers in the refrigerator until mixed with acetonitrile. MO BILE PH ASE: 65 :35 A CE TO NIT RILE-P HO SPHA TE /FO RM AT E BUF FE R (F or bo th pH 6.0 and pH 1.6) Mix 650 mL acetonitrile and 350 mL buffer. Total volume will be less than 1000 mL. The m obile phase made from pH 6.0 buffer is designated mobile phase A. The m obile phase made from pH 1.6 buffer is designated m obile phas e B.

APP EN DIX B: PREPARATION OF PHOSPH ORIC ACID AND MOBILE PHASE FOR POST-COLUMN ADDITION 4.4 N PH OS PH OR IC A CID Add 50 mL phosphoric acid (85%) to 400 mL deionized hi-pure water and adjust to 500 mL. 65:35 ACETONITRILE-(4.4 N PHOSPHO RIC ACID) MOBILE PHASE Mix 650 mL acetonitrile with 350 mL of 4.4 N phosphoric acid.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition