Page:NIOSH Manual of Analytical Methods - 2018.pdf/10

 ALIPHATIC ALDEHYD ES: METHO D 2018, Issue 1, dated 15 March 2003 - page 10 of 10 APP EN DIX The SKC sam pler for aldehydes (DNPH-coated silica gel tube, catalogue No. 226-119) may be used for acetaldehyde, propionaldehyde, valeraldehyde and isovaleraldehyde with mo difications of this method. These modifications include the following. (a) The m aximum recomm ended air volum e sam pled probably should be less than 15 L for an air concen tration n ear 1 0 m g/m 3 (indicated on page 2018-1) because of the upper limits of the method for the SK C, Inc. sa m pler are probably sm aller than the upper lim its in this method (105, 183, 50 and 5 0 µg per s am ple for ace taldeh yde, propio naldehyde, valeraldehyde, and isovaleraldehyde, respectively). However, the maximum recomm ended air volumes for the SKC sam pler are unknown. (b) The procedu re for recovery of analyte from the sorbent wo uld be m odified ; i.e., placem ent of sorben t sec tions into vials and addition of solvent and possible use of ultrasonic bath. (c) A volume of solvent much sm aller than 10 m L ca n be use d for reco very. Howe ver, the m inim um volum e us ed s hou ld be te sted for ad equ ate recoveries. (d) Consequences of using a much sm aller volume of solvent for recovery include a lower LOD, a lower LOQ, the need for a different range of calibration standards, and the need for a different range of levels of fortification (section 8). (e) The maxim um volume of solution for fortification of the front sorbent bed m ust be sm aller than 90 µ L and sh ould be determ ined (section 8).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition