ALIPHATIC ALDEHYD ES: METHO D 2018, Issue 1, dated 15 March 2003 - page 9 of 10
TABLE 6. STABILITIES OF DNPH DERIVATIVES ON SAMPLER AND IN SOLUTION Concentration of Liquid Std.
(days)
Average Rec overy from Sampler (n = 6)
(µg/m L b)
Stability Period for Liquid Std. (days) d
acetaldehyde
30
102%
1.25
>36
propionaldehyde
32
104%
2.20
>35
valeraldehyde
30
105%
2.20
>35
3
90% c
2.20
>35
Compound
isovaleraldehyde
a b
c
d
Storage Perioda
Samplers were stored at 5 °C in the dark. Each liquid standard consisted of aldehyde-DNPH derivative in acetonitrile solution, and each concentration presented is the equivalent concentration of underivatized aldehyde. The average reco very of 90% is not an indication of deterioration of isovaleraldehyde-DNPH; compare the recovery of 90% with recoveries for isovaleraldehyde in Table 5. Liquid standards were stored at 5 °C in the dark in airtight containers.
TABLE 7. 5% BREAKTHRO UGH DATA AND STOICHIOMET RIC QUANTITIES. Compound
Amount of aldehyde found to show 5% breakth rou gh at a flo w rate of 1L/m in (µg/sample) (in Dry Air a)
(in Lab Air b)
Sto ichio metric Quantity ofAldehyded (µg/sample)
(in Hu m id Air c)
acetaldehyde
178
173
158
222 µg
propionaldehyde
322
290
274
293 µg
valeraldehyde
>>500
>>507
>>473
435 µg
isovaleraldehyde
>>400
>>498
>400
435 µg
a b c d
Estimated relative humidity of dry air was 10% at room temperature. The relative humidity of the laboratory air was not measured. Estimated relative humidity of humid air was 85% at room tem perature. The sto ichiom etric quantities shown are the theoretical maximum quantities of aldehydes which can react with 1 mg of DN PH o n the silica gel bed in the Supe lco sam pler.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
