Page:NIOSH Manual of Analytical Methods - 2018.pdf/9

 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