Page:NIOSH Manual of Analytical Methods - 2539.pdf/6

 ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 6 of 10 TABLE 2. MASS SPECTRAL DATA FOR ALDEHYDE DERIVATIVES OF 2-(HYDROXYMETHYL)PIPERIDINE (HMP)

Aldehyde

Formula

Formaldehyde Acetaldehyde Propionaldehyde Acrolein Butyraldehyde Isobutyraldehyde Crotonaldehyde Valeraldehyde Isovaleraldehyde Hexanal Heptanal Furfural

C7 H1 3 NO C8 H1 5 NO C9 H1 7 NO C9 H1 5 NO C1 0 H1 9 NO C1 0 H1 9 NO C1 0 H1 7 NO C1 1 H2 1 NO C1 1 H2 1 NO C1 2 H2 3 NO C1 3 H2 5 NO C1 1 H1 5 NO2

HMP DERIVATIVE Base Peak m/z 97 126 126 126 126 126 126 126 126 126 126 192

Other Characteristic Ions m/z 126, 127* 140, 141* 154, 155* 152, 153* 168, 169* 168, 169* 166, 167* 182, 183* 182, 183* 196, 197* 210, 211* 95, 163, 193*


 * indicates molecular ion.

APPENDIX A: SORBENT PREPARATION (optional if commercially prepared tubes are used ): Extrac t Amb erlite XAD S-2 for 4 h in Soxh let with 50/50 (v/v) aceto ne/m ethylene ch loride. Rep lace with fresh solvent and repeat. Vacuum dry overnight. Add 1 g purified 2-(hydroxymethyl)piperidine in 50 mL toluene fo r each 9 g extrac ted XA D-2 so rbent. Allow this mix ture to stan d 1 h with o ccasio nal swirling. Remo ve the solvent by rotary evaporation at 37 °C and dry at 130 kPa (1 m m Hg) at am bient temperature for ca. 1 h. To determine the amount of background for each batch, extract several 120-mg portions of the coated sorbent with toluene and analyze (steps 6 through 12). No blank peak is expected for any aldehydes other than formaldehyde and possibly acetaldehyde. SYNTHESIS OF ALDEHYDE OXAZOLIDINES: Plac e a so lution of pu rified 2-hyd roxym ethylp iperid ine (0 .57 g, 5 m mo l) in 10 mL of tolu ene in a 50-mL round-bottomed flask. Use several 20 mL portions of toluene to rinse residual 1-(hydrox ymethyl)p iperidine fro m the containe r used fo r weighing. Add anh ydrous m agnes ium su lfate (2.5 g) to the round-bottomed flask to dry the aldehyde solution as it is added and to remove the water which forms during the reaction. Add a solution of 10 mole of aldehyde in 10 mL of toluene to the 2-hydrox ymethylpip eridine so lution dropw ise with stirring over 1 h. S tir the solution o vernight, the n filter to remove the magnesium sulfate. Remove the toluene and excess aldehyde from the solution at reduced pressure by rotary evaporation. PREPARATION AND STANDARDIZATION OF FORMALDEHYDE STOCK SOLUTION (ca. 1 mg/m L): Dilute 2.7 m L 37% aque ous form alin so lution to 1 L w ith dis tilled, d eioniz ed w ater. This solut ion is s table for at least three months. Standardize by placing 5.0 mL of freshly prepared 1.13 M sodium sulfite solution in a 5 0-m L beak er and s tir magn etically. Adjust p H to betw een 8.5 a nd 10 w ith base o r acid. Record the pH. Add 10.0 mL stock formaldehyde solution. The pH should be greater than 11. Titrate the solution back to its original pH with 0.02 N sulfuric acid (1 mL acid  0.60 0 m g HC HO ; abo ut 17 mL acid needed). If the endpoint pH is overrun, back titrate to the endpoint with 0.01 N sodium hydroxide. Calcula te the con centration, C s (mg/mL), of the formaldehyde stock solution:

where:

30.0 = 30.0 g/equivalent of formaldehyde N a = nor ma lity of su lfuric acid NIOSH Manual of Analytical Methods (NMAM), Fourth Edition