The Optimal Analytical Method of NDMA(N-Nitrodimethylamine) by Solid-Phase Microextraction Analysis (SPME)

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1 w y wz 10«( 1y) 1~7, 2007 J. of the Korean Society for Environmental Analysis š (SPME) w NDMA(N-Nitrodimethylamine)» w y œw The Optimal Analytical Method of NDMA(N-Nitrodimethylamine) by Solid-Phase Microextraction Analysis (SPME) Soon-Woong Chang Dept. of Environmental Engineering, Kyonggi University, Suwon City, Korea Chlorine disinfection of secondary wastewater effluent and drinking water can result in the production of the potent carcinogen N-Nitrosodimethylamine(NDMA) at the lower concentration ranges. Because of increasing concern of presence of NDMA in water, effective analytical method to determine NDMA should be developed. In this study, we have investigated to determine optimal condition for the analysis of NDMA(N-Nitrosodimethylamine) and by-products using SPME technique with GC-FID. Four fibers were compared and PDMS/ DVB fiber was found to be the most sensitive when used direct-sampling. An absorption time of 30min and a desorption time of 5min provided to be the most sensitivity. The effects of experimental parameters such as the addition of salts, agitation, absorption time, composition on the analysis were investigated. Key words: SPME, GC/FID, NDMA, DMA, DMF 1. NDMA(N-Nitrosodimethylamine) ww š, š, w Trihalomethane (THM) { ƒw š eù k t N- p yw NDMAƒ š, 1998 e s NDMAƒ NDMA» w. 1,2) x, e s k ƒƒ NDMA w 10 ng/l(10 ppt) 9 ng/l(9 ppt) ³ e w š, NDMA ³ w š wš. NDMA z, ³ w w NDMA w x. ù» t 2) p w k, w p» ey w w NDMA w» yw w., NDMA» w» ƒ ƒw š w. y kœ NDMA š. p, p w k(thm) w y» û ³ wš. w w NDMAƒ. w 39 w w, 27 NDMAƒ š, š 220 ng/l. To whom correspondence should be addressed. swchang@kyonggi.ac.kr

2 2 w ùkü. e s ü e w w NDMA w w, 100 ng/l w š NDMAƒ» w. 2,3) ü 14 w w sw NDMA w w w NDMAƒ. w µg/g š NDMA w wš. w, w ƒ NDMAƒ. ¾ ü NDMAƒ ƒ š ƒ. ù ü 4,5) NDMA l w w. ü w œ š ƒ w, w NDMA ù, ü NDMA w š. SPME(Solid Phase Micro-Extraction)» wš, w w w.» w y w» {»yw (VOCs) ù, w fiber sampling» w matrix l w w š. x y,,, w, w w w SPME { ƒ w w». 6-8) SPME holder fiber, holder fiber e w plungerƒ š k fiber e š g Z-slot. fiber w š (Stationary Phase) x e w. wš w fiber š Ì w w. Sample w bottle fiberƒ holder k bottle septum z Z-slot fiber w. fiber holder š bottle GC-Injector septum š w. Z-slot fiber š k k g carrier gas wì column k z fiber holder š (Fig. 1). p, NDMA x ƒ Table atm m /mol û 3 { ù» Direct extraction w» w. Direct extraction Fiber w.» w Agitation v ù, Fiberù Vial, m Agitation ù Sonication mw k. Agitation w sx w Depletion zone w w j v w. w w ƒ w NDMA GC/MS GC-FID w ppb ƒ w SPME w t w. 2. x Agilent 6890N Gas Chromatography System w, y»(flame Ionization Detector, FID) w. HP-5 column(5% Phenyl Methyl Siloxane, Capillary, 50.0 m 200 µm 0.33 µm film) w š carrier gas 1 ml/min % nitrogen gas Table 1. Physicochemical properties of NDMA, DMA, and DMF property NDMA DMA DMF Molecular weight Vapor pressure 2.7 mmhg 1520 mmhg 3.87 mmhg Solubility mg/l mg/l mg/l Henry's constant atm m 3/ mole atm m 3/ mole atm m 3/ mole

3 š (SPME) w NDMA(N-Nitrodimethylamine) 3 Fig. 1. Structure of SPME and process of adsorption and desorption using SPME. w, make-up gas 30 ml/min w. 280 o C,» 300 C o w, split ratio 2 w. oven» 40 C 1 w ƒ o 5 C/min o w 200 C 3 o w. SPME e Supelco (U.S.A.) SPME manual holder w, Supelco fiber w. x NDMA Sigma-Aldrich (U.S.A.) HPLC, 3 w. fiber k, w» w 100 ml amber serum bottle w yw 100 ml w teflon-silicon septa aluminum crimp cap w z direct-sampling w w. z» w» Coling Co.(Korea) PL-351x w, Sonication w Bransonic Co.(U.S.A.) 5210R-DTH w. w (salts) w r» w yw NaCl 30%(w/w) ƒw w. 3. š 3.1. Fiber fiber w» w SPME fiber PDMS/DVD, CAR/PDMS, PDMS kw xw, NDMA ƒ w 1 DMA, DMF 5 ppb~100 ppb y ww w. Table 2 fiber ùkü. w SPME fiber wš w» w» w gq š ƒ. w z sx Table 2. List of fibers used in the study Stationary Phase/ film thickness ph Max. temp. Rec. Operating temp. Applications PDMS 100 µm o C o C Volatiles PDMS 107 µm o C o C Nonpolar semivolatiles Nonpolar high molecular weight compounds Polyacrylate 85 µm o C o C Polar semivolatiles CAR/PDMS 75 µm o C o C Gases and low molecular weight compounds

4 4 š š (partition). sx w j»ù fiber Ì, fiber ̃ É sx w. ƒ ùkù, fiber š. ƒ j. jš ƒ û ƒ j, ƒ j s x w. Direct-sampling sx (agitating) j ù ƒ, ph, ww fiber k ƒ k. x 6,9) PDMS/DVB(65 µm) >CAR/PDMS(75µm) > PDMS(100 µm) (Fig. 2) Fiber y Fig. 3 ùkü. Fig. 3 w 3ƒ fiber 30 z š, NDMAƒ ù ù kü. yw SPME š, w fiber sx. ù y k ƒ fiber ƒ k x ƒ y w. Fig. 3 ü k y w, w» Fig. 2. Effect of fiber on the adsorption. Fig. 3. Effect of extraction time from 0.5 to 60 min. w x y w» š w w v ƒ. PDMS/DVB(65 µm) ƒ ƒ CAR/PDMS (75 µm) PDMS(100 µm) û. y PDMS/DVB d w 50 ppb w w. ƒƒ 5, 10, 20, w xw z 30 ùkû (Fig. 3) k Fiber l k z. ƒ ƒw gq /» wš, gq w w. GC k ƒ j fiber» ƒ w, w» w k jš ƒ û column w x y k k w w. 150~250 o C fiber l k w. ù j yw x Supelco q gq 310 o C ƒ w k ƒ w. x GC 270 C o w, PDMS/DVB 250~310 o C

5 š (SPME) w NDMA(N-Nitrodimethylamine) 5 Fig. 4. Effect of desorption time from 0.5 to 30 min. ò w k w. x 270 C 5 40 k y o k y r. ƒ w ò û Fig. 4 k k y k 5 z y ùkû. 11) 3.4., Salt, Sonication w y k ƒ fiber ƒ k x, z ƒ. y k SPME» w» w š. 6,12) Headspace SPME ƒ œ ƒ g, j w ƒw. w, ƒ ò ƒ j ò ƒ û k. x 10~40 C¾ y k o r. ùkû, { ƒ (K h ) k fiber j. Headspace SPME headspace v w w. Headspace v fiber Fig. 5. Effect of vial volume from 1 to 100 ml. ƒ v y. w (50 µg/l) 120 ml bottle headspace v 50, 70, 90 ml wš, PDMS/DVB Fiber w 30 k 5 xw. Fig. 5 headspace vƒ NDMA ƒw ùk û. w y j z w x NaCl ƒ z w z r. ƒ ƒ w ùkü. ƒ w ƒ w» ƒ ƒw ƒ ƒw ƒ. x SPME z» w yùp 0, 10, 25, 30(w/vol %) y x w, yùp 550 C o 30 zy w w. ƒƒ 50 µg/l PDMS/DVB w w š, 30, k 5 ³ w x ww. ƒ ƒw w ƒw ùkû, yùp ƒ 30%ƒ w ùk û., y» z y. z w. Sonication sx 1 š w sx m 2~60. sx SPME sampling

6 6 ƒ. Microwave heating ƒ x w gq /». w x w y» fiber yƒ ùkû, sampling sonication w z x. ƒ bottle yw 50 µg/l ³ w w, 25% w 10 w. static < static+salt < stirred < stirred + salt ƒ ùkû, z w z ƒ ù. NDMA» y w w ƒ w z headspace y w fiber j. 3.5 k w. w kƒ yw, y w» w w x w. Fig. 6~7 ƒƒ w NDMA w w z. w single composition Fig. 6. Effect of single composition on the extraction. Fig. 7. Effect of multi composition on the extraction. multi composition ùkü x ƒƒ ƒ Inhibition j. j yw peak area w š. ù, DMA NDMAù DMF w wš j» x w j ù dw. SPME w fiber-pdms/ DVB, -30 min, k -5 min, vial volume-1.5 ml ƒ ùkü w. 4. PDMS/DVD Fiberƒ NDMA w ƒ, NDMAƒ z. 30 ùkû, k 5 ƒ z ùkþ, 10 z k y ƒ.» w NDMA ƒ w DMA DMF, ƒ NDMA»k ùkû. Sonication x NDMA»k w. yw w x w, NDMA yw w

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