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dｅｔeｒmｉｎaｔiｏn oｆ hｅavｙ ｍetaｌｓ in soｉl bｙ ａtｏmic absorpｔioｎ sｐeｃtrｏmeｔry(ａas)
name: ｘuｆｅｉ grｏup： the ３rd g3 / 11
（6） ａdjuｓt ｌighｔ pｏinｔ and waｖeｌｅnｇth so that the mｅｔｅr repｒesents thｅ ｍaｘiｍｕm ｖaｌuｅ.
(8） inｊeｃt ｄiｓtillｅｄ watｅr iｎｔo ｔｈe ｆlaｍｅ aｎd contｉnuｅ to prehｅat the ｂurner． ｉｎjｅcｔ ｄisｔｉlｌed wａter into ｔhe flaｍｅ ａfｔer eacｈ samplｅ.
(9) seｌeｃt ¡°ｅ¡±, iｎｊｅcｔ ｂｌank ｓoluｔion into tｈｅ fｌame and ａdjｕｓｔ ｔhe ｍeter ｔo zｅｒo.
（1０） ｏptimizｅ ａｎaｌysiｓ cｏnｄiｔioｎs anｄ ｍeａsurｅ stanｄard soｌution aｎd ｓamples.
(12) seleｃt ¡°t¡± bｅｆorｅ tｕrning off high ｖｏltage ｐower， decｒeａｓe lａｍｐ current aｎｄ ｔhｅｎ turn ｏff ｔhｅ ｌamp. at tｈｅ saｍe ｔime， ａlｌ bｕttｏnｓ shｏｕld be ｏn orｉｇinａl posｉtioｎs．
(13) cｈeck ｔhｅ equipｍent before leaving tｈｅ ｌaborａｔｏrｙ.
3．２ dｅterｍｉｎａｔion of ｓｏｉｌ saｍｐlｅs
(1) prｅｐａrａtion oｆ eｘtrａcｔｉｎｇ ｓoluｔｉon ( mol/l ｅｄｔａ ｓｏｌｕtioｎ)
１8．6 g of ｅｄtａ is dｉssoｌｖｅｄ with ｗater in a beaｋeｒ （５00 ml)． thｅ ｐｈ ｉs adｊusｔｅd to ｕsｉｎg ｄｉlutｅ amｍｏniａ. ｔhｅ mixｔｕｒe is trａnsferred ｉnto a vｏｌumetric fｌask (100０mｌ), dｉluｔe ｔｏ thｅ marｋ ａnd ｍｉｘｅｄ well.
(2) ｔreaｔment of ｓｏil samples
g ｏf ａir-ｄrｉeｄ ｓoiｌ (６0－ １００ ｍesh) ｉs put ｉnｔo an eｒｌeｎｍｅyｅr ｆlasｋ ｗｉtｈ stopｐｅr (１０0 ml）. 1２．5 ml oｆ edｔa sｏｌuｔｉoｎ ｉｓ ａdded. tｈｅ ｍixｔurｅ is ｓhａｋeｎ ｆor 1ｈ ａnd ｔhｅn fiｌｔｅred. the ｆiｌtrａtｅ is ｐｒeｓeｒｖeｄ foｒ aｎalｙｓｉs.
(3) pｒｅparatioｎ oｆ cu sｔandarｄ sｔock solution
g of cu ｉｓ diｓｓoｌvｅｄ ｉｎ 1５ mｌ of (1：1) niｔｒic ａcid ｓoluｔiｏｎ. tｈe ｍｉxture is ｔｒaｎsfeｒｒeｄ iｎｔo a ｖolｕmetｒic fｌask （1000 mｌ) anｄ diｌutｅd to thｅ ｍaｒk ｗitｈ ｒe－disｔｉｌleｄ watｅr． thｅ cｏｎｃｅｎｔrａtion of ｔhe stoｃk stａndaｒｄ ｓoｌｕｔｉon is 10０g/ｍl. （the coｎcｅnｔratiｏn sｈoulｄ be calculａｔｅｄ acｃorｄing ｔｏ thｅ ｍａｓｓ ｏｆ ｃu).thｅ ｗorkinｇ ｃｕ stａnｄard solutioｎ (１０¦Ìｇ/ml) is obｔaｉned ｂｙ ｄilutｉng 10 mｌ ｏf ｃu sｔanｄarｄ ｓtｏck ｓoｌuｔｉoｎ tｏ 100 ml ｗｉth
rｅ-distｉｌled waｔｅr.
(4) ploｔｔing ｏf tｈe stanｄａrｄ ｃuｒｖｅ
0 ｍl, １ ml， 2 ｍｌ， 3 ml, 4 ｍl and 5 ml of cu staｎｄarｄ soｌutioｎ (10¦Ìｇ/ｍl） are added respecｔiｖely ｔｏ ６ voｌuｍｅtｒic flaｓk (１0 ｍｌ) ｗiｔh １ ｍl oｆ 5 mｏl／ｌ hｙdｒoｃhlｏrｉｃ ａciｄ． th