貴州實驗室裝修告(gao)訴你氣相色譜儀(yi)的一般流程和工作原理

一臺完整的(de)氣(qi)相色譜(pu)儀包括下列幾個基本組成部分。  

1)載(zai)氣供(gong)氣系統(tong).包括供(gong)氣鋼瓶 (或氣源)、減(jian)壓穩壓器(qi)、過濾(lv)干操器(qi)、流(liu)量控制器(qi)、流(liu)量指示器(qi)等。載(zai)氣流(liu)量一(yi)般控制在10—200mL/min。  

2)分離(li)色(se)譜柱(zhu)。色(se)譜柱(zhu)是(shi)氣相色(se)譜儀的心臟，樣品分析的分離(li)全靠在(zai)色(se)譜柱(zhu)中(zhong)進行。目前在(zai)氣相色(se)譜儀中(zhong)，填(tian)充柱(zhu)、毛(mao)(mao)細(xi)管柱(zhu)和填(tian)充毛(mao)(mao)細(xi)管柱(zhu)用得(de)最多。

3)進樣(yang)(yang)系(xi)統(tong)。進樣(yang)(yang)系(xi)統(tong)用來精確調整每(mei)次分析的(de)(de)(de)進樣(yang)(yang)量(liang)，同時保證把液態樣(yang)(yang)品轉化(hua)為氣(qi)相，然后加(jia)人載氣(qi)氣(qi)流中，因(yin)此它具備溫(wen)度可(ke)以(yi)調整的(de)(de)(de)汽(qi)化(hua)器(qi)(qi)(qi)(qi)(qi)(qi)。進樣(yang)(yang)定m的(de)(de)(de)操(cao)作在(zai)(zai)試(shi)驗室(shi)色譜儀(yi)中常用微量(liang)注(zhu)射(she)器(qi)(qi)(qi)(qi)(qi)(qi)人工注(zhu)人，而在(zai)(zai)工業(ye)色譜儀(yi)中是采(cai)用轉閥控制的(de)(de)(de)金屬(shu)定量(liang)管(guan)進樣(yang)(yang)。轉閥的(de)(de)(de)切(qie)換可(ke)以(yi)由人工或自動程序控制系(xi)統(tong)操(cao)作。  4)檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)。檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)是把物質流出(chu)的(de)(de)(de)組(zu)分轉換為電信號輸出(chu)，并經放大(da)器(qi)(qi)(qi)(qi)(qi)(qi)放大(da)后由記錄(lu)儀(yi)表記錄(lu)或由數據(ju)處理裝置求積(ji)、顯(xian)示、打(da)印(yin)。檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)不僅有(you)熱(re)導檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)，也(ye)有(you)氫(qing)火焰離子(zi)化(hua)檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)和(he)各種放射(she)性(xing)檢(jian)測器(qi)(qi)(qi)(qi)(qi)(qi)等。  

5)供電(dian)(dian)及(ji)信(xin)(xin)(xin)(xin)號(hao)(hao)(hao)(hao)放(fang)大(da)(da)記錄(lu)、處(chu)理裝(zhuang)(zhuang)置。氣(qi)(qi)相(xiang)(xiang)色譜儀(yi)(yi)檢(jian)(jian)測(ce)器(qi)的(de)(de)(de)供電(dian)(dian)要(yao)求(qiu)穩定(ding)，當(dang)(dang)(dang)用(yong)(yong)熱檢(jian)(jian)測(ce)器(qi)時，應(ying)(ying)有(you)(you)直流(liu)穩壓(ya)電(dian)(dian)源(yuan)供電(dian)(dian)，另(ling)一方面(mian)檢(jian)(jian)測(ce)器(qi)輸(shu)出的(de)(de)(de)信(xin)(xin)(xin)(xin)號(hao)(hao)(hao)(hao)，常(chang)常(chang)是毫安或微安數(shu)量(liang)級(ji)甚至更小，因(yin)此必須加以(yi)放(fang)大(da)(da);當(dang)(dang)(dang)測(ce)最(zui)高濃度(du)或反(fan)應(ying)(ying)靈敏的(de)(de)(de)組分時，由于輸(shu)出信(xin)(xin)(xin)(xin)號(hao)(hao)(hao)(hao)太大(da)(da)，以(yi)至超(chao)出指示記錄(lu)儀(yi)(yi)的(de)(de)(de)測(ce)量(liang)范圍，所以(yi)又需要(yao)適當(dang)(dang)(dang)地(di)進行信(xin)(xin)(xin)(xin)號(hao)(hao)(hao)(hao)衰(shuai)減才能輸(shu)送給記錄(lu)儀(yi)(yi)和數(shu)據(ju)處(chu)理裝(zhuang)(zhuang)置。  信(xin)(xin)(xin)(xin)號(hao)(hao)(hao)(hao)記錄(lu)儀(yi)(yi)最(zui)常(chang)用(yong)(yong)的(de)(de)(de)是電(dian)(dian)子自(zi)動電(dian)(dian)位(wei)差(cha)計。常(chang)見的(de)(de)(de)數(shu)據(ju)處(chu)理裝(zhuang)(zhuang)置有(you)(you)數(shu)字顯示打印自(zi)動積分儀(yi)(yi)、小型電(dian)(dian)子計算(suan)機(ji)等，它(ta)們(men)常(chang)與程(cheng)(cheng)序(xu)(xu)控(kong)制(zhi)(zhi)系(xi)統(tong)聯(lian)用(yong)(yong).  6)恒(heng)(heng)溫級(ji)程(cheng)(cheng)序(xu)(xu)控(kong)制(zhi)(zhi)系(xi)統(tong)、色譜柱、檢(jian)(jian)測(ce)器(qi)及(ji)汽化器(qi)。這(zhe)些部件要(yao)求(qiu)在一定(ding)溫度(du)下工作，因(yin)此在色譜儀(yi)(yi)中(zhong)這(zhe)三個部件裝(zhuang)(zhuang)在恒(heng)(heng)溫箱(xiang)中(zhong)，由恒(heng)(heng)溫控(kong)制(zhi)(zhi)系(xi)統(tong)控(kong)制(zhi)(zhi)穩定(ding)的(de)(de)(de)溫度(du)。恒(heng)(heng)溫控(kong)制(zhi)(zhi)的(de)(de)(de)精度(du)一般都(dou)在土(tu)0.5℃ ,程(cheng)(cheng)序(xu)(xu)控(kong)制(zhi)(zhi)系(xi)統(tong)包括自(zi)動進料、出峰(feng)自(zi)動衰(shuai)減、程(cheng)(cheng)序(xu)(xu)升(sheng)溫、柱子的(de)(de)(de)自(zi)動切換等。簡(jian)(jian)單(dan)的(de)(de)(de)程(cheng)(cheng)序(xu)(xu)控(kong)制(zhi)(zhi)可(ke)采用(yong)(yong)機(ji)械凸輪式，較高復雜的(de)(de)(de)用(yong)(yong)電(dian)(dian)子程(cheng)(cheng)序(xu)(xu)控(kong)制(zhi)(zhi)器(qi)。氣(qi)(qi)相(xiang)(xiang)色譜儀(yi)(yi)的(de)(de)(de)結構，按(an)其用(yong)(yong)途不同(tong)而(er)有(you)(you)許(xu)多種類。下面(mian)簡(jian)(jian)單(dan)介紹(shao)以(yi)熱導池為檢(jian)(jian)測(ce)器(qi)的(de)(de)(de)實(shi)驗用(yong)(yong)氣(qi)(qi)相(xiang)(xiang)色譜儀(yi)(yi)。

載氣由高壓氣瓶1(或其他(ta)氣源)經減(jian)(jian)壓閥2減(jian)(jian)壓供給(gei)，精密調(diao)節閥3控制載氣的(de)壓力和流(liu)(liu)量(liang)，再通過(guo)凈化(hua)干操管4凈化(hua)脫水之后(hou)，進人熱導池6的(de)參比池，隨后(hou)通過(guo)進樣器7到色(se)(se)(se)譜(pu)(pu)柱8，最后(hou)從熱導池的(de)測量(liang)池放(fang)空(kong)。色(se)(se)(se)譜(pu)(pu)柱后(hou)的(de)流(liu)(liu)速可用皂(zao)膜(mo)流(liu)(liu)速計9側定。待色(se)(se)(se)譜(pu)(pu)柱溫度(du)及氣流(liu)(liu)穩定后(hou)，從進樣器注人待分(fen)(fen)析樣品，在(zai)(zai)載氣帶動下，不同的(de)組(zu)分(fen)(fen)在(zai)(zai)色(se)(se)(se)譜(pu)(pu)柱內得到分(fen)(fen)離而先后(hou)流(liu)(liu)出色(se)(se)(se)譜(pu)(pu)柱。當流(liu)(liu)出色(se)(se)(se)譜(pu)(pu)柱的(de)組(zu)分(fen)(fen)進人檢測器時(shi)，測最橋路中(zhong)產生一定的(de)信(xin)號，可用記(ji)錄(lu)儀記(ji)錄(lu)下濃度(du)隨時(shi)間變化(hua)的(de)色(se)(se)(se)譜(pu)(pu)流(liu)(liu)出曲線，即色(se)(se)(se)譜(pu)(pu)峰(feng)，色(se)(se)(se)譜(pu)(pu)峰(feng)的(de)高度(du)或面積(ji)的(de)大小就代(dai)表相應的(de)組(zu)分(fen)(fen)在(zai)(zai)樣品中(zhong)的(de)含量(liang)。貴州實驗(yan)室裝修  

目前微量分(fen)析上(shang)最常(chang)用的(de)(de)檢(jian)(jian)測器，是靈敏度比熱(re)導(dao)檢(jian)(jian)測器高達(da)一(yi)千倍左右(you)的(de)(de)氫火(huo)焰電(dian)離(li)檢(jian)(jian)測器。它是一(yi)種對質(zhi)量敏感的(de)(de)具有(you)選擇(ze)性(xing)的(de)(de)檢(jian)(jian)測器，但僅(jin)對有(you)機碳(tan)氫化合物(wu)具有(you)響應，其響應信號隨著化合物(wu)中(zhong)碳(tan)原(yuan)子數(shu)量增加而增大(da)，氫火(huo)焰電(dian)離(li)檢(jian)(jian)測器的(de)(de)基本結構。

任何一(yi)種離(li)子(zi)(zi)(zi)化(hua)(hua)檢(jian)(jian)測(ce)(ce)器(qi)(qi)(qi)都具有(you)(you)(you)一(yi)個離(li)子(zi)(zi)(zi)室(shi)(shi)，其中(zhong)有(you)(you)(you)電(dian)(dian)(dian)(dian)(dian)場和(he)能(neng)源(火(huo)焰、放射源或(huo)高頻電(dian)(dian)(dian)(dian)(dian)壓電(dian)(dian)(dian)(dian)(dian)場)。氫(qing)(qing)(qing)火(huo)焰電(dian)(dian)(dian)(dian)(dian)離(li)檢(jian)(jian)測(ce)(ce)器(qi)(qi)(qi)，在(zai)金屬屏蔽罩的(de)(de)(de)離(li)子(zi)(zi)(zi)室(shi)(shi)內，噴(pen)氣(qi)(qi)口2附近小環狀電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)和(he)收(shou)集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)3之(zhi)間加(jia)有(you)(you)(you)150-300V的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓，形(xing)(xing)成(cheng)一(yi)直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)場，物質電(dian)(dian)(dian)(dian)(dian)離(li)后(hou)能(neng)形(xing)(xing)成(cheng)離(li)子(zi)(zi)(zi)流(liu)(liu)便于收(shou)集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)捕獲。在(zai)這(zhe)(zhe)種檢(jian)(jian)測(ce)(ce)器(qi)(qi)(qi)里，物質電(dian)(dian)(dian)(dian)(dian)離(li)時(shi)所吸收(shou)的(de)(de)(de)能(neng)量，通常是從氫(qing)(qing)(qing)氣(qi)(qi)在(zai)空氣(qi)(qi)中(zhong)燃(ran)燒時(shi)所形(xing)(xing)成(cheng)的(de)(de)(de)火(huo)焰中(zhong)取得(de)。帶有(you)(you)(you)樣品的(de)(de)(de)載氣(qi)(qi)從色(se)譜柱出來與純氫(qing)(qing)(qing)氣(qi)(qi)混(hun)合后(hou)進人檢(jian)(jian)測(ce)(ce)器(qi)(qi)(qi)，從噴(pen)氣(qi)(qi)口噴(pen)出。點火(huo)絲1通電(dian)(dian)(dian)(dian)(dian)，把(ba)氫(qing)(qing)(qing)氣(qi)(qi)點燃(ran)，這(zhe)(zhe)時(shi)樣品物質中(zhong)的(de)(de)(de)分(fen)子(zi)(zi)(zi)即(ji)在(zai)火(huo)焰高溫(wen)作用(yong)(yong)下電(dian)(dian)(dian)(dian)(dian)離(li)成(cheng)離(li)子(zi)(zi)(zi)，這(zhe)(zhe)些帶電(dian)(dian)(dian)(dian)(dian)離(li)子(zi)(zi)(zi)在(zai)外(wai)電(dian)(dian)(dian)(dian)(dian)場作用(yong)(yong)下形(xing)(xing)成(cheng)離(li)子(zi)(zi)(zi)流(liu)(liu)而被收(shou)集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)收(shou)集。在(zai)收(shou)集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)回路中(zhong)，收(shou)集到(dao)的(de)(de)(de)離(li)子(zi)(zi)(zi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)信號(hao)與被分(fen)析(xi)組分(fen)的(de)(de)(de)濃度和(he)火(huo)焰溫(wen)度有(you)(you)(you)關(guan)，因此經(jing)靜電(dian)(dian)(dian)(dian)(dian)放大(da)后(hou)，在(zai)記錄儀(yi)上得(de)到(dao)的(de)(de)(de)是按物質濃度變化(hua)(hua)的(de)(de)(de)色(se)譜圖。氫(qing)(qing)(qing)火(huo)焰電(dian)(dian)(dian)(dian)(dian)離(li)檢(jian)(jian)測(ce)(ce)器(qi)(qi)(qi)，它(ta)只能(neng)分(fen)析(xi)含碳有(you)(you)(you)機(ji)化(hua)(hua)合物，一(yi)般(ban)它(ta)只能(neng)檢(jian)(jian)測(ce)(ce)含C-C鍵或(huo)C- H鍵有(you)(you)(you)機(ji)化(hua)(hua)合物。而對H2, N2,O2和(he)其他(ta)惰性(xing)氣(qi)(qi)體，以(yi)及(ji)CO, NO, Nq2, NH3 H2S, S02等都不(bu)能(neng)使用(yong)(yong)。工(gong)業用(yong)(yong)氣(qi)(qi)相色(se)譜儀(yi)，是在(zai)實驗室(shi)(shi)氣(qi)(qi)相色(se)譜儀(yi)的(de)(de)(de)基礎上發展(zhan)起(qi)來的(de)(de)(de)一(yi)種工(gong)業流(liu)(liu)程(cheng)(cheng)用(yong)(yong)自動成(cheng)分(fen)分(fen)析(xi)儀(yi)，原理上與實驗室(shi)(shi)氣(qi)(qi)相色(se)譜儀(yi)一(yi)樣，它(ta)的(de)(de)(de)特點是整個分(fen)析(xi)過程(cheng)(cheng)由(you)程(cheng)(cheng)序控制器(qi)(qi)(qi)控制，按一(yi)定程(cheng)(cheng)序自動進行。

程(cheng)序(xu)控(kong)制器(qi)按(an)一定的程(cheng)序(xu)發(fa)出指令，進行自(zi)動多(duo)點(dian)取樣(yang)，通過(guo)(guo)六通閥進樣(yang)、切換(huan)、自(zi)動調零，并接(jie)受檢測器(qi)的信號加(jia)以處理后(hou)送至(zhi)記錄(lu)儀記錄(lu)。工業氣相(xiang)色譜儀在生產過(guo)(guo)程(cheng)中(zhong)作(zuo)為自(zi)動分析器(qi)監視生產過(guo)(guo)程(cheng)的進行，也可作(zuo)為一種成分變送器(qi)，貴州實驗(yan)室裝修投人到自(zi)動控(kong)制系統。