前言 由Alan Walsh,於1954年發表第一台原子吸收光譜儀（AA）。

理論篇 What is “AA” means The First “A” means : Atomic 原子的 The Atom comes from the “hot” ! We need the 火焰 or 電熱 The Second “A” means : Absorption 吸收 光被吸收了, we need the lamp

理論篇 Atomic Spectroscopy Na 線 原子均有其唯一性的原子組態 Atom Na Atom Fe g y E n e r g y Na 線 Excited states 原子均有其唯一性的原子組態 Ground state Excited state Ground state Excited state Atom Na Atom Fe 原子於原子化區中均是處於基態, 當受到原子線照射時, 相同元素才會提昇能階

AAS 原子吸收光譜儀 火焰式 ppm,sub ppb ppb 爐管式

I = I0 -(IAA+ B) I0 理論篇 Atomic Spectroscopy Excited State Ground State 通過原子化區之入射原子線之剩餘強度 入射原子線 原子化區 Atom absorbs someof the incident light A=log10 Io / It A = a b c, b: beam path, c = concentration Beer’s Law : Absorbance, A is proportional to concentration

理論篇 Concentration vs Absorbance 0.0ppm 0.0000 10000 個光強 2.5ppm 0.0735 I0 500 個光強 5.0ppm 0.1257 10000 個光強 100 個光強 10.0ppm 0.2534 10 個光強

理論篇 Atomic Spectroscopy 火焰式 Bandpath 石墨爐 Hollow cathode lamp source Flame or graphite furnace atom cell Bandpath Monochromator Photomultiplier detector Spray chamber and nebuliser 石墨爐 Processing electronics Data processing and instrument control

A = -Log(I/I0) I I0 Abs. 空液, Blank 2.5ppm 5ppm 10ppm Conc.

理論篇 Atomic Spectroscopy 火焰式 I II III Bandpath 石墨爐 Hollow cathode lamp source Flame or graphite furnace atom cell Bandpath Monochromator Photomultiplier detector Spray chamber and nebuliser 石墨爐 Processing electronics Data processing and instrument control

Hollow Cathode Lamp

Hollow Cathode Lamp Processes Ar+ l (-) (-) M0 (-) Ar+ M0 M0 Sputtering Excitation Emission Electrical potential applied between cathode and anode Metal atoms dislodged and excited by ionised argon filler gas; decay back to ground state results in emission at a specific wavelength(s).

Lamp Drift HCL Beam 漸漸增強的, 所以有兩種因應方式: Single Beam: 等 Double Beam: 立即記憶當時的強度 Intensity Sample/火焰 繞過火焰紀錄強度 Time

A = abc

A = abc

Stockdale Optics Flame Toroid Mirror D2 Lamp Rear Beam Plane Selector Furnace Toroid Mirror Flame Toroid Mirror Plane Mirror Rear Beam Selector Plane Flame HCL Carousel D2 Lamp

理論篇 Atomic Spectroscopy 火焰 爐管 Concentration sensitivity increased by 1000 X relative to flame atomizer

Flame Types Flame Type Flame Temperature Fuel Flow Rate Oxidant Flow Rate Burner Size Air/ Acetylene 2450°C 0.8-2.3L/min 8L/min 50 or 100mm Nitrous Oxide/ Acetylene 3200°C 3.8-5.0L/min 10L/min 50mm only

Burners Excellent corrosion resistance Slot design optimised for high dissolved solids samples Automatic spark ignition system Universal 50mm slot as standard

Spray Chamber

Burner Jaw Profile

Problem II 原子化區 Flame Furnace

Light absorption from the HCL Instrument bandpass 0.2 nm (i) 波長等於多少 強度等於多少 訊號是否樣品? I0 Hollow cathode lamp emission (I0 lost) 光折射 粒子阻擋 分子吸收 B: I 共振光譜吸收 ( Absorbance =area of overlap ) IAA Absorption profile width 0.002 nm

訊號是否等於樣品 B 0.0ppm A: 0.0022, 0.0019, 0.0023 2.5ppm A: 0.0335, 0.0351, 0.0328 I0 500 個光強 5.0ppm 0.1257 10000 個光強 100 個光強 10.0ppm 0.2534 10 個光強

Light absorption from 氘燈 Instrument bandpass 0.2 nm Xxx.32  0.005 nm 原子吸收線 (ii) 以連續波長來量測所有的背景值 氘燈 170 - 450 nm (I0 lost) 光折射 粒子阻擋 分子吸收 B: Broad-band background signal Absorption profile width 0.002 nm

Continuum Source Background Correction Sample B.G. H.C.L. IAA+ B - B = IAA B IAA+ B B

理論篇 Furnace 爐管背景校正 樣品需經過 乾燥 -- 溶劑 灰化 -- 有機基質 原子化 -- 產生氣態原子

理論篇 Furnace 爐管背景校正 爐管中在原子化時僅剩下各種金屬元素成份, 背景單純 , 若因為其中有他大量單一(或少數金屬元素)行成特殊結構式背景 若以連續光作校正則會得到錯誤的平均值

Zeeman - + Absorption Emission Normal hollow cathode lamp radiation Absorption profile split into and magnetic field around atomiser. components by Static Polariser Signal measured = Background only Background Magnet OFF : Normal AA system Signal measured = AA + Background component removed by polariser, HCL measures background only. Magnet ON :

Continuum Source結構式背景 B.G. Sample H.C.L. D2 D2 Sample BHCL BD2 = 0 BZeeman 需

Graphite Furnace Advantages Residence time atoms are confined by hot cuvette walls. residence times typically 10-3 - 10-2 seconds. Cuvette 越長時間越長

Cuvette Heating Cuvette heated electrically Voltage around 10 V Current around 300 A Power 3 kW for 3000°C Rate of temperature increase > 3000°C/second

Cuvette Heating Cuvette heated electrically Voltage around 10 V Current around 300 A Power 3 kW for 3000°C Rate of temperature increase > 3000°C/second

Cuvette Design Cuvette contacts Cuvette Platform Self aligning “sphere in cone” contacts Cuvette Platform Eliminate sample spreading Improve precision

Auto Ash and Atmize Ramps Control temperature between phases Linear and non-linear (exponential) ramps Ash phase Non-linear ramp Linear ramp Temperature Dry phase Time

Starting An Analysis A series of aqueous calibration standards are prepared. The instrumental operating conditions are then optimised for the particular analysis. The aqueous calibration standards are run under optimum conditions. Absorbance values are measured. A calibration graph of concentration versus absorbance is plotted to establish the linear range.

Calibration Graph Conc Abs Abs. 0.00 0.000 0.6 1.00 0.101 2.00 0.202 0.4 3.00 0.304 4.00 0.408 0.2 5.00 0.516 6.00 0.632 1.0 2.0 3.0 4.0 5.0 6.0 Conc mg/L

干擾 光譜干擾 放射干擾 化學干擾 基質干擾 非特定性干擾 離子化干擾

光譜干擾 此干擾主要是樣品中存在其他元素造成的干擾。此干擾近年來因中空陰極射線技術的提昇已很少發生。

放射干擾 此干擾主要來自於樣品放射出與欲吸收的波長相同。此干擾可藉由提高電流強度或降低狹縫寬度來解決。

化學干擾 此干擾最常發生於利用原子吸收來分析鎂、鈣、鍶及鋇等金屬。最常見的干擾物種有矽酸鹽、磷酸鹽及鋁酸鹽等化合物。一般解決的方法有兩種，一為利用螯合劑(EDTA)與金屬錯合，二為添加氯化鑭與造成干擾的陰離子錯合；或者可利用笑氣-乙炔來解決化學干擾的問題。。

化學干擾之去除 Ca3(PO4)2 LaCl3 CaCl2 Air-C2H2 Ca0 Ca + PO43- EDTA Ca-EDTA Air-C2H2 Cao

去干擾離子添加劑 分析元素 干擾離子 去干擾添加劑 鈣(Ca) Al,P Si,SO4-2 La 鎂(Mg) Al,P,Si,Ti Sr 鋅(Zn) Cu,P,Si,SO4-2 La,Sr 鉬(Mo) Ca,Fe Al 鉻(Cr) Fe,Ni NH4+

基質干擾 一般此干擾原因有(a)溶液中含有有機溶劑而造成吸收度的增加，(b)因溶液的黏滯性較高因霧化效率下降而造成吸收度下降，(c)溶液的鹽度較高而造成吸收度下降。以上這些干擾可藉由標準添加法(Standard Addition)或是萃取法將金屬自溶液中萃取出來或者

標準添加法(Standard Addition)

非特定性干擾 此干擾來自樣品中含有高濃度的鹽類，此情形最常發生於波長在250 nm以下，此干擾可用萃取技術及背景校正來克服。

離子化干擾 此干擾最常發生於低游離能元素，如鹼金族及鹼土族元素。解決的方法可在樣品中加入比待測元素更容易解離的化合物，如分析鈣時可添加1000ppm的氯化鉀溶液。

背景校正 (1)雙吸收線法(Double wavelength) (2)連續光源校正法(Continuum Source Method) (3)茲曼效應校正法(Zeeman Effect) (4)Hieftje-Smith校正法 其中以(2)(3)兩種方法較常被廣泛採用。而茲曼效應校正法因具有波長涵蓋範圍廣，較佳的底線穩定度，單一光源之使用，校正線緊鄰特性波長及高背景吸收之校正等優點。因此茲曼效應校正法可直接用於複雜樣品之直接測定，如血液中重金屬直接測定便是一例。

SC100  - 36-Well HotBlock™, 50mL Block Specifications: Footprint: 15" x 15" Weight: 43lb. Electrical: 120VAC, 9A Sample Capacity: 36 Nominal Sample Size: 50mL Temperature Range: Ambient to 180°C Thermocouple: Type K