ANALYTICAL ATOMIC SPECTROSCOPY WITH THE INDUCTIVELY COUPLED PLASMA ICP ATOMIC EMISSION SPECTROMETRY

Size: px

Start display at page:

Download "ANALYTICAL ATOMIC SPECTROSCOPY WITH THE INDUCTIVELY COUPLED PLASMA ICP ATOMIC EMISSION SPECTROMETRY"

Berenice Spencer
6 years ago
Views:

1 ANALYTICAL ATOMIC SPECTROSCOPY WITH THE INDUCTIVELY COUPLED PLASMA 1 R. S. HOUK ICP BASICS ICP ATOMIC EMISSION SPECTROMETRY ICP MASS SPECTROMETRY LASER ABLATION 2 RAFAEL FERNANDES U. MINNESOTA 1

2 ATOMIC SPECTROSCOPY 3 (M + )* ATOMIC LEVELS NO VIB - ROT SUBLEVELS SHARP LINES HIGH SELECTIVITY(+) (M + ) 0 ONLY DETERMINE ELEMENT NOT COMPOUND (-) M* IE AA AE M 0 PRODUCE FREE ATOMS FROM SAMPLE? EXCITE EMISSION (AE) ATOMIZE & EXCITE SAMPLE Vaporization MX (aq) MX (aq, aerosol) MX (s, aerosol) MX (g) Nebulization Desolvation Ionization Atom n (M + ) 0 M 0 (g) + X (g) 4 Excitation absorption Emission (M + )* M* (M + ) 0 ION LINES M (II) Higher E, shorter λ than I lines M 0 ATOM LINES M (I) 2

3 ICP 5 NORMAL ANALYTICAL ZONE (blue) INITIAL RAD. ZONE (red) LOAD COIL INDUCTION REGION TORCH OUTER GAS FLOW AEROSOL GAS FLOW INTO AXIAL CHANNEL Yttrium Emission Zones Y Neutral Lines Y + Lines YO Bands 6 3

4 Diffraction Gratings 7 8 4

5 9 Winge 10 5

6 MANY VALENCE ELECTRONS MANY ENERGY LEVELS COMPLEX EMISSION SPECTRA

7 13 ION SAMPLING FOR ICP-MS 14 ION LENS SAMPLER SKIMMER 7

8 15 AT SPOT USUALLY USED IN ICP-MS: 16 Just off tip of initial radiation zone T gas = 6000 K n total = P/RT gas = 1.5 x cm -3 mostly Ar n e = n + = 1 x cm -3 Flow velocity ~ 25 m/s Residence time ~ 2 ms 8

9 DISSOCIATION 17 MO + M + + O K d = (n M + n O )/n MO + H = D 0 (MO + ) log K d (cm -3 ) = 1.5 log T gas M zelec z + log Z D - T MO O elec + gas MM log M + MO M + o n M+ / n MO+ INCREASES AS: D 0 < T gas > n O < IONIZATION SAHA EQUATION 18 M M + + e - K ion = n M+ n e /n M H = IE (M) log K ion (cm -3 ) = 1.5 log T z + log z ion + M elec M elec IE T + ion SIMILAR RELATIONSHIP FOR M + M 2+ + e - 9

10 IONIZATION IN ICP 19 H He 0.1 Li Be M + /(M + + M) (%) B C N O F Ne e-4 6e-6 Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr , Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe , Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn ,9 90, , Fr Ra Ac %M 2+ Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 96,2 90,10 99* 97,3 100* 93,7 99* 100* 99* 91,9 92,8 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw 100* 100* T = 7500 K n e = 1 x cm -3 *These elements also make M +2 ICP + QUADRUPOLE MASS SPECTROMETER 20 10

11 9E+09 8E+09 7E+09 6E ppb Ce 140 Ce + 8e6 c/s Ce 16 O + 1.3e5 c/s 5E E E ION SIGNAL E E Ce + 2e4 c/s 140 Ce e5 c/s m/z RATIO 21 ICP-MS CAPABILITIES 22 DETECTION LIMITS TOTAL SOLUTES PRECISION ppt routine 10 ppq SOME INSTS. USUALLY BLANK-LIMITED 0.1% USUALLY OK 1% USUALLY PROBLEMS UNLESS USE FLOW INJECTION 3% RSD ROUTINE 1% GOOD 1% ROUTINE W. INT. STDS. ACCURACY COMPARABLE TO PRECISION IF COMPENSATE FOR INTERFERENCES 11

12 INTERFERENCES (REL. TO ICP-AES) 23 SPECTRAL OVERLAP MATRIX INTS. LESS FREQUENT LESS SEVERE MORE PREDICTABLE EASIER TO CORRECT WORSE IN ICP-MS - PLUGGING - CHANGE OF SIGNAL (usually loss) APPLICATION AREAS ENVIRONMENTAL ANALYSIS STANDARD METHODS 2. GEOCHEMISTRY RARE EARTHS PROSPECTING, Pt GROUP ELEMENTS U-Th-Pb DATING LASER ABLATION 3. SEMICONDUCTORS DIW, MINERAL ACIDS ORGANIC SOLVENTS SURFACE LAYERS, VAPOR-PHASE DECOMP.. 12

13 Si Wafer Analysis 25 Wafer Surface Preparation by VPD Vapor Phase Decomposition native oxide layer SiO 2 dissolve native oxide layer soluble contaminants in fluorosilicic acid integral wafer contamination can be collected in one droplet Wafer Preparation by VPD (1,2) 26 a) b) Gaseous HF to SiO 2 Deposition of HF(aq) film 13

14 Wafer Preparation by VPD (3,4) 27 c) d) Etching of SiO 2 Surface Scan for Collecting Contaminants Wafer Preparation by VPD 28 e) f) TO NEBULIZER & ICP-MS adding ROLL scanning AQUEOUS solution ACID DROPLET and AROUND surface scan ETCHED SAMPLE SURFACE, COLLECT CONTAMINANTS *Si SURFACE HYDROPHOBIC ACID DROPLET NOT DISPERSED OVER SURFACE! 14

15 APPLICATION AREAS NUCLEAR INDUSTRY RADIONUCLIDES PURITY OF MATERIALS 5. BIOMEDICAL FLUIDS & TISSUES METALS IN PROTEINS & ENZYMES 6. FORENSICS MATCHING EVIDENCE BASED ON TRACE ELEMENT COMPOSITION 15

16 Th SOLN 1000 ppm SUM OF 3 SPECTRA 31 Th SOLN. SUM OF 60 SPECTRA BLANK 32 16

17 SAMPLE INTRO CONCENTRIC PNEUMATIC NEBULIZER % Teflon Self-aspiration: 20 µl/min 50 µl/min 100 µl/min 400 µl/min ION EXTRACTION 34 17

18 COLOR SLIDES OF SAMPLER - SKIMMER REGION CONDITIONS INSIDE SAMPLER 35 FLOW THROUGH SAMPLER = G 0 = n 0 a 0 D 0 2 a 0 = speed of sound in source = (kt gas,0 /m) 1/2 D 0 = orifice diam. n 0 ~ P/RT gas TYPICAL G 0 ~ atoms/s DEBYE LENGTH = λ D = (ε 0 kt e /e 2 n e ) 1/2 λ D (cm) = 6.9 (T e /n e ) 1/2 T e in K n e in cm -3 (NEXT SLIDE) T e ~ 8000 K n e ~ cm -3 INSIDE SAMPLER λ D ~ 10-4 mm << D 0 SO PLASMA REMAINS QUASINEUTRAL AS FLOWS THROUGH SAMPLER 36 λ D Chen, Intro to Plasma Physics,

19 S. JET & SKIMMING PROCESS ICP T ~ 6000 K N(v) 37 Barrel shock VELOCITY v (Ar) N(v) Collisions Directed flow in zone of silence Skimmer VELOCITY IN JET T ~ 300 K 38 Sampler Skimmer Photo by A. L. Gray 19

20 EXTRACTION PROCESS Douglas & French JAAS 1988 SAMPLER 39 SKIMMER ICP: T ion ~ 7000 K T gas ~ 6000 K AT SKIMMER: T ion ~ 7000 K T gas ~ 155 K TIME ~ 3 µs ~250 colls with Ar CONDITIONS INSIDE SKIMMER TIP 40 FLOW THROUGH SKIMMER = G 1 = n(x s )v(x s )A s v = velocity ~ (5kT 0 /2m) 1/2 A s = area of skimmer TYPICAL G 1 ~ 1 x atoms/s ~ 1% OF FLOW THROUGH SAMPLER ALSO GOES THRU SKIMMER λ D (cm) = 6.9 (T e /n e ) 1/2 n e NOW ~10 12 cm -3 INSIDE SKIMMER λ D ~ 10-2 mm << D s SO PLASMA ALSO REMAINS QUASINEUTRAL AS FLOWS THROUGH SKIMMER ALTHOUGH MAY BE SIGNIFICANT SHEATH INSIDE SKIMMER TIP 20

21 41 ION LENS Equipotential contours V 1 V 2 V 1, V 2 NOT DEP. ON m/z UNLESS: - IE = f (m/z) -SPATIAL DIST. = f (m/z) 21

22 SIMION - EINZEL LENS volts INITIAL ION KE = 200 ev FOCAL POSITION VARIES WITH APPLIED VOLTAGE volts EINZEL LENS 44 INITIAL KE =200 ev FOCAL POSITION VARIES WITH INITIAL ION KE 230 ev 22

24 QUADRUPOLE MASS ANALYZER 47 y x U + V cos ωt Thermo Elemental - (U + V cos ωt) BRUKER AURORA ELITE (now Analytik Jena) 24

25 ESA Detector 49 ELEMENT SCANNING HIGH RES ICP-MS DEVICE Entrance slit Quad lenses Magnet & flight tube Extraction lenses Skimmer Sampler ICP Neb & Spray chamber Zn + 10 ppb Zn PFA Zn + 68 Zn + 67 Zn + 70 Zn + 25

26 51 PEAK SHAPES LOW & HIGH RES. Spectra Photoresist Interferences on Cu C 5 H CH 3 32 S 16 O + 63 Cu + 26

27 53 MATRIX EFFECT Olivares & Houk, Anal. Chem 1986, 58,

28 55 INTERNAL STANDARD 56 Co + 28

REMOVE POLYATOMIC IONS? 57 12 C 5 H 3 + 12 CH 3 32 S 16 O + 63 Cu + GOOD IE BAD IE D 0 58 GUYS/GALS (ev) GUYS (ev) (ev) S + 10.36 O + 2 12.063 6.663 Fe + 7.

29 REMOVE POLYATOMIC IONS? C 5 H CH 3 32 S 16 O + 63 Cu + GOOD IE BAD IE D 0 58 GUYS/GALS (ev) GUYS (ev) (ev) S O Fe ArO + ~ ArN + ~ Se Ar 2 + ~ K ArH + ~ * V ClO Ti SO Zn SO

30 BRUKER AURORA ELITE ADD H 2 &/or He REMOVE POLYATOMIC IONS? 60 30

LASER ABLATION 61 Laser Ablation ICP-MS CETAC LSX 500

31 LASER ABLATION 61 Laser Ablation ICP-MS CETAC LSX Thermo Finnigan Element 31

32 Lasers Laser Coherent Libra Cetac LSX-500 Lasing Medium Ti:Sapph Nd:YAG Wavelength 800 nm Triple to 266 nm Pulse length ~100 fs ~6 ns Repetition rate 1000 Hz 10 Hz Pulse energy 0.20 mj 9.0 mj Laser power ~76 W ~90 W 1064 nm Quadruple to 266 nm 32

33 DEVELOPMENTS IN LASER ABLATION 65 GÜNTHER et al., ANAL. CHEM. 2003, 75, 341A; TrAC 2005, 24, 255. UV LASERS (266, 213, 193 nm) HOMOGENIZED BEAM PROFILE HELIUM TRANSPORT GAS FRACTIONATION 1. VARIATION OF SIGNAL RATIO vs TIME AS DIG SINGLE PIT 2. MEAS. SIGNAL RATIOS DIFFER FROM THOSE IN SAMPLE SOLUTIONS: FLAT BOTTOM CRATERS VERTICAL SIDES SHORT PULSE (fs) LASER (RUSSO et al., ANAL. CHEM. 2002, 74, 70A)

35 Particles from Ablated Y 2 O 3 Pellet 69 Track length velocity ~ 27 m/s 70 Pressed pellet Fernald soil blank 35

36 COHERENT LIBRA 100 fs 266 nm 31 µm/s scan rate, NIST brass C1102 fs LASER ns LASER 100 khz Rep. Rate, ~ 50 µm spot size 20 Hz Rep. Rate, 50 µm spot size 1.8E E Zn Signal (cps) 1.2E E+07 Zn Signal (cps) 1.20E E E Time (s) 1.2E E Time (s) 1.2E+06 Sn Signal (cps) 9.0E E E+05 Sn Signal (cps) 9.0E E E E Time (s) 0.0E Time (s) 36

37 fs argon ms 0.1 ms 0.2 ms 0.3 ms 0.4 ms 0.5 ms 0.6 ms 0.7 ms 0.8 ms 74 37

ABLATION PROCESS MATCHED STANDARDS MEAS.

PIEZOBALANCE camera zoom lens pump Nd:YAG

38 CALIBRATE LASER ABLATION? 75 COMPENSATE FOR MATRIX DEPENDENCE OF ABLATION PROCESS MATCHED STANDARDS MEAS. ANALYTE REL. TO MINOR ISOTOPE OF ELEMENT AT KNOWN CONCENTRATION CALIBRATE REL. TO SOLUTION AEROSOL? BECKER JAAS 2001, 16, AESCHLIMAN JAAS 2003, 18, CETAC LASER ABLATION SYSTEM 76 TSI PIEZOBALANCE camera zoom lens pump Nd:YAG laser (266 nm) argon inlet translation stage 20% 80% impactor electrostatic precipitator argon inlet ESI NEBULIZER FINNIGAN ICP-MS ESA calibration solution 10% ICP magnet 90% waste 38

39 77 Signal (counts s -1 ) / Cr + NIST STEEL Ablated solid 60 Ni + 51 V + Solution Time (s) NIST 612 Glass (13 Elements, 5 Replicates) Particle transport from the LA cell was measured using a piezoelectric microbalance Each replicate was generated by firing 50 laser shots per localized spot on the sample A two-point calibration plot for each replicate was prepared and an average calculated All elements were measured in medium resolution (R = m/ m = 4000) CONCENTRATION (ppm) MEASURED CERTIFIED Relative Diff. (%) Mn ( 55 Mn + ) 40.8 ± 7.9 (39.6) 3.0 Fe ( 56 Fe + ) 51.6 ± Co ( 59 Co + ) 36.0 ± 4.7 (35.5) 1.4 Ni ( 60 Ni + ) 39.2 ± Cu ( 63 Cu + ) 38.5 ± 6.7 (37.7) 2.1 Ba ( 138 Ba + ) 41.6 ± 5.5 (41) 1.5 Nd ( 146 Nd + ) 36.2 ± 2.6 (36) 0.56 Sm ( 147 Sm + ) 39.5 ± 4.7 (39) 1.3 Eu ( 151 Eu + ) 36.5 ± 4.7 (36) 1.4 Dy ( 161 Dy + ) 35.1 ± 2.5 (35) 0.29 Er ( 166 Er + ) 39.3 ± 4.2 (39) 0.77 Tl ( 205 Tl + ) 15.8 ± 1.6 (15.7) 0.64 Pb ( 208 Pb + ) 39.2 ±

40 NIST 1264a Steel (8 Elements) 266 nm QUAD. Nd:YAG LASER, CETAC LSX-100 AVG. 30 SPOTS, TWO-POINT STD. ADDNS. 50 SHOTS PER SPOT, MED. RES. PARTICLE TRANSPORT MEAS. WITH MICROBALANCE 79 CONCENTRATION (wt %) MEAS. CERT. (INFO) V ( 51 V + ) ± Cr ( 52 Cr + ) ± Co ( 59 Co + ) ± Ni ( 60 Ni + ) ± Cu ( 63 Cu + ) ± W ( 184 W + ) ± Pb ( 208 Pb + ) ± Bi ( 209 Bi + ) ± (0.0009) NIST 1264a Steel (8 Elements) 193 nm ArF LASER AVG. 3 SPOTS, TWO-POINT STD. ADDNS. 50 SHOTS PER SPOT, MED. RES. PARTICLE TRANSPORT MEAS. WITH MICROBALANCE 80 CONCENTRATION (wt %) MEAS. CERT. (INFO) V ( 51 V + ) ± Cr ( 52 Cr + ) ± Co ( 59 Co + ) ± Ni ( 60 Ni + ) ± Cu ( 63 Cu + ) ± W ( 184 W + ) ± Pb ( 208 Pb + ) ± Bi ( 209 Bi + ) ± (0.0009) 40

41 81 COLLISION CELLS 82 Rowan & Houk, Appl. Spectrosc. 1989, 43, 976. Douglas, Canad. J. Spectrosc. 1989, 34, 38. King & Harrison, Int. J. Mass Spectrom. Ion Processes 1989, 89, 171. Turner, Speakman et al., Plasma Source MS, Developments & Applications, Royal Society, 1997, p. 28. Baranov & Tanner, JAAS 1999, 14, 1133 JASMS 1999, 10, USE COLLISION - INDUCED DISSOCIATION (CID) &/OR CHEMICAL REACTION TO REMOVE POLY. IONS RETAIN ATOMIC ANALYTE IONS REDUCE KE & SPREAD OF KE OF M + IONS 41

42 83 DYNAMIC REACTION CELL (DRC) mass analyzer reaction gas in reaction cell ions to detector mass analysis of transmitted ions conversion of reactive ions isobar analyte other m/z ions from source 1e7 1e6 m/z = 80 1 ppb Se 40 Ar 2+ + CH 4 products REACTION PROFILES 84 1e5 1e4 m/z = 80 1 ppb Se 80 Se + + CH 4 no rxn m/z = 78 blank 38 Ar 40 Ar + + CH 4 products m/z = 78 1 ppb Se m/z = 82 m/z = 80 blank 1 ppb Se 40 Ar 2+ + CH 4 prods CH 4 FLOW RATE (L/min) 42

43 DEATH TO ArCl +! 85 ION SIGNAL 1 ppb As ppm NaCl 1 ppb As 750 c/s 1000 ppm NaCl 25 c/s DIW m/z = 75 OCTOPOLE COLLISION CELL 86 43

44 KINETIC ENERGY DISCRIMINATION 87 COLL CELL LENGTH L = 10 cm GAS DENSITY n ION HAS CROSS SECTION Ω (cm 2 ) NUMBER OF COLLISIONS = L/λ = L n Ω λ = mean free path (cm) EXPECT ~ 5 TO 10 COLLISIONS POLY ION IS LARGER LARGER Ω MORE COLLISIONS IN SAME LENGTH L KE LOSSES& KE DISCRIMINATION Fraction of KE remaining per coll = α ~ α ~ ( ) 2 = 0.88 for coll of Fe + m and ArO 2 coll gas + m ( m + m ) coll gas + with He 88 2 ion 2 ion SAY Fe + HAS 5 COLLS ArO + HAS 10 COLLS Fe + HAS α 5 = = 0.52 OF INITIAL KE REMAINING ArO + HAS α 10 = = 0.28 OF INITIAL KE Covey & Douglas JASMS 1993 p

45 KINETIC ENERGY DISCRIMINATION NO COLL. GAS Analyte Interferent N KE POLY. ION HAS LARGER CROSS SECTION FOR KE LOSS 90 N POTENTIAL BARRIER ON QUADRUPOLE STOPS POLY. IONS Analyte Interferent KE

polyatomic interferences are removed in He Mode (same cell

46 Unspiked 5% HNO 3 + 5% HCl + 1% H 2 SO 4 + 1% IPA Matrix 91 2E5 cps Unspiked 5% HNO 3 + 5% HCl + 1% H 2 SO 4 + 1% IPA Matrix ALL polyatomic interferences are removed in He Mode (same cell conditions) 92 2E5 cps All polyatomic interferences are removed in He Mode 46

47 93 Gillson, Tanner, Douglas 94 47

48 95 Co + Trajectories 80% Ar + 20% O + 80% Ar + 19% O + 1% U + IONS IN ARGON FLOW 96 SAMPLER SKIMMER ICP SHOCK WAVES 48

49 IONS ENTRAINED IN Ar FLOW ACCELERATED TO SAME VELOCITY AS Ar 97 AVG. KE OF Ar = AVG. KE IN ICP = 2.5 kt gas = 0.5 m Ar v Ar 2 ALL IONS (i) ACHIEVE SAME VELOCITY v i = v Ar KE i = 0.5 m i v i 2 IONS OF DIFFERENT MASS HAVE DIFFERENT KINETIC ENERGIES ION ENERGY MEASUREMENT STOPPING POTENTIAL ON QUAD 98 49

50 ION ENERGY vs m/z 99 MAX. ION KE (ev) m/z Winge, ICP-AES, An Atlas of Spectral Lines

51 STRONGEST LINES FROM GIVEN ELEMENT? 1. DOMINANT IONIZATION STAGE (neutral atom or +1 ion) 2. RESONANCE LINES (involve ground state) (esp. absorption!) 3. UPPER LEVEL CORRESPONDS TO LOWEST ENERGY ALLOWED TRANSITION TO GROUND STATE Some elements only a few strong lines (Ca, Mg) Other elements many lines (Fe, U)

52 103 PARTICLE SIZE EFFECTS IN LASER ABLATION GÜNTHER & GUILLONG JAAS 2002, 17, 831 AESCHLIMAN et al. JAAS 2003, 18, 1008 SINGLE SPOT ABLATION

107 Calibration of LA-ICP-MS with Dried Solution Aerosols Simultaneous introduction of particles from a LA cell and desolvated aerosol particles from a micro-flow nebulizer 108 S total = S solid + S

54 107 Calibration of LA-ICP-MS with Dried Solution Aerosols Simultaneous introduction of particles from a LA cell and desolvated aerosol particles from a micro-flow nebulizer 108 S total = S solid + S solution = R X,solid T LA t[x] solid + R X,soln VT neb [X] soln R X isotope-specific response factor (signal/ng X) T LA transport from LA cell (ng solid/s) t time of ablation transient (s) [X] solid concentration of isotope in solid (ng X/ng solid) V volume of solution injected to ICP (L) T neb nebulizer efficiency isotopic concentration in solution standard (ng X/L) [X] soln 54

55 SPACE CHARGE EFFECTS 109 OLIVARES & HOUK, ANAL. CHEM. 1985, 57, GILLSON et al, ANAL. CHEM. 1988, 60, TANNER, SPECTROCHIM. ACTA B 1992, 47B, 809. PLASMA SOURCE MASS SPECTROMETRY, DEVELOPMENTS & APPLICATIONS, Holland & Tanner, Eds., Royal Society, Cambridge, EXPECT SPACE CHARGE PROBLEM WHEN: 110 I max (µa) > 0.9(z/m) 1/2 (D/L) 2 V 3/2 I max is current of major bkg. ions m/z rel. to 12 C = 12 V in volts FOR ICP-MS I max ~ 0.4 µa Actual I max ~ atoms/s (n ions /n atoms ) ~ (10 15 /10 18 ) ~ 1.5 ma!! 55

56 EINZEL LENS EFFECT OF SPACE CHARGE 111 BEAM CURRENT 0 1 µa

57 OVERALL EFFICIENCY 113 1e3 IONS THRU SKIMMER 1e5 ATOMS INTO ICP 1e5 IONS INTO SAMPLER 1 ION TO DETECTOR!

58 MATRIX EFFECTS

59 DVS CY-TOF ICP-TOFMS 117 SURFACE MARKERS IN LEUKEMIA CELL LINES

61 1 ppb V, Cr, Mn, Ni, Co, Cu, Zn, As 500 ppm each C, Na, S, Cl, Ca 121 ION EXTRACTION 122 FUNDAMENTAL ASPECTS OF ION EXTRACTION IN ICP-MS HOUK & NIU, SPECTROCHIM. ACTA B 1996, 51, 779. GAS DYNAMICS OF THE ICP-MS INTERFACE DOUGLAS & FRENCH, JAAS 1988, 3, 743. IMPROVED INTERFACE FOR ICP-MS DOUGLAS & FRENCH, SPECTROCHIM. ACTA B 1986, 41, 197. ION EXTRACTION IN ICP-MS OLIVARES & HOUK, ANAL. CHEM. 1985, 57, CHAP. IN MONTASER ICP-MS BOOK RECENT PAPERS BY PAUL FARNSWORTH BRIGHAM YOUNG UNIV. 61

Solutions and Ions. Pure Substances

Solutions and Ions. Pure Substances Class #4 Solutions and Ions CHEM 107 L.S. Brown Texas A&M University Pure Substances Pure substance: described completely by a single chemical formula Fixed composition 1 Mixtures Combination of 2 or more