ANALYTICAL CHEMISTRY
1174 mineral whose composition could not be easily determined in the It was identified as barite from the teristic peaks of this mineral a t wave lengths of 10.2 and 15.7 microns. The few examples cited show that the infrared spectrophotometer can be a useful instrument in both the qualitative and quantitative determination of the mineral constituents of rocks.
(2) Heid, J. J., Bell, M. F., and White, J. v., I.vD. ENG.CHEM., ANAL.ED.,19,293 (1947). (3) Hunt, J. M., Wisherd, &I. P., and Bonham, L. C., ANAL.CHEM.. 22,1478 (1950). (4) Keller. W. D.., SDotts. . J. H.. and Binns. __ D. L.. Am. J. Sci.. 250. 463 (1952). ( 5 ) Launer, J. L., Am. Mineralogist, 37,764 (1952). (6) Miller, F.A., and Wilkins, C. H., ANAL.CHEM.,24, 1253 (1952). (7) Wilchinsky, Z., private communication.
RECEIVED for review March 31, 1953. Accepted May 16, 1953. Presented
LITERATURE CITED
(1) Dolinsky, M.,J . Assoc. Ofic. Agr. Chemists, 34, 748 (1951).
at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, Pa., March 7, 1952.
Semiquant itative Spectrographic Method for Analysis of Minerals, Rocks, and Ores C. L. WARING AND C. S. ANIVELL U . S. Geological Survey, Washington, D . C . The quantity and complex nature of materials received for analysis in the spectrographic laboratories of the U. S. Geological Survey have emphasized the need for a spectrographic method to determine a maximum number of elements in a limited time with a reasonable degree of accuracy. The semiquantitative method described determines 68 elements in one arcing of a 10-mg. sample. The method has been used to complete 245,000 determinations during a 3-year period. Each determination is reported as a concentration range or bracket (0.001 to 0.01, 0.01 to O . l % , etc.). A chemical check of 500 such determinations showed 92% in agreement; the remaining 8570 agreed to within one bracket. The method requires a minimum of sample handling, thus reducing the chances of contamination, detects low concentrations of elements, and is rapid. Analyses have been completed on n wide variety of materials.
T
HE spectrographic laboratories of the United States Geo-
logical Survey receive for analysis each year a large number of samples of radioactive minerals, rocks, and ores in connection with the investigation of radioactive raw materials, a program which the Survey is undertaking on behalf of the Atomic Energy Commission. It is desirable to know the trace element content of this material, and for many purposes it is necessary to gain aome knowledge of the amounts of major constituents present without taking the time necessary to make chemical analyses. There is need for a spectrographic method to determine a maximum number of elements in a limited time with a reasonable degree of accuracy. In spectrographic parlance such a method is termed “semiquantitative” and the results are usually reported in orders of magnitude of weight percentages of the elements (not the oxides). A survey of the literature (2-4) reveals that several similar methods are being applied in other laboratories on materials of a different nature with different standardization procedures. As a starting point, pom-dered samples were used in order to eliminate costly dissolution techniques. As it was not intended to provide complete quantitative data, the internal-standard, buffer, and carrier distillation methods were not considered, nor could any definite advantage be anticipated in using the cathode-layer method with its critical optical alinement. ilhrens ( 1 ) compared the cathode-layer and anode-excitation methods and found them approximately equally sensitive.
An investigation of the various excitation sources indicates that the direct-current arc gives the best sensitivity or, in other words, produces a higher degree of sample excitation so that lines emitted by elements in low concentrations may be recorded. The direct-current arc supplied by the Multisource (Applied Research Laboratories) produces a high degree of sensitivity, with the added advantage of simple operation. Because of these advantages the Multisource was selected to excite the samples, which were mixed with graphite and placed in the crater of a graphite electrode a t the positive side of the arc. The purpose of the graphite addition was to prevent the formation of mobile beads of molten salts, oxides, or metals, to assist in the volatilization of elements of high boiling points or of elements in extremely nonvolatile compounds, and to steady the arc with a minimum of spraying or mechanical loss of sample. The method has been applied to the following materials: Minerals
Allanite Alunite Anthophyllite Apatite Auerlite Bastnaesite Bayleyite Betafite Billietite Bostonite Brannerite Britholite Carnotite Celestite Chalcopyrite Columbite-tantalite Corvusite Cyrtolite Davidite Diderichite Eschynite Euxenite Feldspars Fergusonite Florencite
Fritxcheite Galena Garnet Guadarramite Hewettite Huebnerite Hummerite Ianthinite Idocrase Johannite Magnetite Martite 3Ielilite Microlite Monazite Montroseite Xiccolite Novacekite Parisite Perovskite Pickeringite Pitchblende Pyrite Renardite Samarskite
Bauxite ores Boron ores Clays Coal ash Diabase Granite Leach products
Lead ores Lignite ash Limestone Pegmatites Phosphate rocks Placer concentrates Rhyolite
Sabugalite Scheelite Schoepite Schroeckingerite Siderite Smaltite Sphalerite Sphene Stibnite Studtite Thorite Torberni te Tornebohmite Tourmaline Tyuyamunite Uraninite Uranocircite Uranophane Uranothorite Vanoxite Volborthite Wernerite Zippeite Zircon
Rocks
Rock salt Sandstones Shale Sulfur ores Syenite Volcanic rocks
V O L U M E 2 5 , NO. 8, A U G U S T 1 9 5 3 Table I. Standard Sensitivities for the Elements Deteriiiined by the Semiquantitative Method" (It is possible t o detect some elements below values listed, a s standard reference plates were prepared on brtsis of increments covering a tenfold concentration range) Element, 70 0.0001 0.0001 As 0.1 Au 0.01 0.001 B Ba 0.0001 Be 0.0001 0.001 Bi C a 0,001 Cd 0.01 Ce 0.1 c o 0.01 C r 0.001 cs O,l(l)h c u 0.0001 DY 0.01 E u 0.01 E r 0 0;
each element, with the percentage of each element decreasing from 10 to In preparing the standard plates an inorganic solution technique is used. Standard solutions are prepared from the purest chemicals obtainable. These solutions are added to the electrode cups and are evaporated before arcing.
Element, yo
Apparatus. Excitation source, Multisource direct-current arc. Spectrograph, 21-foot Wadsworth-mounted grating. Intensity control, neutral filters. Viewing box, any make. Developing equipment, rocking developing tank, plate washer, and drier. Electrode cutters. Lower electrodes, designed to cut '/,-inch electrodes (outside diameter 0.22 inch, inside diameter 0.19 inch, depth of crater 0.12 inch, depth of shoulder 0.12 inch). Upper electrodes, hemispherical, 0.06-inch radius. Miscellaneous glassware and other accessories.
2
Fe Ga Gd
1175
Composition of Standard Solutions. The standard solutions listed in Table I1 were made from conipounds and elements available in the laboratory. Many of the conipounds and elements used were Johnson, Matthey and Co. Specpure grade ( J and 31) The compounds were dissolved in dictilled water unless otherx-ise noted.
0.1 0.001 0.01
0.01 0.001
0.1 0.1 0.01 0.001 0.1 O.Ol(1) 0.01 0.0001(0.l i b 0.01 0.0001
*
PROCEDURE
Preparation of Standard Plates.
Standard solutions are made These solutions are diluted until 0.1 ml. of each equals 10, 1, 0.1, 0.01, 0.001, and 0.0001% based on a 10-mg. sample. Then to the sealed electrode cup (seal is made with a solution of 1% paraffin in benzene) is added a 0.1-ml. aliquot of the solution from a micropipet. This is dried on an asbestos-covered hot plate a t a temperature of approximately 100" C. -4few milligrams of purr graphite are added to the remaining salts in the electrodes. One set of electrodes is arced for 60 seconds and one for 120 seconds. The following Multisource conditions and plate-processing conditions are used: to contain 10 mg. of the element per milliliter of solution.
a Better sensitivity for many of thpse elements m a y be obtained by special methods. b Second rxposure is required for high sensitivity listed. c Third exposure is required f o r fluorine estimation on samples of low calcium content.
Miscellaneous
Cottrell dust Globigerina ooze Ion exchange resin Bronze Nickel alloys Cadmium furnace Phosphate and mangaresidue nese nodules Carnotite ore mill Phosphoric acid residues Pulps
Arsenic trioxide Bone fragments
Sea-water residues Slags Tap- and mine-water residues Various precipitates Rare-earth concentrates
OUTLINE O F METHOD
A method is provided for determining 68 elements in one exposure. Table I shows the minimum concentration of the elements detectable by the method. Better sensitivity of many of these elements may be obtained by special methods, The sensitivities are continually being modified and improved, resulting in new sensitivity sheets from time to time. A sensitivity sheet accompanies every analytical report. The method is applicable when samples must be inspected previous t o quantitative spectrographic or chemical analysis. For many purposes the semiquantitative results are sufficient and eliminate the need for quantitative tests. The selection of a few samples from a large quantity of materials for more accurate tests is one of the most important applications of the semiquantitative spectrographic method. Lower concentrations of the alkalies (lithium, sodium, rubidium, cesium, and potassium) require a second exposure in the red region of the spectrum (5500 to SO00 A,). Fluorine, the 69th element, requires a separate exposure for all materials. -4powdered sample is weighed, mixed with graphite, and placed in a prepared electrode, which is subjected to a direct-current arc. A grating spectrograph permits a range from 2250 to 4750 -4. to be covered on two adjacent spectrographic plates. After the plates are processed, the quantities of unknown elements are estimated by visual comparison of certain lines of the elements in question with those on standard plates. ii standard plate is prepared for
Resistance, 15 ohms Initiator, high Phase, 0 Strike, strike position Amperes, 12 Spectrograph, 21-foot Wadsworth-mounted grating Slit, 25 p Optics, arc image focused on grating Emulsion, 1-L (Eastman) Development, 4 minutes at 18' C., rt C . , D-19 Gap, 5-6 mm Transmission,64% Analysis of Unknowns. -4 10-mg. sample is weighed, mixed thoroughly with two parts by weight of pure graphite in the weighing pan, and placed in the electrode cup through a small glass funnel drawn from borosilicate glass tubing. The unknowns are arced for either 60 or 120 seconds, depending on the volatility of the sample. On each plate along xith the spectra of the unknowns are recorded spectra of iron and of an aluminum alloy. These latter spectra furnish reference points for locating lines and a general index of exposure, of plate sensitivity, and of development. T h r desired sensitivity of the iron is produced with the following conditions: lower electrode, l/a-inch pure iron rod; upper electrodr. carbon (0.06-inch hemispherical radius); arcing time, 60 seconds : 4 to 5 amperes; 300 volts; G4% transmission. The aluminum alloy of known composition serves as a standard when arced for 120 seconds a t 32% transmission, with no change in the other conditions. The above conditions for i wording the aluminum spectra were determined esperimmtally. After the plates are processed. the quantities of unknown elements are estimated by visual comparison of certain lines of the elements in question (Table 111) with those on standard plates. The results are reported in the following brackets: over lo%, 1 to lo%, 0 1 to 1%, 0.01 toO.l'%, 0.001 toO.Ol%,and0.0001 to 0.001%. TVork has been planned to include a lower percentage bracket (0.00001 to 0.0001%), as a few of the elements are drtwtable in concentrations of less than 0.0001%.
ANALYTICAL CHEMISTRY
1176 Table 11. Element Standardized AI
Compound Used AgKOa, reagent AlCla.6Hz0, C.P.
As
AszOa, N.B.S.
-4g
Au
Solution
?io.
83a Au, metal, J and hf
B Ba Be Bi
HsBOr, C.P. BaClz.2H10, C.P. Be, metal, J and M Bi, metal, J and M
Ca Cd Ce
CaClz.2Hz0, anal. reagent CdClz.Z1/zHzO, C.P. CeOx. J and IM
co Cr cs cu DY Er
CoClz.GHz0. C.P. Cr, metal, J and RI c s c 1 , C.P. CuO, reagent DyzOs, J and M ErxOs, J and M
Eu F
Ge
GeOz,
Gd Hf
GdiOt. J and M HfOz, J and M
2
HgClz. reagent HozOt, J and M
In
In, metal, J and M
Ir
I r metal powder, C.P.
K
Hi0
Dilute HC1 1:l HIiOa, dilute to volume v i t h HzO
C.P.
H K C ~ H I O IN.B.S. , Lanos J and M LisCda reagent LuzOi, 'J and M
Element Standardized M O
Compound Used Mg, metal. J and M MnCIz.4Hz0, C.P. 310,metal, J and h.1
Na Nb
NaC1, reagent Nb, metal, J and 11
Nd Ni
NdzOa, J and M Ni, metal, J and h i
OS
Os
M g
Mn
metal
powder,
C.P.
Solution Dilute HC1 Aqua regia, heated. ume with Hz0
Diluted to vol-
+
48% H F "01. concd. Diluted t o volume with "01, concd. 1 :1 HC1. Diluted to volume w-ith H20 1:l HNOa, heated. Diluted to volume with Hz0 Os metal powder heated with a q u a regia in flask fitted with reflux condenser
P
Pb Pd
NaHzPOcHzO, C.P. Pb(NOdz, C.P. Pd, wire, J and hI
HzSO4, concd., heated t o form ambercolored Ce(SO4)z. 6 % HzSOs added to form colorless Cez(S0a)a. Diluted t o volume with Hz0
Pr
Pt
PreOll. J and hl P t , sheet
1 : 1 HzSOr
Rb Re
RbC1, J and h i Re, metal, J and bl
Rh Ru
Si
RhCls, dry, C.P. (NHdzRuCls, J and hI SbIs. C.P. Scr(SO4)s.5HnO,J and M SiOz, pure
Sm Sn Sr Ta
SmzOr. J and M SnCIx.ZHx0, reagent SrCOa, reagent Ta, metal, J and X
Tb
TbrOl, J and
Te Th Ti
HzTeOc2Hz0, C.P. Th(XOs),.4HzO, C.P. TiOz, C.P.
Tm
TmzOa, J and M
TI
V
TISOE,C.P. (UOz) (CzHa0z)z.2Hz0, C.P. h7H4\'0s, C.P.
w
K, metal
48%. H F
Y
YlOt, J and 11
1 :1 HCl and heat. Diluted to volume with Hz0 1 : 1 HCI, heated. Diluted t o volume with Hz0 Dilute HCl
C.P.
Fe, metal, J and M Ga, metal, C.P.
La Li Lu
Compound dried in oven at 140' C. and dissolved in cold acidified HzO 1 : 1 HNOa. heated. Diluted to volume with Hz0 Aqua regia. Boiled down several times with HC1 (concd.) t o drive off "01. Diluted t o volume with
Dilute HCI 1:1 HCI. Diluted t o volume with HzO 1:l HCI. Diluted t o volume with HzO EuzOt, J and M 1:l HC1, heated. Diluted t o volume with Hs0 CaClz, c.P., and KaF, Hz0 (2 solutions)
Ga
Fe
Standard Solutions
Dilute HzS0, Aqua regia. Diluted to volume with HzO H F 48% HzSOl concd. added ahd heaked to diive off HF. Diluted t o volume with HIO Dilute HCl Dilute HISO& heated and H?Oz, 3%, added until dissolved. Diluted t o volume with HtO 1 : 1 HCI, heated. Diluted t o volume with HtO HNOa, concd. Diluted to volume wlth HzO Fused with 3 parts K O H and 1 part Ki'jOs. Fusion dissolved in aqua regia. Si02 filtered off. Filtrate boiled down to small volume. Crystals of KrIrClc separate upon cooling and dissolve in HxO
Dilute HC1 Dilute HC1 1: 1 HC1. heated. with Hz0
Diluted to volume
DISCUSSION
The choice of lines to be used for estimating concentrations of the elements is guided by the major components of the sample and by possible interferences. For example, when a spectrogram is inspected for zinc, the zinc line 3302.6 A. cannot be used if the sample contains more than 1% of sodium because the sodium line 3302.3 A. interferes. The zinc lines 3345.0 and 4680.1 A. are used instead. More than 1% of uranium interferes with thorium 2837.3 A.: therefore, thorium 4619.5, 3108.3,2870.4, or 2752.2 A. should be used. Titanium 3242.0 A. in amounts more than 0.1% interferes with yttrium 3242.3 A. When the sample contains more than 0.1% of chromium, the 2780.7 A. chromium line has an undesirable effect on arsenic 2780.2 A. Chromium 2731.9 A. and arsenic 2349.84 A. are substituted. Cerium lines 4186.6, 4040.7, and 4012.4 A. below a 1 yo concentration are masked by the cyanogen band. The cerium line 4222.6 A. occurs in a clearer part of the spectrum and has a detectable limit of 0.1 %. The presence of 5% or more of calcium fluoride has a general enhancing effect on aluminum. The spectrum of aluminum in concentration of about 0.01% then appears 10 times too intense. This efi'ect was not observed in phosphate rock samples. In feldspar samples a depressing effect was observed on aluminum to such an extent that a percentage estimation of this element could be incorrect by one bracket.
Sb
so
u
;\I
Yb
YbzOs, J and M
Zn Zr
ZnO, reagent ZrOClz.8Hz0,
Aqua regia. Diluted t o volume with Hi0 1 :1 HCI. Diluted to volume with HIO Bqua regia. Boiled down several times with HCl, concd., to drive off "01. Diluted to volume with Hz0 HNOa, concd. with Hz0 Dilute HCl Hot Hz0 Acetone
Diluted to volume
+ dilute HCI
NazCOs fusion. with HtO Dilute HCl
Diluted t o volume
Dilute HC1 48% H F "01, concd. Diluted to volume with "01, concd. 1:l HCI, heated. Diluted to volume with HzO 1 : 6 "01, heated
+
H F t HrOa HzSOI, concd. added and heated t o drive off HF: Diluted to volume with HxO 1 : 1 HC1, heated. Diluted to volume with HzO
48%
1 : l HC1. Hi0
Diluted to volume with
+ HNOa, ,coned., Diluted to volume with HzO
heat.
C.P.
The estimation of fluorine requires a separate exposure. Two milligrams of calcium as calcium chloride solution is added to the electrodes and dried prior to loading the sample. The addition of calcium is necessary in the formation of the calcium fluoride molecule, which produces the molecular band effect recorded by the photographic emulsion. In analyzing the minerals euxenite and samarskite a 2-minute arcing time instead of the 1-minute period gives higher accuracy for such elements as niobium, tantalum, erbium, and uranium. These and other elements or their compounds having high boiling ' of the weight of the two minerals and points constitute over 50 % therefore require a longer arcing time to vaporize into the arc stream. The time required for an analysis varies with the type of material under test and the skill of the analyst. A trained person can complete the analysis of 14 samples (952 elements) of phosphate rock in 16 hours. This rate of speed is not recommended as a daily practice, however, as eye fatigue may result. Analysis time of 14 samples is broken down approximately as follows: Quarter and weigh samples and proper reference samples Exposure Development Plate interpretation
4 hours 1 . 5 hours 45 minutes 10 hours
Samples containing relatively large amounts of the transition
V O L U M E 25, NO. 8, A U G U S T 1 9 5 3
1177
Table 111. Spectrum Lines Used in the Semiquantitative Method Element Ag
A1
Wave Length, A. 3382.9 3280.7 3092.7 3082.2 3059.9 2660.4 2652.5 2576.1 2568,O
As
2780.2 2349.84 2288.12
Au
B
2362,7 2428.0 2676,O 3122,8 2497.8 2496.7
Ba
Be
5535.55 4554.04 3071.6 2335,3
Ce
4222.6 4186.6 4040.7 4012.4
Co
3465.8 3453.5 3449.2 3405.1 3283.5 3243.8
Cr
cs
Cu
3321.3 2348.6
Bi
3067.7 2897.9
Ca
4456.6 4226.7 3179.3 3158.9
Cd
4289.7 4274.8 4254.3 2780.7 2769.9 2731.9 8521.1 4593.0 4555.5 3347.4 3247.5 3274.0 3247.6 2824.4 2492,Z 2293.9
DY 3645.42
Er
4419.6 3499.1 3372.8 3264.8
Wave Ele- Length. ment A. In 4511.3 3256.09 2710.3
Ir
2664.8 2849.7 2924.8 3220,8
F ( C a F 5291.0 band)
6036.9 6064.4
Fe
K
3100.31 3099 97 3099.9 3020.65 2599.4 2598.38
4429.9 4333,8 3380.9 3337.5
3671.2 3646.2 3358.6 3082.0
Li
6707.9 6103.6 3232.7 2741.3
3039.1 2691.4 2651.2
Lu
2613.4 2615.4 2619.3 2911.4 3198.1
2944.2 2874,Z
Gd
Ge
Hf
3134.7 3072.8 2820.2 2773.4
Mg
4358.3 3650.2 3125.6 2536.5
Hg
Ho
7698,9 7664.9 4047.2 4044.1 3447.7 3446.4
La
Ga
3454.33 3407.8 3393.58
3466.2 3261.1 2763.9 2288.0
Table IV.
Wave Length, A.
Element
Mn
3399.0 3416.5 3453.1 3456.0 4254.4
M O
Wave Ele- Length, ment A. 5895.9 Na 5890.0 3302.9 3302.3 h-b
Sd
3358.4 3094.2 2875.5 4325.8 4303.6 4247.4 3328.3
Pt
Wave Length, A. 4442,6 3064.7 3042.6 2659.4
Rb
4215.6
Element
Wave Ele- Length, ment A. Sm 4424.4 4256,4 Sn
3262.3 3175.0 2863.3 2839.9
Sr
4607.3 3464.5 3351.3 2569.5
Ta
4574.3 3642.1 3317.9 3311.2 3012,5
Tb
3293.1 3324,4 4278.5 4318.9
Te
2383,3 2386.8
Th
4619.5 4019.1 3108.3 2870.4 2837,3 2752,2
4201.8
3360.9 7800.2 7947,6 Re
3460.5 3464.7
Ni
3492.9 3433.6 3414.8 3002.5 2320.1
Rh
3280.5 3283.6 3396,9 3434,9 4374.8
os
2909.1 3058,7 3301.6
Ru
P
2554.9 2555.3 2535.7 2534.0
2810,O 2810.6 3428.3 3436.7 4297.7
Sb
3267.5 2877.9 2598.1 2528.5 2311.5
sc
4246,8 3911.8 3907.5 3369.0 3019.3 2552.4
Ti
2987.7 2881.6 2528,5 2524.1 2516.1 2435.2
3372.8 3242.0 3239.0 3234.5 3224.2 3088.0
T1
3775.7 3629.4 3519.2 2767.9 2379.6
Pb
4351.9 2852.1 2795.5 2779.9 2776.7
2873.3 2833.1 2663.2 2614.2
Pd
2798.3 2605.7 2693.7 2576.1
2763.1 3114.0 3242.7 3421.2 3634,7
Pr
4241.0 4225.3 4206.7
4251.9 3194.0 3170.4 2816.1
Si
Wave Length, A.
Element
U
4287.9 4244.4 4241.7 3566 6 2837.328 2837.187
W
4302.1 4294 6 3049.7
Y
3327.9 3242.3 3216,7 3195.6
Comparison of Chemical and Spectrographic Analyses of Various Phosphate Rock for Phosphorus (Chemical results as oxides converted t o element) Phosphorus, % B y chem. method By spec. method Origin of Sample Samples from caves on Mona Island, 10+ West Indies. varying from red and 10+ 10+ white limestone t o almost pure earthy phosphorite (hydroxylapa10+ 16 4 tite). 10+ 16 0 10+ 16 1 10+ 16 7 10+ 16 n 10+ 16.0 IO+ 16.0 lo+ 16.5 1"0' 10.4
Origin of Sample
Phosphorus, % B y chem. method B y spec. method 0.23 0.1 - 1 N o t detected0 0.07 Not detected 0.07 Not detected 0.17 18.22 IO+ 14.26 lo+ 17.51 10+ 11.57 IO+ 16.32 10+ 6.95 1 10 16.72 10+
-
Detection limit of P is approximately 0.1%.
Table V.
Comparison of Chemical and Spectrographic Analyses, in Per Cent, of Phosphate Rock from Florida (Chemical results a s oxides converted t o elements.
Element P Ca Fe .41 Si Na
K
x 3
Mn V Ti Cr
Chem. 11.3 19.6 1.26 0.32 4.1 0.75 0.25 0.63 0.023 0.006 0.036 0.00
Spec.
IO+ 10+
0.1-1 0.1-1 1-10 0.1-1 0.1-1 1-10 0.01-0.1 0.01-0.1 0.01-0.1 0.001-0.01
Chem. 12.6 18.3 1.19 0.44 3.9 0.82
0.28 0.69 0.023 0.006 0.012 0.00
Spec.
--
,
0.1-1 0.1-1 1-10 0.1-1 0.1-1 1-10 0.01-0.1 0.01-0.1 0.01-0.1 0.001-0.01
For description of Florida phosphates, qee first part of Table IV) Method of Analysis Chem. Spec. Chem. Spec. Chem. 12.7 1015.8 15.5 10f i n &, 17.7 19.4 19.8 10+ 0.1-1 0.1-1 0.87 1.25 0.46 0.66 0.1-1 0.1-1 0.33 0.07 1-10 1-10 7.6 4.0 2.9 0.39 0.1-1 0.22 0.1-1 0.16 0.01-0.1 0.026 0.01-0 1 0.033 0.016 0.09 0.16 0.1-1 0.01-0.1 0.14 0.031 0.01-0.1 , 0.023 0.01-0.1 0.108 0.01-0.1 0.011 0.0056 0.01-0.1 0.014 0.006 0.018 0.01-0.1 0.01-0.1 0.036 0.00 0.00 0.001-0.01 0.00 0.001-0.01
--
Spec. 10+ 10+ 0.1-1 0.1-1 1-10 0.1-1 0.01-0.1 0.1-1 0.01-0.1 0.01-0.1 0.01-0.1 0.001-0.01
ANALYTICAL CHEMISTRY
1178 Table VI.
elements often give complex spectra with heavy background. For some materials this results in serious interferences with the best analysis lines of the less abundant elements and necessitates referring- t o less sensitive lines. This procedure may involve similar scrutiny for a large - number of elements and thus prolong the analysis. Additional testing will be necessary to explain the folloning effects:
Comparison of Chemical and Spectrographic.4nalyses,in Per Cent, of Northwest Phosphates from Montana and Idaho
Chemical results as oxides converted t o elements. Northwest phosphates are from the Phosphoria formation mainly in Montana a n d Idaho. They are dark-colored pelletal phosphorites, consisting of carbonate fluorapatite, with minor admixed calcite and/or dolomite, clays, mica, and organic matter. When samples representing phosphatic facies are analyzed. . the relative amounts of minor constituents will be greater. EleMethod of Analysis ment Si Cr
Chem. 7.06 0.11 0.09
\'
Ti
0.09
P
11.5 0.04 26.6 0.20 0.70 1.46
Mn Ca 14g Fe .41
Spec. 1-10 0.1-1 0.1-1 0.01-0.1 1-10
0.001-0.01 10
+ 0.1-1 1-10 1-10
Chem. 8.28 0.13 0.04 n.11 12.2 0.03 29.0 0.22 0.55 1.44
Spec. 1-10 0.1-1
Chem. Spec. 2 . 2 1 1-10 0 . 0 7 0.1-1 0 . 0 1 0.01-0.1 0 . 0 2 0.01-0.1 15.3 10+ 0 . 0 1 0.001-0.01 33.0 10 0 . 1 5 0.1-1 0 . 4 4 1-10 0 . 4 2 1-10
0.014.1
0.01-0.1 10+ 0.001-0.01
+
IO+
0.1-1 0.1-1
1-10
Table VII. Comparison of Chemical and Spectrographic Analyses, in Per Cent, of a Vanadium Mineral Chemical results as oxides converted t o elements. Red-brown vanadium mineral associated with hummerite, Hummer mine, J o Dandy group of mines, Paradox Valley, Montrose County, Colo. Probably a new mineral: it is mixed with fine-grained clay from which it can not be separated mechanically. The x-ray diffraction powder pattern differs from t h a t of any known vanadium mineral. Method of -4nalysis Element Chem. spec.
Table VIII.
Element A1 Ba I i ab C Fe
K
Mn Pb Si Sr .. Ta Ti U
b
..
6.8
1-10
2:8?
ilia
... ...
..
51.7
IO+
...
\0
...
... ... . .
hfg
Spec. 1-10 0.1-1 0.01-0.1
0.014 1
1-10 0.014.1 10f 0.1-1 0.1-1 1-10
1% nickel in calcium matrices seems to be enhanced. 10% nickel in calcium phosphate matrices seems to b.e depressed. 1% nickel in feldspar matrices seems to be depressed, whereas less than 1% is slightly enhanced, I n schroeckingerite calcium and uranium seem to be depressed. 0.49 0.7;
RESULTS AND TABLES
Comparisons of chemical and spectrographic results for 336 determinations are shown in Tables IV through XII. The chemical check shoyed approximately 92% in agreement, the remaining 8% agreed to within one bracket. Approximately 4% of the disngreements are regarded as borderline cases because of doubt as t o which of two adjacent brackets an element should be placed in.
Comparison of Chemical and Spectrographic iinalyses, in Per Cent, of RIiscellaiieous Samples
Xlontroseitea Chem. Spec. 1 . 5 9 1-10
... ...
Chein. 4.10 0.11 0.02 0.04 10.4 0.06 32.3 0.55
..
Hummerite b 'Jhem. Spec. 0 in n 1-1
. . . .
. .
(Chemical results a s oxides converted t o elements) Sample and lletho!pof .4nalysis Ore Idocrased Hew-rttite a Chem. Spz Chem. Spec. Chem. Spec. ... 0.054 0 1-1 ... o 07 n 1-1 .... . . . . . , . . . . 0 02 0 1-1
. . . . .
0 03
0 01-0 1
3.88
i 3 3 6
1-10 1-10
.... ... ....
n 31 . . ...
37 4
n
. . . . .
0 1-1
0.0i4 0 072
. . . . ......
...
..... IO+"
007
47.5
10.9
....
,
. . . . .
...... ......
0.047
. . .
o.oi-0:i
0.01-0 1
... ...
101
0.23
...... ......
.... ....
......
....
1-10
... .
......
I
45.9
~
~
Euxenitei Cheni. Spec.
... . .
. . ...
1
1-10
n
0:111
...
...
_
_
_
Pitchhlendee Chem. Fpec.
.....
... ...
. . . . . . .
...... ......
.... ....
. . . . .
IO+
ilio o:iii
. . .
17.3
0.1-1
4.6 0.96
...
1-10
. . .
......
...
in+
24.4 3.3 ....
1-10 n.01-0.1
..
......
~
..
. . .
ilia ..
8 4
...
...
0.82 30
o:ili
10f
lo+
Bitter Creek mine. Montrose County. Colo. Jo Dandy mine hlontrose Countv. Colo.
Hand-picked simple from ore-hearing sandstone, M a y D a y mine, Mesa County. Colo. Olmstedville, Essex County. 1.Y. J o Dandy mine, Xlontrose County. Colo. / Euxenite sample from Kragero, Norway, U . S . S . M . Ri144. I Great Bear pitchblende. Canada. c
d
e
Table IX. Element
Chem.
Si FP Ca
d 35 8 0 11 1 4 4 004 6 75 0 06 17 8 0 78
nr g Mn
.4 1
Ti Sa K Ti Zr co Sr
Ba
Mo
... ... ...
0.43 0.27
...
Comparison of Chemical and Spectrographic Analyses, in Per Cent, of Ash from Lignite Samples (Chemical results as oxides converted t o elements. Auger-hole samples from southwestern North Dakota) Method of Analysis Spec. Chem. Spec. Chem. Spec. Chem. Spec. Chem. Spec. 1-10 4 45 1-10 13.1 101-10 1;1. 7 1 10+ 1.5. 8 10; 1-10 in21.4 24 2 23.6 IO+ 1-1 0 14 4 1-10 1-10 1-10 7.8 8 6 2.9 0 1-1 0 072 0 1-1 n iii 0 138 1-10 0.126 0.1'26 0. ill n. 1-1 0.20 0 01-0.1 0.1-1 0 11 n 01-0.1 0 78 0.1-1 0.2 1-10 7.8 1-10 1-10 10.1 9 3 in+ 11,fi IO+ 0 06 0.01-0.1 0 01-0.1 0.1-1 0 06 0 01-0.1 0.36 0 36 0.1-1 2.33 1-10 1-10 ]-in 3 26 1-10 1.41 1-10 2.6 1-10 0.92 1-10 0.68 0 1-1 0 1-1 1 78 0.1-1 0.68 .... ...... ..... .... .... 0.118 0.1-1 ...... . . . . . . . . . ...... ..... .... .... . . . . 0.20 0.1-I .... ...... ...... .... .... . . . ...... 0 04 0.1-1
'?3n
0.1-1 0.1-1
......
.... .... ....
.... ....
....
....
...
....
...
....
...
.... ....
O,l5
......
......
0.1-1
.... ....
....
......
...... ......
Chem. 10 2 8.7
10.2 0.108
0.37 12.6 0.06
2.56 0.92
. . .... ....
....
....
Spec. 1-10 1-10 1-10 0.1-1 0.1-1 10+
0.01-0.1 1-10 0 i-1
......
. . . . . . . ......
......
......
_
V O L U M E 2 5 , NO. 8, A U G U S T 1 9 5 3
1179
Table X. Comparison of Chemical and Spectrographic Analyses, in Per Cent, for Lead in Carnotite-Bearing Sandstones from Various Localities
Table XII. Comparison of Chemical and Spectrographic Analyses, in Per Cent, of Hyatt Pegmatite Samples, Larimer County, Colo.
(Cheiiiical results as oxides reduced t o elements) Method of Analysis ~Locality of Saiiiple Chem. Spec. Mine D. Montroae County Colo. Butterfly mine Montrose County Colo. Radium No. 5 'mine San Miguel County, Colo. Raven mine San bfiiiguel Countv Colo. Calamity Kb. 13 mine, Mesa Codnty, Colo. Vanadous No. 1 mine, San Rli uel County, Colo. Bear Creek mine, San Rliguel t o u n t y , Colo. Primus claim, S a n hliguel County, Colo. Dunning-Greysill mine, San J u a n County, Colo. Stone No. 1 claim, Montrose County, Colo. Bitter Creek mine, hlontrose County, Colo. Club mine, Montrose County Colo. Wild Steer mine Montrose Cbunty Colo. 0.1-1 Eastside mine, S a v a j o Indian Resekration, Ariz. 0.011 0.01-0.1
Chemical results aa oxidea reduced t o elements. Samples from Larimer County, Colo., from plagioclase-perthite-quartzwal! zone of the H y a t t pegmatite. Purpose of analyzing samples waa t o determine presence in wall zone of minor elements t h a t crystallized in relative abundance in the next inner zone. Sample and Method of Analysis Bfi090-A BfiO9O-B B6090-A a n d 6090-B Element Chem. Chem. spec. Si ... 33.8 10 1-10 -41 8.25 8.24 1-10 Ka 4.35 4.28 0.1-1 K 3.3 3.22 0.1-1 Fe 0.51 0.50 0.01-0.1 0.25 0.24 Ca 0.01-0.1 h lg 0. 08 0.07 0.01-0.1 1' 0.02 0.02 Ti 0.006 0.001-0.01 0.006 0.01-0.1 0.031 &In 0.031 0.01-0.1 0.045 0.045 Ba
Table XI. Comparison of Chemical and Spectrographic .inalyses, in Per Cent, of Red and Gray Clays from the Colorado Plateau Chemical results a6 oxides converted t o elements. Red and gray clays consisting chiefly of hydromica quartz and calcite from a zone underlying vanadium-bearing ore a t B i t t i r Creek' mine, llontrose County, Colo. Red Clay Gray Clay Element Chem. Spec. Chem. Spec. Ca 1.7 1-10 1.8 1-10 Si 28.0 IO+ 30.0 1Q+ Fe 3.84 1-10 1.7 1-10 5.6 1-10 4.7 1-10 .41 2.46 1-10 2.42 1-10 1.37 1-10 1.45 1-10 Na 0.03 0.1-1 0.07 0.1-1 K 5.0 1-10 4.6 1-10 Ti 0.35 0.1-1 0.36 0.1-1 v 0.04 0.01-0.1 0.04 0.01-0.1
E:
~
Noted in the chemical aiialyses were several disagreements, especially for the follolYing elements: lead, manganese, magnesium. TmadiUm. aluminum, iron, sodium, zirconium, and cal-
+
cium. Standard plates for these elements have been remade, has been Oband better agreement the served. ACKNOWLEDGMENT
The authors wish to express appreciation to their associates of the Geological Survey: to F. S. Grimaldi, A. M.Sherwood, and ot,hers for the chemical analyses, and to Helen Worthing for performing part of the spectrographic analyses. LITERATURE CITED
(1) Ahrens, L. H., T r a n s . Geol. SOC.S. A f r i c a , 49,133-54 (1946).
(2) Churchill, J. R., IND.ENG.CHEM.,AN.~L.ED.,17, 66-74 (1945). (3) Eeckhout, J., Verhandel. K o n i n k l . Vlaarn. Acad. Wetenschap. Belg., Kl. Wetenschap., 7, (13), 71 (1945). (4) Meggers, SV. F., BXAL. CHEM.,22, 18-23 (1950). RECEIVED for review February 11, 1953. Accepted >,lay 7, 1953. cation authorized b y the Director, U. S. Geological Survey.
Pul-li-
Determination of Methoxychlor on Insecticide-Treated Paperboard by UI t raviolet Spect ro photowetry EDW. C. JENKINGS, JR., AND DAVID G. EDWARDS Reseurrh and Development Division, Fibreboard Products, Inc., Antioch, Calif. ETHOXTCHLOR, 2,2-bis (p-niethoxyphenyl j-1,l-1-trichloroethane, an analog of DDT, is a possible agent for improving the resistance of paperboard containers t,o insect infestation. Methoxychlor loadings above 50 mg. per square foot are being considered for this treatment. In order t o correlate experimental cont>ainer performance properly ryith methoxychlor loading3 in this range, the conrentrations of' methoxychlor present mus: be det,ermined within a precision of 10%. Previously published methods (1- 4 , 6 , 1 1 ) for the spectrophotometric determination of methoxychlor have depended on a tnostep conrrrsion of t,he methoxyrhlor to a colored derivative which could be measured in the visible region and xere designed to hanclle microgram quantities such aa might be present in food products as residues from crop or animal sprays. 111the extraction of methoxychlor from foods, the interfering substances which are also carried d o m are considerably different from those encountered with paperboard. For these reasons a method designed to handle larger quantities of methoxychlor in the presence of interfering agents found in
paperboard was desired. Furthermore] consideration of the molecular structure of methoxychlor suggested that a characteristic absorption should be evidenced in the ultraviolet region ( 6 ) , so that a direct determination could be made which would avoid the laborious preparation of derivatives. The ultraviolet spectral transmittance of methoxychlor dissolved in cyclohexane was explored in the 200- to 300-mp region, The relationship of the logarithm of the molar absorbancy index, UM (sometimes called molar extinction coefficient, E ) , to the wave length in millimicrons is shown in Figure 1. I n this paper the recommendations of the National Bureau of Standards on nomenclature are followed (10) and all terms and symbols used are defined below. I n Figure 1 maxima appear a t 230, 238, 246, 270, and 275 mfi. In the procedure for the quantitative determination of methoxychlor the strong absorption maximum a t 230 mp was of primary interest. Beer's law was found to hold for solutions with transmittances of 20 to 60%. Correction for background interference was made by the method of the double impurity index (8).
