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ANALYTICAL CHEMISTRY, VOL. 50, NO. 8, JULY 1978
nm for the 184-5 explosion is noteworthy. The values shown in Figure 6 compare favorably with values reported for flashlamps operated a t comparable energies. In summary, the extremely high ultraviolet intensity, excellent reproducibility, good long-term stability, and low operating cost should make axial wire explosions an excellent continuum source in a number of analytically significant applications. Additional studies extending into the vacuum-ultraviolet region would be most useful. Studies in Kr, Xe, or mixed heavy gases, while much less cost effective, would be worthwhile.
C. H. Church, R. D. Hawn, Jr., T. A. Oslal, and E. V. Somers, Westlnghouse Research Lab., Sci. Paper 62-1 12-259-PI (July, 1962). W. W. Jones and A. W. Ali, Phys. Lett. A , 5 0 , 101 (1974). A. W. Ali, N.R.L. Memo Report 2792 (1974). J. A. Holcombe and R. D. Sacks, Spectrochlm. Acta, Part B , 28, 451 (1973). J. A. Holcombe, D. W. Brinkman, and R. D. Sacks, Anal. Chem., 47, 441 (1975). R. Stair, W. E. Schneider, and J. K. Jackson, Appl. Opt., 2, 1151 (1963). W. G Chace, Phys. fluids, 2, 230 (1959). R. D. Sacks and J. A. Holcombe, Appl. Spectrosc., 28, 518 (1974). W. Tieman, 2. Naturforsch. A , 23, 1952 (1968). R. D. Sacks, "Shock Tubes, Exploding Conductors and Flashlamps", in "Analytical Uses of Pbsmas", R. M. Barnes, Ed., Wiley-Interscience, New York. N Y , in Dress --J.-L,'Emmett and A. L. Schawlow, Appl. Phys. Lett., 2 , 204 (1963). A. Unsold. Ann. Phvs. Leiozia. 33. 607 (1938). H. Maecker and T. Peters,' Zrbhys., 139, 448 (1954).
LITERATURE CITED D. W. Brinkman and R. D. Sacks, Anal. Chem., 47, 1279 (1975). G. K. Oster and R. A. Marcus, J. Chem. Phys., 27, 189 (1957). G. K. Oster and R. A. Marcus, J. Chem. Phys., 27, 472 (1957). R. A. Marcus, In "Exploding Wires", W. G. Chace and H. K. Moore, Ed., Plenum Press, New York, N.Y., 1959, Voi. 1, p 307. (5) M. J. Stevenson, W. Reuter, N. Braslau, P. P. Sorokin, and A. I. Landon, J. Appl. Phys., 34, 500 (1963).
(1) (2) (3) (4)
RECEIVED for review December 21,1977. Accepted April 19, 1978. The authors acknowledge support of this study by the Science Foundation through grant number MP72-05099 A02.
Atomic Emission Spectrometric Determination of Antimony, Germanium, and Methylgermanium Compounds in the Environment Robert S. Braman" and Michael A. Tompkins' Department of Chemistry, University of
South Florida,
Tampa, Florida 33620
Methods have been developed for the determination of Inorganic antimony and germanium and methylgermanium compounds In the environment. Compounds of these elements In aqueous solutlon at pH 1.5 are converted to the corresponding volatile hydrides by reduction with NaBH,. A dc discharge atomlc emlsslon type detector gave detectlon limits near 0.4 ng for antimony and germanium. Application was made to the analysis of natural waters and air particulate. Low concentrations of inorganic antimony and germanium were detected. No organometallic compounds of either element were detected in any environmental samples analyzed.
Antimony, found primarily in mineral ores, is derived principally from stibite, Sb&. Germanium is generally found as the +4 oxidation state oxide or in solution as germanic acid. Common valence states for S b are +3 and +5, while Ge forms divalent and tetravalent compounds of which only the latter are stable under environmental conditions. The number of known organogermanium compounds is numerous, but none has achieved significant industrial importance. Stibonic, RSbO(OH)2,and stibenic, R2SbOOH, acids are known but are likewise of small commercial importance. Although there are no reports of methylated compounds of antimony or germanium in.the environment, the stability of their alkyl-metal compounds under environmental conditions was sufficient to warrent their study. No methods have been reported for the determination of methylantimony or Present address, Department of Chemistry, Colorado State University, Fort Collins, Colo. 80523. 0003-2700/78/0350-1088$01 .OO/O
methylgermanium compounds at trace concentrations. Prior work has usually involved determination of total antimony or germanium. Antimony and germanium in low concentrations have been largely determined by spectrophotometric methods. While useful for the determination of these elements in the submicrogram range, such methods are sometimes complicated by the need for extraction or distillation procedures to avoid interferences from other trace metals (1,2). The Rhodamine-B method has been used for antimony in the 2-20 pg range (3). The reaction of germanium with phenylflurone in acid solution is used for analyses in the microgram range ( 4 ) . The more sensitive atomic absorption methods for antimony have sensitivities (1% absorption) in the 0.3 to 1.5 mg L-l range ( 5 , 6 ) . Recently, the use of a graphite tube furnace with NaBH, reduction of antimony to SbH3 has achieved a detection limit of 0.5 pg L-l (7). Pollock and West (8) were the first to report the determination of germanium by hydride generation with NaBH4. Standard flame atomic absorption techniques were used and resulted in a detection limit near 0.5 pg. Thomerson and Thompson (9) used a silica tube within an air-acetylene flame to obtain a detection limit of 0.5 pg Ge while a detection limit of 0.3 ng has been obtained with a graphite tube atomizer (10). Neutron activation analysis has demonstrated sensitivities in the low nanogram range for the determination of antimony and germanium in a variety of materials (11, 12). Foreback has done a preliminary study on the development of an analytical method for antimony(II1) and antimony(V), based on generation of stibine, SbH3 by NaBH, reduction with subsequent analysis by atomic emission spectrometry (13). The detection limit found was near 0.1 ng. Preliminary work by Johnson and Braman (14) indicated that germanium could 0 1978 American
Chemical Society
ANALYTICAL CHEMISTRY, VOL. 50, NO. 8, JULY 1978
DC Discharge
He carrier gas, In
n
1089
L
Cop trap packed with NaOH beads
U-trap
Figure 1. Details of the volatilization apparatus
also be analyzed in a similar manner. This work presents details of the application of the NaBH, reduction method to the analysis of antimony in natural waters and in air particulate. Reported here is a n improvement of t h e method of Johnson a n d Braman (14) and its further application includes the determination of methylgermanium compounds. A number of natural waters and air particulate samples were analyzed.
EXPERIMENTAL Apparatus. The apparatus used consisted of a reaction chamber, a U-shaped trapping column approximately 30 cm long, half packed with 60-80 mesh glass beads, a dc discharge detector as shown in Figure 1, and photometric readout system, essentially the same as that used for arsenic analyses (15). Detection of S b depends upon observation of the 252.8 nm atomic emission line when SbH3is carried into the He plasma. Detection of Ge is by observation of the 265.1 nm atomic emission line. This Ge emission line exhibited less interference from the 274.6 nm N2 band than the equally sensitive 275.5 nm Ge line. A short column packed with NaOH beads removes interfering C 0 2from the carrier gas. This was necessary for the separation of C 0 2 from GeH,. Such an absorber was not necessary in the antimony determination procedure as SbH, and C02were satisfactorily separated on the U-trap. The gain of the photometric system depends upon monochromator slit width, photomultiplier type (R-106UH, Hamamatsu, Inc.), photomultiplier voltage, amplifier current range, and recorder range. The slit was usually set a t 200-400 pm and the other instrument parameters were adjusted using standard samples to give the desired response sensitivity. Reagents. Powdered NaBH, (98%) was obtained from Ventron Corporation (Beverly, Mass.). Solutions of 2% NaBH, with 0.01% NaOH added, were made fresh each day. A 10% aqueous solution of oxalic acid, ACS reagent grade (Matheson, Coleman and Bell), was used to maintain the solution between pH 1.5 and 2.0. The C 0 2absorber was filled with ACS reagent grade NaOH beads. Airco laboratory grade helium was used as the carrier gas. No special purification of gases or reagents was necessary. No antimony or germanium blank was observed in any of the chemical reagents. Standards. Germanium dioxide, methylgermanium trichloride, dimethylgermanium dichloride, and potassium antimony tartrate were obtained from Research Organic/Inorganic Chemical
Corporation (Sun Valley, Calif.) for use as standards. Stock solutions from 500 to 1000 mg L-'of these compounds were prepared. The germanium(V1) and antimony(II1) standards were dissolved in deionized water, while the methylgermanium compounds were dissolved in 95% ethanol. Stock solutions were stable over a period of several weeks. Serial dilutions, usually 1:lW of the stock solutions, were freshly prepared when calibration was needed. Diluted standard solutions were delivered by microliter size syringe. Procedure for Antimony. Water samples containing 0-50 ng of soluble Sb compounds in up to 50-mL volume are placed in the sample reaction chamber. Small sample volumes are diluted with distilled water to bring the total volume up to 35 mL. Solution acidity is adjusted to pH 1.5-2.0 by addition of 5 mL of 10% oxalic acid in water. This is sufficient to maintain pH 1.5-2.0 for natural waters even after addition of the NaBH, reducing agent. Use of a pH meter and sample neutralization is not necessary unless substantial amounts of strong acids or bases are present in samples. Samples are degassed for 1-2 min prior to analysis by passing He carrier gas at 250-300 mL/min through the sample reaction chamber while it is detached from the rest of the system. The sample reaction chamber is then attached to the rest of the analysis apparatus (without the NaOH tube) and the U-trap is immersed in liquid N2. Three 1-mL portions of 2% NaBH, reducing solution are then added to the sample through the injection port by syringe. The SbH3 generated by reaction of NaBH, with soluble inorganic Sb(II1) or Sb(V) compounds is entrained in the He carrier gas and frozen out in the liquid N2 cooled U-trap. A period of 5 min is required for complete reaction and removal of SbH3from the reaction chamber. The dc discharge is initiated 1-2 min prior to the end of the 5-min scrubbing period. The liquid N2 Dewar is removed and the U-trap is slowly warmed to provide good separation of SbH, from C02. This procedure does not distinguish Sb(V) or Sb(II1) compounds. Results are, therefore, a sum of Sb(V) and Sb(II1) present. Organoantimony compounds, if present, are detected. Only a few experiments were ever conducted with organometallic antimony compounds. The compound tetramethylbistibine [(CH,),Sb], was prepared and tested for reduction products with NaBH, in aqueous media. Antimony compounds eluting separated from and later than SbH3 were observed in analyses using the procedure. Since no good methylantimony standards were available, no further work was done. Procedure for Inorganic Ge and Methylgermanium Compounds. The procedure for Ge is quite similar to the
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ANALYTICAL CHEMISTRY, VOL. 50, NO. 8, JULY 1978
Table I. Response Curve Data for Antimony, Germanium, and Methylgermanium Compounds slope, m detection sample size wavelength, standard (istd. dev.) limit, ng range, ng compound nm Sb(OH),+ 252.9 2.0-41. 0.35 1.5 (t 0.047) 265.1 3.0-30. 0.18 0.61 (t 0.055) Ge(OH), 265.1 5.5-44. 0.31 0.36 (t 0.037) CH,GeCl, (CH,),GeCl, 265.1 8.0-48. 0.69 0.16 (? 0.028) procedure for antimony. The apparatus used includes the COz trap shown in Figure 1. The carrier gas flow rate is somewhat higher, 350-400 mL/min. Samples containing Ck50 ng of Ge compounds in 50 mL of water are adjusted to pH 1.5-2.0 by addition of 6 mL of 10% oxalic acid solution. Use of a pH meter is not necessary unless large amounts of strong acids or bases are present in the original sample. The sample reaction chamber is degassed for 1-2 min while it is detached from the rest of the apparatus. The U-trap, COBabsorber, and detector are then connected and the U-trap is immersed in liquid Nz. Three 2-mL portions of 2% NaBH4 in 0.01 % NaOH are added t o the sample through the injection port by syringe. Inorganic Ge compounds and methylgermanium compounds are converted to the corresponding germanes, entrained by the carrier gas, and trapped in the cold U-trap after 10-min reduction time. The dc discharge is initiated and the photometric system placed in operation. Upon removal of the liquid nitrogen bath, the strip chart recorder is started and GeH4 passed through the COz absorber into the detector. The COz absorber is then bypassed by use of the three-way stopcock, the U-trap is warmed, and the separated methylgermanes passed into the detector. Analysis of the U-trap requires approximately 3 min. Hydriding was over 95% complete after a 5-min analysis procedure. The 10-min procedure was selected to obtain 100% efficiency as determined by r2-analysis of the already NaBH, treated sample. After using the recommended procedure, no Ge or methylgermanium compounds were detected in the reaction vessel. No disproportionation or demethylation reactions of methylgermanium compounds were observed. Procedure for Air Analyses. Air particulate was also analyzed for antimony and germanium content. The particulate was collected on 25-mm diameter type A-E glass fiber filters (Gelman Instrument Co., Ann Arbor, Mich.). The sample volume was 8-10 m3 of air, collected with Neptune Dyna-Pump, (Fisher Scientific Co.) continuous-duty, rubber diaphragm pumps. After sample collection, the filter was placed in a 200-mL Teflon beaker and treated with 10 mL of 0.1 M NaOH solution, shredded, and warmed with a heat gun. Then, 40 mL of deionized water were added and the pH adjusted to 1by additions of concentrated HC1 and a 10% solution of oxalic acid. This solution was then analyzed in the procedures described above. Filter and reagent blanks were run concurrently with all environmental samples and were never found to contain noticeable quantities of germanium or antimony.
RESULTS AND D I S C U S S I O N Separation. This method for S b and Ge is very similar to the method reported earlier for inorganic and methylarsenic compounds (15). Sodium borohydride reduction of methylgermanium compounds produces the corresponding hydrides GeH4 (bp 88 "C), CH3GeH3 (bp 28 "C), and (CH3)2GeH2(bp 6.5 "C) which are well separated from each other during elution from the cold trap. Although standards were not available for (CH3)3GeHand (CH3I4Ge(bp 48 "C), they would likely also be separated from the other germanes. Response Curves, Precision, a n d Detection Limits. Typical response curves for antimony(III), germanium(IV), methylgermanium, and dimethylgermanium compounds are shown in Figure 2. Area response curves were linear over the concentration ranges studied. Pertinent response data are outlined in Table I. Organometallic compounds of germanium did not give exactly the same response on a germanium weight basis. Consequently, separate calibration curves are needed for each compound to be detected.
intercept, (istd. dev.) 0.22 (t 1.0) -0.85 (i 1.0) -0.21 (i 1.0) -0.41 (k 0.84)
0 Antimony ( I l l ) rn Germanium IlV) A Methylgermanium 0 Dimethylgermanium
8
16
24 32 40 Nanograms (Sb or Ge)
48
Figure 2. Analytical curves for antimony(III),germaniurn(IV),rnethylgerrnaniurn and dimethylgermanium compounds
The detection limit (defined as the ng equivalent of noise in area units) for antimony(II1) a t its 252.9 nm atomic line, is estimated near 0.35 ng. Assuming an average sample volume of 50 mL, the concentration detection limit is 7 ng L-l. Precision for the S b method as determined by analysis of 8 replicate samples of 25 ng of Sb was 2.2% relative standard deviation. For germanium the detection limits were estimated to be 0.18 ng as Ge for germanium(IV), 0.31 ng as Ge for methylgermanium, and 0.69 ng as Ge for dimethylgermanium compounds. Assuming an average sample volume of 50 mL, the concentration detection limits would be 3.6 ng L-l for germanium(IV), 6.0 ng L-l for methylgermanium and 14 ng L-l for dimethylgermanium compounds. Precision for inorganic Ge as determined by 12 replicate analyses of 10 ng of Ge was 7.1 % relative standard deviation. Precision for the methylgermanium compounds as indicated by the uncertainty in the slope of the calibration curves is given in Table I. Interferences a n d Limitations. Carbon dioxide, nitrogen, and water vapor were the three major spectral interferences noted in the analysis procedures. Small amounts of carbon dioxide produced a positive signal following the germane signal, while larger amounts of carbon dioxide quenched and often extinguished the discharge. This problem was corrected by using a sodium hydroxide filled carbon dioxide absorber between the U-trap and the discharge. In the antimony analysis, the carbon dioxide signal was simply separated from the stibine signal by careful warming of the U-trap. While large volumes of nitrogen also quench the discharge, the nitrogen is usually swept from the system and the cold U-trap while the germanes are frozen out. Nevertheless, inboard leakage of air a t points beyond the cold U-trap must be avoided as leakage raises the discharge background. The final major spectral interference, and the most severe, was that due
ANALYTICAL CHEMISTRY, VOL. 50, NO. 8, JULY 1978
Table 11. Interferences in Germane Evolutiona ppm effect ion ppm effect ion
&+ ~ 1 3 +
~ 8 0 ~ 3 -
~i0,3Cdz+
20 2 20 200 20
FFe3+
20 2 20 2 200 20 20 2 200 200
Hg2+
100
coz+ CrO,
2-
cuz+
i
-
Mg2+
10
i
Mn2+ Nil+
20 2 20 20
-
2
-
i
-
NO,-
210
i
-
Pb2+
20
-i
H,PO,
200
-i
S2-
20 2 20 20 2 20 2 200 100 20
-
Sb” Se0,2Sn4+
-
i
-
i -
-
i i -
200 s0,zK+ v0,z410 Zn2+ fresh water and seawater a “i” ion decreases Ge response 10% or more and I ‘ - ” no decrease in Ge response noted. Germanium concentration analyzed, 0,080 fig L-’ , 1-
-
to water vapor entering the discharge and concurrent excitation of the OH band system at 260.8 nm. With the use of the cold-trapping techniques and careful attention to the carrier gas flow rate and U-trap warming rate, the water vapor seldom posed a problem. However, without proper control of these parameters, the germane signals often appeared on the side of a broad, rising OH band. A variety of cations and anions were tested as possible interferences in the germane evolution and detection. The results are shown in Table 11. A number of metal ions, such as silver, copper and nickel produced negative interferences a t 20 mgL-l. Large amounts of these metals, if present in samples can react with NaBH, to form metal borides or free metal suspensions. No metal ion tested interfered at a concentration of 2 mgL-l or less. Additions of large amounts of Antifoam-B (Technicon Instruments, Inc.) to highly surface active samples such as human urine or biological samples must be avoided when using the 265.1 nm germanium atomic line. Scanning the wavelength region about this line, identified a S i 0 band head a t 264.4 nm as producing the interference. In order to minimize silicon interference, no more than 5 mL of 0.1% Antifoam-B should be used. Antifoam-B containing reagent blanks should be run if it is used. Antifoam was not needed for fresh and seawater samples.
ANALYSIS OF ENVIRONMENTAL SAMPLES A number of natural off-shore waters, from in and around the Tampa Bay, Fla., area were analyzed for antimony and germanium content. All samples were analyzed “as is” without any pretreatment. Samples which were not analyzed immediately were frozen until analysis was possible. Polyethylene containers were used for sample acquisition and storage. No storage blank was observed. The results of these analyses appear in Table 111, Table IV, and Table V. T h e average germanium concentrations found in fresh, estuarine, and saline waters were 0.016, 0.029, and 0.079 pg L-’ respectively. Previous workers report an average germanium content of 0.070 pg L-l in seawater (16). Johnson and Braman applied a similar technique to the analysis of Sargasso Sea waters and found an average germanium content
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Table 111. Germanium in Some Fresh Waters inorganic germanium sample fresh waters Hillsborough River Hillsborough River (Fowler Avenue) Hillsborough River (Hillsborough State Park) Withlacoochee River (Dade City) Withlacoochee River Lake Carroll Lake Thonotosassa East Lake Lake Egypt Double Branch River USF Research Pond USF Golf Course (15th Fairway Pond) Pond (N. Rome/Bedingfield Dr.) Lake Fisher (Brandon) Average
ngl sample
”PI L-
NDb ND
ND ND
ND ND ND ND ND 2.9 0.88 1.5 0.46 1.0 4.1 0.33
ND ND ND ND ND 0.058 0.018 0.030 0,009 0.020 0.082 0.007 0.016
-
Oregon well watersa well No. 1 15.0 0.60 well No. 2 11.5 0.46 well No. 3 8.6 0.34 a This set of values not used in computing the average. ND, less than 4 ng L-I. Table IV. Germanium in Some Saline and Estuarine Waters inorganic germanium sample saline waters McKay Bay (North Side) McKay Bay (South Side) Hillsborough Bay (Bayshore Blvd./S. Rome) Hillsborough Bay (22nd St. Causeway) Courtney Campbell Causeway (North Side) Courtney Camplbell Causeway (South Side) Seddon Channel Safety Harbor Safety Harbor (Phillippi Park) Egmont Key Gulf of Mexico (Tarpon Spring) average estuarine waters Alafai River Palm River Rocky Creek Hillsborough River (Buffalo Ave.) Anclote River average a
sample ngl
L”4
10.8 6.4
0.22 0.13
4.7 7.4
0.094 0.15
1.8
0.036
1.2 6.7 2.4 2.1 N Da ND
3.8 1.5 0.53 1.4 ND
-
0.024 0.13 0.048 0.042 ND ND 0.079 0.076 0.030 0.011 0.028 ND 0.029
ND, less than 4 ng L-’.
of 0.042 Fg L-’ (17). No literature values for the average germanium content of fresh waters were found. T h e agreement between the average saline water values for this work and previous researchers appears reasonable. Rain and tap waters were also analyzed, and the average germanium content found was 0.045 and 0.0088 pg L-l, respectively. Methylgermanium compounds were not detected in any of the waters analyzed. If methylgermanium compounds were
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8, JULY 1978
Table V. Antimony in Some Natural Waters inorganic antimony, Pg L-'
fresh waters 15th Fairway Pond, USF Golf Course 9/5/75 Tracea 9/8/75 Trace 11 17/76 0.11 ND 1/28/76 Research Pond, USF 9/8/75 0.092 ND 11/7/75 Hillsborough River, Tampa 9/8/75 N D ~ 9/15/75 0.048 Lake Carroll, Tampa ND 9/15/75 ND 11 17175 Lake West, Tampa 9/5/75 ND ND 1117175 Lake Eckles, Tampa ND Pond, Brandon ND 0.023 average saline and estuarine waters Hillsborough Bay, Seddon Channel, North 9/10/75 0.021 9/12/75 0.030 McKay Bay ND ND Old Tampa Bay, Courtney Campbell Causeway Alafia River Trace 0.027 average Trace, approximately 14 ng L-I. ND, Less than 7 ng L" detection limit. present, they must exist in concentrations of less than 10 ng L-1. Several waters from deep wells in Oregon were found to contain unusually high levels of germanium(1V) but no methylgermanium compounds. The average value reported was 0.41 pg L-l. The average antimony concentration for both the fresh and saline water samples was quite low, approximately 20 ng L-l. Previous workers have reported antimony in seawater at 0.18 to 0.48 pg L-' (27-19). Scharrer reports an average value of 0.30 pg L-l for the open sea (20). The reasons for the discrepancy between the values reported in this work and the literature are not clear. A possible explanation may be that antimony sometimes occurs as the sulfide Sb& or as the oxide Sb203. These solids are insoluble in water and may be present in a particulate phase not analyzed by this hydriding method. In addition, Parris and Brinckman (21)have pointed out that even dimethylantimony compounds such as (CH,),SbO(OH) can exist as an insoluble polymer. This could explain the lack of detection of methylantimony compounds. The strong acid oxidations and digestions, which are the preliminary steps in most colorimetric and atomic absorption work, might aid in the solubilization of the antimony(II1) sulfide and oxides. However, with these treatments the ability to speciate between inorganic and organic type antimony compounds would probably be lost. Air particulate analyses for antimony were also carried out. Results of environmental analyses obtained are given in Table VI and Table VII. The average antimony concentration in air particulate over a 24-h period was 0.40 ng/m3. There are few results from other urban areas with which to compare. John et al. report an average of 4 ng/m3 for the San Francisco Bay area of California (22). Other workers have reported
Table VI. Antimony in Air Particulate Tampa Bay, Florida Area inorganic date antimony,b ng/nm) 9/a/75 0.09 9/9/75 N DC 9/10/75 Traced 10/22/75 0.96 10123175 2.2 101241I 5 1.3 10/26/15 0,03 10121115 0.14 10/28/15 0.09 11/3/75 0.30 Trace 11/4/75 1215176 ND 12/6/75 0.06 average 0.40 All samples taken atop Physics building, USF. Twenty-four hour sampling periods. ND, Less than 0.02 ng/m3 per sample. Trace, approximately 0.02 ng/m3.
4 0.0060
USF
0.0092
Greater Tampa Bay
rr/
Flgure 3. Germanium content (ppb) of natural waters in the Tampa, Fla.
area
average values in the 1 to 4 ng/m3 range (23, 24). As in the case of the natural waters, the antimony concentrations reported here appear to be low as compared to other literature values, possibly due to a refractory, insoluble form of antimony. Attempts to develop methods for the analysis and speciation of volatile methylantimony were unsuccessful. Further method development and refinement is needed. The average concentration of germanium in air particulate, over a 24-h sampling period, was 0.21 ng/m3. These samples
ANALYTICAL CHEMISTRY, VOL. 50, NO. 8, JULY 1978
Table VII. Germanium in Air Particulate, Tampa Bay, Florida Area inorganic germanium, sample location ng/ m USF (Greenhouse) 0.08 BSC (N. Dale Mabry/Columbus Dr.) 0.12 RSB (Carrollwood Dr.) 0.02 USF (Physics Bldg.) 0.02 EAT (Buffalo AveJRome Ave.) 0.05 0.03 BAD (Brandon) JMA (Palma Ceia) NDa NW Tampa (Waters AveJSheldon Rd.) 0.01 RAG (Brandon) ND E D 0 (East Lake) 0.02 EPA (Downtown Tampa) 1.65 JCB (Palma Ceia) 0.48 average 0.21 a Less than 0.01 ng/m3.
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increased as the location of the sampling site nears the urbanized area. The average germanium content in air particulate of 0.022 ng/m3, in the northern sections of the Tampa Bay area, probably represent the ambient germanium levels in a semirural area. There may be a correlation between the germanium content of natural waters and air particulate samples and the fly-ash fallout from urbanized and industralized point sources, more specifically coal-fired power generation plants. This is not surprising when one considers that the germanium content of coal has been estimated a t 70 ppb, but is enriched significantly in the fly-ash to levels near 476 ppb (24). An interesting indication of germanium in air particulate is evidenced by the germanium content of rain water, mentioned previously in this work. The germanium concentration in rain water of 0.045 pg L-l is approximately three times the average germanium concentration of natural fresh waters. A washdown of air particulate during periods of intense rain a t the time of collection might explain the higher germanium levels. A number of differing environmental, commercial, and biological materials were analyzed for antimony and germanium. Examples included sea shells, wines, and human urine. No apparently significant levels of inorganic or methylated forms of antimony or germanium were detected in these samples. LITERATURE C I T E D
Greater Tampa Bay
Flgurs 4. Germanium content (ng/m3) of air particulate in the Tampa,
Fia. area were taken intermittently, over a period of one month and were never found to exceed 2 ng/m3. In Figure 3 and Figure 4 are displayed the approximate location of various sampling stations and their corresponding average germanium concentrations for waters and air particulate, respectively. The (A)symbol marks the location of a coal-fired power generation plant. The germanium content in both the natural waters and in air particulate appears
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RECEIVED for review January 3, 1978. Accepted March 20, 1978. Work supported by the National Science Foundation, RANN Program Grant numbers AEN 74-14598-A01and AEN 74-14598-A02.
