1136
Anal. Chem. 1981, 53, 113’6-1138
1
2 shows that the expected correlation is, by and large, supported by the experimental data. The extent and direction by which the experimental data deviate from the expected conductivity at a given NH3 concentration may be taken as an indication of the type and concentration of other minor impurities. For instance, anionic species such as bicarbonate, chloride, and organic acids will depress the specific conductivity (as long as their total equivalent concentration is less than that of ammonia),whereas cationic species such as alkali ions will tend to raise the specific conductivity. Thus, the simultaneous monitoring of the ammonia concentration by way of an ion-specific electrode and the specific conductivity of LP steam turbine condensate may be a sensitive diagnostic indicator for undesirable steam impurities.
o Plant Data
0.01
0.1 1 Mi3 Concentrationlug kg-1
10
Figure 2. Specific conductivity of NH, solutions and LP turbine steam condensate samples at 25 O C .
conducted at a number of power plants along with chemical analyses. The major ionizable substance in LP steam was found, by ion chromatographicanalysis, to be ammonia which is added to the feedwater for pH control. Thus, the specific conductivity of LP turbine steam condensate is expected to approximate those of NH3 solutions. A plot of the standardized (25 “C) specific conductivities of LP steam condensate as a function of the measured NH3 concentration in Figure
ACKNOWLEDGMENT The author is indebted to W. T. Lindsay, Jr., for advice and assistance. LITERATURE CITED (1) Quist, A. S.; Marshall, W. L. J. fhys. Chem. 1965, 69, 2984. (2) Hitch, B. F.; Mesmer, R. E. J. Solution Chem. 1976, 5, 667.
(3) D’Ans-Lax “Taschenbuch for Chemlker and Physiker”, 3rd ed.; 1967; p 1-802 (density of H,O) and p 1-622 (dynamic viscosity of YO).
RECEIVED for review November 17,1980. Accepted February 27, 1981. This work was sponsored by the Electric Power Research Institute under Contract RP-912 to the Materials Evaluation & Application Department of the Westinghouse R&D Center.
Proposed Certlfled Reference Material for Pond Sediment Yasuo Iwata, Kazuko Matsumoto, Hiroki Haraguchl, and Keiichiro Fuwa‘ Department of Chemistry, Faculty of Science, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Kensaku Okamoto* National Instltute for Environmental Studies, P.0. Yatabe, Ibaraki 305, Japan
In recent years, the importance of certified reference materials (CRMs) for elemental analysis has been well recognized. The present authors, in a cooperative study with National Bureau of Standards (NBS) research groups, have provided some biological reference materials such as Japanese tea leaves (I) and “wet” shark meat (2). The National Institute for Environmental Studies (NIES) has recently initiated a CRM program. The objective of this program is the preparation and certification of environmental reference materials to serve the needs of environmental scientists and laboratories. The first CRM certified was a botanical sample, pepperbush, the preparation, analysis, and certification of which were described in the previous literatures (3,4). More recently, we have performed the preparation of a proposed environmental CRM, “pond sediment”, as the second CRM to be issued by NIES. The material was collected from the Sanshiro-ikepond at the University of Tokyo, which is centrally located in Tokyo, Japan. The material represents a stratum called Kanto loam, which probably consists of volcanic ash erupted a long time ago from Mt. Fuji and other volcanos. Therefore, this pond sediment is significantly different in ita composition from the river sediment Also affiliated with the National Institute for Environmental
Studies.
0003-2700/81/0353-1136$01.25/0
Table I. Homogeneity Test of Pond Sediment Samples’ cu Mn Pb co
X,b&g/g
103 29.1 721 220 1.4 0.75 1.1 1.3 3.1 3.2 2.3 1.7 OD/_‘ (%) 2.4 0.90 1.8 O E / X (%) ~ 2.1 Analytical data are expressed as the dry weight. Samples were dried at 110 “C for 4 h in an oven. average concentration. ‘OA, homogeneity of samples. OD, error of digestion. e OE, error of measurement. OA/~‘(%)
from NBS (5). Hence, we report the potential of the pond sediment powder as a new environmental CRM. EXPERIMENTAL SECTION Sampling and Pretreatment. In May 1977, the sediment was collected to a 1-m depth from the bottom surface at the center of the Sanshiro-ikepond. It was stored in polyethylene bags for about 1 year. Before preparing the CRM,a small quantity of distilled water was added initially to the sample and the sample was stirred well. The wet sample was sieved through a nylon sieve (2 mm) to remove gravel and leaves. Drying. The wet-sieved material was filtered by suction to remove interstitial water, and it was air-dried on fdter paper (Toyo No. 2) at room temperature for 2-3 weeks. About 70 kg of dried pond sediment was obtained. 0 1981 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 53, NO. 7, JUNE 1981
Table 11. Elemental Composition of Pond Sediment Powder and Comparison with Other Environmental and Geological Data river sediment median soil element pond sediment (NBS SRM 1645) mean crustC content
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palace moat sedimentd
Values in % Si A1
Fe Ca
21.4 10.7 6.80 0.77
24.0 2.20 11.3 2.90
27.7 8.20 4.10
4.10
33.0 7.10 4.00 1.50
4.70
Values in pglg Ti Mn
co F Hg
6060 721 360 220 103 70 38 29.1 285 1.5
ILa
17.9
Zn
cu Pb
Cr Ni
5600 785 1720 109 714
950 75
50 14 100 80 20 950 0.05
29600 45.8 8
1.1
5000 1000 90 30 35 70 50 8 200
750 1400 300 300 100
45 18
0.06
Values in % a
Ignition loss at 800 “C.
Cited from ref 5.
Cited from ref 7.
Grinding and Sieving. The dry sediment was ground for about 1 h in a ball-mill (95% A1203, 7 L), which had been previously cleaned by grinding a portion of the sediment to minimize contamination. The pulverized samples were placed on a set of the following sieves from the top to the bottom; a 50-mesh (297 Km) nylon sieve (top), R 100-mesh (151 pm) one (second), a 200-mesh (71 Km) one (third), and a reservoir made of poly(viny1 chloride) (bottom), vibrating the sieves mechanically for 15 min. Mixing. The powder (40 kg) that passed through a 200-mesh sieve was divided into two parts with a riffle sampler (JIS No. 2) made of poly(viny1chloride). The powder was piled up in two layers and again divided by passing through the riffle sampler. The sediment sample W,BS homogenized by repeating this procedure 11times. This homogenized sediment, which constituted the reference material, was packaged in about 2000 bottles (about 20 g each) made of glass for storage. The bottled samples were sterilizedby ‘Wo radiation at 2 Mrads at the Japan Atomic Energy Research Institute (Takasaki, Japan), to minimize deterioration due to biological activity. Determination of Metallic Components for Homogeneity Testing. Three portions of sediment were taken from each bottle and were digested. Eleven bottles were randomly selected from the lot of 2000 bottles. Sampleswere digested as follows: 2 g of sediment powder (dried at 110 “C for 4 h) was transferred to a 100 mL Teflon beaker and heated for 30 min with a mixture of 15 mL of HN03and 15 mL of HC104on a hot plate controlled at 200 “C. After the mixture was cooled 30 mL of HF was added and the sample was left standing for 30 min. Then it was heated (ca. 200 “C) until the appearance of white fumes. Subsequently, HN03 (5 mL) and HC104(5 mL) were added again, and the mixture was heated to near dryness. Finally, 101 mL of HCl(1:l) was added to dissolve the residue, and the solution was filled up to 100 mL. The digested sample solutions were used tn, determine Cu, Mn, Pb, and Co by AAS using an air-acetylene flame. The results are summarized in Table I. Elemental Composition. Besides those elements used to assess homogeneity, some other elements were determined by AAS. These elementswere Cu, Mn, Pb, Zn, Co, Ni, and Cr. These elements were determineld by the Daini-Seiko atomic absorption spectrometer SAS-727, ,Japan, by Zeeman AAS (Hg; Hitachi Zeeman 501, atomic absorption spectrometer, Japan), by colorimetry (Ti and Fe; Shimadzu UV 210A spectrophotometer, Japan), by gravimetry (ignition loss, Si, Al, and Ca), and by the ion-selective electrode method (F; TOA MH-5B potentiometer and Denki Kagaku Keiki fluoride ion selective electrode, Japan). Colorimetricdeterminationsof Ti and Fe were based on the DAM (diantipyrylmethane)and o-phenanthrolinemethods, respectively. Ignition loss was measured as the percentage of weight loss after
Cited from ref 8.
heating at about 800 “C for 1h. For the fluorine determination, the sample (0.5 g) was fused with 3 g of NazOzand dissolved in 20 mL of distilled water; subsequently 0.1 g of hydrazine sulfate was added, and fluorine was separated by steam distillation. RESULTS AND DISCUSSION Homogeneity of Pond Sediment Samples. Homogeneity was checked by the analysis of variance (two-way layout method) (6),and the results are shown in Table I. The results of the F tests show the pond sediment material to be homogeneous. As can be seen in Table I, the expected values for homogeneity of Cu, Mn, Pb, and Co were 1.3, 0.75, 1.1,and 1.4% as relative standard deviations, respectively, whereas those for digestion error of Cu, Mn, Pb, and Co were 1.7,2.3, 3.1, and 3.2%, respectively. It is evident from these data, therefore, that the pond sediment is homogeneous enough to be used as a CRM. Elemental Composition of Pond Sediment a n d Comparison with the Data for Other Environmental a n d Geological Samples. Table I1 shows the elemental composition of the pond sediment sample prepared in the present work. These analytical values have not been certified yet. Analytical determinations to establish the certified values are under way a t the National Institute for Environmental Studies, Japan, by K. Okamoto and K. Fuwa. Table I1 also includes, for comparison, the elemental contents of river sediment, NBS SRM 1645 (5),and the average elemental concentrations in earth crust (7), soils (7), and palace moat sediment (Tokyo) (8). The pond sediment sample contains more heavy metals compared to the average values of soils. However, in general, the elemental concentrations of the pond sediment are not as high as those of the “river sediment”. In particular, the “river sediment” contains Cr a t the percent level which is anomalous for the usual soil or sediment. A comparison of metal contents between pond sediment and palace moat sediment (Tokyo) shows that the compositions are similar and, therefore, pond sediment CRM may be considered as a typical sediment samples found in the vicinity of a large city. ACKNOWLEDGMENT The authors thank K. Chiba, Department of Chemistry, University of Tokyo, for providing the analytical data for the determination of fluorine by the fluoride ion selective electrode method.
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Anal. Chem. 1981, 53, 1138-1 139
LITERATURE CITED (1) Fuwa, K.; Notsu, K.; Tsunoda, K.; Yamamoto, Y.; Okamoto, K.; Doklya, y.; Toda, S. Bull. Chem. SOC. Jpn. 1978, 51, 1078-1082. (2) Dokiya, Y.; Taguchi, M.;Toda, S.;Fuwa, K. Anal. Chem. 1978, 50, 533-536. (3) Okamoto, K.; Yamamoto, Y.; Fuwa, K. Anal. Chem. 1878, 50, 1950-1951. (4) Okamoto, K., Ed. "Preparation, Analysis and Certification of Pepperbush Standard Reference Material"; Research Report No. 18 from the National Institute for Environmental Studies: Ibarakl, Japan, 1980. (5) Certificate of Analysis, River Sediment, SRM 1645, US. Department
of Commerce, National Bureau of Standards, Washington DC, 1978. (6) Ishikawa, K.; Fujlmori, T.; Kume, H. "Jikken Kelkaku-ho"; Tokyo Kagaku Dojln: Tokyo, 1967; p 202. (7) Bowen, H. J. M. "Environmental Chemistry of the Elements"; Academic Press: London, 1979; pp 36, 60. (8) Goldberg, E. D.; Hodge, V.; Koide, M.;Griffin, J. J. Geochem. J . 1876, 10, 165-174.
for review December 8, lggo* Accepted February
26, 1981.
Modification of the Dow-Beckman Carbonaceous Analyzer for Wet Oxidation Kenneth M. Johnson" and John McN. Sleburth Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island 0288 1
Older Dow-Beckman carbonaceous analyzers (Beckman Instruments, Fullerton, CA) which analyze microliter volumes of water samples by dry combustion and detect the resultant COZ by infrared photometry are unsuitable for determining low concentrations of dissolved organic carbon (DOC) in fresh and marine waters. For this purpose the wet oxidation method ( I ) using milliliter sample volumes and infrared detection is recommended (2). However, for laboratories equipped with the Dow-Beckman instrument and unable to purchase newer equipment, we can suggest a way to adapt these carbon analyzers to wet oxidation without sacrificing their direct injection capability. The front panel of the ampule analyzing unit (Model 0524B) manufactured by Oceanography International Corp. (College Station, TX) can be frame mounted to the Dow-Beckman carbonaceous analyzer console and the ampule analyzer output interfaced with the Beckman IR-315 or IR-215 as shown in Figure 1. In this way the unit is quickly adapted to the standard persulfate oxidation method for DOC in natural waters (I). The Dow-Beckman instrument used had already been upgraded by replacing the glass combustion tube with a ceramic tube and all other glass components in the combustion train with stainless steel. The original gas connections on the carbonaceous analyzer were removed and the oxygen carrier gas was reconnected to the ampule analyzer and the Dow-Beckman unit with l/s or 1/4 in. hard white Impolene thermoplastic tubing (Imperial Eastman Corp., Chicago, IL) according to the instruction manuals furnished by the manufacturers. The two units were interfaced by installing two three-way brass ball valves (Whitney Co., Oakland, CA). One at the inlet of the IR analyzer allowed us to select either the output of the ampule analyzer or the oxidation furnace. The second valve on the ampule analyzer unit formed an IR bypass line and rerouted the carrier gas through the combustion furnace or alternatively to an ampule sparging unit when the ampule analyzer was not in use. Thus a single tank of oxygen (purified by a heated catalyst, ascarite and silica gel to remove COz,water vapor, and volatile organics as COz)was regulated by the flow meter on the ampule analyzer panel and sufficed for all phases of carbon analysis. The output of the IR-315 was integrated by a CRS-208 Infotronics digital integrator (ColumbiaScientific, Houston, TX) and the output displayed on a Bristol Recor4%;@ristol Co., Waterbury, CT). For routine deterl;n'Inhtions,the ampule method requires 10 mL of sample while the direct injection method usually requires only 20 wL. This discrepancy is easily handled. To avoid saturating the IR detector, the unit may be adapted to
Table I. Dissolved Organic Carbon Analysis with the Dow-Beckman Carbonaceous Analyzer Modified for the Menzel-Vaccaro Method (I )" sample replino. cates mg L-l std dev % CV 1 2 3 4 5 6
3 3 3 3 3 3
1.53
+0.047
1.95
1-0.028 50.140
2.10 2.21 2.26 1.89 1.99
rtO.180
1-0.130 k0.060
3.1 1.4 6.7 8.1 5.7
3.2 5.2
means 1-0.11 a All samples were collected in lower Narragansett Bay, RI.
the ampule method where DOC levels of 0.5-5.0 mg L-l (5-50 pg C 10 mL-l) are to be expected by injecting into the furnace 20-pL portions of a 3000 mg L-' DOC standard (60 pg C 20 pL-l) and adjusting the amplifier gain for a meter deflection 95% of full scale. However, the wet and high-temperature oxidations should be standardized independently. A calibration gas mixture of 1000 ppm COz in Nz passed through the cells at the same flow rate as the zero gas (200 mL min-l) was used to monitor and correct amplifier drift. Standards utilizing potassium hydrogen phthalate as a carbon source were made up in both filtered distilled water and artificial seawater. The system was tested on seawater samples obtained from lower Narragansett Bay, RI. The samples were gravity filtered through precombusted Gelman glass fiber filters (Type A/E) and analyzed by persulfate oxidation ( I ) with minor modifications and precautions (3). For the initial six analyses shown in Table I, the average standard deviation was 50.11 mg L-l, which is identical with the precision usually cited for the method, and better by a factor of 10 than the k l . 0 mg L-l given by Beckman for the direct injection method. Subsequently, 48 additional DOC analyses have been made on samples from the lower bay. For these data the mean was 1.60 mg L-l, but the average standard deviation decreased to *0.061 mg L-l for a %CV of 3.8%. The latter results compare well with even the newest carbon analyzers. The modification described extends the analytical capability of the Beckman and possibly other high-temperature combustion instruments heretofore considered unsatisfactory for marine samples ( 4 ) . In addition to the required level of precision and sensitivity for determining dissolved organic
0003-2700/61/0353-1138$01.25/00 1981 American Chemical Society
