Environ. Sci. Technol. 1883, 17, 125-127
film development. There did not appear to be a quantitative or qualitative difference in film development under either of these treatment regimes (Figure 3). In another series of experiments the concentration of ferrate was held constant, but the frequency of application was varied. In this case as treatment frequency varied, differences in the rate of film development were noted. Further, there appeared to be a different ferrate-film reaction depending on dosing frequency. In the case where ferrate was added every 12 h no observable film developed, and the few cells that were attached to the surface were atypical of cells in control film. When ferrate was added only once every 24 or 48 h, some film developed initially, and the cell types and organization were typical of that for control films. However, these films were weakly attached, and hence sloughed so that there remained little or no slime growth on any of the experimental slides by the end of the experiment. Control chambers from some of the experiments described above received a or M dose of ferrate for 20 min to test the ability of ferrate to detach an established film. it was noted that in all cases established films on slides prior to ferrate treatment were greater than 60 pm thickness. At concentrations of lo4 and lo6 M, potassium ferrate was unable to detach these established films, and after 24 h following treatment there was no significant difference between slides exposed to ferrate and controls. The optimal dose of ferrate(V1) appears to be slightly less than M when added every 1 2 h for these test systems. A contact time of 5 min was adequate and would be expected to be similar in waters with a lower pH and less buffering capacity as more of the oxidizing power
would be released in a shorter period of time. In waters containing high BOD it would probably be necessary to increase ferrate dose in proportion to the increase in BOD. However, in the model condenser system utilized for this study ferrate(V1) ion appears to be an effective antifoulant, as only short contact times are required for ferrate concentraions of M to maintain condenser cleanliness. Registry No. K2Fe0,, 13718-66-6. L i t e r a t u r e Cited (1) Mattice, J. S.; Zittel, H. E. J . Water. Pollut. Control Fed. 1976,48, 2284-2304. (2) Arthur, J. W.; et al. “Comparative Toxicity of Sewage Effluent Disinfection to Freshwater Aquatic Life”; USEPA Ecological Res. Series, 1975, 600/3-75-012. (3) Brungs, W. A. “Effects of Wastewater and Cooling Water Chlorination on Aquatic Life”; USEPA Ecological Res. Series, 1976, 600/3-76-098. (4) Waite, T. D.; Jorden, R.; Kawaratani, R. In ”Water Chlorination: Environmental Impacts and Health Effects”; Jolley, R. L., Ed.; Ann Arbor Science: MI, 1978; Chapter 59. (5) Waite, T. D.; Fagan, J. In “Condenser Biofouling Control”; Garey, J., Ed.; Ann Arbor Science: MI, 1980; Chapter 30. (6) Schreyer, J. M.; Ockerman, L. T. Anal. Chem. 1951,23, 1412. (7) Waite, T. D. J . Environ. Eng. Diu. (ASCE) 1979,105, No. EE6. Received for review February 8,1982. Revised manuscript received September 23,1982. Accepted October 22,1982. This work was supported by Grant RP-RP61-3 from the Electric Power Research Institute.
Cross-Contamination of Water Samples Taken for Analysis of Purgeable Organic Compounds Steven P. Levine” and Mark A. Puskar Department of Environmentaland Industrial Health, School of Public Health-I I, The Unlverslty of Michigan, Ann Arbor, Michigan 48109 Paul
P. Dymerski
Analytics, Inc., Richmond, Virginia 23260 Beverly J. Warner and Charles S. Friedman Monsanto Research Corporation, Dayton, Ohio 4541 8
Analysis of volatile organic compounds in water, including chlorinated and aromatic species, is usually performed with U.S. EPA methods 601 and 602. The high sensitivity of the method combined with the use of a permeable cap liner and a screw cap with a center hole results in a potential for contamination and/or crosscontamination of samples. Results indicate that contamination and/or cross-contamination can occur through the silicone-Teflon cap of a vial but that this contamination will be low for the case of proximal storage of certain highand low-concentration samples. Introduction
Analysis of volatile organic compounds in water, including chlorinated and aromatic species, is usually performed with US.EPA methods 601 and 602 ( 1 , 2 ) . The 0013-936X/83/0917-0125$01.50/0
methods call for purge and trap concentration of the analytes prior to analysis by gas chromatography (GC) with electrolytic conductivity or photoionization detection or by mass spectrometric detection (MS) (3-6). This results in a limit of detection on the order of 1 pg of analyte/L of water (3). Samples are taken in headspace-free vi& that are fitted with center-hole screw caps and Teflon-lined silicone cap liners. The high sensitivity of the method combined with the use of a permeable cap liner and a screw cap with a center hole results in a potential for contamination and/or cross-contamination of samples. This was recognized in the original publication of the proposed methods 601 and 602 in which the following statement was made: “Samples can be contaminated by diffusion of volatile organics through the septum seal into the sample during their shipment and storage” (1,2). Up to now, no study has been made to quantitate this potential for con-
0 1983 American Chemlcal Society
Envlron. Sci. Technol., Vol. 17, No. 2, 1983 125
tamination. For this reason, this study has been performed to quantitatively measure the cross-contamination of four volatile halogenated organic compounds on the basis of a model of a situation typical of sample shipping and storage conditions. The study included the use of controls (to monitor contamination from the laboratory), neat reagents (to monitor the potential for contamination from reagents stored in the same refrigerator), and halocarbon-saturated water solutions (to monitor the potential for cross-contamination of clean samples by dirty samples). the cross-contamination model and analyses were set up and performed simultaneously at two independent laboratories [O.H. Materials Co. (OHM) and Monsanto Research Corp. (MRC)] to maintain absolute quality assurance. Experimental Section Apparatus. Vials used in this study were obtained from two commercial suppliers “S”and “P”. Vials were 40-mL clear borosilicate glass with a Teflon-lined silicone rubber disc under a hole-cap screw top. The Teflon lining in the discs were 2 mils thick for supplier “S”and 3 mils thick for supplier “P”. All analyses were performed by using a liquid sample concentrator (Tekmar LSC-2 or LSC-2 coupled to an ALS-10 purge and trap device) fitted to a Tracor 560 GC equipped with a Tracor Hall 700A detector operated in the halogen mode. Analysis conditions were as per required by the EPA protocol (I). Reagents. All water used in this study was Burdick and Jackson lot H359. All reagents were Omnisolv, Burdick and Jackson, or the equivalent. Procedure. In order to simulate storage conditions encountered in sample transport and in a small refrigerator, all studies were performed in closed 1.3-ft3aluminum boxes, placed in approximately 9-ft3 refrigerators to maintain a storage temperature of approximately 4 OC. (All lockboxes and refrigerators had been prewashed with Micro detergent and rinsed with Milli-Q water. In addition, lockboxes had been baked overnight at 105 “C.) Into each of the three boxes, one each in three separate refrigerators, the following were placed: box “control”, ten 40-mL vials from suppliers “S”and “P”containing Burdick and Jackson water; box “neat”, one each 20-mL scintillation vials containing neat dichloromethane, trans-1,Zdichloroethylene, chloroform, and 1,2-dichloroethane, plus twenty 40-mL vials from suppliers “S”and “P”containing Burdick and Jackson water; box ”saturated”, ten each 40-mL vials from supplier “S”containing saturated solutions of the above halocarbons, plus twenty 40-mL vials from suppliers “S” and “P”containing Burdick and Jackson water. The following timed sequence of events took place at both participating laboratories. Time zero: all vials were placed into each refrigerated lockbox. 1, 3 (or 4), and 7 days: triplicate vials of water from suppliers ”S”and “P” were removed for analysis at OHM, and duplicates were removed for analysis at MRC. In order to preclude a systematic bias in results between laboratories, GC calibration standards and halocarbon-saturated solutions for this study were prepared at OHM, and one aliquot of each was shipped to MRC. Results and Discussion Results are summarized in Tables I and I1 for the case of the potential for contamination of clean samples (pure water) by storage with neat halocarbon reagents and by halocarbon-saturated solutions. These results indicate that contamination is most significant for trans-1,2-dichloroethylene and that this effect is more significant for the vials from supplier “S”than from supplier “P”. Furthermore, 126
Environ. Sci. Technol., Vol. 17, No. 2, 1983
Table I. Contamination of Clean Water Samples b y Storage with Vials of Neat Reagenta halocarbon concn. ppb (wt/vol) storage time. days
ditrans-l,2chloro- dichloroana- methane ethylene chloroform lvzed ____ S P S P S P by
1,2-dichloroethane
S
P
OHM b NDC 4 ND 2 b 3 0 2 OHM b 1 ND 8 ND 5 b 3 2 5 OHM b 7 1 3 3 2 b 3 3 1 MRC b ND ND ND 1 b 4 N D ND MRC b ND ND ND 1 b 4 N D ND OHM b ND 5 2 4 2 b 7 5 1 OHM b 4 5 3 12 5 h 7 8 3 4 OHMb b 8 4 6 2 7 5 18 7 OHM b ND 5 1 b 90 ND 3 7 OHM b ND 5 ND b 98 ND 3 7 OHM b b 104 2 3 2 6 4 7 MRC 5 8 b ND 3 ND 2 3 ND 3 7 MRC 70 b ND 3 ND 2 3 ND 3 Storage conditions defined in text; “S” and “P” indicate suppliers of vials and silicone-Teflon cap liners. The lowest standard analyzed for dichloromethane that can be distinguished from background levels in the water matrix is 1 5 ppb. ND = not detectable; less than 1 ppb.
1
Table 11. Cross-Contamination of Clean Water Samples by Storage with Vials of Halocarbon-Saturated Watera
storage time, days
halocarbon concn, ppb (wtlvol) ditrans-1,21,2-dichloro- dichlorochloroana- methane ethylene chloroform ethane lyzed by S P S P S P S P ~
NDC ND ND 1 10 b 1 OHM b ND ND ND ND b ND ND OHM b ND ND ND ND b ND ND OHM b ND ND ND ND ND b 2 MRC b ND ND ND ND 2 b 4 MRC b ND ND 2 ND b 6 ND 4 OHM b ND ND 2 ND b 9 ND 4 OHM b ND ND ND 2 ND b 8 4 OHM b N D 2 3 7 5 b 9 7 OHMb ND ND ND 2 ND b 8 7 OHM b ND ND ND 2 ND b 7 7 OHM b a Storage conditions defined in text; “S” and “P” indi. cate suppliers of vials and silicone-Teflon cap liners. The lowest standard analyzed for dichloromethane that can be distinguished from background levels in water matrix is 1 5 ppb. ND = not detectable; less than l ppb. 1 1 1 1 3
while the potential is significant for contamination caused by storage of clean samples with vials of reagent, there is insignificant cross-contamination caused by storage of vials of clean water with saturated aqueous solutions of these halocarbons. For the case of dichloromethane, the potential for contamination could only be assessed above the 15 ppb level. This is because the laboratory blank and control samples varied between 6 and 15 ppb when either Milli-Q or Burdick and Jackson water was used. The only contamination seen above that level was after 7 days of storage of clean water with vials of neat reagent. These results indicate that contamination and/or cross-contaminationcan occur through the silicone-Teflon cap of a vial but that this contamination will be negligible for the case of proximal storage of high- and low-concentration samples. These conclusions are proven valid only for the four halocarbons studied, the vials and caps from two suppliers, and the refrigerated lockbox model. Further tests are required to cover the full range of US. EPA method 601 and 602 compounds. Therefore, it is recom-
Environ. Sei. Technol. 1983, 17, 127-128
(4) Fishman, M. J.; Erdmann, D. E.; Steinheimer, T. R. Anal. Chem. 1981,53, 198R-200R. ( 5 ) Beggs, D. P. Am. Lab. 1978,81-87. (6) Westendorf, R. G. “Optimization of Parameters for Purge and Trap Gas Chromatography”, Tekmar Corp., Cincinnati, OH, 1981. (7) “Handbook for Analytical Quality Control in Water and Wastewater Laboratories”,US.Environmental Protection Agency, Environmental Monitoring Support Laboratory, Cincinnati, OH, EPA-600/4-79-019, 1979; pp 6-12.
mended that the US. EPA Quality Assurance flowchart involving laboratory and field spikes and blanks (7) be strictly followed for all method 601 and 602 samples. Registry No. Dichloromethane, 75-09-2; trans-1,2-dichloroethylene, 156-60-5; chloroform, 67-66-3; 1,2-dichloroethane, 107-06-2; Teflon, 9002-84-0.
Literature Cited (1) Fed. Regist. 1979, 44, Appendix I, 69468-69473. (2) Fed. Regist. 1979, 44, Appendix I, 69474-69478. (3) Bellar, T. A,; Lichtenberg, J. J. J. Am. Water Works Assoc. 197466, 739-744.
Received for review June 1 , 1982. Accepted November 5, 1982. Materials Co., Findlay, OH. This research supported by O.H.
A Simple and Inexpensive Method for Measuring Integrated Light Energy Timothy J. Sullivan” and Mlchael C. Mix
Department of General Science, Oregon State University, Corvallis, Oregon 97331
w The ozalid technique is a simple and inexpensive me-
-
thod for measuring integrated sunlight energy in the field for periods up to a maximum of 1 day. This paper describes a modification of the ozalid technique that makes it suitable for long-term light measurements. Data from the modified ozalid meter were calibrated against an Eppley Precision Spectro Pyranometer, yielding a strong positive correlation (R2= 0.97).
A
14[ 13
10
9
4 5 6 7 8 Number Ozaiid Sheets
Introduction The measurement of light energy from the sun is an important consideration in a variety of environmental field investigations, ranging from ecological studies of primary productivity to photodegradation of chemicals in the environment. Unfortunately, the equipment needed to measure integrated light energy is expensive and not easily transported into the field. Also, it is often advantageous to obtain numerous light readings simultaneously from different study areas, which may be cost-prohibitive. This paper describes a simple and inexpensive method for measuring integrated sunlight energy in the field for periods ranging up to 40 days. Friend (1)proposed the use of photosensitive ozalid paper for measuring light for short periods of time to a maximum of approximately 1 day. We employed stacks of aluminum screening as a neutral density filter, thereby substantially reducing the amount of solar radiation. With this adaptation the ozalid meter can be used accurately for long-term light measurements.
Experimental Section The adapted ozalid meter consists of a stack of 12 sheets of ozalid paper (Shannon and Co., Portland, OR) stapled into a booklet approximately 2 cm X 3 cm with the yellow side up. The ozalid stack is then sandwiched between two discs of black paper, with two small holes (approximately 0.5 cm) punched through the top disc directly above the ozalid stack. A stack of 10 aluminum screens (mesh size 7/cm) with alternating cross-hatching is placed above the top disc, and the entire apparatus is placed in a glass petri dish. Foam rubber or plastic in the bottom of the petri dish will hold the stacks in position. The petri dish is then secured with electrical tape to keep the ozalid paper dry 00 13-936X/83/09 17-0127$01.50/0
a
m -
13
-
12
-
9
L N
€11-
& >
r c 2 10-
m .%
5
Y
9 -
71
4
1
1
1
I
5 6 7 8 Number O z a i i d S h e e t s
I
9
Flgure 1. Incoming solar energy due to total visible light (0.295-2.9 pm) (A) and due to the 0.295-0.530-pm portion of the electromagnetic spectrum (B), expressed as a function of number of ozalid sheets developed. R 2 values equal 0.973 and 0.971, respectively.
in the event of precipitation. The cost for each meter is only a few cents for materials other than the petri dish. Upon exposure to light the ozalid sheets are bleached from yellow to white beneath the holes in the black disc. When the exposure period is completed, the stacks are removed in dim light, labeled and developed in ammonia vapor for 10-20 min (see Friend (1)for instructions on assembling a simple developing jar). The number of positive ozalid sheets (those identified as exposed after development) can then be counted and the degree of development of the last sheet estimated to the nearest 1/4 sheet. It is advantageous to first select standards to represent lI4, l J 2 , and 3 / 4 development, and mount these standards so they may be viewed for easy comparison with test papers. Since there may be slight differences in results between “ozalid meters”, each light measurement should be taken with 3-5 replicates. A mean value for number of positive ozalid sheets is then converted to incoming solar
0 1983 American Chemical Society
Environ. Sci. Technol., Vol. 17, No. 2, 1983
127
