1588
ANALYTICAL CHEMISTRY, VOL. 51, NO. 9, AUGUST 1979
(2) M. L. McConnell, Chromatix. Ref. 1, Paper No. 37. (3) Pulse Dampener Model 709, Laboratory Data Control Division, Milton Roy Company, Riviera Beach, Fia. 33404. (4) Pulse Dampener, Model 80-600Liquid Chromatograph, Gow-Mac Instrument Co., Bound Brook, N.J. 08805. (5) Gienco Scientific, Inc., Houston, Texas 77007, 1978 Liquid Chromatography Products Catalogue, p 9. (6) L. R. Snyder and J. J. Kirkland, "Introduction to Modern Liquid Chromatography", Wiley-Interscience, New York, 1974, pp 101-102. (7) J. N. Done, "Idealized Equipment Design for HPLC", in "Practical High Performance Liqua Chromatography", C. F. Simpson, Ed., Heyden & Son, New York, 1976, pp 71-72.
(8) E. Durrum, Eldex Laboratories, Inc., Menlo Park, Calif. 94025, private communication. (9) D. A. Ventura and J. G. Nikelly, Anal. Chern., 50, 1017 (1978). (IO) N. Parris. duPont Company, Scientific 8 Process Instruments Division, private communication. (1 1) Model 7037 Pressure Relief Valve. Rheodyne. Inc., Berkeley. Calif. 94710. ( 1 2 ) Unpublished work.
RECEIVED for review February 5 , 1979. Accepted April 23, 1979.
Extraction of Semi- and Nonvolatile Chlorinated Organic Compounds from Water A. J. Burgasser"' and J. F. Colaruotolo" Hooker Chemical Company, Research Center, Grand Island Complex, M.P.O. Box 8, Niagara Falls, New York 14302
The category of semivolatile and nonvolatile extractable organic compounds comprises those compounds which are not capable of being analyzed by the purge and trap technique ( I ) but are preferentially soluble in nonaqueous solvents. Eighty-three (83) compounds on the EPA priority pollutant list fall into protocols in this general category ( 2 ) . The compounds fall into three subgroups-base/neutral, acid, and pesticide fractions. Analyses based upon these protocols call for p H adjustment, a triple extraction procedure with methylene chloride/hexane mixture, drying through sodium sulfate, and a concentration/solvent exchange step using a Kuderna-Danish evaporator. For chlorinated organic compound analyses by gas chromatography, the solvent exchange step is essential to remove all of the methylene chloride such that its detector response does not interfere. Once concentrated, the extracts are analyzed by gas chromatography using an electron capture or Hall detector, or concentrated further by dry nitrogen purge for GC/MS analysis ( 3 ) . The extraction procedure specified in the EPA protocols is widely used and considered to produce results with precision and accuracy acceptable to the requirements of the EPA. The primary drawback is that it is inherently slow, requiring long extraction and phase separation times. This effectively cancels out the benefits derived from the use of modern automated chromatographic instrumentation. Also, the procedure has a large number of manipulation steps, increasing the potential for poor performance as a result of technique related problems. We have developed a procedure to greatly increase the efficiency and speed of this extraction step using a Brinkmann Polytron Homogenizer to perform the extraction and a Sorval refrigerated centrifuge to speed up the phase separation process. The extraction of chlorinated organic compounds from water can be carried out in a single vessel in one step taking only 10 min to complete. Previous work on the extraction of pesticides from soils using the Polytron Homogenizer was reported by Johnson and Starr in which the soil was suspended in water and the compounds of interest were extracted from the soil particles into acetone ( 4 ) . Four compounds (hexachlorobutadiene, hexachlorocyclopentadiene, octachlorocyclopentene, and hexachlorobenzene) were evaluated for their extraction efficiencies and linearity of extraction from water by the Polytron Homogenizer 'Present address, Hewlett-Packard,102 8th Ave., King of Prussia, Pa. 19401.
~
~~
~~~
~~~~
Table I. Gas Chromatographic Conditions column: G.C. :
6 ft X 2 mm i.d. glass, 3% Dexsil 300 on 801100 Supelcoport Hewlett-Packard 5840A detector: electron capture ( 6 3 N i )300 'C injector: 220 C column temp: 150 " C carrier gas: 10% methane argon flow: 30 mL per min
__-
technique. The accuracy and precision obtained for the method is also reported.
EXPERIMENTAL Apparatus. The extractions were carried out in Pierce 125-mL hypovials using a Brinkmann Polytron Homogenizer, Model PT-1035, equipped with a model PT-1OST generator. Phase separation was carried out by centrifugation of the sample in the same vessel using a Sorval RC2-B centrifuge. Analysis of the extracts was carried out using a Hewlett-Packard 5840 gas chromatograph with an electron capture detector. The gas chromatographic conditions used are shown in Table I. Reagents. Water used for preparation of standards was triple distilled from potassium permanganate solution and nitrogen sparged to ensure that no organic residues were present. All organic solvents used (acetone, hexane, benzene) were pesticide grade Burdick and Jackson disbilled in glass. All glassware was cleaned by treatment with dichromate and subsequent rinsing with water, acetone, and hexane. The glassware was then oven dried at 250 "C. Procedure. One hundred (100) mL of the water to be analyzed were placed into a Pierce 125-mL hypovial and the pH was adjusted to suit the nature of the compounds being analyzed (for the chlorinated compounds, the pH was adjusted to 9-11). Then 10 mL of 15% benzene in hexane were added t o the vial. The sample was extracted for 30 s with the Polytron Homogenizer at 50% of full speed (approximately 11000 rpm). Following each extraction, the PT-1OST generator was cleaned by successive washings in acetone, hexane, acetone, and hexane. The hypovial containing the emulsified solution was then centrifuged for 5 min at 1500 rpm and 4 "C. This was sufficient time to completely separate the organic and aqueous layers. The organic layer was removed with a Pasteur pipet and sealed in an autosampler vial for analysis on the Hewlett-Packard gas chromatograph. RESULTS AND DISCUSSION The total emulsification of the organic and aqueous phases by the homogenizer had the effect of optimizing the partitioning of the extractable compounds. For compounds with
0003-2700/79/0351-1588$01.00/0 0 1979 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 51, NO. 9, AUGUST 1979
Table 111. Time and Cost Comparisona
Table 11. Precision and Accuracy Dataa recovery, % compound
Polytron homogenizer EPA proprocedure tocol
std. dev., % 0.1 ppb
hexachlorobutadiene hexachlorocyclopentadiene
octachlorocyclopentene hexachlorobenzene
90 80 88 109
0.03 0.01
steps in procedure pieces of glassware required volume of organic solvent used, mL time to perform one extraction, min approximate cost per analysis
_--
0.02 1.0 ppb
hexachlorobu tadiene hexachlorocyclopentadiene
octachlorocyclopentene hexachlorobenzene
85 94 99 96
0.15 0.23 0.15 0.24
a
1 0 PPB
hexachlorobutadiene hexachlorocyclopentadiene
octachlorocyclopentene hexachlorobenzene
hexachlorocyclopentadiene
octachlorocyclopentene hexachlorobenzene
7
11
2 30
6 150
10
44
$9
$31
Costs will be based on individual laboratory costs.
when ultrasonic extraction techniques are used. Table I1 is a summary of the statistical analysis of the data. The percent recovery and standard deviation a t each concentration level and the correlation coefficients for the linearity of each compound over the range studied are given. This demonstrates that the Polytron Homogenizer procedure produces results which meet or exceed the accuracy and precision requirements necessary for trace level environmental monitoring. We have used the technique with success for the determination of the four compounds discussed in both plant effluent and groundwater samples. Additionally the technique has also been used to extract chlorinated organics from soils efficiently with the emulsions formed easily broken with centrifugation. Table I11 is a summary of the time and cost analysis comparison between the EPA protocol and Polytron Homogenizer procedures for the overall analysis of chlorinated organic compounds in water.
___
125 89 119 86
0.24 0.12 0.13
correlation coefficien tb hexachlorobu tadiene
1589
0.997 0.995 0.996 0.996
Data represent three relicates for each compound at each concentration. Correlation coefficient represents how closely the experimental fits with the expected values and is equal to m o x / o y where m = slope of the line and o x and o y are the standard deviations of x and y array of the data points. a strong preferential solubility in the organic phase (such as the chlorinated organic compounds), extraction efficiencies of 90-100% can be obtained in one 30-s step. This makes it possible to minimize the volume of organic solvent used, greatly reducing the time required to perform the extraction. Also, by using hexane, hexane-benzene, or hexane-toluene instead of hexanemethylene chloride, the concentration step can be eliminated except for GC/MS analysis where only concentration by nitrogen purge would be required. For compounds with less favorable distribution coefficients, pH adjustments and multiple extractions might be necessary and these factors should be examined for individual cases. Because of the very short extraction time and the design of the Polytron Homogenizer, essentially no heat is transferred to the sample during the extraction process. This eliminates the potential for thermal degradation or evaporation loss of the compounds of interest, an effect occasionally observed
ACKNOWLEDGMENT The authors thank G. H. Olsen and K. F. Singley for their assistance. LITERATURE CITED (1) T. A. Beilar and J. J. Lichtenberg, J . Am. Water Works Assoc., 66, 739 (1974). (2) "Sampling and Analysis Procedures for Screening of Industrial Effluents for Priority Pollutants", US. EPA Environmental Monitoring and Support Laboratory, Cincinnati, Ohio, March 1977, revised April 1977. (3) Fed. Regist., 38 (125), Part 11, 17318-23 (1973). (4) "Extraction of Insecticides from Soil", R. Johnson and R. Starr, J . Agric. Food Chem., 20,48 (1972).
RECEIVED for review December 26, 1978. Accepted April 9, 1979.
Determination of Trace Antimony in Phosphoric Acid by Hydride Generation and Nondispersive Flame Atomic Fluorescence Spectrometry Taketoshi Nakahara, Syoji Kobayashi, and SBichirB Musha Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture, Sakai, Osaka 59 1, Japan
In our previous work ( I ) , a markedly enhancing effect of phosphoric acid on the antimony atomic fluorescence signals, the extent of which is directly proportional to the concentration of phosphoric acid, has proved to be due to the presence of a significant amount (Fg/mL range) of antimony as an impurity in the phosphoric acid used. On the other hand, present Japanese Industrial Standard (2)and American 0003-2700/79/0351-1589$01,00/0
Chemical Society (3) specifications for phosphoric acid do not include a specification for antimony. It is said that the levels of 20-30 Fg/mL of antimony as an impurity are generally found in ACS reagent grade phosphoric acid ( 4 ) . We undertook to apply a sensitive nondispersive flame atomic fluorescence method to the determination of antimony frequently present in phosphoric acid. This was carried out with
C
1979 American Chemical Society
