Analytical Methods for Water Disinfection Byproducts in Foods and Beverages

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Analytical methods for water disinfection byproducts in foods and beverages

JAMES H. RAYMER,a EDO PELLIZZARI,a BRENDA CHILDS,a KEITH BRIGGSa AND JODY A. SHOEMAKERb aResearch Triangle Institute, Research Triangle Park, North Carolina 27709 bNational Exposure Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268

The determination of exposure to drinking water disinfection byproducts (DBPs) requires an understanding of how drinking water comes into contact with humanthrough multiple pathways. Inorder to facilitate the investigationof humanexposure to DBPs via foods and beverages, analytical method development efforts were initiated for haloacetonitriles, haloketones, chloropicrin, and the haloacetic acids (HAAs) in these matrices. The recoveries of the target analytes were investigated from composite foods and beverages. Individual foods and beverages used to investigate the general applicability of the developed methods were selected for testing based on their water content and frequency of consumption. The haloacetonitriles, the haloketones, and chloral hydrate were generally well recovered (70±130%), except for bromochloroacetonitrile (64%) and dibromoacetonitrile (55%), from foods spiked after homogenization and following extraction with methyl-t-butyl ether (MTBE); the addition of acetone was found to be necessary to improve recoveries from beverages. The process of homogenization resulted in decreased recoveries for the more volatile analytes despite the presence of dry ice. The HAAs were generally well recovered (70±130%), except for trichloroacetic acid (58%) and tribromoacetic acid (132%), from foods but low recoveries and emulsion formation were experienced with some beverages. With both groups of analytes, certain matrices were more problematic (as measured by volatility losses, emulsion formation) than others with regard to processing and analyte recovery. Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 808±815.

Keywords: beverage analysis, food analysis, haloacetic acids, haloacetonitriles, haloketones, water disinfection byproducts.

Introduction childrenwho might be more susceptible to the effects that result from such exposure. Key to the ability to perform The determination of exposure to drinking water disinfec- such assessments of total ingestion of DBPs is the tion byproducts (DBPs) requires an understanding of how understanding of the interactions of foods and DBPs found drinking waters come into contact with human through in disinfected drinking water. Formed as a result of drinking multiple pathways. A very significant, if not the most water disinfection, DBPs have been reported in foods and significant, pathway of exposure for DBPs other than beverages other than drinking water, particularly those trihalomethanes (THMs) is the ingestion of drinking water. prepared with relatively large amounts of tap water. The Other sources of exposure include inhalation of volatilized Food and Drug Administration (FDA) has published DBPs or dermal absorptiondirectly from tap water. reports indicating the presence of THMs and other Ingestion can occur as direct ingestion of drinking water chlorinated aromatic compounds in beverages and several or as a result of the simple inclusion or more complex foods (Heikes et al., 1995; McNeal et al., 1995). Chang et interactions of tap water with foods. Consumption surveys al. (1988) found that carboxylic acids in fruit juices gave (EPA, 1997a) indicate that approximately 2/3 of the rise to DBPs after treatment with chlorine-containing water. drinking water ingested is through other sources, e.g., In addition, THMs and other halogenated volatiles have frozenjuices, coffee, etc. DBPs may also be formed by beendetected inbeverages usingsolid phase microextrac- direct interaction of foods with disinfectants during tion techniques (Page and Lacroix, 1993). The types and production. levels of DBPs in beverages and foods will depend on the The overall goal of this research was to characterize the disinfection process used to produce the tap water, the exposures of humans to DBPs through foods and beverages. chemical constituents of the source water, and the dynamics A complete characterizationis especially needed for of the water inthe distributionsystem. Although literature reports indicate that THMs are present in beverages and/or foods, little is known about other DBPs such as haloacetic Address all correspondence to: Dr. James H. Raymer, Research Triangle acids (HAAs) and haloacetonitriles. A list of the target Institute, Research Triangle Park, NC 27709. Tel.: +1-919-541-5924. Fax: +1-919-541-7208. E-mail: [email protected] analytes is shown in Table 1; these analytes are the same as Received 10 November 1999; accepted 17 July 2000. those inEPA Methods 551.1 and552.2 (EPA, 1997b). The Water disinfection by-products Raymer et al.

Table 1. Target disinfection byproducts. Individual foods and beverages were used in a screening evaluationto test the generalapplicability of the developed Haloacetonitriles Bromochloroacetonitrile methods. Items were chosen to represent a range of foods Dibromoacetonitrile and beverages with an emphasis on those items often Dichloroacetonitrile consumed by children and prepared with relatively large Trichloroacetonitrile amounts of water. Foods selected were frozen green beans, Other DBPs Chloral hydrate quick grits, long-grain white rice, cream of wheat, white Chloropicrin potatoes, oatmeal, infant cereal (oatmeal), vegetarian 1,1-Dichloro-2-propanone vegetable soup, curly noodle soup, chicken noodle soup, 1,1,1-Trichloro-2-propanone gelatindessert, andspaghetti. All items were prepared HAAs Bromochloroacetic acid (BCAA) according to package directions using reagent water. Each Bromodichloroacetic acid (BDCAA) food was homogenized using a Cuisinart food processor Chlorodibromoacetic acid (CDBAA) (Mini-Prep, Windsor, NJ) after being prepared. A portion Dibromoacetic acid (DBAA) of each food was transferred to a large glass jar with screw Dichloroacetic acid (DCAA) cap lid for storage at À108CtoÀ208C inthe freezer until Monobromoacetic acid (MBAA) needed. The beverages selected were milk-based infant Monochloroacetic acid (MCAA) formula powder, soy-based infant formula powder, frozen Tribromoacetic acid (TBAA) lemonade concentrate, frozen grape juice concentrate, Trichloroacetic acid (TCAA) frozen orange juice concentrate, powdered fruit drink with sugar, powdered fruit drink with NutraSweet, tea, and approaches used inthese methods served as the basis for the coffee. The beverages were prepared with reagent water and method development for food and beverage. Methods that transferred to Nalgene bottles with screw cap lids for storage would provide analyte recoveries between 70% and 130% inthe freezer at À108CtoÀ208C until needed. along with relative standard deviations (RSDs) less than 30% were desired. Sample Extraction

Haloacetonitriles and Other DBPs Food was extracted Methods following dispersion of a 2-g aliquot of homogenized food in10 ml reagentwater followed by the additionof the Food and Beverage Selection and Preparation surrogate standard (decafluorobiphenyl, 100 ng), 5 ml of For most of this work, a high-fat composite food sample methyl-t-butyl ether (MTBE), and 2 g of potassium and a composite beverage sample were used. The high-fat sulfate. Samples were shakenfor 15 minusinga wrist action food composite, approximately 46% of calories from fat, shaker. Following centrifugation to aid in the phase was prepared by combining individual servings of apple- separation, the organic layer was removed and extracted sauce, light wheat bread, white bread, all butter pound cake, with 2 ml of 0.1 M sodium bicarbonate saturated with granola, low-fat American cheese, fruit cocktail packed in potassium sulfate to remove acidic, co-extracted material juice, beef bologna, margarine, mayonnaise, frozen cheese that interfered with separation and detection during gas French bread pizza, potato chips, and canned, mixed chromatographic analysis. Bromofluorobenzene (500 ng) vegetables. For initial method development, aliquots of was used as an internal standard and was added to 1 ml of foods were spiked with target analytes following homo- extract just prior to analysis. Method blanks, prepared using genization using a food processor (Robot Coupe; model only reagent water, were used to evaluate background from RSI6V, Ridgeland, MS). Aliquots of food were stored reagents; at least one method blank was included with each frozenat À108CtoÀ208C inglass jars until use. In batch of samples. experiments to measure the recoveries of analytes and to The extractionmethod for beverages was identicalto the determine method detection limits (MDLs), foods were method used for foods except that 4 ml of acetone was spiked prior to homogenization followed by immediate added to 10 ml of beverage prior to the additionof the extraction and analysis. Dry ice (10% of total food mass) MTBE; no additional water was added. The acetone was was added to the foods during homogenization to minimize found to improve the recovery of chloropicrin from losses of target analytes resulting from volatilization. The beverages. composite beverage consisted of equal parts whole milk, orange juice, coffee, and cola. Composite beverage was HAAs The method employed for the HAAs was the same for stored frozenat À108CtoÀ208C until needed. Beverages both foods and beverages. Surrogate standard (2,3- used for the MDL studies were prepared and extracted dibromopropionic acid, 800 ng) was added to foods (2 g immediately following spiking with target analytes. of homogenized food dispersed in 10 ml of reagent water)

Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 809 Raymer et al. Water disinfection by-products or 10 ml of beverage. Three milliliters of 0.5 M phosphate the amount found in the method control. Absolute buffer at pH 6.2 was added, the pH was checked using recoveries from reagent water ranged from 60% for narrow range pH indicator strips, and more buffer was trichloroacetonitrile to 101% for dichloromoacetonitrile added if the pH was less than6.2. The sample was then (all were above 70% except for trichloroacetonitrile). The extracted (15 minusinga wrist actionshaker) with 20 ml of methyl esters of HAAs were quantified relative to MTBE to remove potentially interfering compounds (bases calibration curves generated by adding known amounts of and neutrals). Following centrifugation, the organic layer HAAs to reagent water and subjecting them to the was separated and discarded and the pH was adjusted to extraction/derivatization/analysis method. The majority of near zero using 0.5 ml concentrated sulfuric acid. the preliminary work involving the HAAs were quantitated Anhydrous sodium sulfate (3 g) and copper II sulfate versus a single-point calibration standard resulting from the pentahydrate (0.5 g) were added and mixed. A volume of 4 derivatization and analysis of standard compounds spiked ml of MTBE was added and the sample was extracted for 15 into water at the same concentration as in the test case. min using a wrist action shaker. Following centrifugation, 3 Duplicate or triplicate standards were prepared. A single- ml of the MTBE layer was placed into a conical 15-ml point calibration was used in early development to identify centrifuge tube and 1 ml of 10% sulfuric acid in methanol major problems that would need to be overcome; the degree was added. The tube was capped, vortexed, and equilibrated of accuracy from a single point was considered acceptable ina water bath at 65 8C for 3 h to form methyl esters of the for this purpose. Later experiments to determine overall acids. The sample was cooled for 10 minand4 ml of method precision, recovery, and MDLs were quantitated saturated sodium bicarbonate solution was added in 1-ml versus a five-point procedural calibration curve. increments. After each addition, the samples were capped and shaken with frequent venting. One milliliter of the Studies of Recovery, MDL MTBE layer was transferred to an autosampler vial and The recoveries of the target analytes were investigated at 1250 ng of 1,2,3-trichloropropane was added as an internal approximately 30 ppb infood and6 ppb inbeverage for standard followed by gas chromatography (GC) analysis. haloacetonitriles and 30±135 ppb in food and 10±100 ppb Method blanks, as described above, were also analyzed. in beverage for HAAs. Spiking was conducted by introducing the appropriate mass of analytes dissolved in Sample Analysis MTBE (15±125 l) to 10 ml of composite beverage or 2 g All samples were analyzed using GC with electron capture of food composite dispersed in10 ml of water. Preliminary detection(GC/ECD). A 1- l aliquot of extract was experiments, which involved spiking the food homogenate introduced into the GC using splitless (30 s) /split with the target compounds and mixing them together prior injection. Haloacetonitriles were separated using a DB-1 to the addition of water to determine if the direct interaction capillary column(30 m Â0.25 mm i.d., 1 m film of the analytes with food had an impact on recoveries, were thickness; J&W Scientific, Folsom, CA) installed in a conducted. Following optimization of the methods, recov- Hewlett-Packard 5890 GC. The initial oven temperature eries were evaluated following spiking of the food prior to was 358C for 9 minfollowed by a ramp to 40 8Cat18C/ homogenization to provide the same concentrations. min(3-minhold) then6 8C/minto 260 8C (1-minhold). Recoveries of 70±130% with percent RSDs less than 30% The injector temperature was 2008C and the detector were goals for the methods. temperature was 3008C. Derivatized HAAs were separated Recoveries of analytes from individual test foods were using a DB-5.625 capillary column (30 mÂ0.25 mm i.d., evaluated following spiking of the homogenized aliquot 0.25 m film thickness; J&W Scientific) installed in a prior to the additionof water; beverages were spiked just Fisons 8360 GC. The initial oven temperature was 358C for prior to extraction. Spiking concentrations for the haloace- 10 minfollowed by a temperature ramp to 75 8Cat58C/ tonitriles and ``other'' DBPs were 30 ppb for food and 6 ppb min(15-minhold) andthento 135 8Cat58C/minthento for beverage. Spiking concentrations for the HAAs were 1958Cat108C/min. The injector was maintained at 2008C 200±600 ppb for foods and 40±120 ppb for beverages. and the detector was held at 2608C. Chromatographic data The MDLs were estimated following extraction and were acquired using Multichrom (version 2; VG Data analysis of seven replicates of a composite high-fat food Systems, Cheshire, UK). spiked prior to homogenization and seven replicates of Haloacetonitriles and ``other'' DBPs were quantified spiked beverage. Composite beverage was used for the using calibration curves generated by GC analysis of haloacetonitriles and 100% orange juice was used for standard solutions of the analytes in MTBE. Recoveries of HAAs. The spiking concentrations were chosen to provide analytes from test matrices were corrected for recovery from chromatographic signals corresponding to approximately the method controls (reagent water spiked at the test two times the estimated method detectionlimit (EMDL). concentration and carried through the entire extraction The EMDL was estimated based on the signal-to-noise procedure) by dividing the amount found in the test case by ratio of the chromatographic peaks. The signal-to-noise

810 Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 Water disinfection by-products Raymer et al. ratios were measured and an estimate of the concentrations were less than10%. Bromoacetonitrilewas recovered at required to provide a S/N of approximately 2±3 was made. 23% and dichloroacetonitrile was recovered at 59%. The Calculations were not adjusted for recoveries from method losses appeared to be related to volatility despite the controls. The standard deviation from the seven replicates addition of dry ice during homogenization that rendered the spiked at the EMDL was determined and the MDL was food semi-frozen at the end of processing. In general, these calculated by multiplying this value by 3.143 (student t analytes have relatively low solubility in water which would value for one-tailed distribution with 6 df at the 0.99 favor volatilization. Despite the low recoveries, precisions confidence level; Glaser et al., 1981). were better than30% RSD. The MDLs, which are shownin Table 2, ranged from 2.3 ppb for 1,1,-dichloro-2- propanone to 27 ppb for dibromoacetonitrile. Due to low Results and discussion recoveries, MDLs were not calculated for chloropicrin or trichloroacetonitrile. Haloacetonitriles and Other DBPs A preliminary study of food composites with varying fat When the target analytes were spiked at 30 ppb into high-fat content showed that better recoveries were obtained from food homogenate dispersed in water, background-sub- foods with greater fat content, especially for trichloroace- tracted recoveries relative to the method control (spiked tonitrile where the recovery decreased from 8.6% from a water) were withinthe target 70±130% rangeexcept for composite food that was 46% fat to 0.86% from a food chloropicrin (56%), bromochloroacetonitrile (64%), and composite that was 6% fat (data not shown). This is dibromoacetonitrile (55%). All percent RSDs were less consistent with losses due to volatility. The application of than 30%. Background concentrations in food were <5% of the method to foods prepared, homogenized, and spiked the spike level. Whenthe spikingsolutionwas mixed with 2 with target analytes showed that the method performance g of food aliquot prior to the additionof water, the percent depended on the food under study, although recoveries recovery of chloropicrin dropped to near zero. Increasing within the 70±130% range were achieved for many of the the concentration to 300 ppb did not result in any analytes in many of the matrices. Of all the matrices tested, improvement, indicating that chloropicrin reacts or is the recoveries were worst for the white potatoes with only irreversibly adsorbed to the matrix. The additionof acetone three of eight target analytes within the desired range of 70± did not improve the recovery as it had for beverages. 130%. Inall of the other foods, at least four of the Samples collected during a field study would contain any compounds were acceptable. The results from the food target analyte at the time of collection and before screening experiments are shown in Table 3. The greatest homogenization. Thus, spiking the foods once they had variability inrecoveries was observed for trichloroacetoni- been homogenized is not representative of the situation trile (36±127%), chloropicrin(notdetected to 110%), where an incurred contaminant or residue is present at the bromochloroacetonitrile (45±172%), and dibromoacetoni- time of sample collection. This scenario would be best trile (19±242%). Ingeneral,the RSDs were less than20%. mimicked by spiking the foods prior to homogenization. The brominated compounds also had low ECD responses Recoveries obtained when the food was spiked prior to (S:N12:1) so the greater variability could be attributed, in homogenization were acceptable only for chloral hydrate part, to these low signals. Given that the recoveries were (119%), 1,1-dichloro-2-propanone (75%), and 1,1,1- corrected for measured background concentrations in the trichloro-2-propanone (123%). The recoveries for tri- food composites as well as individual foods, it is difficult to chloroacetonitrile, chlorpicrin, and dibromoacetonitrile explainrecoveries inexcess of 130%, although matrix-

Table 2. MDLs for haloacetonitriles and other DBPs in high-fat composite food and beverage composite.

Compound High-fat composite fooda Composite beveragea Spike level (ppb) SD Calculated MDL (ppb) Spike level (ppb) SD Calculated MDL (ppb) Trichloroacetonitrile 101 ± b NCb 2.0 ± NC Dichloroacetonitrile 10 1.02 3.2 2.0 0.14 0.44 Chloral hydrate 10 0.80 2.5 2.0 0.10 0.31 1,1-Dichloro-2-propanone 10 0.73 2.3 2.0 0.09 0.28 Chloropicrin101 ± NC 2.0 ± NC Bromochloroacetonitrile 101 8.3 26 2.0 0.23 0.72 1,1,1-Trichloro-2-propanone 10 1.2 3.7 2.0 0.13 0.41 Dibromoacetonitrile 101 8.59 27 2.0 0.21 0.66 an=7; measured concentrations not corrected for background. bNot calculated due to low percent recoveries.

Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 811 Raymer et al. Water disinfection by-products

Table 3. Percent recovery of haloacetonitriles and other DBPs from screening foods.a

Analyte Cream Grits Oatmeal Infant Spaghetti White White Green Pinto Carrots Chicken Vegetarian of wheat cereal rice potatoes beans beans noodle soup vegetable soup Trichloroacetonitrile 65 36 66 127 80 92 108 66 65 50 55 83 Dichloroacetonitrile 102 101 105 122 111 116 133 105 116 69 83 97 Chloral hydrate 99 101 102 111 106 122 132 102 103 76 86 102 1,1-Dichloro-2-propanone 109 110 111 128 125 121 158 111 117 89 94 101 Chloropicrin39 3.2 19 110 9.4 13 9.4 19 ND b 20 16 78 Bromochloroacetonitrile 45 45 103 195 137 147 172 103 106 81 77 95 1,1,1-Trichloro-2-propanone 105 110 110 132 126 143 158 110 137 89 102 109 Dibromoacetonitrile 19 23 90 285 173 185 215 90 148 81 73 93 an=2; corrected for background, spiked at 30 ppb. bND=not detected. induced peak enhancement, as reported for organopho- sulfuric acid (data not shown). The recoveries increased for sphorus pesticides inmilk extracts (Erneyet al., 1993, trichoroacetonitrile (65%), dichloroacetonitrile (175%), 1997), could play a role. The recoveries of dichloroaceto- chloropicrin(94%), bromochloroacetonitrile (251%), nitrile and 1,1-dichloro-2-propanone were almost always 1,1,1-trichloro-2-propanone (123%), and dibromoaceto- withinthe 70±130% recovery range;chloral hydrate was nitrile (212%), but only two compounds were within the well recovered from all foods tested. Nonetheless, such desired range of 70±130% (data not shown). Despite a variability indicates that caution should be used when potential change in recovery following acidification, the reporting and comparing concentrations from homogenates disruptionof the emulsiondoes permit ananalysisif a of variable composition, such as those collected in a field greater uncertainty can be accepted. The estimated MDLs study. for composite beverage, showninTable 2, rangedfrom 0.28 The recoveries of the target analytes from different ppb for 1,1-dichloro-2-propanone to 0.72 ppb for bromo- beverages also showed some variability. From composite chloroacetonitrile. Due to the low recoveries measured for beverage spiked at 6 ppb, the recoveries for all target trichloroacetonitrile and chloropicrin, MDLs were not analytes, except trichloroacetonitrile and chloropicrin (less calculated. than 70%) and bromochloroacetonitrile ( >130%), were The method was applied to several test beverages to within the target range for recovery (data not shown). All determine if recovery was dependent on the beverage precisions were within the 30% RSD goal. In experiments matrix. The results from these experiments are shown in conducted with orange juice, recoveries for trichloroaceto- Table 4. As with the foods, the percent recovery for nitrile, chloropicrin, and dibromoacetonitrile were less than trichloroacetonitrile was variable, ranging from 4% in soy- 70%. Persistent emulsions were formed when large amounts based infant formula to 165% in lemonade. Chloropicrin of milk were part of the beverage which prevented the showed low recovery from infant formula and orange juice. remainder of the extraction from being completed in the The recoveries for bromochloroacetonitrile and dibromoa- screening study. A later experiment was done with cetonitrile were in the acceptable range in 25% of the composite beverage that showed that the emulsions could experiments, but were as high as 242% in the remainder. be disrupted through acidificationof the sample with Thus, the method can be applied only to dichloroacetoni-

Table 4. Percent recovery of haloacetonitriles and other DBPs from screening beverages.a

Analyte Powdered fruit Powdered fruit Soy Lemonade Grape juice Orange juice Tea Coffee drink (sugar) drink (Nutrasweet) formula Trichloroacetonitrile 125 124 4.0 165 136 54 118 112 Dichloroacetonitrile 96 111 93 126 100 109 110 117 Chloral hydrate 112 116 115 141 141 114 111 115 1,1-Dichloro-2-propanone 101 106 90 118 102 103 103 106 Chloropicrin118 127 24 112 115 25 115 118 Bromochloroacetonitrile 110 141 58 173 138 75 149 167 1,1,1-Trichloro-2-propanone 103 117 97 131 112 106 111 121 Dibromoacetonitrile 115 154 90 216 174 66 190 242 an=2; corrected for background, spiked at 6 ppb.

812 Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 Water disinfection by-products Raymer et al.

Table 5. MDLs for HAAs from high-fat composite food and orange juice.a

Compound High-fat composite food Orange juice Spike level (ppb) SD Calculated MDL (ppb) Spike level (ppb) SD Calculated MDL (ppb) Chloroacetic acid 100 8.27 26 20 12.1 38 Bromoacetic acid 20 10.8 34 4.0 2.39 7.5 Dichloroacetic acid 30 3.82 12 6.0 4.14 13 Trichloroacetic acid 10 1.27 4 2.0 0.80 2.5 Bromochloroacetic acid 20 4.77 15 4.0 1.02 3.2 Dibromoacetic acid 10 2.54 8 2.0 0.54 1.7 Bromodichloroacetic acid 20 9.86 31b 4.0 ± c NCc Chlorodibromoacetic acid 20 7.95 25b 4.0 ± NC Tribromoacetic acid 20 3.02 9.5b 4.0 ± NC aSeven replicate preparations and extractions; ppb=ng/ml with 10 ml aliquot. bResponse was very low for these compounds in some of the replicates. cNot calculated since recovery was very poor at much higher spike concentrations. trile, 1,1-dichloro-2-propanone, and 1,1,1-trichloro-2- precisions for all analytes except bromoacetic acid were less propanone with any degree of confidence. Larger uncer- than30% RSD. tainties must be accepted for the other analytes. The MDLs, which were calculated from high-fat food spiked with target analytes ranging in concentration from 10 HAAs to 100 ppb, ranged from 4 ppb for trichloroacetic acid to 34 Recoveries for all of the target analytes spiked at 30±135 ppb for bromoacetic acid and are shown in Table 5. ppb after homogenization of high-fat food fell between Applicationof the method to composite beverage spiked 70% and 130% except for trichloroacetic acid (58%) and at 10±100 ppb showed that only bromodichloroacetic acid tribromoacetic acid (132%) (data not shown). The percent fell withinthe target 70±130% recovery and <30% RSD RSDs exceeded 30% for trichloroacetic acid (31%), (data not shown). However, bromodichloroacetic acid from chlorodibromoacetic acid (38%), and tribromoacetic acid one of the three replicates was not detected and this suggests (41%). The ionic nature and lower volatility of these acids that the method is not reliable. It is likely that the milk, at ``typical'' food pH canhelp explainbetter recovery which consistently formed a very persistent emulsion in the relative to haloacetonitriles. When the acids were spiked composite beverage, caused many of the problems. The prior to homogenization, the recoveries were above the beverages resulted incomplex chromatograms. The method 130% level for chloroacetic acid (140%), chlorodibromoa- control samples (spiked water) agreed with the actual spike cetic acid (144%), and tribromoacetic acid (150%). levels to within 25%, indicating reliable performance of the Matrix enhancement is a possible explanation for this. The method for this set of composite beverage samples.

Table 6. Percent recovery of HAAs from screening foods.a

Analyte Spike White Grits White Cream Infant Oatmeal Pinto Green Carrots Chicken Curly Vegetarian concentration potatoes rice of wheat oatmeal beans beans noodle noodle vegetable (ppb) b soup soup soup Chloroacetatic acid 600 93 99 92 93 88 104 88 78 98 88 90 92 Bromoacetic acid 400 100 94 95 97 107 107 95 89 91 96 93 94 Dichloroacetic acid 600 100 91 91 91 66 104 101 94 93 93 91 93 Trichloroacetic acid 200 107 88 86 86 88 103 105 87 96 90 94 97 Bromochloroacetic acid 400 101 88 89 90 97 100 98 87 95 97 93 93 Dibromoacetic acid 200 102 85 88 94 94 92 82 81 92 96 91 92 Bromodichloroacetic acid 400 106 80 86 86 95 100 97 85 96 88 89 90 Chlorodibromoacetic acid 400 108 73 84 84 98 102 84 77 94 94 86 89 Tribromoacetic acid 200 104 70 95 102 94 104 77 67 98 85 79 91 2,3-Dibromopropionate 400 108 91 89 88 99 94 87 88 94 94 88 92 (surrogate standard) an=2, corrected for background. bppb=ng/g.

Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 813 Raymer et al. Water disinfection by-products

Table 7. Percent recovery of HAAs from screening beverages.a

Analyte Spike Powdered Powdered Soy Lemonade Grape Orange Tea Coffee concentration fruit drink fruit drink formula juice juice (ppb) b (sugar) (Nutrasweet) Chloroacetic acid 120 152 93 62 96 134 67 97 82 Bromoacetic acid 80 95 95 85 91 85 65 104 78 Dichloroacetic acid 120 103 93 78 102 99 76 97 94 Trichloroacetic acid 40 93 94 91 97 96 67 55 82 Bromochloroacetic acid 80 92 98 85 95 95 80 81 91 Dibromoacetic acid 40 42 87 78 88 58 71 77 63 Bromodichloroacetic acid 80 12 96 64 73 3 18 40 4 Chlorodibromoacetic acid 80 5 91 46 78 1 6 37 À12c Tribromoacetic acid 40 3 81 20 41 2 NDd 26 ND 2,3-Dibromopropionate (ss) 80 88 110 78 84 90 80 118 91 an=2; corrected for background. bppb=ng/ml. cSubstantial background peak in matrix blank.

The method performance was different when orange Conclusions juice was used as the matrix. Although bromodichloroacetic acid, chlorodibromoacetic acid, and tribromoacetic acid The method developed for haloacetonitriles and haloketones were not recovered, all of the other analytes were within the in foods shows variability in recovery depending on the target performance parameters of 70±130% recovery and food matrix but is generally acceptable for all, but <30% RSD. Irreversible interactions with the orange juice chloropicrin, if the DBPs are spiked into homogenates prior matrix or decompositioninthe presenceof the matrix to dispersion in water. However, significant losses of most cannot be ruled out. of the analytes occur upon homogenization, despite cooling The MDLs determined for orange juice showed that of the sample to minimize volatilization losses. Given the chloroacetic acid, the compound with the lowest response, low recoveries obtained when spiking was done prior to has anMDL of 38 ppb while the others, except for homogenization, substantial uncertainties will result in the bromodichloroacetic, chlorodibromoacetic, and tribromoa- concentrations measured from field samples and the food cetic acids, are 13 ppb or less. These results are shownin method will have limited applicability to exposure analysis Table 5. where the foods must be homogenized prior to extraction. The screening results, using the same foods and Isotope dilutionis a possible analyticalmethod to improve beverages studied with the haloacetonitriles, are presented the accuracy of the measurements as long as the analytes are in Tables 6 and 7. The method was found to provide detectable. Losses facilitated by analyte volatility suggest acceptable recovery and precision for most of the individual reduced humanexposure from foods that are heated before foods tested (Table 6). The RSD for tribromoacetic acid consumption. Studies are ongoing to investigate the impact was large for certain matrices (green beans, grits, pinto of cooking/heating on potential exposure. The method beans) due to the inconsistency in recovery of this analyte. works much better whenapplied to beverages but some The method is not as effective for most individual beverage analytes, especially trichloroacetonitrile, chloral hydrate, matrices (Table 7). The effectiveness of the method is and chloropicrin, are sometimes poorly recovered. For limited mainly by the recoveries of bromodichloroacetic composite beverage, the recoveries for all target analytes, acid, chlorodibromoacetic acid, and tribromoacetic acid. except trichloroacetonitrile and chloropicrin (less than The method showed unsatisfactory performance for whole 70%) and bromochloroacetonitrile ( >130%), were within milk and milk-based infant formula due to the emulsion the target range for recovery. All precisions were within the formation that resulted in an inability to recover any MTBE. 30% RSD goal. Inorangejuice, recoveries for trichlor- The use of larger amounts of extraction solvent to overcome oacetonitrile, chloral hydrate, and chloropicrin were less the phase separationproblems met with limited success but than 70%; the recovery for 1,1-dichloro-2-propanone was resulted ina greatly diluted sample extract. Analternate slightly above the 130% upper limit. The use of this method cleanup based on separation of the lipid or proteinaceous for beverages will have utility inthe determinationof the material from the rest of the extract components, e.g., using significance of exposure to DBPs. In all cases, corrections Florisil for lipids or ultrafiltrationfor proteins,might help for recovery using spiked water (method control samples) but was not attempted in this work. should be used for these analytes.

814 Journal of Exposure Analysis and Environmental Epidemiology (2000) 10(6) Part 2 Water disinfection by-products Raymer et al.

The method developed for HAAs generally shows good authors thank Mr. David P. White for assistance with some recovery from foods for the target analytes both when of the analyses. spiked before or after homogenization. The variability among food types is far less significant for the HAAs compared to the haloacetonitriles and haloketones, pre- References sumably because of their greater polarity and lower volatility. Dichloroacetic acid and tribromoacetic acid were Chang T.-L., Streicher R.P., Zimmer H., and Munch J.W. The interaction each outside of the 70±130% recovery range in 1 of 14 of aqueous solutions of chlorine with malic acid, tartaric acid, and individual foods tested. In the individual beverages, various fruit juices. A source of mutagens. Anal. Lett. 1988: 21 (11): 2049±2067. chlorodibromoacetic acid and tribromoacetic acid were EPA. Exposure Factors Handbook. General Factors, Vol. 1. United States outside of the accepted range in 8 of 10 beverages tested. Environmental Protection Agency, Office of Research and Develop- Trichloroacetic acid and bromoacetic acid were outside the ment, Washington, DC, 1997a, EPA/600/P-95/002Fa. accepted limits in30% of the matrices. Dibromoacetic acid, EPA. Methods and Guidance For Analysis of Water. United States chloroacetic acid, and bromodichloroacetic acid were Environmental Protection Agency, Office of Water, Washington, DC., April 1997b, EPA/821/C-97/001. beyond the range in 50%, 60%, and 70% of the matrices, Erney D.R., Gillespie A.M., Gilvydis D.M., and Poole C.F. Explanation of respectively. Therefore, the method is adequate for use to the matrix-induced chromatographic response enhancement of study the extent of HAA DBP contamination of individual organophosphorus pesticides during open tubular column gas foods as well as food composites. The use of the method for chromatography with splitless or hot on-column injection and flame beverages will give variable results depending on the photometric detection. J. Chromatogr. 1993: 638: 57±63. Erney D.R., Pawlowski T.M., and Poole C.F. Matrix-induced peak matrix, but will be adequate if the window of acceptable enhancement of pesticides in gas chromatography: is there a solution? recovery is expanded to 50% on the low end. The method is J. High. Resolut. Chromatogr. 1997: 20: 375±378. very unreliable for bromodichloroacetic acid, chlorodibro- Glaser J.A., Foerst D.L., McKee G.D., Quave S.A., and Budde W.L. Trace moacetic acid, and tribromoacetic acid in beverages because analyses for wastewaters. Environ. Sci. Technol. 1981: 15 (12): these analytes appear to react with the matrix or decompose 1426±1435. Heikes D.L., Jensen S.R., and Flemming-Jones M.E. Purge and trap under certain conditions. extraction with GC/MS determination of volatile organic compounds in table-ready foods. J. Agric. Food. Chem. 1995: 43: 2869±2875. Acknowledgments McNeal T.P., Hollifield H.C., and Diachenko G.W. Survey of trihalomethanes and other volatile chemical contaminants in processed foods This research was funded by the U.S. Environmental by purge and trap capillary gas chromatography with mass selective detection. J. AOAC. Int. 1995: 78: 391±397. Protection Agency through contract no. 68-C5-0011. This Page B.D., and Lacroix G. Application of solid phase microextraction to research has not been subjected to agency review and no the headspace gas chromatographic analysis of halogenated volatiles in official endorsement by the agency should be inferred. The selected foods. J. Chromatogr. 1993: 648: 199±211.

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