458 MILES ET AL.: J. ASSOC. OFF. ANAL. CHEM. (VOL. 69, NO. 3, 1986)

The method illustrates the usefulness of semiautomation toimprove the speed and reproducibility of analytical methods.

AcknowledgmentsWe thank C. Shewchuk, P. Baddoo, and N. Gurprasad for

technical assistance.

REFERENCESWilliams, D. T., LeBel, G. L., & Junkins, E. (1984) J. Toxicol.Environ. Health 13, 19-29LeBel, G. L., & Williams, D. T. (1983) J. Assoc. Off. Anal.Chem. 66, 691-699

Mes, J., Davies, D. J., & Turton, D. (1982) Bull. Environ.Contam. Toxicol. 28, 97-104Mes, J., Campbell, D. S., Robinson, R. N., & Davies, D. J.(1977) Bull. Environ. Contam. Toxicol. 17, 196-203Ault, J. A., & Spurgeon, T. E. (1984) J. Assoc. Off. Anal. Chem.67, 284-289Tessari, J. D., Griffin, L., & Aaronson, M. J. (1980) Bull. Envi-ron. Contam. Toxicol. 25, 59-64Ribick, M. A., Dubay, G. R., Petty, J. D., Stalling, D. L., &Schmitt, C. J. (1982) Environ. Sci. Technol. 16, 310-318MacLeod, K. E., Hanisch, R. C., & Lewis, R. G. (1982) J.Anal. Toxicol. 6, 38-40Wright, L. H., Lewis, R. G., Crist, H. L., Sovocool, G. W., &Simpson, J. M. (1978) J. Anal. Toxicol. 2, 76-79Lee, B. E., Lacroix, M. D., Dupont, G. A., & Scott, J. A. (1984)J. Assoc. Off. Anal. Chem. 67, 546-548

Determination of Glyphosate Herbicide and (Aminomethyl)phosphonic Acid in Natural Watersby Liquid Chromatography Using Pre-Column Fluorogenic Labeling with 9-FluorenylmethylChlorofor mate

CARL J. MILES, LOUIS R. WALLACE, and H. ANSON MOYE'University of Florida, Department of Food Science and Human Nutrition, Pesticide Research Laboratory,Gainesville, FL 32611

An analytical method has been developed for determination of gly-phosate herbicide and its major metabolite, (aminomethyl)phosphonicacid (AMPA), in natural waters. Sample pretreatment consisted offiltration, addition of phosphate buffer, concentration by rotary evap-oration, and a final filtration before derivatization with 9-fluorenyl-methyl chloroformate. The derivatives were separated by anion exchangeliquid chromatography and measured with a fluorescence detector.Standard curves were linear over 3 orders of magnitude and minimaldetectable quantities were 10 ng/mL for glyphosate and 5 ng/mL forAMPA. The 20-fold concentration factor realized in sample prepara-tion corresponds to ppb method detection limits for glyphosate andAMPA in natural waters. Recovery and storage studies were performedand are discussed.

Glyphosate [N-(phosphonomethyl) glycine; Roundup®] is abroad spectrum, nonselective, post-emergence herbicide thathas found widespread agricultural and domestic use. Recently,it has been introduced for the control of aquatic weeds(Rodeo®). Analytical methods development for the deter-mination of glyphosate in environmental samples has notbeen avidly pursued, largely because of its low mammaliantoxicity (LD 50 = 1568 mg/kg) and subsequent low risk ofenvironmental pollution. Nevertheless, the effect of glyphos-ate on nontarget organisms and its overall environmental fatecannot be fully evaluated unless techniques possessing suit-able sensitivity and selectivity are available.

Several chromatographic methods have been developedfor the analysis of glyphosate and its major metabolite, (ami-nomethyl)phosphonic acid (AMPA), including gas chroma-tography (GC) after chemical derivatization (1-3), thin layerchromatography (4, 5), and liquid chromatography (LC; 6,7). Recently, these methods and several others have beenreviewed (8). The ionic, water-soluble character of glyphos-

Received June 10, 1985. Accepted September 16, 1985.University of Florida Agricultural Experiment Stations Journal Series No.

6577.'Address correspondence to this author.

ate and AMPA make analysis by LC advantageous over GC.Although glyphosate and AMPA cannot be sensitively mea-sured by conventional photometric LC detectors, highly flu-orescent derivatives can be formed pre-column, using 9-flu-orenylmethyl chloroformate (FMOCC1) (6), or post-columnwith orthophthalaldehyde-mercaptoethanol (OPA-MERC) (7).The post-column procedure forms derivatives on-line but itrequires more instrumentation and careful maintenance.Conversely, the pre-column method is rapid and simple andrequires minimal equipment and analyst experience.

Analysis of glyphosate and AMPA by LC as FMOC deriv-atives has been applied to vegetation (9, 10) and water andsoil (11). Glass (11) reported good recoveries and detectionlimits for glyphosate in water but the procedure required ion-exchange cleanup and AMPA was not determined. We haveapplied this pre-column LC procedure to the analysis of gly-phosate residues in natural waters. We report a shortenedsample preparation and include the determination of AMPA.Method limitations and recoveries from fortified water sam-ples are discussed.

Experimental

Sample PreparationNatural waters investigated included rainwater, lake water,

and river water from a forest watershed; samples were col-lected and frozen in polyethylene bottles until analyzed. Peri-odically, frozen samples were thawed and thoroughly shakento mix, and about 150 mL was filtered through Whatman No.1 paper. In recovery experiments, samples were fortified withherbicide and metabolite before this filtration. A 100 mLaliquot of this water was placed into 250 mL round-bottomflask and 1 mL 0.1M K 2HPO, was added. Samples wereconcentrated to near-dryness by rotary evaporation (BuchiModel R; Brinkman) at 30-50°C and diluted to 5.0 mL bycarefully rinsing the flask twice with 2 mL washes of deion-

459MILES ET AL.: J. ASSOC. OFF. ANAL. CHEM. (VOL. 69, NO. 3, 1986)

Table 1. Capacity factors for AMPA and glyphosate derivatives onselected columns'

Derivative

Column°

AMPA Glyphosate

y.NH 2 (Alltech)

1.14

2.45N(CH 3 ) 2 (Macherey-Nagel)

1.38

1.77pLarbohydrate (Waters)`

1.10

3.10SAX (Altex)

0.70 >5.7

'75% v/v mixture of 0.05M KH 2PO4 (pH 6.0) in acetonitrile.°SAX column is a strong anion exchanger; all others are weak anionexchangers.

'75% v/v mixture of 0.1M KH 2PO4 (pH 6.0) in acetonitrile.

ized water. They were stored at 4°C if not analyzed imme-diately.

Standard PreparationFifty mg glyphosate (Monsanto) or AMPA (Sigma) was

dissolved in 500 mL deionized water to yield 100 ug/mL stocksolutions. Mixed standards (glyphosate and AMPA) coveringthe range of 0.005-10 u.g/mL were prepared by appropriatedilutions of the stock solutions in deionized water. Standardsolutions were refrigerated and no degradation was observedover 6 months.

DerivatizationApproximately 0.5-1 mL sample concentrate was passed

through a Gelman GA-8 (0.2 ilm) filter and into a 2 mL glassvial. A 0.10 mL aliquot of filtered sample was placed in asmall glass culture tube, followed by 0.90 mL 0.025M boratebuffer, 0.90 mL LC grade acetone, and 0.10 mL 0.01M 9-fluorenylmethyl chloroformate (FMOCC1; Aldrich) in ace-tone. Tubes were shaken and allowed to react 20 min at roomtemperature. Excess reagent was removed by three 1 mLwashes of ethyl ether (top layer). Samples were analyzedwithin 8 h.

Liquid ChromatographyThe instrument used consisted of an Altex Model 110A

pump, Rheodyne Model 7125 injector (200 p.L loop), 0.4 x25 cm iLNI-1 2 column (Alltech Assoc.), Aminco spectropho-tofluorometer (excitation 270 nm; emission 315 nm) equippedwith 50 u.L flow cell, and Soltec strip chart recorder (50 mV).Mobile phase consisted of 75% (v/v) mixture of 0.05M KH2PO4(pH 6.0 with KOH) in acetonitrile (Fisher LC grade) deliveredat 1.0 mL/min. Glyphosate and AMPA were measured bycomparing peak heights of samples to external standard curveof at least 3 points.

During the development of this method, the following LCcolumns (all 0.4 x 25 cm) were also evaluated: N(CH3)2(Macherey-Nagel),11Carbohydrate (Waters), and SAX (Altex).Also, a Gilson Specta/Glo filter fluorometer (excitation 280nm; emission 300-400 nm) equipped with 8 1.1.L flow cell wascompared with the spectrophotofluorometric instrument.

Storage StudyTwo separate storage studies were performed. Control water

samples with added propionic acid (3 mL/300 mL sample)were fortified with glyphosate and AMPA at 0.05 and 0.50ppm and stored in a refrigerator (4°C) for 3 months. Controlwater samples (no propionic acid) were fortified with gly-phosate at 0.05 and 0.50 ppm and frozen (0°C) for 3 months.Subsequently, these samples were prepared and analyzed asdescribed above.

Results and DiscussionSince glyphosate and AMPA are zwitterionic molecules,

formation of their respective FMOC derivatives by reactionof the amine (analyte) and the acid chloride (FMOCC1) yieldsanionic compounds which can easily be separated by anionexchange liquid chromatography (6). Several anion exchangestationary phases were examined, and in all cases, AMPA-FMOC, the weaker acid, eluted before glyphosate-FMOC(Table I). Efficiency on all of these columns ranged from 2000to 3000 theoretical plates. For the 4 different stationary phasesexamined, maximum retention of AMPA-FMOC was observedwith the dimethylamine moiety (N(CH3)2), while glyphosate-FMOC was retained longest on the SAX column under theconditions tested. These conditions (0.1-0.05M phosphatebuffer with 25% acetonitrile) offered the best compromisebetween good sensitivity and reasonable retention time.Phosphate buffer was the only salt evaluated and other buff-ers could significantly affect separation behavior. Substitu-tion of methanol for acetonitrile resulted in significant dete-rioration of efficiency.

Practical application of chromatographic methods to envi-ronmental samples requires that analyte retention be con-trolled such that interference peaks can be circumvented. Inanion exchange, retention usually can be increased by adecrease in ionic strength of buffer and/or an increase in pH(12). On silica-based stationary phases, a decrease in thepercentage of organic modifier will also increase retention.Our experience with the columns examined has been that adecrease in ionic strength or percentage of acetonitrile increasesretention at the expense of significantly degraded peak shapeand sensitivity (see Figure 1).

Glyphosate-FMOC retention could easily be controlled bychanging the buffer pH, especially on the SAX column. How-ever, for AMPA-FMOC, varying the pH did not significantlyincrease retention on any of the stationary phases evaluated.Retention increased slightly from pH 4 to 6, but decreased aspH was increased to 8. Roseboom and Berkhoff (10) reportedthat the mobile phase pH (5-8) had no effect on the retention

4n_24

0 2 4 6 8 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 16 le 20111 11/11 1111111111111 111

MIH M11,1 M.

Figure 1. Chromatograms of AMPA-FMOC and glyphosate-FMOC stan-dards on ILNH2 column with different mobile phases, demonstratingdecrease In efficiency with decreased percent organic modifier or bufferIonic strength: (A) 75% 0.10M KH 2 PO4 , pH 6'25% CH 3 CN; (B) 90% 0.10M

KH2PO4, pH 6/10% CH 3CN; (C) 90% 0.05M KH2PO4 pH 6/10% CH3CN.

AErn= 3 30nm Ern=315nm

11111110 4 8 12 16 20

MIN8 12 16 20

MIN

460 MILES ET AL.: J. ASSOC. OFF. ANAL. CHEM. (VOL. 69, NO. 3, 1986)

0

Figure 2. Chromatograms of derivatized control forest water showingeffect of emission wavelength on Interference peaks (excitation wave-length 295 nm; mobile phase 75% 0.05M KH 2 PO4, pH 6/25% CH3CN; ;./NH2

column).

of AMPA-FMOC on a Hypersil APS column. On the weakanion exchange columns, the cationic character of the sta-tionary phase decreases as pH approaches the pK value (about9); thus retention should decrease as pH is increased above6. On the strong anion exchange column (SAX), the cationiccharacter should not significantly decrease until the pH isgreater than about 9, but increasing the mobile phase pH didnot increase retention of AMPA-FMOC on this column. Thiswas unfortunate because AMPA-FMOC eluted very early inthe chromatogram which increased the possibility for poten-tial interferences. This is further confounded by the fact thatAMPA resembles many amino acids which are certain to befound in most agricultural samples. For better control ofAMPA-FMOC retention by anion exchange, a change in thebuffer salt offers a good possibility. Since multi-charged ionsare generally held on ion exchangers more strongly, phos-phate buffers at a high pH will compete strongly for ionexchange sites on the stationary phase. It is also possible toseparate the AMPA-FMOC and glyphosate-FMOC deriva-tives by ion-pair or micellar liquid chromatography.

Two fluorescence detectors were evaluated; a filter fluo-rometer and a spectrophotofluorometer (SPF). Typically, fil-ter fluorometers offer better sensitivity because of a higheroptical transmissivity while the SPF has better selectivitybecause of the narrow bandpass. Nevertheless, for the 2systems evaluated here, the spectrophotofluorometric instru-ment was 20-50 times more sensitive. One reason for thisdifference was its larger diameter light path (50 pi cell)compared to the filter fluorometer (8 .L). A smaller celldecreases band spreading in an LC detector, but the relativelywide peaks that are typical of ion-exchange LC are usuallynot significantly affected by larger cells. Another importantdifference in these 2 detectors was the higher intensity of thespectrophotofluorometric light source (200 W xenon arc)compared to the filter fluorometer (5 W mercury lamp). Inaddition, it was found that the selectivity of the spectropho-tofluorometer allowed spectral resolution of some sampleinterferences. A shift in emission wavelength from 330 to 315nm virtually eliminated forest water sample interferences thateluted early from the column (Figure 2). It should also benoted that these derivatives are good chromophores and canbe detected by UV absorbance at 263 nm, however, with asignificant sacrifice in sensitivity.

For most of our applications, we chose the .NH 2 (Alltech)column because it gave good separation and the cost wasabout 1/3 that of the other columns tested. With this column,a mobile phase of 0.05M phosphate (pH 6.0), and the spec-trophotofluorometric detector, standard curves for glyphos-ate and AMPA were linear from about 0.01 to 10 p.g/mL, or3 orders of magnitude. Minimum detectable quantities (S/N= 3) were about 0.01 p.g/mL (0.1 ng) for glyphosate = FMOCand 0.005 µg/mL (0.05 ng) for AMPA-FMOC (example cal-culation: 0.1 mL of a 0.01 µg/mL glyphosate standard is 0.001p.g; 0.001 in a total of 2 mL derivatizing solution yields a0.0005 glyphosate-FMOC solution; a 0.2 mL injectionof that solution is 0.0001 1.14 or 0.1 ng). The 20-fold concen-tration factor achieved in sample preparation allows ppbmethod detection limits in natural water samples.

For analysis of the natural waters examined, sample prep-aration was minimal. Sample preparation by filtration, rotaryevaporation, and a final filtration took about 1.5 h/sample andachieved a 20-fold concentration factor. In contrast, the ionexchange cleanup used previously (11) would take much longerto realize a similar concentration factor in addition to theexpense and preparation time of the ion exchange resin. Fur-thermore, Glass (11) did not determine if AMPA was quan-titatively recovered by the ion exchange method.

During the evaluation of our preparation procedure, recov-eries of glyphosate from fortified deionized water were incon-sistent. Since glyphosate is known to adsorb strongly to soils(5, 13), we believe that similar adsorption to glass surfaceswas responsible for irregular recoveries. Subsequently, wefound that addition of phosphate buffer to the water samplebefore concentration resulted in higher and more reproduc-ible recoveries (see Table 2). It appears that inorganic phos-phate competes with glyphosate for binding sites on glass,thereby minimizing adsorption of the analyte.

All determinations were considered to be "free" glyphos-ate and AMPA since filtration would remove the sorbed frac-tion. The waters reported here had small amounts of parti-culates and recoveries were good, suggesting that sorptionwas minimal. Waters with high levels of suspended matter,especially clays, would probably lose significant amounts ofglyphosate and AMPA through filtration.

Also, the temperature of the sample may have been affect-ing recoveries during the rotary evaporation step. However,concentration of duplicate solutions fortified with glyphosate(plus phosphate) at 30, 40, and 50°C showed no significantdifferences in recovery, indicating that temperature over thisrange is not critical to good recovery. It should be noted thatthe rate of concentration was fastest at 50°C; this temperaturewas used throughout the course of this study.

Recovery of glyphosate and AMPA from fortified naturalwaters was good at all levels tested (Table 2). Standard devia-

Table 2. Recovery of AMPA and glyphosate from fortified forest watersamples, using phosphate buffer addition before concentration

Level of spike, ppm

Av. rec., %

AMPA Glyphosate

0.010 (n = 3) NA' 111(RSD 6%)

0.050 (n = 8) 80 76(RSD 15%) (RSD 16%)

0.50 (n = 3 AMPA) 100 91(n = 6 GLYPH) (RSD 24%) (RSD 7%)

5.0 (n = 3) 97 96(RSD 7%) (RSD 10%)

"NA = Not analyzed in triplicate.

461MILES ET AL.: I. ASSOC. OFF. ANAL. CHEM. (VOL. 69, NO. 3, 1986)

CAM PA-FMOC

75%

GLYPH-FMOC

A

6 6 12 15 0 I I

I 12 115Time (min) Time (min)

L

6 6 ' 112 15Time (min)

Figure 3. Chromatograms of (A) 25 ng each AMPA-FMOC and glyphosate-FMOC, (B) forest water sample (ca 2 ppb glyphosate and AMPA), and (C)same forest water fortified with 50 ppb glyphosate and AMPA (percent recoveries are listed above peaks).

tions were acceptable with the exception of AMPA at the0.50 ppm level. In many water samples analyzed, interfer-ences eluted at or near the AMPA-FMOC retention time,which made quantitation difficult, especially at lower AMPAconcentrations. No interferences were observed for glyphos-ate-FMOC in the samples analyzed, but many samples had apeak that eluted after glyphosate-FMOC (ca 15 min; see Fig-ure 3).

Propionic acid can act as a bactericide and we evaluatedits action as a preservative for glyphosate and AMPA inwater. Fortified samples that were treated with propionic acidand stored in a refrigerator (4°C) for 3 months showed signif-icant loss of glyphosate and AMPA. For triplicate naturalwater samples fortified at 0.05 ppm, recoveries averaged 45%(RSD 29%) for glyphosate and 109% (RSD 32%) for AMPA.These results suggest that glyphosate was degraded to AMPA.For triplicate natural water samples fortified at 0.50 ppm,recoveries of glyphosate averaged 73% (RSD 20%) whileAMPA recoveries averaged 30% (RSD 68%). The results ofthis storage study indicate that addition of propionic acid andrefrigeration of water samples at 4°C is not sufficient to retarddegradation of glyphosate for long periods.

Sometimes sample concentrates could not be analyzedimmediately and were refrigerated for up to 2 weeks. Toensure stability of glyphosate, spiked samples were reana-lyzed periodically. No significant decrease was observed inspiked water sample concentrates stored in the refrigeratorfor up to one month.

Subsequent experiments where glyphosate was fortifiedinto a natural water (no propionic acid) and frozen at 0°C for3 months showed that it was not significantly degraded. Forduplicate natural water samples fortified at 0.05 and 0.50 ppm,recoveries of glyphosate averaged 81% (RSD 11%) and 86%

(RSD 3%), respectively. Thus, freezing water samples assoon as possible after collection is suggested to ensure thestability of glyphosate in samples to be analyzed at a laterdate.

Acknowledgment

This work was supported by contract PNW-83-306 fromthe U.S. Forest Service, U.S. Department of Agriculture.

REFERENCES

Food and Drug Administration (1977) Pesticide Analytical Man-ual, Vol. II, Washington, DC, sec. 180.364Guinivan, R. A., Thompson, N. P., & Wheeler, W. B. (1982) J.Assoc. Off. Anal. Chem. 65, 35-39Moye, H. A., & Deyrup, C. L. (1984) J. Agric. Food Chem. 32,192-195Young, J. C., Khan, S U , & Marriage, P. B. (1977) J. Agric.Food Chem. 25, 918-922Sprankle, P., Meggitt, W. F., & Penner, D. (1975) Weed Sci.23, 229-234Moye, H. A., & Boning, A. J., Jr (1979) Anal. Lett. 12(B1), 25-35Moye, H. A., Miles, C. J., & Scherer, S. J. (1983) J. Agric.Food Chem. 31, 69-72Bardalaye, P. C., Wheeler, W. B., & Moye, H. A. (1985) in TheHerbicide Glyphosate, E. Grossbard & D. Atkinson (Eds), But-terworths, London, UK, pp. 263-285Moye, H. A., & St. John, P. A. (1980) ACS Symp. Ser., No.136, Chapter 6, pp. 89-102Roseboom, H., & Berkhoff, C. J. (1982) Anal. Chim. Acta 135,373-377Glass, R. L. (1983) J. Agric. Food Chem. 31, 280-282Snyder, L. R., & Kirkland, J. J. (1979) Introduction to ModernLiquid Chromatography, 2nd Ed., Wiley-Interscience, New York,NY

(13) Hance, R. J. (1976) Pestic. Sci. 7, 363-366

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67A Banquet Address—Joseph P. Hile

Harmonization of Collaborative Analytical Studies: Second International Symposium391 Introduction—William Horwitz392 Method Validation: The Harmonization of Collaborative Analytical Studies

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William Horwitz396 Parameters and Definitions in Harmonization of Collaborative Analytical

StudiesM. Parkany

398 Role of Collaborative and Cooperative Studies in Evaluation of AnalyticalMethodsJohn K. Taylor

401 Evaluation of Collaborative Studies with Special Consideration of the OutlierProblemP-H. Goetsch, Ch. Junge, and W. Kroenert

403 Collaborative Testing of Methods for Food AnalysisY Malkki

405 View of the International Dairy Federation on Interlaboratory AnalyticalStudiesR. Grappin

408 Design and Conduct of Collaborative Studies: CIPAC Collaborative Experiencein Pesticide FormulationsJ. Henries and A. Martijn

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Copyright, 1986, by the Association of Official Analytical Chemists, Inc., 1111 N 19th St, Suite 210, Arlington, VA 22209, USA, 703/522-3032.Published six times a year: January, March, May, July, September, November. Second class postage paid at Arlington, VA, and additionalmailing offices. Abstracted and/or indexed in Analytical Abstracts, Biological Abstracts, Chemical Abstracts, Current Advances in EcologicalSciences, and Current Contents. Printed in USA.

410 Role of IUPAC Commission on Analytical Nomenclature in Harmonization ofCollaborative Analytical StudiesG. Svehla

411 Analytical Quality Control in United Kingdom Water Industry, with ParticularReference to Harmonized Monitoring Scheme for River Water QualityJ. A. Tetlow and D. T. E. Hunt

417 A Statistician's Approach to Repeatability and ReproducibilityH. C. Hamaker

429 Outliers in Collaborative Studies: Coping with UncertaintyRichard H. Albert

432 Minimum Criteria for Validation of Analytical MethodsD. R. Williams

Chemical Contaminants Monitoring437 Enzyme Immunoassay-Based Survey of Prevalence of Gentamicin in Serum of

Marketed SwineDavid B. Berkowitz and Donald W. Webert

441 Fluoroacetate Residues in Ground Squirrel and Coyote Tissues Due to Primaryor Secondary 1080 PoisoningHoward H. Casper, Michael E. Mount, Rex E. Marsh, and Robert H.Schmidt

Drug Residues in Animal Tissues

443 Liquid Chromatographic Determination of Monensin in Chicken Tissues withFluorometric Detection and Confirmation by Gas Chromatography-MassSpectrometryKeigo Takatsuki, Shigeru Suzuki, and Isamu Ushizawa

448 Determination of Ampicillin Residues in Fish Tissues by LiquidChromatographyTomoko Nagata and Masanobu Saeki

Pesticide and Industrial Chemical Residues

451 Determination of Halogenated Contaminants in Human Adipose TissueGuy L. LeBel and David T. Williams

458 Determination of Glyphosate Herbicide and (Aminomethyl)phosphonic Acid inNatural Waters by Liquid Chromatography Using Pre-Column FluorogenicLabeling with 9-Fluorenylmethyl ChloroformateCarl J. Miles, Louis R. Wallace, and H. Anson Moye

462 Rapid, Semimicro Method for Determination of Polycyclic AromaticHydrocarbons in Shellfish by Automated Gel Permeation/LiquidChromatographyCharles J. Musial and John E Uthe

466 Determination of Halogenated Phenols in Raw and Potable Water by SelectedIon Gas Chromatography-Mass SpectrometryBishop B. Sithole, David T. Williams, Chester Lastoria, and John L.Robertson

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474 Rapid Method for Determination of 2-Hydroxy-4-(Methylthio)butanoic Acid inPoultry Feeds by Capillary IsotachophoresisDutt V. Vinjamoori and Robert M. Schisla

Color Additives478 Liquid Chromatographic Determination of Leuco Base in FD&C Blue No. 1

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Meat and Meat Products483 Development of Poultry Rapid Overnight Field Identification Test (PROFIT)

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Pesticide Formulations488 Gas Chromatographic Determination of Fensulfothion in Formulations:

Collaborative StudyWilliam R. Betker

490 Liquid Chromatographic Method for Determination of Oxythioquinox inTechnical and Formulated Products: Collaborative StudyStephen C. Slahck

Veterinary Analytical Toxicology 493 Determination of Diagnostic Levels of Arsenic in Animal Tissue: Collaborative

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496 Colorimetric Determination of Alkaline Phosphatase as Indicator of MammalianFeces in Corn Meal: Collaborative StudyHarriet Gerber

499 Improved Spray Reagent for Thin Layer Chromatographic Method for DetectingUric Acid: Collaborative Study -Robert S. Ferrera, Jack L. Boese, and Joel J. Thrasher

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504 Gas Chromatographic-Thermal Energy Analysis Method for N-Nitrosodibutylamine in Latex Infant Pacifiers: Collaborative StudyHarold C. Thompson, Jr, Stanley M. Billedeau, and Barbara J. Miller

Mycotoxins

508 Optimum Methanol Concentration and Solvent/Peanut Ratio for Extraction ofAflatoxin from Raw Peanuts by Modified AOAC Method IIThomas B. Whitaker, James W. Dickens, and Francis G. Giesbrecht

510 Production and Isolation of Aflatoxin M, for Toxicological StudiesDennis P. H. Hsieh, Linda M. Beltran, Mark Y. Fukayama, David W Rice,and Jeffrey J. Wong

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513 Colorimetric Determination of Certain Phenothiazine Drugs by UsingMorpholine and Iodine-Potassium Iodide ReagentsAdel E Youssef Salwa R. EI-Shabouri, Fardous A. Mohamed, and AbdelMaboud I. Rageh

51-9 Liquid Chromatographic Determination of Chlorproparnide in Tablet DosageForms: Collaborative StudyRichard L. Everett

521 Liquid Chromatographic Determination of Hydrazine in PolyvinylpyrrolidoneFumiko Matsui, Roger W. Sears, and Edward G. Lovering

Decomposition in Foods524 Headspace Gas Chromatographic Method for Determination of Ethanol in

Canned Salmon: Collaborative StudyThomas A. Hollingworth, Jr, Harold R. Throm, Marleen M. Wekell, WilliamE Trager, and Michael W. O'Donnell, Jr

Microbiological Methods 527 Enumeration of Total Bacteria and Coliforms in Milk by Dry Rehydratable Film

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531 DNA Colony Hybridization Method Using Synthetic Oligonucleotides to DetectEnterotoxigenic Escherichia coli: Collaborative StudyWalter E. Hill, Barry A. Wentz, William L. Payne, James A. Jagow, andGerald Zon

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Food Additives

537 Gas Chromatographic Profile Analysis of Basic Nitrogen-Containing AromaticCompounds (Azaarenes) in High Protein FoodsGernot Grimmer and Klaus-Werner Naujack

542 Determination of Sulfite in Food by Flow Injection AnalysisJohn J. Sullivan, Thomas A. Hollingworth, Marleen M. Wekell, Richard T.Newton, and Jack E. LaRose

Seafood Toxins547 Variability of Mouse Bioassay for Determination of Paralytic Shellfish Poisoning

ToxinsDouglas L. Park, Willard N. Adams, Stuart L. Graham, and Randolph C.Jackson

Fruit and Fruit Products551 Gas Chromatographic Determination of Fatty Acids and Sterols in Orange Juice

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Technical Communications557 Chemical Derivatization Analysis of Pesticide Residues. X. Analysis of Ten

Acid Herbicides in Natural WatersHing-Biu Lee, Yvonne D. Stokker, and Alfred S. Y. Chau

560 On-Line Generation of Cyanogen Chloride in Semiautomated Determination ofNiacin and Niacinamide in Food ProductsHoon Ge, Gary N. Oman, and Frank J. Ebert

563 General Referee Report: Forensic SciencesJohn W. Hicks

563 Report of the Archives CommitteeCharlotte Brunner

564 Report of the Ways and Means CommitteeStanley E. Katz

564 Report of the Committee on State and Provincial ParticipationHershel F. Morris, Jr

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