METHODS OF ANALYSIS BY THE U.S. GEOLOGICAL SURVEY

NATIONAL WATER QUALITY LABORATORY--DETERMINATION OF

TRIAZINE AND OTHER NITROGEN-CONTAINING COMPOUNDS BY

GAS CHROMATOGRAPHY WITH NITROGEN PHOSPHORUS DETECTORS

By Dennis J. Markovchick, James A. Lewis, Ronald W. Brenton, Jana L. Iverson, 

and Helen L. Wharry

———————————————————————————————————————————

U.S. GEOLOGICAL SURVEY

Open-File Report 94-37

Denver, Colorado

1994
U.S. DEPARTMENT OF THE INTERIOR

 BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

 Robert M. Hirsh, Acting Director

————————————————————————————————————————

For additional information Copies of this report can be

write to: purchased from:

Chief, National Water Quality Laboratory U.S. Geological Survey

U.S. Geological Survey Open-File Reports--ESIC

Box 25046, Mail Stop 407 Box 25425

Federal Center Federal Center

Denver, Colorado 80225-0425 Denver, Colorado 80225-0425
CONTENTS

 Page

Abstract ............................................................................... 1

Introduction .......................................................................... 1

Analytical method .................................................................. 2

1. List of parameters, reporting levels, and codes ................... 2

2. Application ............................................................. 3

3. Summary of method .................................................. 3

4. Interferences ........................................................... 3

5. Instrumentation ........................................................ 4

6. Apparatus ............................................................... 5

7. Reagents ................................................................ 5

8. Standards ............................................................... 6

9. Sample preparation ................................................... 7

10. Instrument performance ............................................. 8

11. Target compound calibration ....................................... 8

12. Sample analysis and data evaluation .............................. 8

13. Calculations ........................................................... 9

 14. Reporting of results .................................................. 9

 15. Precision ............................................................... 9

Discussion of results ................................................................ 10

Conclusions ........................................................................... 16

Quality assurance .................................................................... 16

References cited ..................................................................... 17

TABLES

Table 1. Compounds included in National Water Quality Laboratory

triazine schedule 1389 ........................................ 3

2. Triazine recovery data from three water matrices .......... 11

CONVERSION FACTORS AND ABBREVIATIONS

Multiply By To obtain

———— —— ————

centimeter (cm) 0.3937 inch

gram (g) 0.0353 ounce, avoirdupois

liter (L) 1.06 quart

meter (m) 3.3 foot

microgram (μg) 35.27 x 10-8 ounce, avoirdupois

microliter (μL) 33.8 x 10-6 ounce, fluid

micrometer (μm) 3.3 x 10-6 foot

milligram (mg) 35.27 x 10-5 ounce, avoirdupois

microgram per liter (μg/L) 1 part per billion

milligram per liter (mg/L) 1 part per million

milliliter (mL) 0.0338 ounce, fluid

millimeter (mm) 0.0394 inch

nanogram (ng) 35.27 x 10-11 ounce, avoirdupois

picogram (pg) 35.27 x 10-14 ounce, avoirdupois

iii
Temperature can be converted from degree Celsius ( ̊C) to degree Fahrenheit ( ̊F) by using the following

equation: 

 ̊F = 9/5 ( ̊C) + 32. 

Water-quality units abbreviated in this report are as follows:

centimeter per second (cm/sec) picogram per area (pg/area)

milliliter per minute (mL/min) picogram per microliter (pg/μL)

microgram per liter (μg/L) pound per square inch (lb/in2)

The following abbreviations also are used in this report;

ACS American Chemical Society

DI deionized water

EDL estimated detection limit

FRW fortified reagent water

GC gas chromatography

GC/MS gas chromatography/mass spectrometry

K-D Kuderna-Danish

LRB laboratory reagent-water blank

MSDS material safety data sheet

MTBE methyl tert-butyl ether

NAWQA National Water-Quality Assessment Program

NPD nitrogen phosphorus detector

NWQL National Water Quality Laboratory

RSD relative standard deviation

Sim selected ion monitoring

TFE tetrafluoroethylene

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

WATSTORE Water Data Storage and Retrieval System

—————————

Use of firm and brand names in this report is for identification purposes only and does not constitute

endorsement by the U.S. Geological Survey.

iv
METHODS OF ANALYSIS BY THE U.S. GEOLOGICAL SURVEY

NATIONAL WATER QUALITY LABORATORY--

DETERMINATION OF TRIAZINE AND OTHER NITROGEN-CONTAINING

COMPOUNDS BY GAS CHROMATOGRAPHY

WITH NITROGEN PHOSPHORUS DETECTORS

By Dennis J. Markovchick, James A. Lewis,

Ronald W. Brenton, Jana L. Iverson, and Helen L. Wharry

ABSTRACT

A gas chromatographic technique using nitrogen phosphorus detection and two dissimilar fused-silica capillary columns is

the method currently (1994) used by the National Water Quality Laboratory (NWQL) for the analysis of triazine and other selected

nitrogen-containing compounds (NWQL schedule 1389). The original method was developed for a schedule containing 10

compounds.

This report provides updated recovery and precision information obtained for 22 compounds, 2 metabolites, and 1 fungicide

(carboxin) currently (1994) on NWQL schedule 1389. This information was compiled by spiking all compounds into three different

water matrices at two different levels of concentration. Seven replicates were analyzed at each concentration level in each matrix.

The recoveries ranged from 69 to 120 percent for all compounds except the six that follow: bromacil, butylate,

desisopropylatrazine, hexazinone, terbacil, and vernolate. For these compounds, the recoveries had a much wider range and generally

were less than 69 percent.

 INTRODUCTION

This report describes a U.S. Geological Survey (USGS) method for determining triazine and other nitrogen-containing

compounds. The method supplements other methods of USGS for determination of organic substances in water that are described by

Wershaw and others (1987). Historically, the National Water Quality Laboratory (NWQL) has analyzed water samples for 10

nitrogen-containing compounds, using NWQL schedule 1389 (Triazine Herbicides). An NWQL organic schedule is a list of

compounds usually determined by one methodology. This method of analysis is described in Wershaw and others (1987, p. 46-49).

Subsequently, two additional compounds--metolachlor and metribuzin--were added to the schedule.

In 1986, Battelle developed method 507 for the U.S. Environmental Protection Agency (USEPA), which included a number

of additional nitrogen-containing compounds (Graves, 1988, p. 143-170). Administrators for USGS, National Water-Quality

Assessment (NAWQA) Program, requested that the NWQL provide the analysis for several additional compounds included in USEPA

method 507.

The 12 compounds reported using NWQL schedule 1389 are as follows: alachlor, ametryn, atrazine, cyanazine, metolachlor,

metribuzin, prometon, prometryn, propazine, simazine, simetryn, and trifluralin. The 10 additional compounds requested by the

NAWQA Program are bromacil, butachlor, butylate, carboxin, cycloate, diphenamid, hexazinone, propachlor, terbacil and vernolate.

Also, there has been considerable interest in atrazine metabolites. Two of these metabolites--desethylatrazine and

desisopropylatrazine--can be recovered from water samples by liquid-liquid extraction and analyzed using gas chromatographic

techniques. Terbuthylazine--a compound not used in the United States--also is included in this schedule for use as a surrogate

compound.

1
Several meetings were held to agree on the experimental protocol that would be used to develop the information. The

meetings were attended by members of the NWQL Organic Program, the Chief of the NWQL Quality Management Program, and the

Chief of the NWQL Methods Research and Development Program.

The main guidelines for the protocol are as follows:

1. The recovery, precision, and bias information would be based on analytical data produced from three different spiked-water

matrices: ground water, surface water, and reagent water.

2. Each water matrix would be spiked at two different concentration levels. One concentration

would be 10 times the estimated reporting level, and the other concentration would be large

enough to help define the upper concentration limit of the analysis.

3. There would be seven replicates for each concentration in each matrix.

4. The spiked-water samples would be held in a refrigerator at about 4 ̊C for at least 48 hours

prior to the start of analysis, to approximate the holding time for real samples.

5. The method used would be an adaptation of USEPA method 507. Fifty g of sodium

chloride (NaCl) would be added to each sample and dissolved prior to extraction with

methylene chloride (5 g has been used in the method since 1980). The extract would be

concentrated by evaporation in a steam bath. The concentrated extract would be solvent

exchanged into methyl t-butyl ether. Final analysis would employ dual capillary column

gas chromatography (GC) and two nitrogen phosphorus detectors.

Precision and bias information need to be developed for the analytical method used before

compounds can be assigned parameter codes and analytical data entered into the Water Data

Storage and Retrieval System (WATSTORE). Precision and bias information for the 10 additional

compounds were not available in 1987 when analyses of water samples for the NWQL schedule

1389 compounds were begun.

The purpose of the method described in this report is (1) to enhance recovery and precision by improving the technique; (2)

to use the method to gather information on recovery, precision, and bias; and (3) to expand the method to include 24 compounds and a

surrogate. This revised method was implemented in the NWQL in January 1994.

ANALYTICAL METHOD

 Parameter and Code:

Triazines, total recoverable, gas chromatography, O-3106-93

1. List of parameters, reporting levels, and codes

 Compounds, reporting levels, and codes included in the triazine schedule are listed in table 1. 

2
Table 1.--Compounds included in National Water Quality Laboratory triazine

schedule 1389

[μg/L, micrograms per liter; WATSTORE, Water Data Storage and Retrieval System]

———————————————————————————————————————————————

 Reporting

level WATSTORE code,

Compounds (μg/L) total recoverable Laboratory code

———————————————————————————————————————————————

Alachlor 0.2 77825 1331

Ametryn .1 82184 848

Atrazine .1 39630 717

Bromacil .2 30234 1463

Butachlor .1 30235 1468

Butylate .1 30236 1470

Carboxin . 2 30245 1464

Cyanazine . 2 81757 846

Cycloate .1 30254 1469

Desethylatrazine . 2 75981 1612

Desisopropylatrazine . 2 75980 1613

Diphenamid .1 30255 1465

Hexazinone .2 30264 1466

Metolachlor .2 82612 1334

Metribuzin .1 82611 1333

Prometon .2 39056 718

Prometryn .1 39057 631

Propachlor .1 30295 1471

Propazine .1 39024 844

Simazine .1 39055 719

Simetryn .1 30954 720

Terbacil 2 30311 1462

Trifluralin .1 39030 1332

Vernolate .1 30324 1467

2. Application

This method is suitable for the determination of triazine herbicides and other selected nitrogen-containing

compounds in water and mixtures of water-suspended sediment.

3. Summary of method

The pH of a measured volume (about 1 L) of sample is adjusted to range from 7.0 to 9.0. Then 50 g of NaCl is

added and dissolved. The sample is extracted with methylene chloride. The methylene chloride extract is isolated, dried,

and concentrated to a volume of 1 mL during a solvent exchange to methyl t-butyl ether (MTBE). Chromatographic

conditions are described that permit the separation and determination of the compounds in the extract by capillary column

GC with a nitrogen phosphorus detector (NPD).

4 . Interferences

4.1 Method interferences might be caused by contaminants in solvents, reagents, glassware, and other

sample-processing apparatus that lead to discrete artifacts or elevated baselines in gas chromatograms. All reagents and

apparatus need to be routinely demonstrated to be free from interferences under the conditions of the analysis by running

laboratory reagent blanks.

3
4.1.1 Prior to use, rinse all glassware with the solvent to be used in the sample preparation procedure. Clean all glassware

as soon as possible after use by thoroughly rinsing with deionized (DI) water. This procedure is followed by washing with hot water

and detergent and a thorough rinsing with tap water followed by deionized water. Drain dry, and heat in an oven or muffle furnace at

450 ̊C for 8 hours. Do not heat volumetric glassware. Thermally stable materials might not be eliminated by this treatment. After

drying and cooling, store glassware in a clean environment to prevent any accumulation of dust or other contaminants. The use of

ultrapure solvents and reagents will help to minimize interference problems.

4.1.2 System contamination might interfere when a sample containing small concentrations of compounds is analyzed

immediately following a sample containing large concentrations of compounds. After a sample is injected, the syringe is rinsed 10

times with solvent to reduce the chance of cross-contamination.

4.2 Matrix interferences might be caused by contaminants that are coextracted from the sample. The extent of matrix

interferences will vary from source to source, depending on the water sampled. This potential problem is addressed using a dual

column confirmation procedure. If there are further questions about compound identification, the sample is submitted for confirmation

using gas chromatography/mass spectrometry (GC/MS).

4.2.1 It is important that samples and calibration standards be contained in the same solvent. If this is not the case,

chromatographic comparability of standards to sample might be affected.

5. Instrumentation

5.1 Gas chromatograph/nitrogen phosphorus detector (NPD). Hewlett-Packard 5890 or equivalent. An automated

sample injector may be used.

5.1.1 Gas chromatographic configuration

Column 1 (primary column)--30-m long X 0.25-mm inside diameter (ID) RTX-5 bonded fused-silica columns, 0.25-μm film

thickness (Restec Corp.) or equivalent.

Column 2 (confirmation column)--30-m long X 0.25-mm ID RTX 35 bonded fused-silica column, 0.25-μm film thickness

(Restec Corp.) or equivalent.

Carrier gas--Helium flow, 1 to 3 mL/min. This flow range corresponds to a linear flow velocity of 20 to 40 cm/sec on the

Van Deemter plot, when using 30-m X 0.25-mm ID columns.

Make-up gas--Helium flow, 30 mL/min. Nitrogen may be used as a substitute gas.

Detector gases--Hydrogen flow, 3 to 5 mL/min Air flow, 90 to 110 mL/min

Injection mode- -Splitless, injection port sweep 30 mL/min. Column head pressure 20 lb/in2. Septum purge rate 1 to 2

mL/min. Purge valve on (open) at 2 minutes and off (closed) 2 minutes prior to end of sample run.

Both columns are connected to one injection port. An injection volume of 4 μL is divided onto both columns.

4
Oven temperature program--Initial temperature 50 ̊C, hold 1 minute.

Ramp 1 -- 10°C/min to 157 ̊C, hold 28.3 minutes.

Ramp 2 -- 5°C/min to 175 ̊C, hold 1.4 minutes.

Ramp 3 -- 3°C/min to 225 ̊C, hold 6.34 minutes.

5.1.2 Detector system

Use two nitrogen phosphorus detectors (NPD) to generate the validation data presented in

the method. Detector temperature is 300 ̊C. Alternative detectors, including a mass spectrometer in a selected ion monitoring (SIM)

mode, may be used.

6. Apparatus

6.1 Separatory funnel--2,000-mL, with tetrafluoroethylene (TFE) fluorocarbon stopcock, ground glass or TFE

fluorocarbon stopper.

6.2 Flask, Erlenmeyer--500-mL.

6.3 Concentrator tube, Kuderna-Danish (K-D)--10-mL, graduated (Kontes K-570050-1025 or equivalent). Calibration

needs to be checked at the volumes used in the test. Ground glass stoppers are used to prevent evaporation of eluants.

6.4 Evaporative flask, K-D--500-mL (Kontes K-570001-0500 or equivalent). Attach to concentrator tube with springs.

6.5 Snyder column, K-D--Three-ball macro (Kontes K-503000-0121 or equivalent).

6.6 Vials--- l-mL, gas chromatographic, Wheaton type or equivalent.

6.7 Boiling stones- -Carborundum, No. 12, granules (Arthur H. Thomas Co., No.

1590-033 or equivalent). Heat at 400°C for 30 minutes prior to use. Cool and store in desiccator.

6.8 Water bath--Heated, capable of temperature control (± 5°C). Use the bath in a well-ventilated hood.

6.9 Balance--Analytical, capable of accurately weighing to the nearest 0.00001 g.

7. Reagents

7.1 Acetone, methylene chloride, methyl t-butyl ether (MTBE)--Distilled-in-glass, pesticide analysis grade. Organic-free

reagent water.

7.2 Potassium hydroxide (KOH) solution, American Chemical Society (ACS) grade.

7.3 Sodium chloride (NaCl), crystal, ACS grade--Heat treat in a shallow tray at 450°C for a minimum of 4 hours to

remove interfering organic substances.

7.4 Sodium sulfate, granular, anhydrous, ACS grade--Heat treat in a shallow tray at 450°C for a minimum of 4 hours to

remove interfering organic substances.

5
7.5 Stock standard solutions--Stock standard solutions may be purchased as certified solutions or prepared from pure

standard materials using the following procedure:

7.5.1 Prepare accurate stock standard solutions by weighing about 0.00300 g of pure material. Dissolve the material in

MTBE or acetone, and dilute to volume in a 25-mL volumetric flask. Larger volumes may be used at the convenience of the analyst. If

compound purity is certified at 96 percent or greater, the weight may be used without correction to calculate the concentration of the

stock standard solutions.

7.5.2 Transfer the stock standard solutions into TFE fluorocarbon-sealed screw cap amber vials. Store at from 5 to 15°C

and protect from light.

7.5.3 Replace stock standard solutions after 2 months if comparison with laboratory fortified blanks or with QC samples

indicate a problem.

7.5.4 Material safety data sheets (MSDS) need to be on file for the materials used, and all personnel need to be informed

of the safe storage use and disposal of these materials.

8. Standards

8.1 External instrument calibration standard. Prepare calibration standards at a minimum of two concentration levels

for each compound of interest and surrogate compound by adding known volumes of one or more stock standard solutions to a

volumetric flask. Dilute to volume with MTBE. The lowest standard needs to represent compound concentrations near, but greater

than, their respective estimated detection limit (EDL). The remaining standards need to bracket the compound concentrations expected

in the sample eluants, or need to be within the working range of the detector. Starting with the standard of highest concentration,

analyze each calibration standard and tabulate response (peak height or area) in relation to the concentration in the standard. Use the

results to prepare a calibration curve for each compound. When manual calculations are necessary and the ratio of response to

concentration (response factor) is a constant over the working range [20 percent relative standard deviation (RSD) or less], linearity

can be assumed. In that case, the average ratio or calibration factor can be used in place of a calibration curve.

8.1.1 Working calibration curve. Response factors need to be recalculated and verified on each working day by analyzing

the high- and low-level standard solutions prior to analyzing samples. The variance between the response factors for each compound

in the high- and low-level standards needs to be ±20 percent. If the instrument is out of calibration, rerun the calibration standards.

8.2 Surrogate standard solution. Prepare a solution of terbuthylazine in methanol, in a 25-mL volumetric flask. The

concentration of this solution should be approximately midway between the high and low calibration standards, for terbuthylazine,

when 100 μL is added to a 1-L sample. Add the surrogate standard solution to the sample at the time of extraction and use it to

monitor sample preparation procedures.

8.3 Target compound spike solutions. Prepare two target compound spike solutions, each containing half the compounds

of interest in 25-mL volumetric flasks. The concentration level of each compound needs to be sufficient to produce concentration

values, in micrograms per liter (μg/L), within the range of the high and low calibration standards when 100 μL is added to 1 L of

reagent water. Use the spike solutions to monitor recovery efficiencies for all target compounds.

6
9. Sample preparation

9.1 Extraction (manual method)

9.1.1 Weigh the bottle containing the sample to the nearest 0.1 g. Record the weight.

9.1.2 Adjust the sample to between pH 7 and 9 by adding potassium hydroxide solution.

9.1.3 Add 100 μL surrogate solution to each sample,

9.1.4 Add 100 μL spike solution to 1 L of organic-free water

9.1.5 Pour sample into separatory funnel and add 50 g NaCl; seal and shake to dissolve.

9.1.6 Add 75 mL methylene chloride to the sample bottle; seal and shake 30 seconds to rinse the inner walls. Transfer the

solvent to the separatory funnel, and extract the sample by vigorously shaking the funnel for 1 minute with periodic venting to release

excess pressure. Allow the organic layer to separate from the water phase for a minimum of 5 minutes. If the emulsion interface

between layers is more than one-third the volume of the solvent layer, the analyst will need to use mechanical techniques to complete

the phase separation. The appropriate technique depends on the sample, but may include stirring, filtration of the emulsion through

glass wool, and centrifugation. Collect the methylene chloride extract in a 500-mL glass-stoppered Erlenmeyer flask.

9.1.7 Add a second 50-mL volume of methylene chloride to the sample bottle and repeat the extraction procedure a

second time, combining the extracts in the Erlenmeyer flask. Perform a third extraction in the same manner.

9.1.8 Weigh the empty sample bottle to the nearest 0.1 g, and record the weight. Determine the weight (and volume in

milliliters; 1.000 mL = 1.000 g) of the sample by subtracting the weight of the empty bottle from the weight of the bottle and sample.

9.1.9 Add about 5 g anhydrous sodium sulfate to the extract in the glass-stoppered Erlenmeyer flask; shake the flask to

dry the extract and allow to sit overnight.

9.2 Extract concentration

9.2.1 Assemble a Kuderna-Danish (K-D) concentrator by attaching a 10-mL receiver tube to a 500-mL evaporative flask.

Other equivalent concentration devices or techniques may be used in place of the K-D concentrator.

9.2.2 Decant the methylene chloride extract into the K-D concentrator. Rinse the remaining sodium sulfate with two

25-mL portions of methylene chloride, and decant the rinses into the K-D concentrator. Add 0.5 mL MTBE to the K-D concentrator.

9.2.3 Add one or two clean boiling stones to the evaporative flask, and attach a macro-Snyder column. Prewet the Snyder

column by adding about 1 mL methylene chloride to the top. Place the K-D apparatus on a hot water bath, with the temperature set

between 60 and 67°C, so that the receiver tube is partially immersed in the hot water, and the entire lower rounded surface of the flask

is bathed with hot vapor. Adjust the vertical position of the apparatus and the water temperature as required to complete the

concentration in about 15 to 20 minutes. At the proper rate of concentration, the balls of the column will actively chatter, but the

chambers will not flood. When the apparent volume of liquid extract reaches 2 mL, remove the K-D apparatus and allow it to drain

and cool for at least 10 minutes.

7
9.2.4 Dry the joint between the receiver tube and the K-D flask. Remove the receiver tube and place it on a nitrogen

evaporating device. Evaporate with a stream of dry nitrogen until the volume of the sample is less than 1 mL. Add 1 mL of MTBE,

mix, and evaporate again to less than 1 mL. Repeat this procedure three times.

9.2.5 Adjust the volume of the sample to exactly 1.0 mL; mix well and transfer to a 2-mL crimp cap vial. Crimp a cap on

the vial and store at 4°C until ready for analysis.

10. Instrument performance

10.1 Instrument calibration. Prior to the analysis of each set of samples, compare the response factor between the high

and low calibration standards for each compound. A variance of ±20 percent RSD is acceptable.

10.2 Signal stability. Monitor the signal stability of the NPD during sample analysis by placing a low standard in the

middle and also at the end of each set of samples. Compare the area counts for each compound in these standards to the corresponding

low standard used for instrument calibration. A variance in signal level reflected by the area count of ±20 percent RSD is acceptable.

10.3 Retention time stability. Also, use the low standards in the middle and at the end of each run of samples to monitor

shifts in retention time.

11. Target compound calibration

Prior to the analysis of each sample set, analyze the calibration standards to recalibrate the instrument. Because of the large

number of compounds, prepare the standard in three separate mixtures and at two concentration levels. The variance in response

(amount per area count) for each compound at two concentration levels needs to be within ±20 percent RSD to be considered

acceptable.

12. Sample analysis and data evaluation

12.1 Analyze sample extracts

Inject approximately 2 μL of sample onto each column. The injection volume of the standard solutions needs to be the same

as the injection volume of the sample extracts. Record the resulting peak size in area units. If the response exceeds the working linear

range of the instrument, dilute the extract and reanalyze.

12.2 Identification of compounds

Identify compounds by comparing their retention time to a reference chromatogram on both columns. If the retention time of

an unknown compound corresponds, within limits, to the retention time of a standard compound, then consider identification positive.

The width of the retention-time window used to identify compounds needs to be based on measurements of actual retention-time

variations of standards over the course of a day. Calculate a suggested window size for a compound by using three times the standard

deviation of a retention time. However, use the experience of the analyst to interpret the chromatograms.

8
13. Calculations

13.1 Calculate the response factor of each identified component in the calibration standard:

A1

RF = ————

CS x Vl

where RF = response factor of the identified component in the calibration standard,

in area per picograms;

A1 = integrated peak area of identified component in the calibration standard;

CS = concentration of the standard, in picograms per microliter; and

V1 = volume of standard injected, in microliters.

13.2 Calculate the concentration of each identified component in the original water sample from the equation

A2 x V2

Concentration (μg/L) = ——————————

 V3 x W x RF

where A2 = integrated peak area of identified sample component; 

V2 = final volume of sample extract, in milliliters; 

V3 = volume of sample extract injected, in microliters; 

W = weight of sample in grams, expressed in milliliters (1.000 mL = 1.000 g); and

RF = response factor of identified component in the calibration standard, in area per picograms. 

14. Reporting of results

Report the concentrations of triazine compounds as follows: less than 0.1 μg/L, as <0.1 μg/L or 0.2 μg/L, as <0.2

μg/L; 0.1 to 1.0 μg/L, one significant figure; 1.0 μg/L and greater, two significant figures. For the recovery study, results

are reported to two significant figures (table 2). 

15. Precision

Precision and bias information for all 25 compounds are listed in table 2 in the following section. All compounds

were spiked into three different water matrices at two different levels of concentration. The three matrices were ground

water, surface water, and reagent water. There were seven replicates of each concentration level in each matrix.

9
DISCUSSION OF RESULTS

The results produced by the analysis of the spiked ground-water, surface-water, and reagent-water samples approximate

single operator precision because they were extracted by three people, and then concentrated, solvent exchanged, and analyzed by one

person. All of these data sets are listed in table 2.

Terbuthylazine is the surrogate used in this method. The recovery of the surrogate from all three matrices was greater than or

equal to 79 percent.

As listed in table 2, all the compounds except for bromacil, butylate, desisopropylatrazine, hexazinone, terbacil, and vernolate

had adequate recoveries from all three matrices; recovery ranged from 69 to 120 percent. Recoveries for bromacil ranged from 39 to

50 percent in samples of reagent water; the river water and well water matrices recovered 82 to 100 percent. Butylate recovery was

low from all three matrices, ranging from 53 to 64 percent. Desisopropylatrazine recovery was less than 50 percent from all three

matrices; recoveries ranged from 39 to 42 percent. Recovery of hexazinone ranged from 65 to 94 percent in samples of ground and

surface water; the recovery of this compound in reagent water ranged from 53 to 75 percent. Recovery of terbacil ranged from 89 to

120 percent in samples of ground and surface water as compared to about 75 percent in the reagent-water matrix. Recovery of

vernolate was low for all three matrices, ranging from 59 to 73 percent. Triazine compound recovery data are listed in table 2.

10
Table 2.--Triazine recovery data from three water matrices

[Note: There were seven replicates of each concentration level in each matrix. μg/L, micrograms per liter]

——————————————————————————————————————————————————————————

Relative

 Spike Standard standard

 concentration Concentration deviation deviation Recovery

und Matrix (μg/L) found (μg/L) (μg/L) (percent) (percent)

——————————————————————————————————————————————————————————

Arvada well water 0.97 0.96 0.05 5.6 99

Arvada well water 4.8 4.7 .34 7.1 97

South Platte River water .97 .92 .04 4.4 95

South Platte River water 4.8 4.0 .38 7.9 83

Reagent water 1.0 .96 .14 13 93

Reagent water 5.2 4.4 .24 4.6 86

Arvada well water .96 .83 .11 11 86

Arvada well water 4.8 4.5 .47 9.7 94

South Platte River water .96 .83 .05 5.5 86

South Platte River water 4.8 3.8 .22 4.5 80

Reagent water .89 .82 .02 2.3 92

Reagent water 4.5 3.9 .35 8.0 88

Arvada well water 1.0 .88 .05 4.8 90

Arvada well water 4.9 4.2 .27 5.5 86

South Platte River water .98 .91 .04 3.6 93

South Platte River water 4.9 3.8 .19 3.9 78

Reagent water 1.0 .93 .02 2.3 90

Reagent water 5.1 4.5 .23 4.5 87

l Arvada well water 1.2 1.2 .06 5.4 100

Arvada well water 6.0 5.8 1.0 17 96

South Platte River water 1.2 1.2 .05 4.3 98

South Platte River water 6.0 4.9 .52 8.6 82

Reagent water 1.0 .50 .70 7.0 50

Reagent water 5.0 2.0 .24 4.7 39

r Arvada well water .96 .93 .06 6.7 97

Arvada well water 4.8 4.9 .28 5.8 100

South Platte River water .96 .86 .04 4.2 90

South Platte River water 4.8 3.8 .37 7.6 79

Reagent water 1.0 .96 .13 13 93

Reagent water 5.1 4.4 .27 5.3 95

———————————————————————————————————————————————————————————————

11
Table 2.--Triazine recovery data from three water matrices--Continued

————————————————————————————————————————————————————————————

Relative

Spike Standard standard

concentration Concentration deviation deviation Recovery

Matrix (μg/L) found (μg/L) (μg/L) (percent) (percent)

————————————————————————————————————————————————————————————

Arvada well water 1.0 0.63 0.09 8.5 61

Arvada well water 5.2 3.3 .50 9.6 64

South Platte River water 1.0 .63 .11 10 60

South Platte River water 5.2 2.8 .28 5.3 53

Reagent water 1.2 .76 .06 5.0 64

Reagent water 6.0 3.2 .46 7.7 54

Arvada well water .94 .83 .05 4.9 88

Arvada well water 4.7 3.9 .28 5.9 83

South Platte River water .94 .79 .03 3.1 84

South Platte River water 4.7 3.6 .14 3.0 76

Reagent water 1.1 .89 .03 2.9 82

Reagent water 5.5 4.5 .23 4.2 82

Arvada well water 1.0 .97 .07 7.2 96

Arvada well water 5.0 5.6 .38 7.6 110

South Platte River water 1.0 1.0 .04 4.2 99

South Platte River water 5.0 4.4 .36 7.1 87

Reagent water 1.0 .98 .13 13 94

Reagent water 5.2 4.5 .25 4.9 87

Arvada well water 1.0 .83 .09 8.7 82

Arvada well water 5.0 4.0 .5 8 11 79

South Platte River water 1.0 .79 .08 7.7 78

South Platte River water 5.0 3.6 .39 7.7 71

Reagent water 1.2 .91 .20 16 73

Reagent water 6.3 4.4 .22 3.6 70

Arvada well water 1.0 .81 02 2.0 81

Arvada well water 5.0 3.9 .16 3.3 79

South Platte River water 1.0 .77 .05 4.5 77

South Platte River water 5.0 4.1 .29 5.9 82

Reagent water 1.4 1.0 .03 2.3 73

Reagent water 6.9 4.9 .57 8.2 71

——————————————————————————————————————————————————————————————

12
Table 2.--Triazine recovery data from three water matrices--Continued

———————————————————————————————————————————————————

Relative

Spike Standard standard

concentration Concentration deviation deviation 

Compound Matrix (μg/L) found (μg/L) (μg/L) (percent) 

———————————————————————————————————————————————————Desisopropyl- Arvada well water 1.1 0.45 0.02 1.7 atrazine

Arvada well water 5.4 2.1 .08 1.5 South Platte River water 1.1 .43 .04 3.4 South Platte River water 5.4 2.2 .18 3.4 Reagent water .91 .36 .01 1.3 Reagent water 4.5 1.8 34 7.5 

Diphenamid Arvada well water .99 .94 .94 5.3 

Arvada well water 5.0 4.4 .29 5.9 South Platte River water .99 .90 .04 3.7 South Platte River water 5.0 3.8 .18 3.6 Reagent water .98 .89 .02 2.5 Reagent water 4.9 4.3 .21 4.2 

Hexazinone Arvada well water 1.2 .78 .16 13 

Arvada well water 6.0 5.4 .46 7.7 South Platte River water 1.2 1.1 .04 3.5 

South Platte River water 6.0 4.9 .45 7.6 Reagent water 1.0 .53 .07 6.9 Reagent water 5.0 3.8 .29 5.9 

Metolachlor Arvada well water 1.1 1.0 .06 5.3 

Arvada well water 5.5 5.2 .29 5.2 South Platte River water 1.1 .97 .04 3.9 South Platte River water 5.5 4.3 .38 6.9 Reagent water 1.2 .99 .11 9.3 Reagent water 5.7 4.9 .28 5.0 

Metribuzin Arvada well water 1.1 1.1 .06 5.6 

Arvada well water 5.6 5.4 .51 9.1 South Platte River water 1.1 1.1 .03 3.1 South Platte River water 5.6 4.5 .21 3.7 Reagent water 1.1 .95 .13 12 Reagent water 5.3 4.5 .24 4.6 

————————————————————————————————————————————————————————

13
Table 2.--Triazine recovery data from three water matrices--Continued

———————————————————————————————————————————————————

Relative

Spike Standard standard

concentration Concentration deviation deviation Reco

Compound Matrix (μg/L) found (μg/L) (μg/L) (percent) (perc

———————————————————————————————————————————————————Prometon Arvada well water 0.93 0.69 0.10 11 7

Arvada well water 4.6 4.4 .29 6.3 9South Platte River water .93 .87 .04 4.0 9South Platte River water 4.6 3.7 .36 7.7 8Reagent water 1.0 .89 .10 9.1 8Reagent water 5.3 4.4 .27 5.0 8

Prometryn Arvada well water 1.1 1.0 .09 8.4 8

Arvada well water 5.5 4.6 .59 11 8South Platte River water 1.1 1.0 .04 3.8 9South Platte River water 5.5 4.4 .22 3.9 7Reagent water 1.1 1.0 .04 3.1 9Reagent water 5.7 4.9 .24 4.2 8

Propachlor Arvada well water 1.0 .86 .05 5.2 8

Arvada well water , 5.0 4.3 .34 6.8 8South Platte River water 1.0 .85 .03 3.4 8South Platte River water 5.0 3.8 .19 3.7 7Reagent water .84 .69 .02 2.6 8Reagent water 4.2 3.5 .21 4.9 8

Propazine Arvada well water .96 1.0 .06 6.2 9

Arvada well water 4.8 4.8 .25 5.2 10South Platte River water .96 .85 .04 3.9 8South Platte River water 4.8 3.6 .53 11 7Reagent water 1.0 .99 .15 14 9Reagent water 5.2 4.5 .25 4.8 8

Simazine Arvada well water .89 1.1 .05 5.9 12

Arvada well water 4.5 5.1 .32 7.1 11South Platte River water .89 .87 .03 3.8 9South Platte River water 4.5 3.7 .18 3.9 8Reagent water 1.0 .96 .02 1.6 9Reagent water 5.2 4.6 .24 4.6 8

————————————————————————————————————————————————————————

14
Table 2.--Triazine recovery data from three water matrices--Continued

———————————————————————————————————————————————————

Relative

Spike Standard standard

concentration Concentration deviation deviation 

Compound Matrix (μg/L) found (μg/L) (μg/L) (percent) 

———————————————————————————————————————————————————Simetryn Arvada well water 1.1 0.86 0.14 12 

Arvada well water 5.5 4.5 .38 6.9 South Platte River water 1.1 1.0 .04 3.5 South Platte River water 5.5 4.4 .21 3.9 Reagent water 1.2 1.0 .02 1.6 Reagent water 6.0 5.1 .27 4.5 

Terbacil Arvada well water 1.1 1.1 .12 11 

Arvada well water 5.6 5.2 .39 6.9 South Platte River water 1.1 1.3 .04 3.6 South Platte River water 5.6 5.0 .27 4.7 Reagent water 1.2 .93 .10 8.1 Reagent water 6.2 4.6 .35 5.6 

Terbuthy- Arvada well water .97 .88 .04 4.6 lazinel

Arvada well water 4.9 4.2 .27 5.6 South Platte River water .97 .90 .04 3.6 South Platte River water 4.9 3.9 .18 3.7 Reagent water 1.1 .98 .02 2.2 Reagent water 5.5 4.8 .18 3.3 

Trifluralin Arvada well water .96 .82 .07 7.2 

Arvada well water 4.8 4.1 .42 8.8 South Platte River water .96 .76 .03 3.6 South Platte River water 4.8 3.4 .15 14 Reagent water 5.2 3.6 .23 4.4 

Vemolate Arvada well water 1.0 .70 .10 10 

Arvada well water 5 3.4 .57 11 South Platte River water .99 .70 .17 18 South Platte River water 5 3.1 .49 9.8 Reagent water 1.2 .79 .17 14 Reagent water 6.0 3.5 .29 4.9 

———————————————————————————————————————————————————1Terbuthylazine is the surrogate compound.

15
CONCLUSIONS

Recoveries are adequate for alachlor, ametryn, atrazine, butachlor, carboxin, cyanazine, cycloate, desethylatrazine,

diphenamid, metolachlor, metribuzin, prometon, prometryn, propachlor, propazine, simazine, simetryn, terbacil, and trifluralin.

The recoveries of bromacil and hexazinone were marginal in the reagent-water matrix, but adequate for both the

surface-water and ground-water matrices.

Vernolate and butylate recoveries were marginal from all three matrices. Recoveries generally were in the 60-percent range

for both compounds. Vernolate recoveries ranged from 59 to 73 percent. The recovery of desisopropylatrazine ranged from 39 to 42

percent in all three water matrices.

Requests for bromacil, butylate, desisopropylatrazine, hexazinone, and vernolate need to be made with the understanding that

recoveries for these compounds are less than ideal. Greater recoveries for some of these compounds are available from the NWQL

using other procedures. For example, schedule 2001/2010 includes butylate with a recovery of about 80 percent, and schedule 1379

includes bromacil (80-percent recovery), hexazinone (87-percent recovery), vernolate (57-percent recovery, also low), and

desisopropylatrazine (also low at 48-percent recovery).

QUALITY ASSURANCE

Minimum quality-control requirements include analysis of laboratory reagent blanks, determination of surrogate recoveries in

each sample, reagent-water blank, laboratory-spiked reagent water, and assessment of the instrument system. As an additional check,

reagent-water and natural-water matricies are occasionally spiked in the field and sent to the laboratory as a routine sample.

Laboratory reagent-water blanks (LRB). Before processing any samples, the analyst needs to demonstrate that all glassware

and reagents are free of contaminants that might interfere with the analysis. Each time a set of samples is extracted or reagents are

changed, an LRB needs to be analyzed. If an unknown peak is within a range of three standard deviations of the retention-time

window of a compound of interest, then the source of contamination must be determined and eliminated before processing samples.

Assessing surrogate recovery. When surrogate recovery from a sample or method blank is low, on the basis of accepted

statistical methods of establishing control limits, check the following: (1) calculations to locate possible errors, (2) spiking solutions

for degradation, (3) contamination, and (4) instrument performance. If those steps do not reveal the cause of the problem, reanalyze

the extract.

If an LRB extract reanalysis fails the control limit criterion, the problem needs to be identified and corrected before

continuing.

If sample extract reanalysis meets the statistical control limits for surrogate recovery, report data for the analyzed extract. If

sample extract continues to fail the recovery criterion, report that the quality of the data for that sample is questionable.

16
Assessing laboratory performance--fortified reagent water. A fortified reagent-water (FRW) sample is reagent water that has

received measured quantities of selected compounds. The laboratory needs to analyze at least one FRW sample with every 10 samples

or one per sample set. The concentration of each compound in the FRW is within the range of the calibration standards. Standard

statistical techniques are used to establish control limits for compound recovery. If the recovery of any compound falls outside the

control limit criterion, that compound is judged out of control, and the source of the problem needs to be identified and resolved

before continuing analyses. The laboratory periodically needs to determine and document its detection limit capabilities for the

compounds of interest.

Assessing instrument system. Monitor instrument performance daily by placing a standard with known concentrations of the

compounds in the middle and at the end of each run of samples. The instrument is considered stable if the signal generated for each

compound in the standard is within a 10-percent variance. If the signal level exceeds the 10-percent variance limit, those samples need

to be rerun.

The laboratory may adopt additional quality-control practices for use with this method. The specific practices that are most

productive depend on the needs of the laboratory and the nature of the samples. For example, onsite or laboratory duplicates might be

analyzed to assess the precision of the environmental measurements, or onsite reagent blanks might be used to assess contamination of

samples under site conditions, transportation, and storage.

REFERENCES CITED

Graves, R.L., 1988, Method 507--Determination of nitrogen- and phosphorus-containing pesticides in water by gas chromatography

with a nitrogen-phosphorus detector, Revision 2.0, in Methods for the determination of organic compounds in drinking water,

USEPA/600/4-88/039, p. 143-170.

Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., 1987, Methods for the determination of organic substances in water and

fluvial sediments: U.S. Geological Survey Techniques of Water-Resources Investigations, book 5, chap. A3, p. 46-49.

17

 

 * U.S. GOVERNMENT PRINTING OFFICE: 1994-573-191/80021 REGION NO. 8