The concentrations of compounds in the extract are measured using a fused silica capillary column gas chromatography GC system equipped a linearized electron capture detector ECD. Scope and Application This method determines certain chlorinated or halogenated compounds disinfection byproducts, pesticides, herbicides, and solvents in finished drinking water, drinking water during intermediate stages of treatment, and raw source water. Applicable Concentration Range Ranges differ for each analyte. Interferences A Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse. B Solvent contamination: Use high purity solvents, and test solvents to prevent contamination: Contamination of MTBE and pentane with chlorinated solvents common occurrence can be reduced by double distillation. C Extracted interferences: Interference from extracted non-target compounds, with retention times similar to target compounds, can be reduced using confirmation analysis.
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Results for the THMs and the eight solvents may be obtained from the analysis of samples employing either dechlorinating agent. Section 8. Actual MDL values will vary according to the particular matrix analyzed and the specific instrumentation employed.
Each analyst must demonstrate the ability to generate acceptable results with this method using the procedure described in Section 9. However, due to safety concerns associated with MTBE and the current use of pentane by some laboratories for certain method analytes, pentane is offered as an optional extraction solvent for all analytes except If project requirements specify the analysis of chloral hydrate, MTBE must be used as the extracting solvent.
This method includes sections specific for pentane as an optional solvent. Procedural standard calibration is used to quantitate method analytes. Confirmation of the eluted compounds may be obtained using a dissimilar column Section 6.
The internal standard must be an analyte that is not a sample component. The purpose of a surrogate analyte is to monitor method performance with each sample. Analyses of LD1 and LD2 indicate precision associated with laboratory procedures, but not with sample collection, preservation, or storage procedures. This method cannot utilize laboratory duplicates since sample extraction must occur in the sample vial and sample transfer is not possible due to analyte volatility.
Analyses of FD1 and FD2 give a measure of the precision associated with sample collection, preservation and storage, as well as with laboratory procedures. Since laboratory duplicates The LRB is used to determine if method analytes or other interferences are present in the laboratory environment, the reagents, or the apparatus.
The purpose of the FRB is to determine if method analytes or other interferences are present in the field environment. The LFB is analyzed exactly like a sample, and its purpose is to determine whether the methodology is in control, and whether the laboratory is capable of making accurate and precise analyte quantitation at various concentrations including the required method detection limit.
The LFM is analyzed exactly like a sample, and its purpose is to determine whether the sample matrix contributes bias to the analytical results. The background concentrations of the analytes in the sample matrix must be determined in a separate aliquot and the measured values in the LFM corrected for background concentrations. The CAL solutions are used to calibrate the instrument response with respect to analyte concentration. The QCS is obtained from a It is used to check laboratory performance with externally prepared test materials.
All steps in the process from addition of sampling preservatives through instrumental analyses are included in the calibration. Using procedural standard calibration compensates for any inefficiencies in the processing procedure. Each new bottle of solvent should be analyzed for interferences before use. Indirect daily checks on the extracting solvent are obtained by monitoring the laboratory reagent blanks Section 9.
Whenever an interference is noted in the reagent blank, the analyst should analyze the solvent separately to determine if the source of the problem is the solvent or another reagent. Clean all glassware as soon as possible after use by thoroughly rinsing with the last solvent used in it. Follow by washing with hot water and detergent and thoroughly rinsing with tap and reagent water. Do not muffle volumetric ware but instead rinse three times with HPLC grade or better acetone.
Thoroughly rinsing all glassware with HPLC grade or better acetone may be substituted for heating provided method blank analysis confirms no background interferant contamination is present.
After drying and cooling, seal and store all glassware in a clean environment free of all potential contamination. To prevent any accumulation of dust or other contaminants, store glassware inverted on clean aluminum foil or capped with aluminum foil.
When present, these impurities can normally be removed by double distillation. Thus, confirmation is quite important, particularly at lower analyte concentrations. A confirmatory column Section 6. The active sites are usually the result of micro fragments of the injector port septa and high boiling sample residual deposited in the injection port sleeve or on the inner wall at the front of the capillary column.
These are believed to be due to phthalate contamination. Each laboratory is responsible for maintaining awareness of OSHA regulations regarding safe handling of chemicals used in this method. Additional references to laboratory safety are available for the information of the analyst.
Susceptible individuals may experience adverse affects upon skin contact or inhalation of vapors. Therefore, protective clothing and gloves should be used and MTBE should be used only in a chemical fume hood or glove box. The same precaution applies to pure standard materials.
Catalog numbers are included for illustration only. Prior to use or following each use, wash vials and septa with detergent and tap water then rinse thoroughly with distilled water. After removal from the oven allow the vials to cool in an area known to be free of organics. The syringe plunger, after repeated sample extract injections, developed resistance when withdrawn or inserted into the This resistance was due to salt deposits in the syringe barrel which were left behind following the evaporation of hydrated MTBE.
To minimize this problem, a unique syringe wash procedure was employed. After sample injection, the syringe was first rinsed three times with reagent water then three times with MTBE. This effectively removed all the residual salt after each injection from the syringe and surmounted the problem. Some autosampler designs may not encounter this problem but this precaution has been mentioned to alert the analyst.
When pentane was used as the extraction solvent, this was not a problem. Column A is recommended as the primary analytical column unless routinely occurring analytes are not adequately resolved. Other GC columns or conditions may be employed provided adequate analyte resolution is attained and all the quality assurance criteria established in Section 9. As a result of the different boiling points of MTBE b.
Retention times for target analytes were slightly different using the pentane oven temperature program but elution order, analyte resolution, and total analysis time were not effected. This sleeve design was found to give better analyte response than the standard 2 mm sleeve. The column oven was temperature programmed exactly as indicated for column A Tables 1 and The same temperature program was utilized to allow for simultaneous confirmation analysis.
To ensure the column ends are centered in the injection port sleeve and not angled to the side, an inlet adaptor fitting is installed at the base of the injection port Restek , or equivalent. Use caution when installing columns in this manner to ensure the column does not break at the base of the injector due to the two columns twisting as the ferrule nut is tightened.
To minimize this hazard, the ferrule nut can be reverse twisted four to five times once the ferrule has been seated. Then using a Y-press tight union Restek or equivalent join the 1 m uncoated column to the primary and secondary columns. Using this procedure will reduce detection limits when compared to the procedure outline in Section 6.
Each time such method modifications are made, the analyst must repeat the procedures in Section 9. It may be necessary to double distill the solvent if impurities are observed which coelute with some of the more volatile compounds. Store in a capped glass bottle, not in a plastic container. Store in a capped glass bottle not in a plastic container. Powder would be ideal but would require extended cleanup time as outlined below in Section 7. Although this is not the traditional dechlorination mechanism, ammonium chloride is categorized as a dechlorinating agent in this method.
Add 1. Two separate mixtures are prepared, one containing ammonium chloride and the other with sodium sulfite. These contaminants may coelute with some of the high molecular weight herbicides and pesticides.
This solvent rinsing procedure is applied to the homogeneous mixture prepared in Section 7. To one, add the correct amount of ammonium chloride and to the other add the correct amount of sodium sulfite.
Three separate solvents are then used to rinse the mixture. This solvent rinsing must be performed in a fume hood or glove box. First, add approx. It may be necessary to perform this procedure up to four times with methanol.
Note: By softly lifting and tapping the base of the beaker against the fume hood counter surface, more of the solvent is brought to the surface of the buffer. Next, perform the identical procedure up to two times using acetone. After the final solvent rinse, place the "wet" buffer on a hot plate at approx. Stir the mixture every five minutes to aid the evaporation of excess solvent. Once dry, place the buffer in a glass bottle with either a ground glass stopper or TFE-faced septum.
Distilled water that has been charcoal filtered may also be suitable. Dilute to volume with acetone. Due to the low solubility of simazine, this stock should be prepared at 0. Alternatively, simazine stock standard solutions may be prepared in ethyl acetate at approximately 0. Stock standard solutions for analytes which are liquid in their pure form at room temperature can be accurately prepared in the following manner. Allow the flask to stand, unstoppered, for about 10 minutes to allow solvent film to evaporate from the inner walls of the volumetric flask, and weigh to the nearest 0.
Caution should be observed to be sure that the standard material falls dropwise directly into the acetone without contacting the inner wall of the volumetric flask.
Calculate the concentration in milligrams per milliliter from the net gain in weight. Final concentration should be between 0. When purchasing commercially prepared stock standards, every effort should be made to avoid solutions prepared in methanol chloral hydrate is an exception, Section 7. Methanol can cause degradation of most of the haloacetonitriles.
In addition, some commercial suppliers have reported instability with solutions of simazine and atrazine prepared in methanol For these reasons, acetone should be used as the primary solvent for stock standard and primary dilution standard preparation and all sources of methanol introduction into these acetone solutions should be eliminated.
EPA Method 551.1
Figure 4 Linearity of calibration for the halogenated organics in water from 0. EPA Method Therefore, the I am using the same column they suggest DB1 but my peaks start 20 minutes after theirs do they start showing on minute 5hence I think my heat ramps do not work well with the compounds at my settings. The method was later modified to include the concurrent determination of cyanogen chloride LeBel and Williams,; LeBel and Benoit, and other halogenated acetaldehydes Koudjonou and LeBel, Fig 2 The instrument configuration used for large volume injection.
EPA METHOD 551.1 PDF