1993-09-24_HYDROLOGY - M1977378 - Laserfiche WebLink

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fortified sample matrix covering the 3.5 Laboratory performance check 4.2 The water dip or negative peak that anions of interest. The fortification standards (LPC) - a solution of elutes near and can interfere with the procedure is described in Section 11 6 analytes prepared in the laboratory by fluoride peak can usually be eliminated adding appropriate volumes of the stock by the addition of the equivalent of 1 mL 2. Summary of Method standard solutions to reagent water of concentrated eluent (7.3 100X)to used to evaluate the performance of the 100 mL of each standard and sample. 2.1 A small volume of sample, typically instrument system with respect to a 2 to 3 mL, is introduced into an ion defined set of method criteria. 4.3 Method interferences may be chromatograph. The anions of interest caused by contaminants in the reagent are separated and measured, using a 3.6 Laboratory duplicates(LD) -two water, reagents,glassware, and other system comprised of a guard column, aliquots of the same sample that are sample processing apparatus that lead separator column, suppressor device, treated exactly the same throughout to discrete artifacts or elevated baseline and conductivity detector. laboratory analytical procedures. in ion chromatograms. Analyses of laboratory duplicates 2.2 The main differences between indicate precision associated with 4.4 Samples that contain particles Method A and B are the separator laboratory procedures but not the larger than 0.45 microns and reagent columns, guard columns and eluents. sample collection, preservation,or solutions that contain particles larger Sections 6 and 7 will elicit the differ- storage procedures. than 0.20 microns require filtration to ences. prevent damage to instrument columns 3.7 Field duplicates (FD) -two and flow systems. 2.3 In order to use this method for samples taken at the same time and solids an extraction procedure must be Placed under identical circumstances 4.5 Any anion that is not retained by performed (See 11.7). and treated exactly the same through- the column or only slightly retained will out field and laboratory procedures. elute in the area of fluoride and inter- 3. Definitions Analyses of field duplicates indicate the fere. Known coelution is caused by precision associated with sample carbonate and other small organic 3. collection, preservation and storage, as anions. At concentrations of fluoride co Stock standard solution a well as with laboratory procedures. above 1.5 mg/L this interference may concentrated solution containing a not be significant, however, it is the single certified standard that is a are u . Stock standard 3.8 Laboratory fortified sample matrix responsibility of the user to generate method a (LFM)-An aliquot of an environmental precision and accuracy information in solutions are used to prepare calibra sample to which known quantities of the each sample matrix. lion standards. method analytes are added in the laboratory. The LFM is analyzed exactly 4.6 The acetate anion elutes early solution Calibration standards (CAL) -a like a sample, and its purpose is to during the chromatographic run. The solution analytes prepared in the determine whether the sample matrix retention times of the anions also seem laboratoryy from stock standard solutions contributes bias to the analytical results. to differ when large amounts of acetate and diluted as needed and used to The background concentrations of the are present. Therefore,this method is calibrate the instrument response with analytes in the sample matrix must be not recommended for leachates of solid respect to analytic concentration. determined in a separate aliquot and samples when acetic acid is used for the measured values in the LFM pH adjustment. 3.3 Quality control sample (OCS) -a corrected for background concentra- solution containing known concentra- tions, 4.7 The quantitation of unretained tions of analytes, prepared by a peaks should be avoided, such as low laboratory other than the laboratory 3.9 Laboratory fortified blank (LFB) - molecular weight organic acids (for- performing the analysis. The analyzing An aliquot of reagent water to which mate, acetate, propionate, etc.)which laboratory uses this solution to demon- known quantities of the method are conductive and coelute with or near strate that it can obtain acceptable analytes are added in the laboratory. fluoride and would bias the fluoride identifications and measurements with The LFB is analyzed exactly like a quantitation in some drinking and most a method. sample, and its purpose is to determine waste waters. whether the methodology is in control, 3.4 Performance evaluation sample and whether the laboratory is capable 5. Safety (PE)- a solution of method analytes of making accurate and precise meas— distributed by the Quality Assurance urements at the required method de— Research Division (OARD), Environ 5.1 Normal, accepted laboratory safety practices should be followed during mental Monitoring Systems Laboratory tection limit. P 9 (EMSL-Cincinnati), USEPA, Cincinnati, reagent preparation and instrument Ohio,to multiple laboratories for 4. Interferences operation. No known carcinogenic analysis. A volume of the solution is materials are used in this method. added to a known volume of reagent 4.1 Interferences can be caused by water and analyzed with procedures substances with retention times that are 6. Apparatus and Materials used for samples. Results of analyses similar to and overlap those of the anion are used by the OARD to determine of interest. Large amounts of an anion 6.1 Balance-Analytical, capable of statistically the accuracy and precision can interfere with the peak resolution of accurately weighing to the nearest that can be expected when a method is an adjacent anion. Sample dilution 0.0001 g. performed by a competent analyst. and/or fortification can be used to solve Analyte true values are unknown to the most interference problems. analyst. 300.0-2 August 1991