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7 4 5 MIxed standard solutIon V - Antlmony, boron, magnesium, silver, and thallium NOTE 1 If the addition of silver to the recommended aCid combination results In an initial preCipitatIOn. add 15 mL of deloOlzed distilled water and warm the flask until the so,lutlon clears Cool and dilute to 100 mL with delOOIzed, distilled water For this acid combination the silver con- centration should be limited to 2 mg/L Silver under these conditIOns Is stable In a tap water matrix for 30 days Higher concentrations of silver require additional HCI 7 5 Two types of blanks are required for the analysIs The calibration blank (3 13) Is used In establishing the analytical curve while the reagent blank (3 12) IS used to correct for pOSSible contamination resulting from varying amounts of the aCIds used In the sample processing detection limits given In Table 1 (For effluent samples of expected high concentrations, spike at an appropriate level) If the type of samples analyzed are varied a synthetically prepared sample may be used If the above criteria and Intent are met A limited supply of a synthetiC Interference check sample will be available from the Quality Assurance Branch of EMSL- CinCinnati (See 12 1 2) 7 6 3 The quality control sample should be prepared In the same aCid matrix as the calibratIOn standards at a concentration near 1 mg/L and In accordance With the instructions prOVided by the supplier The Quality Assurance Branch of EMSL-Clnclnnatl Will either supply a quality control sample or information where one of equal quality can be procured (See 121 3) an active analytical quality control p(ogram uSing spiked samples and re- agent blanks. that certam steps 10 the cleaning procedure are not reqUired for routine samples, those steps may be eliminated from the procedure 8 2 Before collection of the sample a deCISion must be made as to the type of data deSired, that IS dissolved, suspended or total, so that the appro- pnate preservation and pretreatment steps may be accomplished Filtration, aCid preservation, etc, are to be per- formed at the time the sample IS collected or as soon as pOSSible thereafter 8 2 1 For the determination of diS- solved elements the sample must be filtered through a o45-Jim membrane filter as soon as practical after collec- tion (Glass or plastIC flltenng appara- tus are recommended to aVOid pOSSI- ble contamination) Use the first 50- 100 mL to rinse the filter flask DIS- card thiS portIon and collect the reqUired volume of filtrate ACidify the filtrate With (1 +1) HN03 to a pH of 2 or less Normally,3 mL of (1+1) aCid per liter should be suffiCient to pre- serve the sample 7 5.1 pared by diluting 2 mL of (1 +1) HN03 and 10 mL of (1+1) HCI to 100 mL with deionized. distilled water (See Note 6) Prepare a sufficient quantity to be used to flush the system be- tween standards and samples 7 5 2 7.6 In addition to the calibratIOn standards, an Instrument check stan- dard (3 7), an Interference check sample (38) and a quality control sample (39) are also reqUired for the analyses 7 6 1 The mstrument check standard is prepared by the analyst by com- bining compatible elements at a con- centration eqUivalent to the mIdpOint of their respective calibration curves (See 12 1 1) 7 6 2 The mterference check sample is prepared by the analyst In the follOWing manner Select a representative sample which contains minimal concentrations of the analytes of Interest by known con- centration of mterfenng elements that Will prOVide an adequate test of the correction factors Spike the sample with the elements of Interest at the approximate concentration of either 100 pg/L or 5 times the estimated 8 The calibration blank IS pre- The reagent blank must con- contain all the reagents and 10 the same volumes as used In the pro- cessing of the samples The reagent blank must be carned through the complete procedure and contam the same aCid concentration In the fmal solution as the sample solution used for analysIs Sample handling an preservation For the determination of trace elements, contamination and loss are of prime concern Dust In the labora- tory environment ImpUrities In reagents and ImpUrities on laboratory apparatus which the sample contacts are all sources of potential contamination Sample containers can Introduce either pOSItive or negative errors In the measurement of trace elements by (a) contributing con- taminants through leaching or surface desorption and (b) by depleting concentrations th rough adsorption Thus the collectIOn and treatment of the sample prior to analYSIS reqUires particular attention Laboratory glassware including the sample bottle (whether polyethylene, polyproplyene or FEP-fluorocarbon) should be thoroughly washed With detergent and tap water. nnsed With (1+1) nrtrlc aCid. tap water, (1 +1) hydrochlOriC aCid. tap al'd finally deionized, distilled water In that order (See Notes 2 and 3) NOTE 2 ChromiC aCid may be useful to remove organic depOSits from glass- ware. however. the analyst should be be cautioned that the glassware must be thoroughly nnsed With water to remove the last traces of chromium ThiS IS especially Important If chromium IS to be Included In the analytical scheme A commercial product, NOCH- ROMIX. available from Godax Labor- atones. 6 Vanck St. New York. NY 10013. may be used In place of chromiC aCid Chomlc aCid should not be used With plastiC bottles NOTE 3 Ifltcan be documented through 8 1 Meta/s-24 Dec 1982 8 2 2 pended elements a measured volume of unpreserved sample must be fil- tered through a o45-Jim membrane filter as soon as practical after collection The filter plus suspended material should be transferred to a SUitable container for storage and/or shipment No preservative IS reqUired 9 9 1 Sample PreparatIon For the determinations of diS- For the determrnatlon of sus- 8 2 3 or total recoverable elements, the sample IS aCidified WIth (1+1) HN03 to pH 2 or less as soon as pOSSible, preferable at the time of collection The sample IS not filtered before processing For the determination of total solved elements. the filtered, preserved sample may often be analyzed as received The aCid matrix and concentration of the samples and calibration standards must be the same (See Note 6 ) If a preCipitate formed upon aCidification of the sample or during transit or storage. It must be redissolved before the analYSIS by adding additIOnal aCid and/or by heat as deSCribed In 93 9 2 For the determination of sus- pended elements. transfer the mem- brane filter containing the Insoluble material to a 150-mL Griffin beaker and add 4 mL conc HN03 Cover thePDF Image | Methods for Chemical Analysis of Water and Wastes
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