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1 t- <br />'1'A131,1: l (CUNT) <br />~ Vol. , <br />Rcy. Holding <br />Measurement (ml) Container"' Preservative Time"' <br />NTA 50 1',G Cool, 4"C 24 Ilrs. <br />Marc specific instructions fur prescrv:uion and sampling arc found with each procedure as <br />detailed in This manual. A general discussion on sampling water and industrial wastewater may <br />be found in ASTM, fart 31, p. 72-82 (1976) Method U-3370. <br />2. Plastic (P) or Glass (G). For metals, polyethylene with a polypropylene cap (no liner) is <br />preferred. <br />3. It should be pointed out that holding times listed above arc recommended (or properly <br />preserved samples based on currently available data. It is recognized Ihat for some sample <br />types, extension of Ihcse times may be possible while fur other types, Ihcsc times may be too <br />long. Where shipping regulations prevent the use of the proper preservation technique or the <br />holding lime is exceeded, uich as the case of a 24-hour composite, the final reported data for <br />these samples should indicate the specific variance. <br />( 4. 1 If the sample is stahirzcd by cooling. it should be warmed to 25"C for reading, or temperature <br />~.J correction made and results reported at 25°C. <br />5. Where 1INO, cannot be used hecausc of shipping restrictions, the sample may be initially <br />^ presen~ed by icing and immaliatcly shipped to the laboratory. Upon receipt in the laboratory, <br />the sample must be acidified to a pll <2 with IINO, (normally 3 ml l:l HNO,/liter is <br />sulTicicnt). AI the time of;tnalysis, the sample coutaincr should be thoroughly rinsed wish I:I <br />HNO, and the washings added to the sample (voVume correction may be required). <br />6. Data obtained from National Enforccmcnl lnvcsligatiuns Cct>tcr-Denver, Colorado, support a <br />four-week holding time for this parameter in Sewerage Syslcros. (SIC 4952). <br />/tA xix <br />