Laserfiche WebLink
pH PAPER METHOD <br /> t 1.0 SCOPE AND APPLICATION <br /> 1.1 Method 9041 may be used to measure pH as an alternative to Method <br /> 9040 or in cases where pH measurements by Method 9040 are not possible. This <br /> method may be used to define a waste as corrosive or noncorrosive under <br /> certain conditions (see Paragraph 1.3) . <br /> 1.2 Method 9041 is not applicable to wastes that contain components that <br /> may mask or alter the pH paper color change. <br /> 1.3 pH paper is not considered to - be as accurate- a form of pH <br /> measurement as pH meters. For this reason <br /> taken <br /> 9041 can be used to define a waste as corrosiveuorments noncorrosiveith Method <br /> regulations 261.22 (a) (1) only if the measured values differ from either <br /> threshold limit (pH 2 or 12.5) by a fullH unit: <br /> - If rs within the <br /> ranges of either pH 1-3 or pH 11.5-13.5 'are obtained witheadinMethod 9041, then <br /> Method 9040 should be used if possible to determine whether or not the waste <br /> is corrosive. <br /> 2.0 SUMMARY OF METHOD <br /> 2.1 The approximate pH of the waste is dete with wide-range <br /> paper. Then a more accurate pH determination is made using "narrow-range" p <br /> paper whose accuracy has been determined (1) using a series of buffers or Z <br /> by comparison with a calibrated pH meter. ( , <br /> _3.0 INTERFERENCES <br /> 3.1 Certain wastes may inhibit or mask changes in the pH paper. This <br /> interference can be determined by adding small amounts of acid or base to a <br /> small aliquot of the waste and observing whether the pH paper undergoes the <br /> appropriate changes. <br /> CAUTION: THE ADDITION OF ACID OR BASE TO WASTES MAY RESULT IN VIOLENT <br /> REACTIONS OR THE GENERATION OF TOXIC FUMESE.G. <br /> Thus, a decision to take this step requires someYknowledgeDROGENAofDthe <br /> waste. See Step 7.3.3 for additional precautions. <br /> 4.0 APPARATUS AND MATERIALS <br /> 4.1 Wide-range ;.H ::h.fir, <br /> 4.2 Narrow-ran e H 21per: W1th a distinct color change for ever 0.5 <br /> PH unit (e.g. , A caaci d Fu -Ran e y <br /> Each batch of narrow-range g PH Kit, Fisher Scientific or equivalent) . <br /> buffers or by comparison with paper must be calibrated versus certified pH <br /> certified pH buffer. <br /> PH meter which has been calibrated with <br /> 9041 — 1 . <br /> Revision 0 <br /> Date Septem er 1986 <br />