( ( ( As ( all Scott ) ) ( ( false ( positive substances ) ) ( ( have ( ( lower ( pKa values ) ) ( ( ( ( than cocaine ) , ) or ) ( in ( their basic ) ) ) ) ) ( from ( ( higher ( pKa values ) ) ( than ( the ( cocaine base ) ) ) ) ) ) ) ) ( , ( they ( ( can ( be ( ( discriminated ( from cocaine ) ) ( by ( ( a ( suitable ( pH test ) ) ) ( of ( the solution ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (PP (IN As) (NP (DT all) (NNP Scott))) (NP (JJ false) (JJ positive) (NNS substances)) (VP (VBP have) (NP (NP (JJR lower) (NN pKa) (NNS values)) (PP (PP (IN than) (NP (NN cocaine))) (, ,) (CC or) (PP (IN in) (NP (PRP$ their) (JJ basic))))) (PP (IN from) (NP (NP (JJR higher) (NN pKa) (NNS values)) (PP (IN than) (NP (DT the) (NN cocaine) (NN base))))))) (, ,) (NP (PRP they)) (VP (MD can) (VP (VB be) (VP (VBN discriminated) (PP (IN from) (NP (NN cocaine))) (PP (IN by) (NP (NP (DT a) (JJ suitable) (NN pH) (NN test)) (PP (IN of) (NP (DT the) (NN solution)))))))) (. .)))
As all Scott false positive substances have lower pKa values than cocaine, or in their basic from higher pKa values than the cocaine base, they can be discriminated from cocaine by a suitable pH test of the solution.
(ROOT (S (SBAR (IN If) (S (NP (DT a) (NN substance)) (VP (VBZ has) (NP (DT a) (NN ph) (NN value)) (NP (QP (JJR greater) (IN than) (CD 7)))))) (, ,) (NP (DT that)) (VP (VBZ indicates) (SBAR (IN that) (S (NP (PRP it)) (VP (VBZ is) (NP (NN base)))))) (. .)))
If a substance has a ph value greater than 7,that indicates that it is base.