pfo pforzheim pfos pfp pfr pfs pft pfu polymerase pfullendorf pfuscher pfx pg pga pgd pgdip pgem-t pgh pgi pgl pgm pgms pgp pgs ph ph adjusted ph adjuster ph adjusters ph adjusting ph adjusting agent ph adjustment ph and conductivity ph and temperature ph balance ph balanced ph buffer ph buffering ph buffers ph can ph change ph changes ph close ph conditions ph control ph decreases ph dependence ph dependent ph dropped ph drops ph electrode ph gradient ph greater ph had ph has ph higher ph increased ph increases ph indicator ph is adjusted ph is greater ph is less ph is maintained ph is measured ph less ph level ph levels ph lower ph may ph measurement ph measurements ph meter ph meters ph modifier ph monitoring ph neutral ph of a solution ph of at least ph of greater ph of less ph of the buffer ph of the medium ph of the mixture ph of the product ph of the reaction medium ph of the resulting ph of the resulting solution ph of the soil ph of the solution ph of the water ph of this solution ph of water ph optimum ph paper ph probe ph range ph ranges ph regulation ph regulator ph scale ph sensitive