ents ▁and ▁sed iment ▁( so il ). ▁Organ omet all ic ▁comp ounds . ▁ ▁Method s ▁ ▁Quant itative ▁chemical ▁analysis ▁is ▁a ▁key ▁part ▁of ▁environmental ▁chem istry , ▁since ▁it ▁provides ▁the ▁data ▁that ▁frame ▁most ▁environmental ▁studies . ▁ ▁Common ▁analyt ical ▁techniques ▁used ▁for ▁quant itative ▁determin ations ▁in ▁environmental ▁chem istry ▁include ▁classical ▁wet ▁chem istry , ▁such ▁as ▁grav imet ric , ▁tit rim et ric ▁and ▁electro chem ical ▁methods . ▁More ▁s oph istic ated ▁approaches ▁are ▁used ▁in ▁the ▁determ ination ▁of ▁trace ▁met als ▁and ▁organ ic ▁comp ounds . ▁Met als ▁are ▁commonly ▁measured ▁by ▁atomic ▁spect ro sc opy ▁and ▁mass ▁spect rom etry : ▁At omic ▁Abs or ption ▁Spect roph ot ometry ▁( A AS ) ▁and ▁Ind uct ively ▁Cou ple d ▁Pl asma ▁At omic ▁Em ission ▁( IC P - A ES ) ▁or ▁Ind uct ively ▁Cou ple d ▁Pl asma ▁Mass ▁Spect rom et ric ▁( IC P - MS ) ▁techniques . ▁Organ ic ▁comp ounds , ▁including ▁PA H s , ▁are ▁commonly ▁measured ▁also ▁using ▁mass ▁spect rom et ric ▁methods , ▁such ▁as ▁Gas ▁chrom at ography - mass ▁spect rom etry ▁( GC / MS ) ▁and ▁Li qu id ▁chrom at ography - mass ▁spect rom etry ▁( LC / MS ). ▁Tan dem ▁Mass ▁spect rom etry ▁MS / MS ▁and ▁High ▁Resol ution / Acc ur ate ▁Mass ▁spect rom etry ▁H R /