Since the introduction of ion chromatography (IC) almost 50 years ago, it has become the most dominant method for ion analysis, in particular for the analysis of inorganic and organic anions and cations in water samples. Traditional IC is based on ion-exchange separations of the ionic analytes in combination with suppressed conductivity detection. Utilizing direct-injection techniques, detection limits in the single-digit μg/L range are standard today. If detection limits in the lower ng/L range are required, for instance for the analysis of anions or cations in high-purity water, preconcentration techniques have to be applied. Traditionally, sample delivery pumps are used to direct large sample volumes through the respective concentrator columns, bearing a significant contamination problem. To avoid such contamination risks, the concept of Reagent-Free™ IC has been expanded to include electrolytic sample preparation (RFIC-ESP) utilizing an electrolytic water polisher (EWP). In this presentation, the setup for calibrating and measuring ions in high-purity water at single-digit ng/L levels will be presented.
For the determination of perchlorate at levels <1 ΜG/L="" IN="" SAMPLES="" WITH="" HIGH="" ELECTROLYTE="" CONTENT,="" DIRECT-INJECTION="" TECHNIQUES="" ARE="" INADEQUATE.="" AS="" AN="" ALTERNATIVE="" TO="" IC-MS,="" A="" HEART-CUTTING="" TECHNIQUE="" (IC×IC)="" BASED="" ON="" A="" DUAL="" CONFIGURATION="" ION="" CHROMATOGRAPHY="" SYSTEM="" HAS="" BEEN="" INTRODUCED.="" ONE="" OF="" THE="" PRIMARY="" ADVANTAGES="" OF="" THE="" IC×IC="" METHOD="" IS="" THAT="" LARGE="" VOLUMES="" OF="" SAMPLE="" CAN="" BE="" INJECTED="" ONTO="" THE="" FIRST-CHANNEL,="" HIGH-CAPACITY="" SEPARATOR="" COLUMN="" WITHOUT="" ANY="" SAMPLE="" PREPARATION="" OTHER="" THAN="" FILTRATION,="" WHICH="" CONSIDERABLY="" SIMPLIFIES="" THE="" ANALYSIS.="" KNOWN="" TODAY="" AS="" U.S.="" EPA="" METHOD="" 314.2,="" THIS="" METHOD="" CAN="" BE="" FULLY="" AUTOMATED.="" DETECTION="" LIMITS="" EQUIVALENT="" TO="" IC-MS="" METHODS="" CAN="" BE="" ACHIEVED="" FOR="" PERCHLORATE="" AND="" OTHER="" EMERGING="" CONTAMINANTS="" SUCH="" AS="">
While for the majority of applications, suppressed conductivity detection represents the most versatile detection system in IC today, a growing number of applications are based on hyphenation, thus coupling IC with ICP or ESI‒MS. The advantage of coupling ICP with IC includes the ability to separate and detect metals with different oxidation states. The analytical interest in chemical speciation is based on the fact that the oxidation state of an element determines toxicity, environmental behavior, and biological effects. Hyphenation with ESI‒MS provides the analyst with mass-selective information. Challenging applications such as the determination of polar pesticides at trace levels in food products by IC‒MS/MS shown in this presentation clearly demonstrate the need for MS hyphenation to achieve the required sensitivity and selectivity.
