Polyethylene comonomer characterization by using FTIR and a multivariate classification technique.

Many polyethylene (PE) films used in various packaging applications are based on multi-layer systems and are fabricated by using the coextrusion techniques that can combine different raw materials. The identification of the comonomer type (octene - C, hexene - C and butene - C) in films, where two or more different linear low density polyethylene (LLDPE) resins are present, is becoming a frequent request. This report presents a novel approach where multivariate classification techniques are used in combination with FTIR for the identification of the comonomer type in coextruded films.

Outlier detection for the Generalized Rank Annihilation Method in HPLC-DAD analysis.

The Generalized Rank Annihilation Method (GRAM) is a second-order calibration method that is used in chromatography to quantify analytes that coelute with interferences. For a correct quantification, the peak of the analyte in the standard and in the test sample must be aligned and have the same shape (i.e.

Quantification from highly drifted and overlapped chromatographic peaks using second-order calibration methods.

For determining low levels of pesticides and phenolic compounds in river and wastewater samples by high performance liquid chromatography (HPLC), solid phase extraction (SPE) is commonly used before the chromatographic separation. This preconcentration step is not necessarily selective for the analytes of interest and it may retain other compounds of similar characteristics as well. In this case, we present, humic and fulvic acids caused a large baseline drift and overlapped the analytes to be quantified.

Using second-order calibration to identify and quantify aromatic sulfonates in water by high-performance liquid chromatography in the presence of coeluting interferences.

We used the Generalized Rank Annihilation Method (GRAM), a second-order calibration method, to quantify aromatic sulfonates in water with high-performance liquid chromatography (HPLC) when interferences coeluted with the analytes of interest. With GRAM, we can quantify in only two chromatographic analyses, one for a calibration sample and one for the unknown sample. The calculated concentrations were not statistically different to those obtained when the chromatographic separation of the unknown sample was modified in order to completely separate the analyte from the interferences before univariate calibration.