Resume

• 1965

  PhD

  Chemistry

• Research

  HPLC

  Organic Chemistry

  Mass Spectrometry

  LC-MS

  Higher Education

  Life Sciences

  Chemistry

  Chromatography

  Spectroscopy

  NMR

  Science

  Physical Chemistry

  UV/Vis

  Leadership

  R&D

  Analytical Chemistry

  Use of gradient dilution to flag and overcome matrix interferences in axial-viewing Inductively Coupled Plasma-Atomic Emission Spectrometry

  Despite the undisputed power of inductively coupled plasma-atomic emission spectrometry (ICP-AES)

  its users still face serious challenges in obtaining accurate analytical results. Matrix interference is perhaps the most important such challenge. Dilution of a matrix-containing sample is a common practice to reduce matrix interference. However

  determining the optimal dilution factor requires tedious and time-consuming offline sample preparation

  since emission lines and the effect of matrix interferences are affected differently by the dilution. The current study exploits this difference by employing a high-performance liquid chromatography gradient pump prior to the nebulizer to perform on-line mixing of a sample solution and diluent. Linear gradient dilution is performed on both the calibration standard and the matrix-containing sample. By ratioing the signals from two emission lines (from the same or different elements) as a function of dilution factor

  the analyst can not only identify the presence of a matrix interference

  but also determine the optimal dilution factor needed to overcome the interference. A ratio that does not change with dilution signals the absence of a matrix interference

  whereas a changing ratio indicates the presence of an interference. The point on the dilution profile where the ratio stabilizes indicates the optimal dilution factor to correct the interference. The current study was performed on axial-viewing ICP-AES with o-xylene as the solvent.

  Use of gradient dilution to flag and overcome matrix interferences in axial-viewing Inductively Coupled Plasma-Atomic Emission Spectrometry

  George C.-Y. Chan

  Spatial emission maps across an end-on-viewed inductively coupled plasma were used to flag matrix interferences and system drift for organic-solvent-based samples. This method is based on the fact that a matrix interference affects emission signals differently from one cross-sectional location in the plasma to another. The method is straightforward: a set of calibration curves made with standard solutions is obtained at several cross-sectional locations in the plasma; each unknown sample is then analyzed by means of those curves. If a matrix interference exists

  the determined concentration in the sample will appear to change from spatial location to another. Fundamentally

  this behavior arises because the plasma is spatially heterogeneous and is affected by a sample matrix in a spatially dependent way. Isopropanol was used as the solvent for the determination of ten analytes (As

  Cd

  Co

  Cu

  Cr

  Fe

  Mg

  Mn

  Ni

  and Zn). Three types of matrix interference were examined: spectral

  plasma-related and sample-introduction-related. It was found possible to flag errors as small as ±2% caused by any of the three types of matrix interference

  as well as system drift.

  Flagging Matrix Effects and System Drift in Organic-solvent-based Analysis by Axial-Viewing Inductively Coupled Plasma–Atomic Emission Spectrometry

  Hieftje

  Indiana University Bloomington

  Bloomington

  Indiana Area

  Distinguished Professor Emeritus

  Indiana University Bloomington

  Indiana University