Use of gradient dilution to flag and overcome matrix interferences in axial-viewing inductively coupled plasma-atomic emission spectrometry

Cheung, Yan; Schwartz, Andrew J.; Hieftje, Gary M.

doi:10.1016/j.sab.2014.05.014

Cited by 12 publications

(6 citation statements)

References 24 publications

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“…11 More recently, a gradient dilution method that overcomes matrix interferences in ICP OES has been described. 12 This approach uses an HPLC pump to dilute the sample provided to the ICP while monitoring two emission lines continually. This allows an automated approach to finding the highest sample concentration where the matrix effects are minimized.…”

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confidence: 99%

“…The same research group has described a manifold for calibration in flow injection analysis, and also a technique for flow injection gradient titration . More recently, a gradient dilution method that overcomes matrix interferences in ICP OES has been described . This approach uses an HPLC pump to dilute the sample provided to the ICP while monitoring two emission lines continually.…”

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Standard Dilution Analysis

et al. 2015

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Standard dilution analysis (SDA) is a novel calibration method that may be applied to most instrumental techniques that will accept liquid samples and are capable of monitoring two wavelengths simultaneously. It combines the traditional methods of standard additions and internal standards. Therefore, it simultaneously corrects for matrix effects and for fluctuations due to changes in sample size, orientation, or instrumental parameters. SDA requires only 200 s per sample with inductively coupled plasma optical emission spectrometry (ICP OES). Neither the preparation of a series of standard solutions nor the construction of a universal calibration graph is required. The analysis is performed by combining two solutions in a single container: the first containing 50% sample and 50% standard mixture; the second containing 50% sample and 50% solvent. Data are collected in real time as the first solution is diluted by the second one. The results are used to prepare a plot of the analyte-to-internal standard signal ratio on the y-axis versus the inverse of the internal standard concentration on the x-axis. The analyte concentration in the sample is determined from the ratio of the slope and intercept of that plot. The method has been applied to the determination of FD&C dye Blue No. 1 in mouthwash by molecular absorption spectrometry and to the determination of eight metals in mouthwash, wine, cola, nitric acid, and water by ICP OES. Both the accuracy and precision for SDA are better than those observed for the external calibration, standard additions, and internal standard methods using ICP OES.

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Standard Dilution Analysis

et al. 2015

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“…A drawback of this method is that the intensity-ratio profile is less sensitive to changes in plasma conditions (and therefore to the presence of a matrix interference) than is the spatial emission profile. We have shown [17] that a 10% change in solvent composition can cause significant matrix effects. Unfortunately, the intensity-ratio method was not able to flag this error.…”

Section: Introductionmentioning

confidence: 93%

“…and standard additions [10][11][12][13]) must be used to correct for matrix interference, among which dilution is one the most common [14][15][16]. A previous study [17] by our research group showed that the intensity ratio of two emission lines (from the same or different elements) can be used as a matrix-effect indicator when the sample is progressively diluted by means of a gradient high-performance liquid chromatography (HPLC) pump. Due to a disparity in the upper-state energies of two emission lines, the effect of the progressively diluted matrix on these emission lines is different.…”

Section: Introductionmentioning

confidence: 99%

Flagging and correcting non-spectral matrix interferences with spatial emission profiles and gradient dilution in inductively coupled plasma-atomic emission spectrometry

Cheung

Schwartz

Chan

et al. 2015

Spectrochimica Acta Part B: Atomic Spectroscopy

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Matrix interference remains one of the most daunting challenges commonly encountered in inductively coupled plasma-atomic emission spectrometry (ICP-AES). In the present study, a method is described that enables identification and correction of matrix interferences in axialviewed ICP-AES through a combination of spatial mapping and on-line gradient dilution. Cross sectional emission maps of the plasma are used to indicate the presence of non-spectral (plasmarelated and sample-introduction-related) matrix interferences. In particular, apparent concentrations of an analyte species determined at various radial locations in the plasma differ in the presence of a matrix interference, which allows the interference to be flagged. To correct for the interference, progressive, on-line dilution of the sample, performed by a gradient highperformance liquid-chromatograph pump, is utilized. The spatially dependent intensities of analyte emission are monitored at different levels of sample dilution. As the dilution proceeds, the matrix-induced signal variation is reduced. At a dilution where the determined concentrations become independent of location in the plasma, the matrix interference is minimized.

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“…In addition, from the same ratio profile employed to detect a matrix effect, one can also locate the optimal dilution factor for the minimization of interference. This gradient-pump method was first developed to flag and correct matrix interference in ICP-OES 22 with encouraging results. The present study builds on the previous work, expanding its application to flag and correct for interferences within ICP-MS. Of course, prolonging analysis time is not ideal for routine analysis despite its benefits; however, this gradient-dilution run need be performed on only a single sample among a batch of samples with similar matrices.…”

Section: Introductionmentioning

confidence: 99%

Use of Gradient Dilution to Detect and Correct Matrix Interferences in Inductively Coupled Plasma–Time-of-Flight Mass Spectrometry (ICP-TOFMS)

et al. 2016

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Our research group earlier used dispersion that occurs during flow injection to detect and reduce matrix interference in inductively coupled plasma-time-of-flight mass spectrometry (ICP-TOFMS). In the absence of a matrix interference, the ratio of signals from any two sample constituents should remain constant, independent of the dilution, over the course of a flow-injection transient. However, when an interferent is present, the signal ratio from different analytes will change with dilution, owing to the difference in severity of the interference on specific analytes. As a result, matrix interference can be recognized (flagged) by monitoring the signal ratios of two analytes over the course of a flow-injection transient; a ratio that changes over time indicates the presence of an interferent. The drawback of this earlier method was that dispersion, and therefore dilution, was somewhat element-specific, causing the ratios to wander even when no interference existed. Here, a gradient HPLC pump is used to overcome this drawback by creating a longer, better-controlled dilution. Under these conditions, variation in dispersion between elements is negligible and difficulties associated with it are reduced or eliminated. Further, when an interference exists, the optimal dilution factor to reduce the interference to an acceptable level can be found from the gradient-dilution curve as the point where the signal ratio between two elements becomes constant.

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Use of gradient dilution to flag and overcome matrix interferences in axial-viewing inductively coupled plasma-atomic emission spectrometry

Cited by 12 publications

References 24 publications

Standard Dilution Analysis

Standard Dilution Analysis

Flagging and correcting non-spectral matrix interferences with spatial emission profiles and gradient dilution in inductively coupled plasma-atomic emission spectrometry

Use of Gradient Dilution to Detect and Correct Matrix Interferences in Inductively Coupled Plasma–Time-of-Flight Mass Spectrometry (ICP-TOFMS)

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