A drift correction procedure for ICP-AES systems

Marcos, Ana; Hill, Steve J.

doi:10.1039/b002408m

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…For such conditions, the authors have developed a new correction procedure. 41 (2) With medium power (rf power~1250 W), the data obtained indicate that the instrument is generally quite stable, showing drift values below 5% and complex drift patterns. Although drift correction under such conditions might be not necessary, internal standardisation methods will not be appropriate.…”

Section: Discussionmentioning

confidence: 99%

Application of a multi-way method to study long-term stability in ICP-AES

Marcos

Foulkes

Hill

2001

J. Anal. At. Spectrom.

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Although major advantages have been made in developing robust, easy-to-use ICP-AES instruments offering sub mg g 21 detection limits and relative interference free operation, long-term drift of the analytical signal continuous to be problematic and necessitates regular re-calibration. The work presented here focuses on the effect of two instrumental parameters, i.e. the rf power and the nebuliser gas ¯ow rate, on the robustness of the signals. The effects on the long-term stability when varying these two factors was systematically studied using an experimental design protocol. A ``drift diagnosis'' on thirty emission lines was performed at 12 different sets of operating conditions by repeated determination of a multi-element solution over several hours. The results were studied using standard parameters, i.e., Mg ratio, sensitivity, drift error, drift patterns and multi-way analysis. Parallel factor analysis (PARAFAC) was employed to analyse the 3-way data array generated: ``emission lines 6 replicates 6 operating conditions''. The physical interpretation of the new PARAFAC-factors is shown to enable a better understanding of the drift phenomenon by mathematically characterising the causes of long-term instability. Finally, the robustness of the technique using different operating conditions is evaluated and the appropriate use of internal standards to correct for drift is discussed.

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Section: Discussionmentioning

confidence: 99%

Application of a multi-way method to study long-term stability in ICP-AES

Marcos

Foulkes

Hill

2001

J. Anal. At. Spectrom.

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“…The concentrations of Ca and Mg were measured from the spectral lines at 407.776 and 279.553 nm, respectively. Instrumental drift was corrected according to Schrag [] and Marcos and Hill []. The ECRM 752‐1 standard (Bureau of Analyzed Samples) was analyzed twice for every three samples and the results were used for correction of measured sample Mg/Ca ratios.…”

Section: Methodsmentioning

confidence: 99%

Climatic evolution of the central equatorial Pacific since the Last Glacial Maximum

Seo

Lee

et al. 2016

Geochem Geophys Geosyst

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This paper investigates paleoceanographic changes at a central equatorial Pacific site (6°40′N, 177°28′W) since the last glacial maximum using planktic foraminifera assemblages, together with the oxygen isotope (δ18O) and Mg/Ca compositions of three species (Globigerinoides sacculifer, Pulleniatina obliquiloculata, and Globorotalia tumida) that dwell in the mixed layer, upper thermocline, and lower thermocline, respectively. While the Mg/Ca‐derived temperatures of the mixed layer and lower thermocline varied within a narrow range from 18 ka onward, the upper thermocline temperature increased by as much as 3°C during the last deglaciation (18–12 ka) with a simultaneous decrease of δ18O. These changes are best explained by an enhanced mixing of the upper ocean and a reduced habitat depth separation between P. obliquiloculata and G. sacculifer during the 18–12 ka interval. The planktic foraminifera assemblage during the same period resembles modern composition at subtropical central Pacific sites that are strongly influenced by the northeasterly Trades and North Equatorial Current (NEC). We suggest that the study site, presently under the control of the Intertropical Convergence Zone (ITCZ)‐North Equatorial Countercurrent, had been influenced by the northeasterly Trades and NEC during the 18–12 ka interval. This interpretation is consistent with previous documentation of a more southerly location of the ITCZ during two Northern Hemisphere cooling events; the Heinrich Stadial 1 and the Younger Dryas, and implies that the mean annual position of the ITCZ was located south of the study site, by at least 2° of latitude.

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“…It can be seen that the trends are slightly different for both operating conditions. 19,20 Fig. 3 Drift pattern under different experimental conditions: A, standard conditions; B, robust conditions.…”

Section: Drift Diagnosis In Icp-aes: Long-term Stabilitymentioning

confidence: 99%

Evaluation of the effect of data pre-treatment procedures on classical pattern recognition and principal components analysis: a case study for the geographical classification of tea

Moreda-Piñeiro

Marcos

Fisher

et al. 2001

J. Environ. Monitor.

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A simple transformation that uses the half-range and central value has been used as a data pre-treatment procedure for principal component analysis (PCA) and pattern recognition techniques. The results obtained have been compared with the results from classical normalisation of data (mean normalisation, maximum normalisation and range normalisation), autoscaling and the minimum-maximum transformation. Three data sets were used in the study. The first was formed by determining 17 elements in 53 tea samples (901 pieces of data). The second and third data sets arose from two long-term drift studies performed to examine instrumental stability at standard and robust conditions. The instruments used were an inductively coupled plasma atomic emission spectrometer and an inductively coupled plasma mass spectrometer. Each drift diagnosis experiment consisted of replicate determinations of a test solution containing 15 analytes at 10 mg l-1 over 8 h without recalibration. Twenty-nine emission lines were determined 99 times, thus, each data set was formed by 2881 pieces of data. Data pre-treatment was applied to the three data sets prior to the use of principal component analysis, cluster analysis, linear discrimination analysis and soft independent modelling of class analogy. The study revealed that the half-range and central value transformation resulted in a better classification of the tea samples than that achieved using the classical normalisation. The loadings in the PCA for the long-term stability study, under both standard and robust conditions, were found to be similar to the drift trends only when the minimum-maximum transformation and the mean or maximum normalizations were used as data pre-treatments.

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A drift correction procedure for ICP-AES systems

Cited by 7 publications

References 7 publications

Application of a multi-way method to study long-term stability in ICP-AES

Application of a multi-way method to study long-term stability in ICP-AES

Climatic evolution of the central equatorial Pacific since the Last Glacial Maximum

Evaluation of the effect of data pre-treatment procedures on classical pattern recognition and principal components analysis: a case study for the geographical classification of tea

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