Combination of single-point standard addition calibration and natural internal standardization for quantification of terpenes in Pisco samples

Abstract An AOAC official method for quantitating cholesterol in multicomponent foods, which was first published in the 13th edition of the Official Methods of Analysis, is rarely used. The method includes so many operations and manipulations—all described in excruciating detail—that most laboratories shun it altogether. Intent on finding an alternative, laboratories have developed their own methods for specific foods. As a result, new methods have proliferated, but still no practical method has been developed for the broader categories of multicomponent foods. The aim of AOAC, which is to promote greater accuracy and uniformity of analytical results primarily through collaborative testing, has not been well served under these circumstances. A different approach guided the work reported in the present paper. This approach was directed toward updating and dramatically simplifying the existing AOAC official method. The method's chloroformmethanol-water mixed-solvent extraction is preserved; however, all the remaining steps have been streamlined, updated, or eliminated by using newer technology. Cholesterol is quantitated with highly specific capillary gas-liquid chromatography using the internal standardization technique. The lipid extract is prepared for the chromatography step by a brief saponification carried out in a culture tube. The resulting method has been validated by using Standard Reference Materials and the standard addition method. Because a simplified method is now available for quantitating cholesterol in the lipid extracts, the expectation is that more attention can be given to the development of improved and efficient extraction methods. This step remains as the central difficulty in any number of methods of analysis for lipid analytes.

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Single-point calibration and standard addition assays on calibrant-loaded paper-based analytical devices

Talanta ◽

10.1016/j.talanta.2019.04.008 ◽

2019 ◽

Vol 201 ◽

pp. 149-155 ◽

Cited By ~ 1

Author(s):

George Giannoulas ◽

George Z. Tsogas ◽

Dimosthenis L. Giokas

Keyword(s):

Single Point ◽

Standard Addition

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Comparison of approaches to deal with matrix effects in LC-MS/MS based determinations of mycotoxins in food and feed

World Mycotoxin Journal ◽

10.3920/wmj2014.1872 ◽

2016 ◽

Vol 9 (2) ◽

pp. 149-161 ◽

Cited By ~ 18

Author(s):

N. Fabregat-Cabello ◽

P. Zomer ◽

J.V. Sancho ◽

A.F. Roig-Navarro ◽

H.G.J. Mol

Keyword(s):

Matrix Effect ◽

Matrix Effects ◽

Single Point ◽

Internal Standard ◽

Standard Addition ◽

The European Union ◽

Single Level ◽

Internal Calibration ◽

The Matrix ◽

Multi Level

This study deals with one of the major concerns in mycotoxin determinations: the matrix effect related to LC-MS/ MS systems with electrospray ionization sources. To this end, in a first approach, the matrix effect has been evaluated in two ways: monitoring the signal of a compound (added to the mobile phase) during the entire chromatographic run, and by classical post-extraction addition. The study was focused on nine selected mycotoxins: aflatoxin B1, fumonisins B1, B2 and B3, ochratoxin A, deoxynivalenol, T-2 and HT-2 toxins and zearalenone in various sample extracts giving moderate to strong matrix effects (maize, compound feed, straw, spices). Although the permanent monitoring of a compound provided a qualitative way of evaluating the matrix effects at each retention time, we concluded that it was not adequate as a quantitative approach to correct for the matrix effect. Matrix effects measured by post-extraction addition showed that the strongest ion suppression occurred for the spices (up to -89%). Five different calibration approaches to compensate for matrix effects were compared: multi-level external calibration using isotopically labelled internal standards, multi-level and single level standard addition, and two ways of single-point internal calibration: one point isotopic internal calibration and isotope pattern deconvolution. In general, recoveries and precision meeting the European Union requirements could be achieved with all approaches, with the exception of the single level standard addition at levels too close to the concentration in the sample. When an isotopically labelled internal standard is not available, single-level standard addition is the most efficient option.

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Compensation for matrix effects in gas chromatography–tandem mass spectrometry using a single point standard addition

Journal of Chromatography A ◽

10.1016/j.chroma.2009.04.018 ◽

2009 ◽

Vol 1216 (23) ◽

pp. 4798-4808 ◽

Cited By ~ 84

Author(s):

Antonia Garrido Frenich ◽

José Luis Martínez Vidal ◽

José Luis Fernández Moreno ◽

R. Romero-González

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Tandem Mass Spectrometry ◽

Matrix Effects ◽

Single Point ◽

Standard Addition ◽

Tandem Mass ◽

Chromatography Tandem Mass Spectrometry

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Trace impurities analysis in UF4 via standard addition and 103Rh internal standardization techniques combined with ICP-MS

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/s10967-019-06884-0 ◽

2019 ◽

Vol 322 (3) ◽

pp. 2025-2032 ◽

Cited By ~ 1

Author(s):

Haixia Cong ◽

Chunxia Liu ◽

Ruifen Li ◽

Yuxia Liu ◽

Qiang Dou ◽

...

Keyword(s):

Standard Addition ◽

Trace Impurities ◽

Icp Ms ◽

Internal Standardization

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X-ray Fluorescence Analysis of High-Density Brines Using a Compton Scattering Ratio Technique

Advances in X-ray Analysis ◽

10.1154/s0376030800014579 ◽

1990 ◽

Vol 34 ◽

pp. 285-292

Author(s):

Michael L. Samuelson ◽

Stanley B. McCormell

Keyword(s):

Oil And Gas ◽

Matrix Effects ◽

Fluorescence Analysis ◽

Standard Addition ◽

High Density ◽

Ratio Method ◽

Gas Well ◽

X Ray ◽

Internal Standardization ◽

Scattering Ratio

AbstractHigh-density brines are used to control high pressure during oil and gas well operations. These dense brines (15 to 20 lb/gal) are solutions prepared from sale such as calcium chloride, calcium bromide, zinc bromide and/or combinations. During stages of completion, excessive losses of these expensive brines to the production zone can occur. Before the brine is reused in other oil and/or gas well operations, the brine may need to be reweighted. An analysis of the brine composition must be obtained to properly add the correct amount of salts.Standard addition or internal standardization methods are commonly used in X-ray fluorescence (XRF) applications but negate one of the advantages of XRF-elimination of tedious sample preparation. Scattered X-ray intensity has been used successfully to correct matrix effects in XRF applications. A Compton scatter ratio method is very advantageous for samples having a low atomic number, for which the scattered intensity is high. This paper describes an XRF method for determining Ca, CI, and Zn in high-density brines as well as the matrix correction for Br using a scattered X-ray ratio technique.

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Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

Marine Ecology Progress Series ◽

10.3354/meps13513 ◽

2020 ◽

Vol 655 ◽

pp. 185-198

Author(s):

J Weil ◽

WDP Duguid ◽

F Juanes

Keyword(s):

Energy Density ◽

Chinook Salmon ◽

Temporal Variability ◽

Energy Content ◽

Single Point ◽

Single Species ◽

Fine Scale ◽

Temporal Differences ◽

Juvenile Chinook Salmon ◽

Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

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