Assessment of Repeatability in Supercritical Fluid Chromatography with Electrochemical Detection Based on the ISO 11843 Part 7

Abstract

The present study proposes a method for the assessment of repeatability in supercritical fluid chromatography with electrochemical detection (SFC-ECD), based on the ISO 11843 part 7 (ISO 11843-7:2018) which can theoretically provide detection limits and standard deviation (S.D.) through the stochastic properties of baseline noise without repetitive measurements of real samples. On the baseline noise of SFC-ECD, large-amplitude and periodic noises with less than 0.05 Hz were observed, and the power spectrum of the baseline noise showed 1/f fluctuation ( f frequency). It was found that the present power spectrum analysis, according to the law of error propagation, can provide suitable noise parameters to calculate S.D. of baseline noise and a relative S.D. (RSD) of peak area by ISO 11843-7. The chromatographic determinations of α-, β-, γ-and δ-tocopherol have been taken as examples. In the present SFC-ECD, the RSDs of peak areas for α-, β-, γ-and δ-tocopherol obtained by ISO 11843-7 were within 95% confidence intervals of the RSD of them obtained by repetitive measurements (n 6). Thus, we found that ISO 11843-7 is applicable to the assessment of repeatability in SFC-ECD for determining tocopherols without repetitive measurements.

Effects of sampling rate and noise filter processing on repeatability assessment in UHPLC with ultraviolet detection based on the ISO 11843-7

“…In the ISO 10 11843-7, the scattering of an SD estimate is almost the same as that of the SD estimate from more than 40 repetitive measurements. 24,25 In Fig. 3 In the present UHPLC-UV system, we recommend a sampling rate of 20 points s -1 for the following reasons; the measurement time of a chromatogram can be saved to perform repeatability assessment based on the ISO 11843-7, because the measurement of a baseline of about 1 min gives 1024 points of data to determine a SB, and a reliable chromatographic peak can be obtained to determine the peak area because the chromatographic peak of ergosterol consists of 480 digital data (= 20 points s -1 ×24 s of peak wide).…”

Chemometric Evaluation of Repeatability Using the Autocorrelation Method in High-Performance Liquid Chromatography with Ultraviolet Detection

“…To reduce this experimental burden, various theoretical approaches have been developed to enable the mathematical interpretation of noise that ubiquitously exists in analytical equipment regardless of whether a sample is being analyzed. [6][7][8][9][10][11][12][13][14] The principal advantages of these chemometric strategies include reducing the need for materials, time, energy, and human effort that would otherwise be required to perform repeated measurements. As an example, the function of mutual information (FUMI) theory, the practical applicability of which has been proved experimentally in a variety of settings, has been adopted as an international standard (ISO 11843-7).…”

“…15) The FUMI theory approximates the baseline noise with the mixed random processes of the first order autoregressive process (designated AR(1)) and white noise, the parameterization of which is attained by the least-squares fitting to noise power spectra. 13,14) Recently, Hayashi and Zhang proposed another method that utilized the autocorrelation method instead of the power spectrum. 16) The most prominent merit of their method is the simplicity of the algorithm used to elicit the information needed for repeatability assessments of baseline noise.…”