Uncertainty profiles for the validation of analytical methods

Simultaneous Quantification of Two Neonicotinoids Using QuEChERS-LC-MS/MS in Moroccan Spearmint (Mentha Spicata.L): Qualimetry of the Method by Uncertainty Estimation Using Generalized Pivotal Quantities Approach and Monte Carlo Simulation

BACKGROUND

Neonicotinoids (NEOs) are used for the phytosanitary treatment of Mentha Spicata.L crops, and this practice requires precise control of these harmful substances at very low concentrations.

OBJECTIVE

The objective of this study is to apply an approach allowing simultaneously validation and evaluation of measurement uncertainty based on total error methodology, in order to accurately quantify the presence of two NEOs in Mentha Spicata.L utilizing a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS)-LC-MS/MS methodology.

METHODS

 The quantification of imidacloprid and acetamiprid employing a QuEChERS extraction method, coupled with LC-MS/MS, ensuring the accuracy of the analytical method and managing the risks associated with its routine use. A complete and exhaustive validation approach based on the "β-content, γ-confidence" tolerance interval was used for the uncertainty assessment, using the generalized pivot quantity (GPQ) concept and Monte Carlo simulation, which avoids the need for additional data while achieving intermediate precision for each concentration level within predetermined acceptable limits.

RESULTS

The validation procedure is based on the choice of a quadratic model for the two NEOs, allowing the validation of acetamiprid and imidacloprid by LC-MS/MS assay within the range of working concentration. The flexibility of the uncertainty profile intervals was demonstrated with a variation in β-content values (66.7, 80, and 90%) and risk values (10 and 5%), which remained within the acceptability limits of 20%, and the relative expanded uncertainty did not exceed 15 and 11%.

CONCLUSION

A QuEChERS-LC-MS/MS method for the analysis of two NEOs has been successfully fully validated using the uncertainty profile strategy.

HIGHLIGHTS

Implementation of an overall validation strategy, which involves both the validation and uncertainty assessment known as the uncertainty profile, for the quantification of two important NEOs in Mentha Spicata.L using QuEChERS-LC-MS/MS. This qualimetric approach has been conducted by computing the measurement uncertainty of the method utilizing data from analytical validation under conditions of intermediate precision at each level of concentration without additional effort. After that we have demonstrated the flexibility of this strategy for the LC-MS/MS quantification of acetamiprid and imidacloprid, using a decision tool that enables the choice and modification of β-content and γ-confidence values.

Measurement uncertainty

Over time, the metrological concept of uncertainty in measurement has been very successfully integrated into laboratory sciences. For proper implementation, an understanding of specific metrology terminology and additional concepts such as metrology traceability and commutability is necessary. Although the original thinking about measurement uncertainty in laboratory medicine suggests the complexity of the concept, it basically refers to the result as the end product of the entire laboratory process. Although the data on measurement uncertainty can be expressed quantitatively, the basis of this concept is the continuous evaluation of all phases of the laboratory process. This means that laboratory experts should keep in mind that the extra-analytical phases (on which the uncertainty of the measurement results may depend the most) must be continuously monitored. The analytical phase can be "held in check" by established internal and external quality control processes. It is the internal/external quality control data that is used to calculate the numerical value of the measurement uncertainty of the measurement results. Although over time the awareness of laboratory experts regarding the concept of measurement uncertainty has increased, there are still many challenges that need to be followed, and the last one is how to achieve a balance between understanding, evaluation process and application of measurement uncertainty data of measurement results for complete and ultimate practical use.

The Flexibility of β-Content, γ-Confidence Tolerance Intervals to Qualimetry a Simultaneous 22 Aromatic Amines Derived from Azo Dyes in Fabric Using a Sensitive GC-MS Technique

BACKGROUND

Azo dyes are among the most widely used dyes in the textile industry, releasing a series of carcinogenic aromatic amines that can be absorbed through the skin.

OBJECTIVE

This work aims to show that 22 azo dye amines in a textile matrix can be quantified using a GC-MS method.

METHODS

Based on the notion of total error and β-content, γ-confidence tolerance intervals (β,γ-CCTI), a chemometric approach known as the "uncertainty profile" has been used to completely validate a GC-MS method for the simultaneous assay of 22 azo amines in fabrics. According to International Organization for Standardization (ISO) in ISO 17025 guidelines, analytical validation and measurement uncertainty estimates have evolved to be two main principles for ensuring the accuracy of analytical results and controlling the risk associated with their use.

RESULTS

The calculated tolerance intervals allowed for the determination of the uncertainty limits at each concentration level. These limits when compared to the acceptable limits show that a significant portion of the expected outcomes is in conformity. Additionally, the relative expanded uncertainty values, calculated with a proportion of 66.7% and a 10% risk, do not exceed 27.7, 12.2, and 10.9% for concentration levels 1, 15, and 30 mg/L, respectively.

CONCLUSION

The capability and flexibility of the β-content, γ-confidence intervals have been established through the use of this innovative approach to carrying out qualimetry of the GC-MS method depending on the behavior, required conformity proportion, and acceptable tolerance limits of each amine.

HIGHLIGHTS

An efficient GC-MS technique for the simultaneous determination of 22 azo amines in a textile matrix has been developed. Analytical validation using a new strategy based on the uncertainty concept is reported, uncertainty associated to measurement results is estimated, and the applicability of our approach to the GC-MS method is investigated.

An effective validation of analytical method for determination of a polar complexing agent: the illustrative case of cytotoxic bleomycin

The effectiveness of highly polar agents in cancer treatment is well recognized, but their physicochemical properties make their analytical determination a demanding task. Their analysis requires peculiar sample preparation and chromatographic separation, which heavily impacts the precision of such an analytical method. As a case study, we chose a polar cytotoxic bleomycin, which is a mixture of complexing congeners with relatively high molecular mass, a fact that creates an added challenge in regard to its detection via electrospray mass spectrometry. These issues combined lead to a deprived method performance, so the aim of this study is manifold, i.e., to optimize, validate, and establish quality performance measures for determination of bleomycin in pharmaceutical and biological specimens. Quantification of bleomycin is done at diametrically different concentration levels: at the concentrations relevant for analysis of pharmaceutical dosage forms it is based on a direct reversed-phase HPLC-UV detection, involving minimum sample pretreatment. On the contrary, analysis of bleomycin in biological specimens requires phospholipid removal and protein precipitation followed by HILIC chromatography with MS/MS detection of bleomycin A2 and B2 copper complexes being the predominant species. This study further attempts to solve the traceability issue in the absence of certified reference standards, determines measurement uncertainty, investigates BLM stability and method performance characteristics, and, last but not least, provides an explanatory example of how a method quality assurance procedure should be established in case of an exceedingly complex analytical method.

Establishment and Validation of Fourier Transform Infrared Spectroscopy (FT–MIR) Methodology for the Detection of Linoleic Acid in Buffalo Milk

Buffalo milk is a dairy product that is considered to have a higher nutritional value compared to cow’s milk. Linoleic acid (LA) is an essential fatty acid that is important for human health. This study aimed to investigate and validate the use of Fourier transform mid-infrared spectroscopy (FT-MIR) for the quantification of the linoleic acid in buffalo milk. Three machine learning models were used to predict linoleic acid content, and random forest was employed to select the most important subset of spectra for improved model performance. The validity of the FT-MIR methods was evaluated in accordance with ICH Q2 (R1) guidelines using the accuracy profile method, and the precision, the accuracy, and the limit of quantification were determined. The results showed that Fourier transform infrared spectroscopy is a suitable technique for the analysis of linoleic acid, with a lower limit of quantification of 0.15 mg/mL milk. Our results showed that FT-MIR spectroscopy is a viable method for LA concentration analysis.

Accurate measurement of uranium and thorium in naturally occurring radioactive materials to overcome complex matrix interference

A standard addition (SA) calibration method for determining uranium and thorium in naturally-occurring radioactive materials (NORMs) was studied. Pretreatment method using fusion was established and optimized. The SA method was validated (LOD, LOQ, linearity, selectivity, and accuracy) using certified reference materials (SRM 2709a, RM-ZR, and RM-BX). The results were evaluated for bias, and a correction equation that included a contribution to the expanded uncertainty was used. All performance criteria were satisfied; the results agreed well with certified and reference values.

The Uncertainty Profile Used for Full Validation of the HPLC Method to Determine 22 Azo Amines in Fabrics

Background

Azo dyes are synthetic dyes that can degrade to carcinogenic amines, therefore determining their exact concentration is crucial.

Objective

The purpose of this study is to demonstrate that an HPLC method may be used to quantify 22 azo dye amines in a textile matrix.

Methods

The HPLC–DAD (Diode Array Detector) technique for measuring 22 amines in a textile matrix was tested using a new graphical statistical strategy based on the building of β-content, γ-confidence tolerance intervals, which allows for good qualimetry of analytical procedures. In this way, we established the approach's ability to perform a full validation of the analytical technique as well as its ability to estimate measurement uncertainty in a simple and uncomplicated way with minimum effort, utilizing only the data collected during the analytical validation.

Results

The findings suggest that this technique can properly assess the validity of the HPLC method for simultaneous determination of 22 amines, with 67–90% of compliance results falling within acceptable limits.

Conclusion

Using the uncertainty profile methodology, the full validation of an HPLC method for the determination of 22 azo amines in a textile matrix was successfully established.

Highlights

The development and evaluation of an efficient HPLC technique for the simultaneous determination of 22 azo amines in a textile matrix have been completed. The total reliability of the analytical procedure was established by evaluating its measurement uncertainty at each concentration level using the suggested uncertainty profile approach and confirming proportions 67 to 90% of compliance.

Accuracy Profiles for Analyzing Residual Solvents in Textiles by GC-MS

Excess residual solvents (RSs) in clothes or other textiles could be toxic and pose risks to both humans and the environment. N,N-Dimethylformamide (DMF), N,N-dimethylacetamide (DMAc) and 1-methyl-2-pyrrolidinone (NMP) are important chemicals frequently used as solvents in the textile industry. Several organizations have proposed limiting DMF, DMAc and NMP in textiles, but an appropriate detection method has not been proposed. A sensitive GC-MS method for the quantification of DMF, DMAc and NMP in textiles was developed. After extraction with ethyl acetate, these RSs were separated on a DB-5MS capillary column. The oven temperature was increased from 50°C (held for 0.5 min) at 10°C/min to 120°C (held for 1 min). The method was fully validated according to the accuracy profile procedure, which is based on β-expectation tolerance intervals for the total measurement bias. Linearity was observed in the range of 0.5-10 mg/L for the solvents with limit of quantification values of 4.2, 3.5 and 2.5 mg/kg for DMF, DMAc and NMP, respectively. The repeatability and intermediate precision were <5.34% and 7.95% for DMF, 5.37% and 9.68% for DMAc, and 2.68% and 5.85% for NMP. The recoveries of DMF, DMAc and NMP were 91.2-106.3%, 89.5-97.7% and 85.6-101.3%, respectively.

Overall uncertainty measurement for near infrared analysis of cryptotanshinone in tanshinone extract

This study presented a new strategy of overall uncertainty measurement for near infrared (NIR) quantitative analysis of cryptotanshinone in tanshinone extract powders. The overall uncertainty of NIR analysis from validation data of precision, trueness and robustness study was fully investigated and discussed. Quality by design (QbD) elements, such as risk assessment and design of experiment (DOE) were utilized to organize the validation data. An "I×J×K" (series I, the number of repetitions J and level of concentrations K) full factorial design was used to calculate uncertainty from the precision and trueness data. And a 2(7-4) Plackett-Burmann matrix with four different influence factors resulted from the failure mode and effect analysis (FMEA) analysis was adapted for the robustness study. The overall uncertainty profile was introduced as a graphical decision making tool to evaluate the validity of NIR method over the predefined concentration range. In comparison with the T. Saffaj's method (Analyst, 2013, 138, 4677.) for overall uncertainty assessment, the proposed approach gave almost the same results, demonstrating that the proposed method was reasonable and valid. Moreover, the proposed method can help identify critical factors that influence the NIR prediction performance, which could be used for further optimization of the NIR analytical procedures in routine use.

Comments on "innovative method for carbon dioxide determination in human postmortem cardiac gas samples using headspace-gas chromatography-mass spectrometry and stable labeled isotope as internal standard" by Varlet et al

Varlet et al. recently proposed a headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable for the routine determination of CO2 in gaseous biologic matrices. This developed bioanalytical method was fully validated according to the SFSTP 1997 guidelines using the accuracy profile as a graphical decision-making tool.In this letter, we discuss the validity of HS-GC-MS method based on the newest SFSTP guideline. In particular, we demonstrate by the estimation of the β-expectation tolerance interval that the error total exceeds the acceptance limits (30%) for the second concentration level (0.5μmol mL(-1) vial HS). Furthermore, we show through the risk profile that the probability to have future results inside the ±30% acceptance limits is smaller than 95%.

Reply to the responses on the comments on "Uncertainty profiles for the validation of analytical methods" by Saffaj and Ihssane

Saffaj and Ihssane, recently proposed an uncertainty profile for evaluating the validity of analytical methods using the statistical methodology of γ-confidence β-content tolerance intervals. This profile assesses the validity of the method by comparing the method measurement uncertainty to a predefined acceptance limit stating the maximum uncertainty suitable for the method under study. In this letter we comment on the response (T. Saffaj, B. Ihssane, Talanta 94 (2012) 361-362) these authors have made to our previous letter (E. Rozet, E. Ziemons, R.D. Marini, B. Boulanger, Ph. Hubert, Talanta 88 (2012) 769-771). In particular, we demonstrate that β-expectation tolerance intervals are prediction intervals, we show that β-expectation tolerance intervals are highly useful for assessing analytical methods validation and for estimating measurement uncertainty and finally we show what are the differences and implications for these two topics (validation and uncertainty) when using either the methodology of β-expectation tolerance intervals or the γ-confidence β-content tolerance tolerance interval one.

Critical review of near-infrared spectroscopic methods validations in pharmaceutical applications

Based on the large number of publications reported over the past five years, near-infrared spectroscopy (NIRS) is more and more considered an attractive and promising analytical tool regarding Process Analytical Technology and Green Chemistry. From the reviewed literature, few of these publications present a thoroughly validated NIRS method even if some guidelines have been published by different groups and regulatory authorities. However, as any analytical method, the validation of NIRS method is a mandatory step at the end of the development in order to give enough guarantees that each of the future results during routine use will be close enough to the true value. Besides the introduction of PAT concepts in the revised document of the European Pharmacopoeia (2.2.40) dealing with near-infrared spectroscopy recently published in Pharmeuropa, it agrees very well with this mandatory step. Indeed, the latter suggests to use similar analytical performance characteristics than those required for any analytical procedure based on acceptance criteria consistent with the intended use of the method. In this context, this review gives a comprehensive and critical overview of the methodologies applied to assess the validity of quantitative NIRS methods used in pharmaceutical applications.