In Situ Validation Methodology for Weighing Methods Used in Preparing of Standardized Sources for Radionuclide Metrology

Round 1

Reviewer 1 Report

In situ validation methodology for weighing methods used in preparing of standardized sources for radionuclide metrology

Fabio Cacais, José Delgado, Victor Loayza, Johnny Rangel

 

The paper aims to discuss the relative standard uncertainty obtained for a weighing procedure, intended to comply with a tolerance of 0.1% and a comparison to the validation of mass measurements using the elimination weighing method.

The paper is well organized, with detailed explanation of all uncertainty contributions and conclusions that answer properly to the aims described in the introduction, including the analysis by comparison of the methods results.

Line 72 – delete “to”

Line 102 – clarify which type of hypothesis tests were performed.

Line 154 – recommendation to use the same letter type of quantities as those used in equations – e.g. variable “Dw”

Lines 169 to 171 – Variables should be in italic.

Figure 2 – some quantities in the diagram below should be in italic.

Lines 412 and 415 – Variation of temperature is represented using “t” in lower and upper case.

Line 421 – delete larger space

Equations 41, 42 and 43 – Use of the terms “a”, “b” ad “w” as index, representing the quantity only by “D” should be verified according to the proper use of SI terminology.

Line 610 – correct italic and index of variables “d₀” and “KT”.

618 – delete large space

628 – describe what is “LNMRI”

629 – delete large space in references 48 and 49.

639 – Delete large space

649 – correct “set” with “sets”

656 – correct “Dhr”

Lines 658 and 659 – the use of values inside parentheses is misleading to the reader, e.g., -1.3(0.2) hPa

Figure 5 – include time scale in x-axis

Line 670 – introduce a comma after “measurements”

Line 681 – density symbol in italic.

Line 706 – “U” in italic

Table 1 – header of 2nd column, “U” should have as index the confidence interval (95%)

Table 2 – for readers not used to the terminology used in weighing measurement, regarding identification of similar standard weights, a short explanation should be given regarding the use of the asterisks “*” and “**”

Figure 8 – note that that are other geometric possibilities for the load receptor

Table 4 – missing units in Table

Table 4 – explanation to have all values equal to “0” – what is the added value of this presentation in the Table?

Table 4 – uncertainty usually is represented with the quantity, e.g., u(q)

Line 1015 – explain meaning of “MRA”

Ref. 12 – Correct the reference of ISO 17025 standard was issued (latest version) in 2017, older version, if applied, was issued in 2005.

Author Response

Response letter

Dear reviewers,

Thank you very much for your review and valuable comments on our manuscript.

Thanks very much for the professional comments of the reviewers, which reflect the high level of Metrology. We have carefully revised the manuscript according to the reviewers' comments, and the quality of the manuscript has been greatly improved. We have also carefully checked the whole manuscript to improve the grammar, logic, and sentence structure. Responses to your comments are appended in the response letter.

 

#Reviewer 1

 

Comment 0

The paper aims to discuss the relative standard uncertainty obtained for a weighing procedure, intended to comply with a tolerance of 0.1% and a comparison to the validation of mass measurements using the elimination weighing method.

The paper is well organized, with detailed explanation of all uncertainty contributions and conclusions that answer properly to the aims described in the introduction, including the analysis by comparison of the methods results.

Thanks very much for your comment.

 

Comment 1

Line 72 – delete “to”

Thanks very much for your comment. We have implemented it according to your comment.

Comment 2

Line 102 – clarify which type of hypothesis tests were performed.

Thanks very much for your comment. We have explained about T and F tests were used to set limits to check for adeverse effects on weighing.

Comment 3

Line 154 – recommendation to use the same letter type of quantities as those used in equations – e.g. variable “Dw”

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 4

Lines 169 to 171 – Variables should be in italic.

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 5

Figure 2 – some quantities in the diagram below should be in italic.

Thanks very much for your comment. Figure 2 was corrected.

Comment 6

Lines 412 and 415 – Variation of temperature is represented using “t” in lower and upper case.

Thanks very much for your comment. It was corrected and just “t” in lower case is used for temperature.

Comment 7

Line 421 – delete larger space

Thanks very much for your comment. We have implemented it according to your comment.

Comment 8

Equations 41, 42 and 43 – Use of the terms “a”, “b” ad “w” as index, representing the quantity only by “D” should be verified according to the proper use of SI terminology.

Thanks very much for your comment. In order to avoid any meaning problem we have changed D by Q.

Comment 9

Line 610 – correct italic and index of variables “d₀” and “KT”.

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 10

618 – delete large space

Thanks very much for your comment. We have implemented it according to your comment.

Comment 11

628 – describe what is “LNMRI”

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 12

629 – delete large space in references 48 and 49.

Thanks very much for your comment. We have implemented it according to your comment.

Comment 13

639 – Delete large space

Thanks very much for your comment. We have implemented it according to your comment.

Comment 14

649 – correct “set” with “sets”

Thanks very much for your comment. We have implemented it according to your comment.

Comment 15

 

656 – correct “Dhr”

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 16

Lines 658 and 659 – the use of values inside parentheses is misleading to the reader, e.g., -1.3(0.2) hPa

Although the use of parentheses is correct for the expression of the uncertainty of measurement, according to the SI, we prefer to use the most well-known expression with the use of the symbol ±.

Comment 17

Figure 5 – include time scale in x-axis

Thanks very much for your comment. The Figure 5  was revised to include time scale in x-axis.

Comment 18

Line 670 – introduce a comma after “measurements”

Thanks very much for your comment. We have implemented it according to your comment.

Comment 19

Line 681 – density symbol in italic.

Thanks very much for your comment. We have implemented it according to your comment. The whole document was revised.

Comment 20

Line 706 – “U” in italic

Thanks very much for your comment. We have implemented it according to your comment.

Comment 21

Table 1 – header of 2nd column, “U” should have as index the confidence interval (95%)

Thanks very much for your comment. We have change “U” by “U(k=2)” according to the Guide to the expression of uncertainty in measurement.

Comment 22

Table 2 – for readers not used to the terminology used in weighing measurement, regarding identification of similar standard weights, a short explanation should be given regarding the use of the asterisks “*” and “**”

Thanks very much for your comment. A short explanation is presented at Table 1 title:

Table 1. Calibration Error (E) and expanded uncertainty U(k=2) for standard weights, * and ** represents marking on the weight surface used to distinguish weights with the same nominal value.

Comment 23

Figure 8 – note that that are other geometric possibilities for the load receptor

Thanks very much for your comment. The geometry is now specified in Figure 8 in order to highlights for other possibilities.

Comment 24

Table 4 – missing units in Table

Thanks very much for your comment. The “*” in Table 4 title highlights for the footnote at the table end “*Unless otherwise stated, all values are in milligrams.” So, we have considered the information about units is provided.

Comment 25

Table 4 – explanation to have all values equal to “0” – what is the added value of this presentation in the Table?

Thanks very much for your comment. Some explanation about values equal to “0” was add to de footnote of table 4. “Value zero for the effects are shown in order to avoid any doubt about how they were considered for each method.”

Comment 26

Table 4 – uncertainty usually is represented with the quantity, e.g., u(q)

Thanks very much for your comment. We have changed Quantity for Quantity (X) and u for u(X).

 

Comment 27

Line 1015 – explain meaning of “MRA”

Thanks very much for your comment. We have implemented it according to your comment.

Comment 28

Ref. 12 – Correct the reference of ISO 17025 standard was issued (latest version) in 2017, older version, if applied, was issued in 2005.

Thanks very much for your comment. We have implemented it according to your comment.

 

Reviewer 2 Report

Title

Reviewer: ok

Abstract

Reviewer: The abstract has a structure of introduction, methodology, results, and conclusions easily observable how should be.

Keywords:“radionuclide metrology, source preparation, weighing methods, modified elimination method, measurement uncertainty evaluation”

Reviewer: The keyword "measurement uncertainty evaluation" appears only once in the paper, it in the keyword list itself.

1.   Introduction

Reviewer:

1)P1L27: Becquerel(Bq);

2) P2andP3: Although obvious to the authors, it is necessary to define all abbreviations, acronyms before mentioning them directly;

3) P4L62: “ The pycnometer, substitution and elimination methods have been available for use in the preparation routines for radioactive sources for a long time and much effort were invested to characterize the systematic effects that act on these methods[add references].”

4) P5L84:LNMRI and Inmetro- consider comment 2;

5) last paragraph, L124: GUM- consider comment 2

6) It left something to be desired regarding the approach to radionuclides and also about the pycnometer, it would be valid to include at least some explanation on these two topics.

2.  Modeling

2.1. Mass measurement

2.1.1. Weighing result

Reviewer:

1) Call all equations in the text before presenting them;

2)If there is no 2.1.2 then it doesn't make sense to have a 2.1.1 only;

 

3) Replace Figure 1 with a better quality one and position them horizontally, placing the weighing sequence as (a), (b), and (c) in the images and their description in the figure legend.

2.2. Uncertainty evaluation for mass measurement

3. Measurement

Reviewer: change this title

4. Measurement 

Reviewer: keep this title

 

5. Conclusion

Reviewer: Could the authors include some recommendations for future work? Mentioning some additional improvements in the quest to establish a methodology closer to what would be ideal in the quest to try to reconcile the reliability of mass measurements and uncertainty assessments established in technical laboratory procedures.

References

Reviewer: The author should try to include at least one reference from this Journal.

Author Response

Response letter

Dear reviewers,

Thank you very much for your review and valuable comments on our manuscript.

Thanks very much for the professional comments of the reviewers, which reflect the high level of Metrology. We have carefully revised the manuscript according to the reviewers' comments, and the quality of the manuscript has been greatly improved. We have also carefully checked the whole manuscript to improve the grammar, logic, and sentence structure. Responses to your comments are appended in the response letter.

#Reviewer 2

 

Comment 0

 

Title

Reviewer: ok

Thanks very much for your comment.

Comment 1

Abstract

Reviewer: The abstract has a structure of introduction, methodology, results, and conclusions easily observable how should be.

Thanks very much for your comment.

Comment 2

Keywords:“radionuclide metrology, source preparation, weighing methods, modified elimination method, measurement uncertainty evaluation”

Reviewer: The keyword "measurement uncertainty evaluation" appears only once in the paper, it in the keyword list itself.

Thanks very much for your comment. We have change "measurement uncertainty evaluation" by “uncertainty evaluation” which is very used in the paper

 

1. Introduction

Reviewer:

1)P1L27: Becquerel(Bq);

Thanks very much for your comment. We have implemented it according to your comment.

Comment 3

2) P2andP3: Although obvious to the authors, it is necessary to define all abbreviations, acronyms before mentioning them directly;

Thanks very much for your comment. The acronyms Inmetro, LNMRI,CCRI, LNHB, INMs and GUM were defined.

3) P4L62: “ The pycnometer, substitution and elimination methods have been available for use in the preparation routines for radioactive sources for a long time and much effort were invested to characterize the systematic effects that act on these methods[add references].”

Comment 4

4) P5L84:LNMRI and Inmetro- consider comment 2;

Thanks very much for your comment. References [12] and [13] were introduced and references numbering revised.

12. Campion, P. J. et al. A study of weighing techniques used in radionuclide standardization. Instrum. Methods 1964, 31 253-61.
13. Gallic, Y.L. Problems in microweighing. Instrum. Methods 1973, 112 333–41.

 

Comment 5

5) last paragraph, L124: GUM- consider comment 2

Thanks very much for your comment. The acronyms Inmetro, LNMRI,CCRI, LNHB, INMs and GUM were defined.

Comment 6

6) It left something to be desired regarding the approach to radionuclides and also about the pycnometer, it would be valid to include at least some explanation on these two topics.

Thanks very much for your comment. The explanation below was add at the beginning of the section 2.1 Mass measurement.

“Radionuclides are unstable atoms, characterized by the number of neutrons and protons in their nucleus (nuclides), which decay into stable or unstable nuclides and the activity quantity, A, whose SI unit is the becquerel, is applied for measurements of spontaneous and random nuclear transformations in radionuclide nuclei. Detection systems are used for activity measurements and in order to provide traceability to them liquid sources are employed as activity concentration standards. Once these sources are standardized, aliquots from these sources with measured mass or volume will have known activity values.

In radionuclide metrology the standardization of high accuracy liquid radionuclide sources requires sampling for activity and mass determination by weighing. In this process, microdroplets from radionuclide sources are sampled with the aid of polyethylene pycnometers made in a way that their manipulation allows a control of the size of these microdrops.

 

 Comment 7

2.  Modeling

2.1. Mass measurement

2.1.1. Weighing result

Reviewer:

1) Call all equations in the text before presenting them;

Thanks very much for your comment. We have implemented it according to your comment.

Comment 8

2)If there is no 2.1.2 then it doesn't make sense to have a 2.1.1 only;

Thanks very much for your comment. Section 2.1.1 was avoided.

Comment 9

3) Replace Figure 1 with a better quality one and position them horizontally, placing the weighing sequence as (a), (b), and (c) in the images and their description in the figure legend.

Thanks very much for your comment. We have implemented it according to your comment.

Comment 10

2.2. Uncertainty evaluation for mass measurement

3. Measurement

Reviewer: change this title

Thanks very much for your comment. The title was change for “Materials and Methods”.

Comment 11

4. Measurement 

Reviewer: keep this title

Thanks very much for your comment. We have implemented it according to your comment.

Comment 12

5. Conclusion

Reviewer: Could the authors include some recommendations for future work? Mentioning some additional improvements in the quest to establish a methodology closer to what would be ideal in the quest to try to reconcile the reliability of mass measurements and uncertainty assessments established in technical laboratory procedures.

Thanks very much for your comment.

The recommendation for future work was introduced as “Certainly, a new comparison of uncertainty budgets using this methodology would be a beneficial work to confirm its performance.”

It is cited in conclusion “and still be used as a methodoly to ensure the validity of measurement results” as some additional improvement from in situ validation methodology application

Comment 13

References

Reviewer: The author should try to include at least one reference from this Journal.

Thanks very much for your comment. Reference [61] was introduced.

 

61. Molloy, E.; et al. The Statistical Power and Confidence of Some Key Comparison Analysis Methods to Correctly Identify Participant Biases. 2021 Metrology 1 52–73.