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Fapas® – Food Chemistry Proficiency Test Report 20143
Illegal Dyes in Hot Pepper Sauce
October-November 2017
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PARTICIPANT LABORATORY NUMBER
Participants can log in to Fapas® SecureWeb at any time to obtain their laboratory number for this proficiency test. Laboratory numbers are displayed in SecureWeb next to the download link for this report.
REPORT INTEGRITY
Fapas® reports are distributed as digitally signed Adobe® PDF files. When these files are opened with Adobe® Reader v9 or later, a blue ribbon and information bar indicates that the certificate has been validated. This confirms that the author of the report is Fapas® and that the document has not been altered since it was signed [1, 2]. The integrity of hard copies of Fapas® reports cannot be assured in this way, i.e. printed copies are not controlled. A watermark stating this appears on every page when a Fapas® report is printed. End users of Fapas® reports should ensure that either the PDF file they are viewing displays a valid Fapas® digital signature or that the content of their hard copy exactly matches the content of a PDF file that displays a valid Fapas® digital signature.
QUALITY SYSTEMS
Fapas® – Food Chemistry is accredited by UKAS as complying with the requirements of ISO/IEC 17043:2010 [3]. Fera is an ISO 9001 certified organisation.
0009
Fera hereby excludes all liability for any claim, loss, demands or damages of any kind whatsoever (whether such claims, loss, demands or damages were foreseeable, known or otherwise) arising out of or in connection with the preparation of any technical or scientific report, including without limitation, indirect or consequential loss or damage; loss of actual or anticipated profits (including loss of profits on contracts); loss of revenue; loss of business; loss of opportunity; loss of anticipated savings; loss of goodwill; loss of reputation; loss or damage to or corruption of data; loss of use of money or otherwise, and whether or not advised of the possibility of such claim, loss demand or damages and whether arising in tort (including negligence), contract or otherwise. This statement does not affect your statutory rights. Nothing in this disclaimer excludes or limits Fera liability for: (a) death or personal injury caused by Fera negligence (or that of its employees, agents or directors); or (b) the tort of deceit; [or (c) any breach of the obligations implied by Sale of Goods Act 1979 or Supply of Goods and Services Act 1982 (including those relating to the title, fitness for purpose and satisfactory quality of goods);] or (d) any liability which may not be limited or excluded by law (e) fraud or fraudulent misrepresentation. The parties agree that any matters are governed by English law and irrevocably submit to the non-exclusive jurisdiction of the English courts. © Copyright Fera Science Ltd (Fera) 2017. All rights reserved.
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SUMMARY
1. The test material for Fapas® – Food Chemistry proficiency test 20143 was dispatched in October 2017. Each participant received a hot pepper sauce test material. From a list of fourteen illegal dyes participants had to identify and, optionally, quantify those present.
2. The test material contained Sudan III, Sudan IV and Sudan Orange G. An assigned value (xa) was determined for each analyte and in conjunction with the standard deviation for
proficiency (σp) was used to calculate a z-score for each result. However, those for Sudan
Orange G were given for information only.
3. Results for this proficiency test are summarised as follows:
analyte assigned value, xa µg/kg
number of scores, |z| ≤2
total number of scores
% |z| ≤2
Sudan III 399 46 67 69
Sudan IV 87.6 39 53 74
Sudan Orange G 128 22 41 54
italics indicate for information only
4. Qualitative results for this proficiency test are summarised as follows:
analyte number of satisfactory qualitative assessments
total number of qualitative assessments
(including <LOD and NS)
satisfactory %
Sudan III 8 15 53
Sudan IV 6 22 27
Sudan Orange G 7 10 70
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CONTENTS
1. INTRODUCTION 5
1.1. Proficiency Testing 5
2. TEST MATERIAL 5
2.1. Preparation 5
2.2. Homogeneity 5
2.3. Dispatch 5
3. RESULTS 5
4. STATISTICAL EVALUATION OF RESULTS 6
4.1. Calculation of the Assigned Value, xa 7
4.2. Standard Deviation for Proficiency, σp 7
4.3. Individual z-Scores 7
4.4. Assessment of Qualitative Results 8
4.5. Additional Dyes Identified 8
5. INTERPRETATION OF SCORES 8
6. REFERENCES 9
TABLES Table 1: Qualitative Results and assessments for Sudan III and Sudan IV 10
Table 2: Qualitative Results and assessments for Sudan Orange G 12
Table 3: Quantitative Results and z-Scores for Sudan III and Sudan IV 13
Table 4: Quantitative Results and z-Scores for Sudan Orange G 17
Table 5: Additional Dyes Reported 21
Table 6: Participants’ Comments 22
Table 7: Summary of Qualitative Assessments 23
Table 8: Assigned Values and Standard Deviations for Proficiency 23
Table 9: Number and Percentage of z-Scores where |z| ≤2 23
FIGURES Figure 1: z-Scores for Sudan III 24
Figure 2: z-Scores for Sudan IV 25
Figure 3: z-Scores for Sudan Orange G 26
APPENDICES APPENDIX I: Analytical Methods Used by Participants 27
APPENDIX II: Fapas® SecureWeb, Protocol and Contact Details 47
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1. INTRODUCTION
1.1. Proficiency Testing
Proficiency testing aims to provide an independent assessment of the competence of participating laboratories. Together with the use of validated methods, proficiency testing is an essential element of laboratory quality assurance. Further details of the Fapas® – Food Chemistry proficiency testing scheme are available in our protocols [4, 5].
2. TEST MATERIAL
2.1. Preparation
Preparation of the samples for this proficiency test was sub-contracted to a laboratory meeting the quality requirements of the scheme’s accreditation [3]. The hot pepper sauce was purchased from a retail source. Sudan III, Sudan IV, and Sudan Orange G were spiked into the test material. Samples were stored at ambient until dispatch.
2.2. Homogeneity
To test for homogeneity, randomly selected test materials were analysed in duplicate. Testing was sub-contracted to a laboratory meeting the quality requirements of the scheme’s accreditation [3]. These data showed sufficient homogeneity and were not included in the subsequent calculation of the assigned values.
2.3. Dispatch
The start date was 4 October 2017. Test materials were sent to 89 participants.
3. RESULTS
The instructions for reporting results were as follows: 1) This sample may contain any of the illegal dyes listed below:
Dye (common name) CAS number Dye (common name) CAS number
Butter Yellow (Dimethyl yellow) 60-11-7 Sudan IV 85-83-6 Orange II 633-96-5 Sudan Black B 4197-25-5 Para Red 6410-10-2 Sudan Orange G 2051-85-6 Rhodamine B 81-88-9 Sudan Red B 3176-79-2 Sudan I 842-07-9 Sudan Red 7B 6368-72-5 Sudan II 3118-97-6 Sudan Red G 1229-55-6 Sudan III 85-86-9 Toluidine Red 2425-85-6
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2) You may submit either qualitative OR quantitative results for each dye.
a) To submit a positive QUALITATIVE result, i.e. if you analysed for a dye and found it present, enter your result as ‘detected’.
b) To submit a positive QUANTITATIVE result, enter your result in µg/kg (corrected for recovery).
c) For negative results, i.e. if you analysed for a dye qualitatively and found it absent or quantitatively and it was below your LOD, enter your result as ‘not detected’.
d) In all cases: a. please enter an LOD via the ‘review/resubmit’ link on your list of tests. NB
this has to be done after you have submitted results for all dyes detected. Entering an LOD is important because if you analyse for a dye that is in the test material but you do not detect it, then your LOD is taken into account when assessing your result. If you do not give an LOD, your result will be assessed as if your LOD was zero.
b. please enter the percentage purity of the dye standard and whether or not your result was corrected for this percentage purity.
e) If you do not test for a dye please ensure you tick the ‘not tested’ box for that dye. 3) Your attention is drawn to Statutory Analysis Government Chemist Programme Ad Hoc
Project 1, October 2006, Analysis of Illegal Dyes in Paprika Powder by LC-MS/MS which concerns illegal dye determination and can be obtained in pdf format by using the following web address, https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/510960/Analysis_of_illegal_dyes_in_paprika_powder_by_LC_MSMS.pdf.
Results were submitted by 86 participants (97%) before the closing date for this test, 15 November 2017. Each participant was given a laboratory number, assigned in order of receipt of results. The reported analyte concentrations and assessments are given in Table 1 to Table 4. Participants’ comments are given in Table 6. The analytical methods used by each participant are summarised in APPENDIX I.
4. STATISTICAL EVALUATION OF RESULTS
The results submitted by participants were statistically analysed in order to provide an assigned value for each analyte. The assigned values were then used in combination with the standard deviation for proficiency, σp, to calculate a z-score [6] for each result. The procedure is detailed in the relevant protocols [4, 5]. Further background on the procedure followed can be found in the IUPAC International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories [7].
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4.1. Calculation of the Assigned Value, xa
The assigned value, xa, for each analyte was derived from the consensus of the results submitted by participants. The following results were excluded from the calculation of the assigned value:
i) non numerical results i.e. qualitative or semi-quantitative results, ii) results reported as approximately 10, 100 or 1000 × greater or smaller than the
majority of submitted results (as these were considered to be reporting errors). For Sudan III and Sudan IV, this procedure was straightforward and the robust mean was chosen as the assigned value. For Sudan Orange G, the major mode was chosen as the assigned value due to the distribution of results being skewed, as shown in the kernel density plot in Figure 3. The assigned value and z-scores are given for information only for this analyte due to the high uncertainty. The assigned values for all analytes are shown in Table 8.
4.2. Standard Deviation for Proficiency, σp
The standard deviation for proficiency, σp, was set at a value that reflects best practice for the analyses in question. For all three added illegal dyes, σp was derived from the appropriate form of the Horwitz equation [8]. The values for σp used to calculate z-scores from the reported results of this test are given in Table 8.
4.3. Individual z-Scores
Participants’ z-scores were calculated as:
p
axxzσ
)( −=
where x = the participant’s reported result,
xa = the assigned value and σp = the standard deviation for proficiency.
Participants’ z-scores for all three added illegal dyes are given in Table 3 and Table 4, and shown as histograms in Figures 1–3. Those for Sudan Orange G are given for information only. It is possible for the z-scores published in this report to differ slightly from the z-score that can be calculated using the formula given above. These differences arise from the necessary rounding of the actual assigned values and standard deviations for proficiency prior to their publication in Table 8. The number and percentage of z-scores in the range -2 ≤ z ≤ 2 for all analytes are given in Table 9.
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4.4. Assessment of Qualitative Results
For Sudan III, Sudan IV, and Sudan Orange G participants who had reported their results qualitatively were assessed as follows: • For each of the three dyes reported as ‘detected’, participants were assessed as
satisfactory or not satisfactory. • Where participants had reported one of these three dyes as ‘not detected’ they were
assessed against their limit of detection (LOD). If their LOD was lower than the value required to receive a z-score of -3 they were assessed as ‘NS’ (not satisfactory). If their LOD was equal to or greater than the value required to receive a z-score of -3 then they are marked in Table 1 and Table 2 as ‘<LOD’. If no LOD was given, the participant’s result was assessed as if their LOD was zero.
Qualitative assessment of participants’ results are given in Table 1 and Table 2, and a summary of qualitative assessments is given in Table 7. For the three illegal dyes knowingly added to the matrix during test material preparation it can confidently be assumed that the participants’ consensus should be ‘detected’. Where a test material is known to be positive with respect to added dyes, results may be expressed as Satisfactory or Not Satisfactory.
4.5. Additional Dyes Identified
Any participants identifying dyes other than Sudan III, Sudan IV, and Sudan Orange G are listed in Table 5 together with the dyes reported, the level determined if applicable, and the LOD.
5. INTERPRETATION OF SCORES
In normal circumstances, over time, about 95% of z-scores will lie in the range -2 ≤ z ≤ 2. Occasional scores in the range 2 <|z| <3 are to be expected, at a rate of 1 in 20. Whether or not such scores are of importance can only be decided by considering them in the context of the other scores obtained by that laboratory. Scores where |z| >3 are to be expected at a rate of about 1 in 300. Given this rarity, such z-scores very strongly indicate that the result is not fit-for-purpose and almost certainly requires investigation. The consideration of a set or sequence of z-scores over time provides more useful information than a single z-score. Examples of suitable methods of comparison are provided in the IUPAC International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories [7].
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6. REFERENCES
1 Adobe Approved Trust List, https://helpx.adobe.com/acrobat/kb/approved-trust-list2.html#Whatisit accessed 01/06/2017.
2 GlobalSign PDF Signing Tool, https://www.globalsign.com/en/pdf-signing/ accessed 01/06/2017.
3 ISO/IEC 17043:2010, Conformity assessment – General requirements for proficiency testing.
4 Fapas®, 2017, Protocol for Proficiency Testing Schemes, Version 6, April 2017, Part 1 – Common Principles.
5 Fapas®, 2017, Protocol for Proficiency Testing Schemes, Version 5, April 2017, Part 2 – Fapas® Food Chemistry scheme (FAPAS).
6 AMC Tech Brief No. 74, z-Scores and other scores in chemical proficiency testing – their meanings, and some common misconceptions, Anal. Methods, 2016, 8, 5553.
7 Thompson, M., Ellison, S.L.R. and Wood, R., 2006, The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories, Pure Appl. Chem., 78, No. 1, 145–196.
8 Thompson, M., 2000, Recent trends in inter-laboratory precision at ppb and sub-ppb concentrations in relation to fitness for purpose criteria in proficiency testing, Analyst, 125, 385-386.
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Table 1: Qualitative Results and assessments for Sudan III and Sudan IV
laboratory number analyte
Sudan III Sudan IV expected result: detected
53% satisfactory expected result: detected
27% satisfactory
result LOD µg/kg
purity of standard
%
assessment result LOD µg/kg
purity of standard
%
assessment
001 detected 10 S detected 10 S
003 detected 2.706 S detected 4.728 S 004 not detected 1000 <LoD not detected 1000 <LoD
005 not detected NS 010 Detected NA NA S not detected NS
015 detected 3 S
018 not detected NS not detected NS 022 not detected 150 Y <LoD
023 DETECTED 250 N S DETECTED 250 N S 024 not detected 2000 <LoD not detected 2000 <LoD
025 detected 500 S not detected NS
026 not detected NS 031 not detected NS
036 not detected 500 <LoD not detected 500 <LoD 045 not detected 2.00 N NS
S = Satisfactory NS = Not Satisfactory
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Table 1 (continued): Qualitative Results and assessments for Sudan III and Sudan IV
laboratory number analyte
Sudan III Sudan IV expected result: detected
53% satisfactory expected result: detected
27% satisfactory
result LOD µg/kg
purity of standard
%
assessment result LOD µg/kg
purity of standard
%
assessment
048 not detected NS
049 detected 50 S 050 detected 20 S detected 20 S
065 not detected NS not detected NS 066 not detected NS
069 not detected NS
070 not detected NS 071 not detected 500 Y <LoD not detected 500 Y <LoD
073 detected S detected S 076 not detected NS
079 detected 65 N S
082 detected S detected S 083 not detected 250 <LoD
086 not detected 300 70-130 <LoD
S = Satisfactory NS = Not Satisfactory
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Table 2: Qualitative Results and assessments for Sudan Orange G
laboratory number analyte
Sudan Orange G expected result: detected
70% satisfactory
result LOD µg/kg
purity of standard %
assessment
001 detected 10 S
003 detected 8.022 S
004 not detected 1000 <LoD
007 not detected 200 N <LoD
010 Detected NA NA S
025 detected S
049 detected 50 S
050 detected 20 S
071 not detected 500 Y <LoD
073 detected S
082 detected S
086 not detected 300 70-130 <LoD
S = Satisfactory NS = Not Satisfactory
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Table 3: Quantitative Results and z-Scores for Sudan III and Sudan IV
laboratory number
analyte
Sudan III Sudan IV
assigned value 399 μg/kg assigned value 87.6 μg/kg
result LOD μg/kg
purity of standard, %
z-score result LOD μg/kg
purity of standard, %
z-score
001
002 452 10
0.7 99 5
0.6
003
004
005 585 500 98.1% Y 2.5
006 433.8 50 92.8 0.5 75.2 50 91.8 -0.6
007 460 200 N 0.8 360 200 N 14.1 008
009 260 10 78 N -1.9 50 10 80 N -2.0
010 011 259.00 10 105%; N (not
applied to result)
-1.9 17.00 10 113%; N (not applied to
result)
-3.7
012 122 10 80 (N) -3.8 75 10 80 (N) -0.7
013 273.3 100
-1.7 74.8 100
-0.7
014 478 10
1.1 83 10
-0.2
015 420 3
0.3 016 393 3,33 -0.1 017 500.5 100 N 1.4 135 100 N 2.5 018
019 308.99 40 Y -1.2 88.51 40 Y 0.0
020 592 10 97 Y 2.6 131 10 91 Y 2.2 021 367 10 Y -0.4 75 10 Y -0.7
022 927 150 Y 7.2 023
024 025
z-scores outside |z| >2 are shown in bold, see Section 5
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Table 3 (continued): Quantitative Results and z-Scores for Sudan III and Sudan IV
laboratory number
analyte
Sudan III Sudan IV
assigned value 399 μg/kg assigned value 87.6 μg/kg
result LOD μg/kg
purity of standard, %
z-score result LOD μg/kg
purity of standard, %
z-score
026 667 500 Y 3.7 027 303.92 2.00 N, 100% -1.3 65.56 2.00 N, 99% -1.1
028 546 10 80%, Y 2.0 110 10 85%, Y 1.2
029 238 10 106%, N -2.2 030 804 10 5.5 77 10 -0.6
031 433 30 N 0.5 032 551 10 474% Y 2.1 86 10 367% Y -0.1
033 0.53 0.2 y -5.4 0.37 0.2 y -4.5 034 305 15 N -1.3 111 15 N 1.2
035 267 50 N -1.8 60 50 N -1.4
036 037 299.81 10 Y -1.4 128.25 10 Y 2.1 038 442 N 0.6 84 N -0.2
039 437.67 100 56% yes 0.5 79.03 100 65% yes -0.4
040 157 10 72% & Y -3.3 17 10 82% & Y -3.7 041 415.5 500 N 0.2 120.8 500 N 1.7
042 96 -4.1 81 -0.3
043 303 4 Y -1.3 51.7 4 Y -1.9
044 266.22 1 -1.8 76.33 1 -0.6
045 212.2 2.00 N -2.5 046 257.21 4 N -1.9 28.21 10 N -3.1 047 515 10 100, N 1.6 99 10 100, N 0.6
048 293 50 Y -1.4 049 050
z-scores outside |z| >2 are shown in bold, see Section 5
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Table 3 (continued): Quantitative Results and z-Scores for Sudan III and Sudan IV
laboratory number
analyte
Sudan III Sudan IV
assigned value 399 μg/kg assigned value 87.6 μg/kg
result LOD μg/kg
purity of standard, %
z-score result LOD μg/kg
purity of standard, %
z-score
051 > 200 5 83%, N
78 5 87%, N -0.5
052 694 50 100, Y 4.0 14 10 100, Y -3.8 053 506 4 102/y 1.5 51 10 74/y -1.9
054 642 30 73,8 % & Yes
3.3 123 30 83,5 % & Yes
1.8
055 515 50
1.6 117 50
1.5
056 463.473 4 N 0.9 93.555 10 N 0.3
057 426.8 50
0.4 187 50
5.2 058 334 LOQ =
10µg/kg 80% Y -0.9 56 LOQ =
10µg/kg 82% Y -1.6
059 293 20 -1.4 98.5 20 0.6
060 336.5 20 -0.9 103.5 20 0.8
061 547 5 N 2.0 103 10 110%, N 0.8
062 333 5 N -0.9 74 5 N -0.7
063 178 10 N -3.0 131 10 N 2.2 064 259.80
-1.9 92.19
0.2
065
066 240.93 10 -2.2 067 183.64
n -2.9 64.86
n -1.2
068 1133 10 97.3 corrected
10.0 80 10 89 corrected -0.4
069
201.114 5.8
5.9
070 352 10
-0.6
071 072 476 10 Y & 100 1.1 100 10 Y & 115 0.6
073
074 419.6 10 87% Y 0.3 075 312 100 N -1.2
z-scores outside |z| >2 are shown in bold, see Section 5
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Table 3 (continued): Quantitative Results and z-Scores for Sudan III and Sudan IV
laboratory number
analyte
Sudan III Sudan IV
assigned value 399 μg/kg assigned value 87.6 μg/kg
result LOD μg/kg
purity of standard, %
z-score result LOD μg/kg
purity of standard, %
z-score
076
077 475.20 1 N 1.0 102.83 1 N 0.8
078 689 20
4.0 118 20
1.6
079 287 65 N -1.5
080 137 30 99% Y -3.6 31 30 91% Y -2.9 081 472 2 PPb 80% (Y) 1.0 125 2 PPb 80%(Y) 1.9
082
083 370 250 Y -0.4 084 518 10 N 1.6 45 10 N -2.2 085 373 20 N -0.4 86 20 N -0.1
086 703 200 90-110, N 4.2
z-scores outside |z| >2 are shown in bold, see Section 5
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Table 4: Quantitative Results and z-Scores for Sudan Orange G
laboratory number analyte
Sudan Orange G assigned value 128 μg/kg
result LOD μg/kg
purity of standard %
z-score
001
002 189 10
2.2
003
004
005
006
007
008
009 120 10 63 N -0.3
010 011 137.00 10 91%; N (not applied
to result) 0.3
012 69 10 80 (N) -2.1
013
014 64 10
-2.3
015 110 3
-0.7
016 110 3,33 -0.7
017 74 100 N -1.9
018
019 322.81 40 Y 7.0
020 1297 10 95 Y 41.8
021 195 10 Y 2.4
022 023
024 025
italics indicate for information only
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Table 4 (continued): Quantitative Results and z-Scores for Sudan Orange G
laboratory number analyte
Sudan Orange G assigned value 128 μg/kg
result LOD μg/kg
purity of standard %
z-score
026
027
028
029 138 10 91%, N 0.3
030 81 10
-1.7
031
032 587 10 108% Y 16.4
033
034 240 15 N 4.0
035 036
037 428.69 10 Y 10.7
038 557
N 15.3
039
040
041 042 70
-2.1
043 104 4 Y -0.9
044 57.84 1
-2.5
045 228.1 2.00 N 3.6
046 047 048
049 050
italics indicate for information only
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Table 4 (continued): Quantitative Results and z-Scores for Sudan Orange G
laboratory number analyte
Sudan Orange G assigned value 128 μg/kg
result LOD μg/kg
purity of standard %
z-score
051 122 5 100%, N -0.2
052 85 50 100, Y -1.5
053
054 221 30 89,1 % & Yes 3.3
055 148 50
0.7
056
057
058
059 89.3 20 -1.4
060 103.8 20 -0.9
061 141 5 95%, N 0.5
062 190 5 N 2.2
063 28 10 N -3.6
064 136.73
0.3
065 405 200 N 9.9
066 146.92 10 0.7
067 145.96
n 0.6
068 175 10 94.9 corrected 1.7
069
070 177 10
1.7
071 072 318 10 Y & 81 6.8
073
074 152.7 10 82% Y 0.9
075
italics indicate for information only
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Table 4 (continued): Quantitative Results and z-Scores for Sudan Orange G
laboratory number analyte
Sudan Orange G assigned value 128 μg/kg
result LOD μg/kg
purity of standard %
z-score
076
077
078
079
080 199 200 117% N 2.5
081
082
083
084 152 10 N 0.8
085 107 20 N -0.8
086
italics indicate for information only
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Table 5: Additional Dyes Reported
lab number
dye qualitative quantitative
result lod purity % corrected
result lod purity % corrected
007 Para Red
90 200 N
011 Sudan Red B 17 10 72%; N (not
applied to result)
015 Sudan Red B detected 3
025 Para Red detected
025 Sudan I detected 500
025 Sudan II detected 1000
025 Sudan Black B detected
025 Sudan Red G detected
025 Toluidine Red detected
033 Sudan II 0.28 0.2 y
037 Orange II 417.48 20 Y
052 Toluidine Red 42 10 100, Y
056 Sudan I 2.334 4 N
068 Sudan Red B 48.4 10 87 corrected
069 Butter Yellow (Dimethyl Yellow)
detected 4
069 Para Red 86.4 4
069 Sudan I 154.5 4.5
069 Sudan II 68 4.5
070 Sudan Red B 279 20
073 Sudan Red B detected
082 Sudan I detected
084 Sudan red B 45 10 N
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Table 6: Participants’ Comments
participant number comments
001 calculated amounts of detected analytes SOG, SIII, SIV as follows: 203, 490, 107 ug/kg respectively. (Not corrected to Recovery, n=6, RSD < 10%
003 Tests are done qualitative _ detected
008 Sudan I LOD 1000µg/kg
012 Trace of Sudan Black B
013 LODs of our method are 100µg/kg for all dyes but in fact we can quantifie 50µg/kg
015 Sudan IV and Sudan Red B coelute with the same transitions in our LC/MS system. Our 'quantitative' results are 100ppb of either single analyte, or some combination of the two.
018 NO this analysis is not under ISO scope.
020 Results are corrected for recovery
021 LOD for Para Red is 50ug/kg; LOD for Butter Yellow (Dimethyl Yellow) ,Sudan I,Sudan Black B,Sudan Red G ,Para Red,Sudan II,Sudan Red 7B,Toluidine Red are 10ug/kg
026 Recovery applied to result by ISTD
034 Matrix effect was taken to account
036 Results are below LOQ of our method
041 A working limit of 500 µg/kg is proposed as the reporting LOQ.
051 LOD means LOQ
054 Sudan Red B is a positional isomer of Sudan IV - we don't have possibilities to separate these parameters.
069 dimethyl yellow detected qualitativly
071 We don´t recieved the first sample. We requested a new sample to FAPAS that recieved en November. We can see peak at the same time that Para Red, Sudan II, Sudan III and Sudan Red 7B (under LOD), but they can not be spectroscopy identified
072 Coelution Sudan IV and Sudan Red B - result expressed in Sudan IV
074 We cannot separate Sudan IV and Sudan Red B, so we report them as a sum in routine. In this test we got a signal for these compounds, which is calculated with 48.7 µg/kg.
083 LOQ: 250 ug/kg for Sudan I,II,IV
086 ASTA Method 28.0 (2005) (HPLC-UV), LOD= 300 µg/kg, LOQ= 1000 µg/kg
comments are as submitted by participants
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Table 7: Summary of Qualitative Assessments
analyte number of satisfactory (S) qualitative assessments
total number of qualitative assessments
(S, NS & <LOD)
satisfactory %
Sudan III 8 15 53
Sudan IV 6 22 27
Sudan Orange G 7 10 70
Table 8: Assigned Values and Standard Deviations for Proficiency
analyte data points, n
assigned value, xa, µg/kg
uncertainty, u
standard deviation for proficiency, σp, µg/kg
Sudan III 66 399 20 Horwitz [8] 73
Sudan IV 52 87.6 4.8 Horwitz [8] 19.3
Sudan Orange G 41 128 12 Horwitz [8] 28
italics indicate for information only
Table 9: Number and Percentage of z-Scores where |z| ≤2
analyte number of scores where |z| ≤2
total number of scores
% |z| ≤2
Sudan III 46 67 69
Sudan IV 39 53 74
Sudan Orange G 22 41 54
italics indicate for information only
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Figure 1: z-Scores for Sudan III
33 42 12 80 40 63 67 45 29 66 46 11 64 9 44 35 13 79 48 59 37 43 27 34 19 75 62 58 60 70 21 83 85 16 41 74 15 57 31 6 39 38 2 7 56 81 77 72 14 17 53 47 55 84 28 61 32 5 20 54 26 78 52 86 30 22 68
545 µg/kg
399 µg/kg
252 µg/kg
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
z-score
Laboratory Number
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Figure 2: z-Scores for Sudan IV
33 52 11 40 46 80 84 9 53 43 58 35 67 27 62 13 12 21 6 44 30 51 39 68 42 14 38 32 85 19 64 56 59 2 47 72 77 61 60 28 34 55 78 41 54 81 37 20 63 17 57 69 7
126.2 µg/kg
87.6 µg/kg
49.1 µg/kg
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
z-score
Laboratory Number
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Figure 3: z-Scores for Sudan Orange G
this histogram is given for information only
63 44 14 12 42 17 30 52 59 60 43 85 15 16 9 51 64 11 29 61 67 66 55 84 74 68 70 2 62 21 80 54 45 34 72 19 65 37 38 32 20
184 µg/kg
128 µg/kg
72 µg/kg
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
z-score
Laboratory Number
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APPENDIX I: Analytical Methods Used by Participants
Methods are tabulated according to the information supplied by participants, but some responses may have been combined or edited for clarity.
Is the Method Used Accredited? laboratory number
yes 004 005 008 009 011 015 019 020 021 022 026 027 028 032 036 037 043 045 047 052 053 060 061 065 069 073 074 080 081 083
no 006 007 010 018 025 034 035 041 048 054 055 057 063 067 068 072 078 079
What is Your Method Based On? laboratory number
International Standard 015 022 028 063 081
National Standard 047
Paper Published In An International Journal 020 043 068 069
Manufacturer/Kit Instructions/Technical Note 010 019 032 035 048 057
In house method 004 005 006 007 008 009 011 018 021 025 026 027 034 036 037 041 045 052 053 054 055 060 061 065 067 070 073 074 078 079 080 083
Sample Amount Used for Analysis (g) laboratory number
<1 018 055 083
≥1 - <2 004 010 011 043 045 048 052 067 068 073
≥2 - <5 007 008 022 025 026 027 032 035 037 041 047 053 054 061 065 069 070 078 079
≥5 - <10 005 006 009 034 036 057 063 072 074 080
≥10 - <15 020 028 081
≥20 - <30 019 021
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Sample Treatment Prior to HPLC laboratory number
blend / homogenise with solvent 005 018 019 034 037 041 057 069 070 079 080
centrifuge 004 007 010 011 018 019 027 036 045 052 061 067 068
dilute 004 015 019 045 047 052 065 067 078
dissolve in water 006 010
evaporate 036
filter 005 009 015 018 019 022 036 037 052 063 065 067
hydrolysis 036
internal standard addition 019 061
liquid/liquid extraction 067
solid phase extraction (SPE) 057
solvent extraction 008 010 011 015 019 021 025 026 028 032 035 043 048 053 054 055 061 065 072 073 074 081 083
sonicat 068
sonicate 041
Syringe filter 020
Sample Clean-up Technique for Vet Drugs/Illegal Dyes
laboratory number
filter 005 007 008 011 020 021 022 034 035 036 037 048 055 060 063 065 069 070 073 074 079 080 081
GPC/HPGPC 009 026 037
liquid/liquid extraction 006 027 036 052 061 068 083
solid phase extraction (SPE) (column/cartridge)
032 057
solvent exchange 036
none 004 010 015 018 025 028 041 045 047 054 072 078
SPE Sorbent Type laboratory number
C18 032 057 069 081
none 025
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Calibrations laboratory number
solvent 011 018 035 041 055 057 065 073
matrix-matched 027 028 037 043 053 067 068 070 081 083
single-level 005 020
multi-level 006 007 008 009 022 026 032 034 036 037 048 063 065 069 072 074 079 080
standard addition 015 019 021 025 034 045 047 052 054 055 060 061 074 078
Type of Internal Standard Added laboratory number
none 006 009 015 018 021 022 025 028 032 034 035 041 048 052 057 063 065 069 072 080 083
Stable Isotope Labelled Analogue 019 026 027 045 055 070
structural analogue 073 074 078 081
addition of the same standard 054
Sudan1-D5 and Sudan 4-D6 011
HPLC Column Packing for Illegal Dyes laboratory number
C18 004 005 006 007 008 009 010 011 018 020 021 022 026 027 028 032 034 035 036 037 041 045 047 048 053 054 057 061 063 065 067 068 069 070 072 073 074 078 079 080 081 083
HPLC Column Temperature (°C) laboratory number
ambient 005 007 018 021 037 054 061 065 069 074 078 079 080 081
>ambient - <50 004 006 008 009 010 015 019 020 022 026 027 028 032 034 035 036 041 045 048 052 053 057 063 067 068 070 072 073 083
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Mobile Phase Components laboratory number
acetate 037 045
ethanoic acid (acetic acid) 005 026 067 079
acetone 004
acetonitrile 005 006 008 010 015 018 019 021 022 028 035 037 045 047 053 054 055 061 067 068 069 072 074 079 081 083
formic acid (methanoic acid) 010 011 015 019 032 037 045 054 061 072 074 083
ion pair agent 065
methanol 010 011 026 032 036 037 052 065 067 070 078
phosphate 065
water 004 007 009 011 015 018 019 020 021 026 028 032 035 036 037 047 052 054 055 057 061 063 067 068 072 074 078 079 083
0.1% Formic acid in water and in methanol 041
A:0.10% Formic acid in H2O, B: 0.10% Formic acid in MeOH
027
acetic acid 080
Ammonim formate/formic acid buffer/methanol
034
ammonium acetate 073
Buffer 0.04% TFA : ACN 048
Mobile Phase Programme laboratory number
isocratic 005 018 028 045 081
gradient 004 006 007 008 009 010 011 015 019 020 021 022 026 027 032 034 035 036 037 041 043 048 052 053 054 055 057 061 063 065 067 068 069 070 072 073 074 078 079 080 083
HPLC Detector Type laboratory number
Diode Array Detector 004 007 018 022 036 048 065 069 080
MS-MS 009 010 011 015 019 020 021 026 027 028 032 034 035 037 041 043 045 047 052 053 054 055 057 060 061 063 067 068 070 072 073 074 078 081 083
UV 006
UV/Vis 005 008 079
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Non HPLC Method Used laboratory number
direct sample analysys (DSA) coupled with MS-TOF
025
Sudan III
If a recovery was calculated for this analyte please state recovery
laboratory number
100 027 052
100.5% 021
102% 053
105% 011
107.9 019
474% 032
78 009 048
87 074
89.3 022
89.71 037
90 068
92% 007
92.8 006
95 083
96 020
98.1 005
99% 080
no 047
Standard Addition 063
Was your result corrected for recovery? laboratory number
yes 005 006 019 020 021 026 032 037 048 052 053 068 074 080 083
no 007 009 010 011 022 027 034 035 041 045 047 055 060 061 063 067 072 073 078
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Source of Standards laboratory number
Acros 006 080
Dr Ehrenstorfer 009 021 022 026 027 035 041 048 074 078
Sigma/Aldrich 005 007 010 011 020 032 034 037 045 052 060 061 063 068 072 073 083
Wako 019
ACCU 047
TRC 067
If the purity of the dye standard was determined please state purity
laboratory number
%98 067
>95% 041
100% 034
105.5% 061
85 068 080
90% 047
94,8 078
95% 072
96 052
96% 009
96%; Standard purity was determined by Sigma/ Aldrich.
011
96,0% 074
96.0% 021
96.1 083
96.5% 022
97 048
99% 027 032
99.9% 007
Did you correct for the purity of the dye standard?
laboratory number
yes 007 009 011 022 027 032 034 045 048 052 055 061 067 068 072 074 078 080 083
no 006 019 020 021 026 037 041 047 060 063 073
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Wavelength (nm) for DAD/UV detectors laboratory number
478 048
478 & 500 005
500 006
505 022
510 007 080
Ions monitored (MS/MS confirmation) laboratory number
156/197.1 010
156-196 073
353 078
353,2-197,2 / 128,1 / 156,1 074
353.0, 77.0 037
353.1/197 019
353.1>196.1 ; 353.1>197.1 052
353.1>197.1,128.0 045
353.1>76.9 026
353.19>77.06 063
353.1-92.1-197.1 083
353/128 009
353/77;353/196 032
353>196, 353>120 027
353>77, 92 041
353-120 061
353-156;353-120 021
353-77 072
77 034
es? 067
UPLC/MS/MS 047
yes 068
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Sudan IV
If a recovery was calculated for this analyte please state recovery
laboratory number
100 052
102.5 037
107.9 019
113% 011
367% 032
74% 053
80 009
80% 080
91.8 006
92% 007
93 020
93.0% 021
99 027
no 047
Standard Addition 063
Was your result corrected for recovery? laboratory number
yes 006 019 020 021 032 037 052 053 080
no 007 009 011 027 034 035 041 047 055 060 061 063 067 069 072 073 078
Source of Standards laboratory number
Acros 006 080
Dr Ehrenstorfer 009 021 027 035 041 047 078
Sigma/Aldrich 007 011 020 032 037 052 060 061 063 072 073
Wako 019
Institut of Leather Industry 034
sigma 069
TRC 067
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If the purity of the dye standard was determined please state purity
laboratory number
%98 067
>95% 041
?80% 060
100 072
118.9% 061
85 080
88.5% 034
94% 009 047
96 020 052
96%; Standard purity was determined by Sigma/ Aldrich.
011
99% 027 032 069
99,6 078
99.0% 021
99.9% 007
Did you correct for the purity of the dye standard?
laboratory number
yes 007 009 011 027 032 034 052 055 060 061 067 069 072 078 080
no 006 019 020 021 037 041 047 063 073
Wavelength (nm) for DAD/UV detectors laboratory number
488 069
500 006
510 007 080
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Ions monitored (MS/MS confirmation) laboratory number
381-224; 381-106 021
224-276 073
381 078
381.0, 91.0 037
381.1/224.1 019
381.1>224.1 ; 381.1>225.1 052
381.2- 224.2, 106.1 020
381.22>91.11 063
381/224 009
381/91;381/224 032
381>224, 381>91 027
381>91, 106 041
381-106 061
381-91 072
91 034
es? 067
UPLC/MS/MS 047
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Sudan Orange G
If a recovery was calculated for this analyte please state recovery
laboratory number
100 052
107.9 019
108% 032
117% 080
63 009
82 074
86.9 037
89.5% 021
90 020
91% 011
Standard Addition 063
Was your result corrected for recovery? laboratory number
yes 019 020 021 032 037 052 074
no 009 010 011 034 055 060 061 063 065 067 072 073 080
Source of Standards laboratory number
Acros 063 080
Dr Ehrenstorfer 009 021
Fluka 063
Sigma/Aldrich 010 011 020 032 034 037 045 052 060 061 063 065 072 073 074
Supelco 063
Wako 019
TRC 067
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If the purity of the dye standard was determined please state purity
laboratory number
%98 067
100 072
85 080
85% 034
85.0 045
96%; Standard purity was determined by Sigma/ Aldrich.
011
97 052
98,5% 074
98.5% 061
98.6% 009 021
99% 032
Did you correct for the purity of the dye standard?
laboratory number
yes 009 011 032 034 045 055 061 067 072 074 080
no 019 020 021 037 060 063 065 073
Wavelength (nm) for DAD/UV detectors laboratory number
401 080
430 065
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Ions monitored (MS/MS confirmation) laboratory number
212.9>92.1 ; 212.9>121.0 052
215,2-93,0 / 121,9 074
215.1, 93.1 037
215.1/92.9;215.1/122.1 032
215.1>93.0,122.0 045
215.13>93.13 063
215/93 009
215-122 061
215-93;215-122 021
251.1/93.1 019
381-91 072
92-120 073
93 034
93/122 010
es? 067
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Butter Yellow (Dimethyl Yellow)
Was your result corrected for recovery? laboratory number
no 069
Source of Standards laboratory number
sigma 069
If the purity of the dye standard was determined please state purity
laboratory number
96.2 069
Did you correct for the purity of the dye standard?
laboratory number
yes 069
Wavelength (nm) for DAD/UV detectors laboratory number
488 069
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Orange II
If a recovery was calculated for this analyte please state recovery
laboratory number
99.5 037
Was your result corrected for recovery? laboratory number
yes 037
Source of Standards laboratory number
Sigma/Aldrich 037
Did you correct for the purity of the dye standard?
laboratory number
no 037
Ions monitored (MS/MS confirmation) laboratory number
327.0, 171.1 037
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Para Red
If a recovery was calculated for this analyte please state recovery
laboratory number
92% 007
Was your result corrected for recovery? laboratory number
no 007 069
Source of Standards laboratory number
Sigma/Aldrich 007
sigma 069
If the purity of the dye standard was determined please state purity
laboratory number
95% 007 069
Did you correct for the purity of the dye standard?
laboratory number
yes 007 069
Wavelength (nm) for DAD/UV detectors laboratory number
488 069
510 007
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Sudan I
Was your result corrected for recovery? laboratory number
no 069
Source of Standards laboratory number
sigma 069
If the purity of the dye standard was determined please state purity
laboratory number
99% 069
Did you correct for the purity of the dye standard?
laboratory number
yes 069
Wavelength (nm) for DAD/UV detectors laboratory number
488 069
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Sudan II
Was your result corrected for recovery? laboratory number
no 069
Source of Standards laboratory number
sigma 069
If the purity of the dye standard was determined please state purity
laboratory number
87% 069
Did you correct for the purity of the dye standard?
laboratory number
yes 069
Wavelength (nm) for DAD/UV detectors laboratory number
488 069
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Sudan Red B
If a recovery was calculated for this analyte please state recovery
laboratory number
72% 011
90 068
Was your result corrected for recovery? laboratory number
yes 068
no 011 073
Source of Standards laboratory number
Sigma/Aldrich 011 068 073
If the purity of the dye standard was determined please state purity
laboratory number
85 068
97%; Standard purity was determined by Sigma/ Aldrich.
011
Did you correct for the purity of the dye standard?
laboratory number
yes 011 068
no 073
Ions monitored (MS/MS confirmation) laboratory number
224-209-156-91 073
yes 068
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Toluidine Red
If a recovery was calculated for this analyte please state recovery
laboratory number
100 052
Was your result corrected for recovery? laboratory number
yes 052
Source of Standards laboratory number
Sigma/Aldrich 052
If the purity of the dye standard was determined please state purity
laboratory number
96 052
Did you correct for the purity of the dye standard?
laboratory number
yes 052
Ions monitored (MS/MS confirmation) laboratory number
381.1>224.1 ; 381.1>225.1 052
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APPENDIX II: Fapas® SecureWeb, Protocol and Contact Details
1. Fapas® SECUREWEB
Access to the secure area of our website is only available to participants in our proficiency tests. Please contact us if you require a UserID and Password. Fapas® SecureWeb allows participants to:
• Obtain their laboratory numbers for the proficiency tests in which they have participated.
• View the results they submitted in past and current proficiency tests. • Submit their results and methods for current tests. • Review future tests they have ordered. • Order proficiency tests, reference materials and quality control materials. • Freely download copies of reports (PDF file), of proficiency tests in which they have
participated. • View charts of their z-scores obtained in previous Fapas® – Food Chemistry
proficiency tests.
2. PROTOCOL
The Protocols [4, 5] set out how Fapas® – Food Chemistry is organised. Copies can be downloaded from our website.
3. CONTACT DETAILS
This report was prepared and authorised on behalf of Fapas® by Guy Beavis (Round Coordinator). Participants with any comments or concerns about this proficiency test should contact:
Fapas® Fera Science Ltd (Fera)
National Agri-Food Innovation Campus Sand Hutton
York YO41 1LZ
UK
Tel: +44 (0)1904 462100 Fax: +44 (0)1904 500440
[email protected] www.fapas.com