# Agri-Food & Biosciences Institute Annual Report Marine Biotoxin Analysis Official Control Monitoring Programme For Northern Ireland 1St January 2019 - 31St **December 2019** Final Version 28/02/2020

 
 
Contract Reference: FS515003 

## 9 Pages

 
Quality statement: This report is a compilation of the information included on the reports provided weekly/monthly to the FSANI and showing the results of the toxin analyses undertaken on samples submitted by third parties. All results were quality checked and approved prior to release to the FSANI and the results compiled in this report have been further checked against a copy of the original reports held on a central database. Information relating to the origin of the samples (place, date and time of collection) is as provided by sampling staff and has not undergone verification checks by AFBI. 

## Method Standard Operating Procedures Used During The Course Of The Programme:

 
Determination of Domoic Acid in Shellfish by High Performance Liquid Chromatography (CSD 406) 
Determination of Paralytic Shellfish Poison by High Performance Liquid Chromatography (CSD 408) 
Determination of Lipophilic Toxins in Shellfish Species by LC-MS/MS (CSD 379) 

## Results Of Programme

| Sample Type             |   Number of samples  |
|-------------------------|----------------------|
| Oyster                  |                 134  |
| Mussel                  |                 326  |
| Total number of samples |                 460  |
|                         |                      |
|                         |                      |
|                         |                      |
|                         |                      |
Test 
Oyster 
Mussel 
Total 
Domoic Acid 
129 
316 
445 
PSP  
129 
315 
444 
Lipophilic Toxins 
134 
325 
459 
Total number of tests 
1348 
Test 
Oyster 
Mussel 
Total 
Domoic Acid 
0 
0 
0 
PSP  
0 
0 
0 
Lipophilic Toxins 
0 
4 
4 
Total number of positive tests 
4 
Test 
Target 
Percentage within Target 
Domoic Acid  
95% in 3 Days 
100% 
PSP  
95% in 3 Days 
100% 
Lipophilic Toxins  
95% in 3 Days 
100% NI classified production areas  


No of 
Site Identification 
Shellfish 
Site location 
Reference (SIR) 
samples 
received  
Species 
Belfast Lough 
B1-AFFNI 55 
51 
Mussel 
65 
NEG 
NEG 
NEG 
<0.3 
Belfast Lough 
B3-AFFNI 50 
51 
Mussel 
135 
NEG 
NEG 
NEG 
1.2 
Belfast Lough 
B12-AFFNI 54 
51 
Mussel 
155 
NEG 
NEG 
NEG 
1.6 
Belfast Lough 
B20-AFFNI 53 
51 
Mussel 
134 
NEG 
NEG 
NEG 
0.5 
Carlingford Lough 
C1-AFFNI 27 
13 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Carlingford Lough 
C11-AFFNI 84   
13 
Oyster 
63 
NEG 
NEG 
NEG 
0.32 
Carlingford Lough 
C15-AFFNI 89 
12 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Carlingford Lough 
C17-AFFNI 92 
11 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Carlingford Lough 
C7-AFFNI 73 
13 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Carlingford Lough 
C9-AFFNI 39 
11 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Carlingford Lough 
NW-Wild Fishery 
13 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Dundrum Bay 
DB1-AFFNI 95A 
14 
Oyster 
30 
NEG 
NEG 
NEG 
<0.3 
Dundrum Bay 
DB1-AFFNI 95A 
17 
Mussel 
261 
NEG 
NEG 
NEG 
<0.3 
Dundrum Bay 
DB2-AFFNI 95B 
13 
Mussel 
170 
NEG 
NEG 
NEG 
0.74 
Killough 
K1-AFFNI 18 
6 
Mussel 
43 
NEG 
NEG 
NEG 
<0.3 
Killough 
K1-AFFNI 18 
13 
Oyster 
11 
NEG 
NEG 
NEG 
0.54 
Larne Lough 
L5-AFFNI 21B 
10 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Larne Lough 
L5-AFFNI 21B 
10 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Larne Lough 
L3-AFFNI 88 
12 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Lough Foyle 
PA3M-Wild Fishery 
12 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Lough Foyle 
PA3O-Wild Fishery 
5 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Lough Foyle 
PA4M-Wild Fishery 
12 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Lough Foyle 
PA4O- Wild Fishery 
5 
Oyster 
NEG 
NEG 
NEG 
NEG 
<0.3 
Strangford Lough 
S7-AFFNI 76 
12 
Mussel 
NEG 
NEG 
NEG 
NEG 
<0.3 
Strangford Lough 
S7-AFFNI 76 
15 
Oyster 
NEG 
NEG 
NEG 
NEG 
0.33 
Strangford Lough 
S2-AFFNI 42 
14 
Mussel 
60 
NEG 
NEG 
NEG 
<0.3 
Maximum toxin levels detected in 2019 
DSP 
OA/DTX/PTX 
DSP 
AZA 
DSP YTX 
PSP 
ASP 
(µg/kg) 
(µg/kg) 
(mg/kg) 
(µg/kg) 
(µg/g) 

## Proficiency Test Results For Methods Used For Official Control Purposes In 2019

Performance in proficiency tests is assessed using a Z-score. This is calculated for each participant's data. 

Each sample /matrix combination is given an assigned value and Z-score is calculated thus: 
 
Z-score = Mean from Laboratory - Assigned Value 
                      
Total Error 
 
The total error is based on values set for the proportional error and the constant error. These values are set by the organisers. The numbers in the z column indicate: 
 
|Z| < 2 satisfactory performance  
 
2 < |Z| < 3 questionable performance 
 
|Z| > 3 unsatisfactory performance 

## Domoic Acid 2019 Proficiency Test Summaries

Reported 
Sample ID 
Sample description 
Assigned 
value 
value 
Units 
z-score 
EURLMB/19/A/01 
Shellfish homogenate 
7.3 
7.2 
mg/kg 
-0.10 
EURLMB/19/A/02 
Shellfish homogenate 
76.5 
77.9 
mg/kg 
0.10 
Reported 
Sample ID 
Sample description 
Assigned 
value 
value 
Units 
z-score 
QST260BT 
Scallop tissue 
27 
26 
mg/kg 
-0.29 
QST261BT 
Queen scallop aductor muscle 
28.1 
29.5 
mg/kg 
0.39 
QST262BT 
Pacific oyster 
8.4 
8.3 
mg/kg 
-0.09 
Reported 
Sample ID 
Sample description 
Assigned 
value 
value 
Units 
z-score 
QST269BT 
Oyster tissue  
17.1 
18.7 
mg/kg 
0.7 
QST270BT 
Queen scallop aductor muscle 
28.3 
32.2 
mg/kg 
1.1 
QST271BT 
Blue mussel 
52.1 
45.9 
mg/kg 
-0.9 
 

 

## Psp 2019 Proficiency Test Summaries

| Sample ID            | Matrix               | Determinant    |
|----------------------|----------------------|----------------|
| Assigned             |                      |                |
| EURLMB/19/P/01       | Shellfish homogenate | Total toxicity |
| EURLMB/19/P/01       | Shellfish homogenate | dcGTX-2,3      |
| EURLMB/19/P/01       |                      |                |
|                      |                      |                |
| Shellfish homogenate | dcSTX                | 642.8          |
| EURLMB/19/P/01       | Shellfish homogenate | GTX-2,3        |
| EURLMB/19/P/01       | Shellfish homogenate | GTX-5          |
| EURLMB/19/P/01       | Shellfish homogenate | STX            |
| EURLMB/19/P/01       | Shellfish homogenate | dcNEO          |
| EURLMB/19/P/01       | Shellfish homogenate | GTX-6          |
| EURLMB/19/P/02       | Shellfish homogenate | Total toxicity |
| EURLMB/19/P/02       | Shellfish homogenate | C-1,2          |
| EURLMB/19/P/02       | Shellfish homogenate | dcSTX          |
| EURLMB/19/P/02       | Shellfish homogenate | GTX-2,3        |
| EURLMB/19/P/02       | Shellfish homogenate | GTX-5          |
| EURLMB/19/P/02       | Shellfish homogenate | dcNEO          |
| EURLMB/19/P/02       | Shellfish homogenate | C-3,4          |
| EURLMB/19/P/02       | Shellfish homogenate | GTX-6          |
| EURLMB/19/P/03       | Shellfish homogenate | Total toxicity |
| EURLMB/19/P/03       | Shellfish homogenate | GTX-2,3        |
|                      |                      |                |
| 2.20                 |                      |                |
| EURLMB/19/P/03       | Shellfish homogenate | STX            |
| Sample ID        | Sample description    |   Determinant  |
|------------------|-----------------------|----------------|
| Assigned         |                       |                |
| Value            |                       |                |
| QST 266BT        |                       |                |
| Mussel tissue    |                       |                |
| GTX-2,3          |                       |                |
| 3.21             | 3.04                  |                |
| µmol/kg          |                       |                |
| -0.37            |                       |                |
| QST 266BT        |                       |                |
| Mussel tissue    |                       |                |
| STX              |                       |                |
| 1.74             | 1.57                  |                |
| µmol/kg          |                       |                |
| -0.62            |                       |                |
| QST 266BT        |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 1334             | 1263                  |                |
| µgSTXdiHCleq./kg |                       |                |
| -0.42            |                       |                |
| QST 267BT        |                       |                |
|                  |                       |                |
| Mussel tissue    |                       |                |
| GTX-2,3          |                       |                |
|                  |                       |                |
| 2.94             | 2.77                  |                |
| µmol/kg          |                       |                |
| -0.38            |                       |                |
| QST 267BT        |                       |                |
|                  |                       |                |
| Mussel tissue    |                       |                |
| STX              |                       |                |
| 1.41             | 1.3                   |                |
| µmol/kg          |                       |                |
| -0.48            |                       |                |
| QST 267BT        |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 1156             | 1101                  |                |
| µgSTXdiHCleq./kg |                       |                |
| -0.37            |                       |                |
| QST 268BT        |                       |                |
| Mussel tissue    | dc-Neo                |           0.21 |
| µmol/kg          |                       |                |
| 0.48             |                       |                |
| QST 268BT        |                       |                |
| Mussel tissue    | dc-STX                |           1.87 |
| µmol/kg          |                       |                |
| -1.54            |                       |                |
| QST 268BT        |                       |                |
| Mussel tissue    | GTX-2,3               |           0.07 |
| µmol/kg          |                       |                |
| 0.00             |                       |                |
| QST 268BT        |                       |                |
| Mussel tissue    | STX                   |           0.08 |
| µmol/kg          |                       |                |
| -0.33            |                       |                |
| QST 268BT        |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 762.4            | 592                   |                |
| µgSTXdiHCleq./kg |                       |                |
| -1.54            |                       |                |

## 

Reported 
Value 
Value 
Units 
z-Score 
Reported  
Value 
Units 
z-score 
| Sample ID        | Sample description    |   Determinant  |
|------------------|-----------------------|----------------|
| Assigned         |                       |                |
| Value            |                       |                |
| Reported         |                       |                |
| Value            |                       |                |
| Units            | z-score               |                |
| QST275BT         |                       |                |
| Mussel tissue    |                       |                |
| GTX-2,3          |                       |                |
| 5.02             | 4.56                  |                |
| µmol/kg          |                       |                |
| -0.5             |                       |                |
| QST275BT         |                       |                |
| Mussel tissue    |                       |                |
| STX              |                       |                |
| 3.4              | 3.24                  |                |
| µmol/kg          |                       |                |
| -0.3             |                       |                |
| QST275BT         |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 2327             | 2224                  |                |
| µgSTXdiHCleq./kg |                       |                |
| -0.3             |                       |                |
| QST276BT         |                       |                |
| Mussel tissue    |                       |                |
| dc-STX           |                       |                |
| 0.51             | 0.44                  |                |
| µmol/kg          |                       |                |
| -0.6             |                       |                |
| QST276BT         |                       |                |
| Mussel tissue    |                       |                |
| GTX-2,3          |                       |                |
| 5.35             | 4.98                  |                |
| µmol/kg          |                       |                |
| -0.4             |                       |                |
| QST276BT         |                       |                |
| Mussel tissue    |                       |                |
| STX              |                       |                |
| 1.27             | 1.11                  |                |
| µmol/kg          |                       |                |
| -0.7             |                       |                |
| QST276BT         |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 1768             | 1689                  |                |
| µgSTXdiHCleq./kg |                       |                |
| -0.3             |                       |                |
| QST277BT         |                       |                |
| Mussel tissue    | GTX-2,3               |           6.85 |
| µmol/kg          |                       |                |
| -0.5             |                       |                |
| QST277BT         |                       |                |
| Mussel tissue    | STX                   |           1.88 |
| µmol/kg          |                       |                |
| -0.7             |                       |                |
| QST277BT         |                       |                |
| Mussel tissue    |                       |                |
| Total toxicity   |                       |                |
| 2163             | 2012                  |                |
| µgSTXdiHCleq./kg |                       |                |
| -0.5             |                       |                |
|                  |                       |                |
|                  |                       |                |
|                  |                       |                |
|                  |                       |                |
|                  |                       |                |
|                  |                       |                |
|                  |                       |                |

## Lipophilic Toxins 2019 Proficiency Test Summaries

 
 
Table 12: EURL 2019 - LC-MS/MS 
Reported 
Sample ID 
Matrix 
Determinant 
Assigned 
Value 
Value 
Units 
z-score 
EURLMB/19/L/01 
Mussel homogenate 
Total OA group 
1659.5 
1435.8 
µg OA eq./kg 
-0.80 
EURLMB/19/L/01 
Mussel homogenate 
Free OA 
200.6 
150.0 
µg/kg 
-1.20 
EURLMB/19/L/01 
Mussel homogenate 
Free DTX2 
165.0 
123.0 
µg/kg 
-1.10 
EURLMB/19/L/01 
Mussel homogenate 
Total OA 
1418.8 
1266.0 
µg/kg 
-0.70 
EURLMB/19/L/01 
Mussel homogenate 
Total DTX2 
330.2 
283.0 
µg/kg 
-0.80 
EURLMB/19/L/01 
Mussel homogenate 
Total YTX 
3.0 
3.0 
mg YTX eq./kg 
0.10 
EURLMB/19/L/01 
Mussel homogenate 
YTX 
0.2 
0.2 
mg/kg 
0.00 
EURLMB/19/L/01 
Mussel homogenate 
homo-YTX 
2.1 
1.9 
mg/kg 
-0.50 
EURLMB/19/L/01 
Mussel homogenate 
45 OH YTX 
0.3 
0.2 
mg/kg 
-0.80 
EURLMB/19/L/01 
Mussel homogenate 
45 OH homo YTX 
1.2 
1.5 
mg/kg 
1.40 
EURLMB/19/L/02 
Mussel homogenate 
Total OA group 
82.1 
47.2 
µg OA eq./kg 
-1.90 
EURLMB/19/L/02 
Mussel homogenate 
Free OA 
43.5 
27.8 
µg/kg 
-1.60 
EURLMB/19/L/02 
Mussel homogenate 
Total OA 
80.7 
47.2 
µg/kg 
-1.80 
EURLMB/19/L/02 
Mussel homogenate 
AZA group 
476.5 
451.3 
µg AZA eq./kg 
-0.30 
EURLMB/19/L/02 
Mussel homogenate 
AZA1 
262.2 
253.0 
µg/kg 
-0.20 
EURLMB/19/L/02 
Mussel homogenate 
AZA2 
73.8 
74.1 
µg/kg 
0.00 
EURLMB/19/L/02 
Mussel homogenate 
AZA3 
55.2 
46.4 
µg/kg 
-0.70 
EURLMB/19/L/03 
Mussel homogenate 
Total OA group 
904.9 
877.4 
µg OA eq./kg 
-0.20 
EURLMB/19/L/03 
Mussel homogenate 
Free OA 
20.8 
14.8 
µg/kg 
-1.20 
EURLMB/19/L/03 
Mussel homogenate 
Free DTX1 
225.2 
229 
µg/kg 
0.10 
EURLMB/19/L/03 
Mussel homogenate 
Total OA 
49.4 
23.4 
µg/kg 
-2.10 
EURLMB/19/L/03 
Mussel homogenate 
Total DTX1 
787.7 
854 
µg/kg 
0.40 
Reported 
Sample ID 
Sample Description 
Determinant 
Assigned 
Value 
Value 
Units 
z-Score 
QST263BT 
Mussel tissue 
45-OH-homo-YTX 
0.51 
0.60 
mg/kg 
1.09 
QST263BT 
Mussel tissue 
45-OH-YTX 
0.12 
0.15 
mg/kg 
1.17 
QST263BT 
Mussel tissue 
AZA-1 
737.7 
639 
µg/kg 
-1.06 
QST263BT 
Mussel tissue 
AZA-2 
209.6 
217 
µg/kg 
0.28 
QST263BT 
Mussel tissue 
AZA-3 
124.7 
110 
µg/kg 
-0.91 
QST263BT 
Mussel tissue 
AZA-total 
1303.6  
1183 
µg AZA eq./kg 
-0.73 
QST263BT 
Mussel tissue 
Free-DTX1 
85.8 
71.2 
µg/kg 
-1.27 
QST263BT 
Mussel tissue 
Free-DTX2 
567.2 
520 
µg/kg 
-0.65 
QST263BT 
Mussel tissue 
free-Okadaic-Acid 
149.1 
134 
µg/kg 
-0.79 
QST263BT 
Mussel tissue 
Homo-YTX 
1.1 
1.04 
mg/kg 
-0.37 
QST263BT 
Mussel tissue 
Total OA group + PTX group 
904.1 
804 
µg OA eq./kg 
-0.87 
QST263BT 
Mussel tissue 
Total DTX1 
112.6 
101 
µg/kg 
-0.79 
QST263BT 
Mussel tissue 
Total DTX2 
786.6 
690 
µg/kg 
-0.95 
QST263BT 
Mussel tissue 
Total-free- OA+DTX1+DTX2 
562.9 
517 
µg OA eq./kg 
-0.63 
QST263BT 
Mussel tissue 
Total-hy- OA+DTX1+DTX2 
924.4 
804 
µg OA eq./kg 
-1.01 
QST263BT 
Mussel tissue 
Total okadaic acid 
339.1 
289 
µg/kg 
-1.14 
QST263BT 
Mussel tissue 
Total-YTX 
1.76 
1.75 
mg YTX eq./kg 
-0.03 
QST263BT 
Mussel tissue 
YTX 
0.23 
0.26 
mg/kg 
0.79 
QST264BT 
Mussel extract 
AZA-1 
97 
87 
µg/kg 
-0.77 
QST264BT 
Mussel extract 
AZA-2 
20.5 
22.8 
µg/kg 
0.84 
QST264BT 
Mussel extract 
AZA-3 
36.8 
32.3 
µg/kg 
-0.93 
QST264BT 
Mussel extract 
AZA-total 
187 
173.6 
µg AZA eq./kg 
-0.54 
QST264BT 
Mussel extract 
Free-DTX2 
3.9 
3.6 
µg/kg 
-0.50 
QST264BT 
Mussel extract 
free-Okadaic-Acid 
38.7 
37.9 
µg/kg 
-0.16 
QST264BT 
Mussel extract 
Total OA group + PTX 
group 
47.9 
49.8 
µg OA eq./kg 
0.31 
QST264BT 
Mussel extract 
Total-DTX2 
4.1 
3.4 
µg/kg 
-1.20 
QST264BT 
Mussel extract 
Total-free- OA+DTX1+DTX2 
41.3 
40 
µg OA eq./kg 
-0.23 
QST264BT 
Mussel extract 
Total-hy-OA+DTX1+DTX2 
48.4 
49.8 
µg OA eq./kg 
0.22 
QST264BT 
Mussel extract 
Total-Okadaic-Acid 
46 
47.7 
µg/kg 
0.29 
QST265BT 
Mussel  
AZA-1 
422.2 
367 
µg/kg 
-1.02 
QST265BT 
Mussel 
AZA-2 
118.6 
130 
µg/kg 
0.75 
QST265BT 
Mussel 
AZA-3 
84.7 
72.9 
µg/kg 
-1.06 
QST265BT 
Mussel 
AZA-total 
767.5 
703 
µg AZA eq./kg 
-0.66 
QST265BT 
Mussel 
Free-DTX2 
101.4 
82.8 
µg/kg 
-1.41 
QST265BT 
Mussel 
free-Okadaic-Acid 
45.9 
35.8 
µg/kg 
-1.69 
QST265BT 
Mussel 
Total-DTX2 
146.5 
119 
µg/kg 
-1.44 
QST265BT 
Mussel 
Total-free- OA+DTX1+DTX2 
106.9 
85.5 
µg OA eq./kg  
-1.52 
QST265BT 
Mussel 
Total-hy-OA+DTX1+DTX2 
186.3 
154.4 
µg OA eq./kg 
-1.33 
QST265BT 
Mussel 
Total-Okadaic-Acid 
99.1 
83 
µg/kg 
-1.23 
 
Reported 
Sample ID 
Sample Description 
Determinant 
Assigned 
Value 
Value 
Units 
z-Score 
QST272BT 
Mussel tissue 
Free-DTX2 
407 
392.4 
µg/kg 
-0.3 
QST272BT 
Mussel tissue 
Free-Okadaic acid 
153 
142.6 
µg/kg 
-0.5 
QST272BT 
Mussel tissue 
Total-free- OA+DTX1+DTX2 
404 
378.1 
µg OA eq./kg 
-0.5 
QST272BT 
Mussel tissue 
Total-DTX2 
706 
693.7 
µg/kg 
-0.1 
QST272BT 
Mussel tissue 
Totalk-Okadaic acid 
484 
475.2 
µg/kg 
-0.1 
QST272BT 
Mussel tissue 
Total-hy- OA+DTX1+DTX2 
920 
891.4 
µg OA eq./kg 
-0.2 
QST272BT 
Mussel tissue 
Total OA group + PTX 
group 
924 
891.4 
µg OA eq./kg 
-0.3 
QST273BT 
Mussel extract 
AZA-1 
13.6 
10.7 
µg/kg 
-1.6 
QST273BT 
Mussel extract 
AZA-2 
3.87 
3.5 
µg/kg 
-0.7 
QST273BT 
Mussel extract 
AZA-3 
3.94 
3.9 
µg/kg 
-0.1 
QST273BT 
Mussel extract 
AZA-total 
25.4 
22.5 
µg AZA eq./kg 
-0.9 
QST273BT 
Mussel extract 
Free-DTX2 
60.8 
53.4 
µg/kg 
-0.9 
QST273BT 
Mussel extract 
Free-Okadaic Acid 
11.0 
10.5 
µg/kg 
-0.3 
QST273BT 
Mussel extract 
Total-free-
OA+DTX1+DTX2 
49.4 
42.5 
µg OA eq./kg 
-1.1 
QST273BT 
Mussel extract 
Total-DTX2 
74.2 
68.8 
µg/kg 
-0.5 
QST273BT 
Mussel extract 
Total-Okadaic Acid 
18.7 
16.7 
µg/kg 
-0.8 
QST273BT 
Mussel extract 
Total-hy- OA+DTX1+DTX2 
63.0 
57.9 
µg OA eq./kg 
-0.6 
QST273BT 
Mussel extract 
Total OA group + PTX group 
64.4 
57.9 
µg OA eq./kg 
-0.8 
QST273BT 
Mussel extract 
YTX 
0.031 
0.031 
mg/kg 
0.0 
QST273BT 
Mussel extract 
Homo-YTX 
0.302 
0.328 
mg/kg 
0.5 
QST273BT 
Mussel extract 
45-OH-homo-YTX 
0.174 
0.196 
mg/kg 
0.6 
QST273BT 
Mussel extract 
45-OH-YTX 
0.023 
0.025 
mg/kg 
0.1 
QST273BT 
Mussel extract 
Total-YTX 
0.432 
0.481 
mg YTX eq./kg 
0.7 
QST274BT 
Blue mussel 
AZA-1 
218 
180.8 
mg/kg 
-1.3 
QST274BT 
Blue mussel 
AZA-2 
59 
59.2 
mg/kg 
0.0 
QST274BT 
Blue mussel 
AZA-3 
49.6 
50.9 
µg/kg 
0.2 
QST274BT 
Blue mussel 
AZA-total 
392 
358.5 
µg AZA eq./kg 
-0.7 
QST274BT 
Blue mussel 
Free-DTX2 
297 
284.7 
µg/kg 
-0.3 
QST274BT 
Blue mussel 
free-Okadaic-Acid 
67.5 
57.9 
µg/kg 
-1.1 
QST274BT 
Blue mussel 
Total-free- OA+DTX1+DTX2 
250 
228.7 
µg OA eq./kg 
-0.6 
QST274BT 
Blue mussel 
Total-DTX2 
439 
368.6 
µg/kg 
-1.2 
QST274BT 
Blue mussel 
Total-Okadaic-Acid 
156 
125.5 
µg/kg 
-1.5 
QST274BT 
Blue mussel 
Total-hy- OA+DTX1+DTX2 
435 
346.7 
µg OA eq./kg 
-1.6 
QST274BT 
Blue mussel 
Total OA group + PTX group 
433 
346.7 
µg/kg 
-1.5 

## Overall Summary Of Proficiency Tests

 The proficiency tests for domoic acid were 100% satisfactory (8/8). For PSP they were 84% satisfactory (31/37); both rounds of the Quasimeme tests were 100% satisfactory but for the EURL there were 5 questionable and 1 unsatisfactory z-scores. The EURL report indicated that there were some problems with the identification and quantification of dcNEO in sample 1 with only half of participants identifying it. The sample was homogenised clam tissue originating from Spain during an episode of *Gymnodinium catenatum*, the toxin profiles of which have previously been particularly problematic to determine. The EURL report provided z-scores for total toxicity with and without the contribution of dcNeo and without it our z-score was 0.4 (satisfactory). The z-scores with the contribution of dcNeo and all other analytes were z'-scores (z prime) indicating a degree of uncertainty for the assigned value. Analysis of samples 2 and 3 led to one questionable z-score for each. Sample 2 was a homogenate of mussels again displaying a typical *Gymnodinium catenatum* profile. For this sample only 35% of participants identified dcNeo and again the scores for all analytes were given as z'-scores. The failing zscores were exclusively by overestimation of the assigned values and so may be attributed to the application of recovery correction creating falsely exaggerated results; this is not applied for the reporting of routine samples. The lipophilic exercises were 99% satisfactory (94/95). There was a single questionable z-score (-2.1) in the EURL exercise for the hydrolysed OA result for sample 3 but the total toxicity was satisfactory as was the hydrolysed OA results for samples 1 and 2. Internal non-conformance reports have been raised on our quality assurance system to address the discrepancies. Overall performance for the three toxin groups in the three proficiency tests is 95% satisfactory (133/140), 4.3% questionable and 0.7% unsatisfactory.