SAMPLING METHODS AND METHODS OF ANALYSIS FOR THE OFFICIAL CONTROL OF THE LEVELS FOR CERTAIN CONTAMINANTS

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

SUBSIDIARY LEGISLATION 437.65

SAMPLING METHODS AND METHODS

OF ANALYSIS FOR THE OFFICIAL CONTROL

OF THE LEVELS FOR CERTAIN CONTAMINANTS

IN FOODSTUFFS RULES

8th April, 2005

LEGAL NOTICE 97 of 2005.

(1) The title of these rules is the Sampling Methods and

Methods of Analysis for the Official Control of the Levels for

Certain Contaminants in Foodstuffs Rules.

(2) The scope of these rules is to implement the rules found

under European Union Council Directive 98/53/EC establishing

methods of analysis for the official control of feedingstuffs.

Methods of sampling for official checking control of the levels of aflatoxins

in certain foodstuffs

1. Purpose and scope

Samples intended for official checking of the levels of aflatoxin content in

foodstuffs shall be taken according to the methods described below. Aggregate

samples thus obtained shall be considered as representative of the lots. Compliance

with maximum limits laid down in European Commission Regulation 98/1525/EC

shall be established on the basis of the levels determined in the laboratory samples.

2. Definitions

Lot

an identifiable quantity of a food commodity delivered at

one time and determined by the official to have common

characteristics, such as origin, variety, type of packing,

packer, consignor or markings.

Sublot

designated part of a large lot in order to apply the sampling

method on that designated part. Each sublot must be

physically separate and identifiable.

Incremental sample

a quantity of material taken from a single place in the lot or

sublot.

Aggregate sample

the combined total of all the incremental samples taken

from the lot or sublot.

Laboratory sample

sample intended for the laboratory ( = subsample).

3. General provisions

3.1. Personnel

Sampling shall be performed by an authorised person as specified by the

competent authority.

3.2. Material to be sampled

Each lot which is to be examined must be sampled separately. In accordance with

the specific provisions in point 5 of this Schedule, large lots should be subdivided

into sublots to be sampled separately.

3.3. Precautions to be taken

In the course of sampling and preparation of the laboratory samples, precautions

must be taken to avoid any changes which would affect the aflatoxin content,

adversely affect the analytical determination or make the aggregate samples

unrepresentative.

3.4. Incremental samples

As far as possible incremental samples should be taken at various places

distributed throughout the lot or sublot. Departure from this procedure must be

recorded in the record provided for in 3.8.

3.5. Preparation of the aggregate sample and the laboratory samples

(subsamples)

The aggregate sample is made up by uniting and sufficiently mixing the

incremental samples. After mixing, the aggregate sample must be divided into equal

subsamples in accordance with the specific provisions of point 5 of this Schedule.

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

The mixing is necessary to ensure that each subsample contains portions of the

whole lot or sublot.

3.6. Replicate samples

The replicate samples for enforcement, trade (defence) and referee purposes are to

be taken from the homogenised laboratory sample, unless this conflicts with Member

States' rules on sampling.

3.7. Packaging and transmission of laboratory samples

Each laboratory sample shall be placed in a clean, inert container offering

adequate protection from contamination and against damage in transit. All necessary

precautions shall be taken to avoid any change in composition of the laboratory

sample which might arise during transportation or storage.

3.8. Sealing and labelling of laboratory samples

Each sample taken for official use shall be sealed at the place of sampling and

identified following the Member State's regulations. A record must be kept of each

sampling, permitting each lot to be identified unambiguously and giving the date and

place of sampling together with any additional information likely to be of assistance

to the analyst.

4. Explanatory provisions

4.1. Different types of lots

Food commodities may be traded in bulk, containers, or individual packings

(sacks, bags, retail packings, etc.). The sampling procedure can be applied to all the

different forms in which the commodities are put on the market. Without prejudice to

the specific provisions as laid down in point 5 of this Schedule, the following

formula can be used as a guide for the sampling of lots traded in individual packings

(sacks, bags, retail packings, etc.)

Weight of the lot x weight of the incremental sample

Sampling frequency (SF) =

Weight of the aggregate sample x weight of individual packing

-

Weight: in kg

Sampling frequency (SF): every nth sack or bag from which an incremental

sample must be taken (decimal figures should be rounded to the nearest

whole number).

4.2. Weight of the incremental sample

The weight of the incremental sample should be about 300 grams unless otherwise

defined in point 5 of this Schedule and with the exception of spices in which case the

weight of the incremental sample is about 100 grams. In the case of retail packings,

the weight of the incremental sample depends on the weight of the retail packing.

4.3. Number of incremental samples for lots of less than 15 tonnes

The number of incremental samples to be taken depends on the weight of the lot,

with a minimum of 10 and a maximum of 100, unless otherwise defined in point 5 of

this Schedule. The figures in the following table may be used to determine the

number of incremental samples to be taken.

Table 1: Number of incremental samples to be taken depending on the weight of

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

the lot

Lot weight

No of incremental samples

(tonnes)

< 0,1

> 0,1 - < 0,2

> 0,2 - < 0,5

> 0,5 - < 1,0

> 1,0 - < 2,0

> 2,0 - < 5,0

> 5,0 - < 10,0

> 10,0 - < 15,0

For the purposes of these rules -

"the competent authority" means the Veterinary Services within

Malta as provided under article 2 of the Veterinary Services Act, or

any other authority to which such responsibility has been delegated

by the Veterinary Services.

Sample preparation and criteria for methods of analysis

used in official checking of the levels of aflatoxins in certain foodstuffs

1. Introduction

1.1. Precautions

Daylight should be excluded as much as possible during the procedure, since

aflatoxin gradually breaks down under the influence of ultra-violet light. As the

distribution of aflatoxin is extremely non-homogeneous, samples should be prepared

- and especially homogenised - with extreme care.

All the material received by the laboratory is to be used for the preparation of test

1.2. Calculation of proportion of shell / kernel of whole nuts

The limits fixed for aflatoxins in European Union Commission Regulation (EC)

No 1525/98 apply to the edible part.

The level of aflatoxins in the edible part can be determined by

shelling samples of nuts ‘in shell’ and the level of aflatoxins is directly

determined in the edible part,

homogenise the nuts ‘in shell’ by taking them through the sample

preparation procedure. The sampling and analytical procedure must

estimate the weight of nut kernel in the aggregate sample. The weight of

nut kernel in the aggregate sample is estimated after establishing a

suitable factor for the proportion of nut shell to nut kernel in whole

nuts. This proportion is used to ascertain the amount of kernel in the

bulk sample taken through the sample preparation and analysis

procedure. Approximately 100 whole nuts are taken at random

separately from the lot or are to be put aside from each aggregate

sample. The ratio may, for each laboratory sample, be obtained by

weighing the whole nuts, shelling and re-weighing the shell and kernel

portions. However, the proportion of shell to kernel may be established

by the laboratory from a number of samples and so can be assumed for

future analytical work. But if a particular laboratory sample is found to

be in contravention of any limit, the proportion should be determined

for that sample using the approximately 100 nuts that have been set

aside.

2. Treatment of the sample as received in the laboratory

Finely grind and thoroughly mix each laboratory sample using a process that has

been demonstrated to achieve complete homogenisation. In case the maximum level

applies to the dry matter, the dry matter content shall be determined on a part of the

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

homogenised sample, using a procedure that has been demonstrated to determine

accurately the dry matter content.

3. Subdivision of samples for enforcement and defence purposes

The replicate samples for enforcement, trade (defence) and referee purposes shall

be taken from the homogenised material unless this conflicts with Member States’

rules on sampling.

4. Method of analysis to be used by the laboratory and laboratory control

requirements

4.1. Definitions

A number of the most commonly used definitions that the laboratory will be

required to use are given below

The most commonly quoted precision parameters are repeatability and

reproducibility.

repeatability, the value below which the absolute difference between two

single test results obtained under repeatability conditions (i. e. same

sample, same operator, same apparatus, same laboratory, and short

interval of time) may be expected to lie within a specific probability

(typically 95%) and hence r = 2,8 × s r

Standard deviation, calculated from results generated under repeatability

conditions

RSD r = relative standard deviation, calculated from results generated under

repeatability conditions [(S r/x) × 100], where x is the average of results

over all laboratories and samples

reproducibility, the value below which the absolute difference between

single test results obtained under reproducibility conditions (i. e. on

identical material obtained by operators in different laboratories, using

the standardised test method) may be expected to lie within a certain

probability (typically 95%); R = 2,8 s R

standard deviation, calculated from results under reproducibility

conditions

RSD R = relative standard deviation calculated from results generated under

reproducibility conditions [(S R/x) × 100]\

4.2. General requirements

Methods of analysis used for food control purposes must comply whenever

possible with the provisions of points 1 and 2 of the Annex to European Union

Council Directive 85/591/EEC.

4.3. Specific requirements

Where no specific methods for the determination of aflatoxin levels in foodstuffs

are prescribed at European Community level, laboratories may select any method

provided the selected method meets the following criteria

Criterion

Concentration

Recommended

Maximum

range

value

permitted value

All

Negligible

Recovery - Aflatoxin

0,01 - 0,05 µg/kg

60 to 120%

> 0,05 µg/kg

70 to 110%

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

Recovery - Aflatoxins

< 1,0 µg/kg

50 to 120%

1 - 10 µg/kg

70 to 110%

-

>10 µg/kg

80 to 110%

Precision RSD R

All

As derived from

2 × value derived

Horwitz equation

from Horwitz

equation

Precision RSD r may be calculated as 0,66 times precision RSD R at the concentration of

interest.

Notes

-

Values to apply to both B1 and sum of B 1 + B 2 + G 1 + G 2 ,

-

if sum of individual aflatoxins B 1 + B 2 + G 1 + G 2 are to be reported, then

response of each to the analytical system must be either known or equivalent,

-

the detection limits of the methods used are not stated as the precision

values are given at the concentrations of interest,

-

the precision values are calculated from the Horwitz equation, i. e.: RSD R =

2 (1-0,5 logC) where

-

RSD R is the relative standard deviation calculated from results

generated under reproducibility conditions [(S R /x) × 100]

-

C is the concentration ratio (i. e. 1 = 100 g/100 g, 0,001 = 1 000 mg/kg).

This is a generalised precision equation which has been found to be independent

of analyte and matrix but solely dependent on concentration for most routine

methods of analysis.

4.4. Recovery calculation and reporting of results

The analytical result is to be reported corrected or uncorrected for recovery. The

manner of reporting and the level of recovery must be reported. The analytical result

corrected for recovery is used for checking compliance (see Schedule I, points 5.2.2,

5.3.2, 5.4.2, 5.5.1.2 and 5.5.2.3).

The analytical result has to be reported as x +/- U whereby x is the analytical

result and U is the expanded measurement uncertainty, using a coverage factor of 2

which gives a level of confidence of approximately 95%.

4.5. Laboratory quality standards

Laboratories must comply with European Council Directive 93/99/EEC.

The competent authority shall take all measures necessary

to ensure that the sampling for the official control of the levels of

aflatoxins in foodstuffs is carried out in accordance with the

methods described in Schedule I.

The competent authority shall take all measures necessary

to ensure that sample preparation and methods of analyses used for

the official control of the levels of aflatoxins in foodstuffs comply

with the criteria described in Schedule II.

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

Specific provisions

5.1. General survey of the sampling procedure for groundnuts, nuts, dried fruit,

spices and cereals

Table 2: Subdivision of lots into sublots depending on product and lot weight

Commodity

Lot weight

Weight or

Number of

Aggregate

(tonnes)

number of

incremental

sample

sublots

samples

Weight (kg)

Dried figs and other

> 15

15 - 30 tonnes

10 - 100 ( 1 )

dried fruit

< 15

-

< 30

Groundnuts,

> 500

100 tonnes

pistachios,

> 125 and < 500

5 sublots

Brazil nuts and other

> 15 and < 125

25 tonnes

10 - 100 ( 1 )

< 15

-

< 30

Cereals

> 1 500

500 tonnes

> 300 and < 1 500

3 sublots

> 50 and < 300

100 tonnes

10 - 100 ( 1 )

< 50

-

1 - 10

Spices

> 15

25 tonnes

10 - 100 ( 1 )

< 15

-

1 - 10

(1) Depending on the lot weight - see point 4.3 or 5.3 of this Schedule.

5.2. Groundnuts, pistachios and Brazil nuts

Dried figs

Cereals (lots > 50 tonnes)

Spices

5.2.1. Sampling procedure

On condition that the sublot can be separated physically, each lot must be

subdivided into sublots following Table 2 at point 5.1. Taking into account

that the weight of the lot is not always an exact multiple of the weight of the

sublots, the weight of the sublot may exceed the mentioned weight by a

maximum of 20%,

each sublot must be sampled separately,

number of incremental samples: 100. In the case of lots under 15 tonnes, the

number of incremental samples to be taken depends on the weight of the lot,

with a minimum of 10 and a maximum of 100 (see point 4.3),

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

weight of the aggregate sample = 30 kg which has to be mixed and to be

divided into three equal subsamples of 10 kg before grinding (this division

into three subsamples is not necessary in the case of groundnuts, nuts, dried

fruit and maize intended for further sorting or other physical treatment,

however, this will depend upon the availability of equipment which is able to

homogenise a 30 kg sample). In cases where the aggregate sample weights

are under 10 kg, the aggregate sample must not be divided into three

subsamples. In the case of spices the aggregate sample weighs not more than

10 kg and therefore no division in subsamples is necessary,

laboratory sample: a subsample of 10 kg (each subsample must be separately

ground finely and mixed thoroughly to achieve complete homogenisation, in

accordance with the provisions laid down in Schedule II),

if it is not possible to carry out the method of sampling described above

because of the commercial consequences resulting from damage to the lot

(because of packaging forms, means of transport, etc.) an alternative method

of sampling may be applied provided that it is as representative as possible

and is fully described and documented.

5.2.2. Acceptance of a lot or sublot

For groundnuts, nuts, dried fruit and maize subjected to a sorting or other

physical treatment and spices

-

acceptance if the aggregate sample or the average of the subsamples

conforms to the maximum limit, taking into account the measurement

uncertainty and correction for recovery,

-

rejection if the aggregate sample or the average of the subsamples

exceeds the maximum limit beyond reasonable doubt taking into

account the measurement uncertainty and correction for recovery,

for groundnuts, nuts, dried fruit and cereals intended for direct human

consumption and cereals, with the exception of maize, to be subjected to a

sorting or other physical treatment

-

acceptance if none of the subsamples exceeds the maximum limit,

taking into account the measurement uncertainty and correction for

recovery,

-

rejection if one or more of the subsamples exceeds the maximum limit

beyond reasonable doubt taking into account the measurement

uncertainty and correction for recovery,

-

where the aggregate sample is under 10 kg

-

acceptance if the aggregate sample conforms to the maximum

limit, taking into account the measurement uncertainty and

correction for recovery,

-

rejection if the aggregate sample exceeds the maximum limit

beyond reasonable doubt taking into account analytical

uncertainty and correction for recovery.

5.3. Nuts other than groundnuts, pistachios and Brazil nuts

Dried fruit other than figs

Cereals (lots under 50 tonnes)

5.3.1. Sampling procedure

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

For these products, the sampling procedure laid down in point 5.2.1 may be

applied. However, taking into account the low incidence of contamination for these

products and / or the newer forms of packaging in which products can be traded,

simpler sampling methods may be applied.

For cereal lots under 50 tonnes, a sampling plan consisting of, depending on the

lot weight, 10 to 100 incremental samples each of 100 grams, resulting in an

aggregate sample of 1 to 10 kg may be used. The figures in the following table can

be used to determine the number of incremental samples to be taken.

Table 3: Number of incremental samples to be taken depending on the weight of

the lot of cereals

Lot weight

No of incremental samples

(tonnes)

< 0,1

> 3 - < 10

> 10 - < 20

> 20 - < 50

5.3.2. Acceptance of a lot or sublot

See point 5.2.2.

5.4. Milk

5.4.1. Sampling procedure

Sampling in accordance with European Union Commission Decision 91/180/EEC

of 14 February 1991 laying down certain methods of analysis and testing of raw milk

and heat-treated milk

-

number of incremental samples: minimum 5,

-

weight of aggregate sample: minimum 0,5 kg or litres.

5.4.2. Acceptance of a lot or sublot

-

Acceptance if the aggregate sample conforms to the maximum limit,

taking into account the measurement uncertainty and correction for

recovery,

-

rejection if the aggregate sample exceeds the maximum limit beyond

reasonable doubt taking into account the measurement uncertainty and

correction for recovery.

5.5. Derived products and compound foods

5.5.1. Milk products

5.5.1.1. Sampling procedure

Sampling in accordance with European Union Commission

Directive 87/524/EEC of 6 October 1987 laying down European

Community methods of sampling for chemical analysis for the

monitoring of preserved milk products.

Number of incremental samples: minimum 5.

For the other milk products an equivalent method of sampling is

used.

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

5.5.1.2. Acceptance of a lot or sublot

Acceptance if the aggregate sample conforms to the maximum

limit, taking into account the measurement uncertainty and

correction for recovery,

rejection if the aggregate sample exceeds the maximum limit

beyond reasonable doubt taking into account the measurement

uncertainty and correction for recovery.

5.5.2. Other derived products with very small particle weight, i.e. flour, fig paste,

peanut butter (homogeneous distribution of aflatoxin contamination).

5.5.2.1. Sampling procedure

Number of incremental samples: 100. For lots of under 50 tonnes

the number of incremental samples should be 10 to 100, depending

on the lot weight (see Table 3 at point 5.3.1 of this Schedule),

the weight of the incremental sample should be about 100 grams. In

the case of lots in retail packing, the weight of the incremental

sample depends on the weight of the retail packing,

weight of aggregate sample = 1-10 kg sufficiently mixed.

5.5.2.2. Number of samples to be taken

The number of aggregate samples to be taken depends on the lot

weight. The division of large lots into sublots must be done as

defined for cereals in Table 2 under point 5.1,

each sublot must be sampled separately.

Acceptance of a lot or sublot

Acceptance if the aggregate sample conforms to the maximum

limit, taking into account the measurement uncertainty and

correction for recovery,

rejection if the aggregate sample exceeds the maximum limit

beyond reasonable doubt taking into account the measurement

uncertainty and correction for recovery.

5.6. Other derived products with a relatively large particle size (heterogeneous

distribution of aflatoxin contamination)

Sampling procedure and acceptance as defined at points 5.2 and 5.3 of this

Schedule for the raw agricultural product.

5.7. Foods intended for infants and young children

5.7.1. Sampling procedure

The sampling procedure as mentioned for milk and derived products as well as for

compound food in points 5.4, 5.5 and 5.6 applies.

5.7.2. Acceptance of a lot

Acceptance if the aggregate sample conforms to the maximum limit,

taking into account the measurement uncertainty and correction for

recovery,

Rejection if the aggregate sample exceeds the maximum limit beyond

reasonable doubt, taking into account the measurement uncertainty and

correction for recovery.

FOR CERTAIN CONTAMINANTS IN FOODSTUFFS

Sampling at retail stage

Sampling of foodstuffs at the retail stage should be done where possible in

accordance with the above sampling provisions. Where this is not possible, other

effective sampling procedures at retail stage can be used provided that they ensure

sufficient representativeness for the sampled lot.