Deviating Samples
UKAS TPS 63
Tim Platt
Technical Manager
Introduction
• EA LC identified ISO/IEC 17025 REQUIREMENTS
not being met Clause 5.8 and 5.10
• Integrity of test samples maintained
• Results reported
–
–
–
–
–
Accurately
Clearly
Unambiguously
Objectively
Include comments on sample quality or adequacy
that may have compromised the result
Terminology
• Deviating
– an abnormality or departure from what is
expected
• Deviating samples
– Those not correctly cared for or sampled
inappropriately.
Deviating Samples
• Exceeded their holding time
• Lack pertinent information
– Date
– Time
– Location
– Identity of sampler/contact
• Not retained at appropriate temperature
Deviating Samples
• Presented in inappropriate containers
/packaging
• Inappropriate headspace
• Insufficient quantity
• Denatured through heat/ light/ humidity
• Suffered microbiologically
UKAS TPS 63
• 4.1 Policies and procedures in place
– Sample integrity maintained
– Ensure results reported accurately
– Include comments on quality /adequacy
where this may have impacted on results
UKAS TPS 63
• 4.2 Laboratory to define “deviating sample”
– Holding time (stability)
– Storage /transit conditions
– Pertinent sample information (date/time/identity)
– Use of appropriate containers
– Use of preservatives
– Sample type as defined in accreditation schedule
Holding times
Parameter
Sample Size Holding time
Holding time (days)
(ml)
(days)BS/ISO 5667-3 USEPA
Metals
100
28
180
BOD
250
1
2
Total and free
Cyanide
100
7
14
Sulphide
100
7
7
PAHs
500
7
7 pre 40 post
extraction
VOCs
2x60
1
14
pH
50
6Hours
Immediate
Sample Containers
• Waters
– Volatiles ,BTX, GRO – 60ml amber glass
containers*
– Other organics 1x 1 litre amber glass container*
– Inorganics 1x1 litre plastic container
– Sulphide, Phenols, Cyanide, Metals , individual
plastic containers with preservative
– * no headspace
Preservatives
•
•
•
•
•
•
•
Analyte Cyanide Phenol Metals Mercury BOD Sulphide -
Preservative
Sodium hydroxide
Sodium hydroxide
Nitric acid
Potassium dichromate
Unpreserved, no headspace
Zinc acetate
Temperature control
• Volatile and Organic samples or those affected
by biological activity should be stored at 5°C
• Samples should be stored in the dark
• MCERTS for waters “the sample storage
environment shall maintain a temperature of
5 ± 3°C”
• Cool transportation – cool boxes, ice packs, fill
box, pre-chill, min/max thermometer.
UKAS TPS 63
• 4.3 On identifying a deviating sample.
– Consistent application/actions taken
– Consult with customer and record
– Initiate investigation into non- conforming
work procedures if allowed to deviate in
laboratory
– Report results in appropriate manner.
UKAS TPS 63
• 4.4 Laboratory required to demonstrate
– Sample assessed upon receipt
– If found to be deviating – contact customer
for instructions
– If customer requests to proceed, report will
include a disclaimer indicating deviating
sample and results may be invalid
– If deviation occurred after receipt –
investigation required
Deviating Samples
UKAS TPS 63
Tim Platt
Technical Manager