deviating samples ukas tps 63 tim platt technical manager
TRANSCRIPT
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 timesParameter Sample Size
(ml)Holding time (days)BS/ISO 5667-3
Holding time (days) 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 - Preservative• Cyanide - Sodium hydroxide• Phenol - Sodium hydroxide• Metals - Nitric acid• Mercury - Potassium dichromate• BOD - Unpreserved, no headspace• Sulphide - 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