Deviating SamplesUKAS TPS 63

Tim PlattTechnical 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 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

Deviating SamplesUKAS TPS 63

Tim PlattTechnical Manager