Sampling and Sample Integrity

Transcription

1 Sampling and Sample Integrity Hazel Davidson Technical Marketing Manager

2 Sampling and Sample Integrity BS 10175: 2011 Deviating samples Containers/Preservatives/Filtration Temperature/Transportation Storage/Holding times Documentation

3 Recent Guidance - BS10175:2011 Supersedes BS10175:2001 which is now withdrawn Published by BSi and came into effect 31 st March 2011 Relates to good practice (not necessarily best practice) Not mandatory (unless specified in contract or planning condition) However failure to follow good practice would need to be defended

4 Soils BS Sampling Cluster Sampling (incremental samples collected over a 1m 2 area in the same strata) Sampling uncertainty should be considered as part of every investigation (Annex D) Non Targeted Sampling - typical densities of sampling grids changed Waters Samples are only collected following well development Wells are not screened across more than one hydrogeological unit

5 Sampling Protocols The quality of the samples taken is based upon: Sampling methods Correct containers Preservation methods Appropriate storage/transportation Field QA/QC procedures Chain of custody documentation

6 Deviating Samples Recent UKAS policy statement Deviating samples are samples which are not (correctly) preserved, for example they may have exceeded their maximum preservation time, lack the date and time of sampling, are not cooled, have inappropriate headspace and so on. As a result, deviating samples may jeopardise the validity of the reported test result. - Upon receipt of each sample, a competent laboratory shall assess whether the sample is suitable with regard to the requested test(s); - When the sample is deviating, a competent laboratory shall contact the customer for further instructions; - When the customer wants the deviating sample to be analysed, a competent laboratory shall include a disclaimer in the report, clearly stating that the sample was deviating and that, as a result, the test result(s) may be invalid; The EA Laboratory Committee and the EA peer evaluation system will also ensure the continuation of this focus as deviating samples play a role in many fields: such as environment, food, medicine and agriculture.

7 Deviating Samples Deviating or non-conforming samples: No separate VOC samples Headspace in VOC samples No preservatives used Incorrect bottles used, e.g. plastic Holding times exceeded Temperature exceeded The lab must notify the client, and include a statement in final report

8 How not to do it

9 Correct Sample Containers Plastic Tub (TUB1000) 1 Litre Plastic Bottle (PB1000) 1 Litre Amber Jar (GB1000) To the brim To the brim, minimum headspace To the brim, minimum headspace 250ml Amber Jar (GB 250) To the brim, minimum headspace Amber Vial (GV40) Positive meniscus before replacing lid Zero headspace 60ml Amber Jar (GB60) To the brim, minimum headspace

10 Waters A Dynamic System Factors affecting stability of water samples: Temperature Exposure to light Oxidation Precipitation Interaction with suspended solids Carbon dioxide affecting ph and alkalinity Interaction with bottle surface Microbial content ph of sample Relevance of the above to parameter of interest

11 Sampling Volumes Waters Standard inorganics 1 x 1 litre plastic bottle Standard organics 1 x 1 litre glass bottle VOC, glycols, VFAs, GRO 2 x 40 ml glass vials Cyanide, phenols, sulphide, ammoniacal nitrogen, COD, ferrous iron, metals, mercury 1 x 100 ml each preserved as per next slide Dissolved Oxygen 1 x 250ml BOD bottle preserved as per next slide

12 Preservatives Analyte Preservative Cyanide - sodium hydroxide Phenol - sulphuric acid or sodium hydroxide Sulphide - alkaline zinc acetate Ammonium, COD, Ferrous Iron - sulphuric acid Metals - nitric acid Mercury - nitric acid + dichromate Dissolved Oxygen - alkaline-iodide + manganese sulphate

13 Filtration Often not carried out in the field due to time constraints Now specified in MCERTS for waters for dissolved analytes Use 0.45 micron cellulose filters NOT for organics (except dissolved) Crucial for dissolved metal analysis, if using preserved bottles Filtration is not required for total concentrations (effluents, commonly) Filtering apparatus and bottles containing preservatives, together with an instruction sheet on their use can be provided

14 Soil Sampling Suitable for a large number of organic tests, including EPH, PAHs, PCBs, etc. (250g jar) Fill to capacity Suitable for large range of inorganic tests, including chloride, sulphate, ph etc. ( g), For leach tests, it is advisable to include an additional tub. Ensure that the material in each tub is representative of the whole Fill to capacity Ensure that the lid is secured properly and excess soil from around the container is removed Ensure label is legible

15 Organics Volatiles e.g. GRO, BTEX, chlorinated species and other solvents Waters - All require 2 x 40 ml glass volatile vials - no preservatives, with no headspace Soils 1 x 60g glass jar, per analysis with no headspace Semi volatiles e.g. oils, grease, DRO, PAHs, pesticides, PCBs Waters - All require either 500 ml or 1 litre coloured glass bottle, either no preservative or acid (H 2 SO 4 or HCl) Soils 1 x 250 g glass jar, per analysis ALL ORGANIC SAMPLES SHOULD BE STORED IN GLASS VESSELS AT 5 o C

16 VOC Sampling Soils Suitable for GRO, chlorinated solvents, TML/TEL It is good practice to take duplicates for each of the above analyses Also supply a tub of soil for moisture content No headspace Waters Volatile organic compounds as above, including VFAs and dissolved gases It is good practice to take duplicates, as above Minimise aeration and agitation when sampling No headspace, check by inverting vial 60 g glass jar 40 ml vial with PTFE septum

17 Deviating Samples sample containers Correct sample containers significant improvement over last 18 months Now < 10% of VOC samples received in incorrect containers Still some resistance to preserved bottles Still significant resistance to filtering on site Programme of seminars to raise client awareness

18 Transportation / Storage Packing samples correctly Labelling correctly Couriers use and abuse Storage/temperature

19 Maintaining Temperature MCERTS for waters states: the sample storage environment shall maintain a temperature of 5 +/- 3 o C now extended down to 1 o C If possible, pre-chill samples before packing Use a minimum of three ice packs per cool box Ice packs should be freshly frozen, preferably in a freezer Completely fill the cool box, to minimise headspace

20 Deviating samples - temperature MCERTS for soils does not specify a temperature MCERTS for waters only relates to UWW, and only refers to the temperature of the storage environment The laboratory only records the surface temperature of the containers, using IR Same day samples do not have time to reach temperature Currently, temperature exceedence is therefore not included in deviating samples on final report

21 Summary of Soil Holding Times Parameter Sample Holding time Holding time Method LoD Size (g) USEPA ISO (mg/kg) (days) (days) ph 100 n/a 7 Meter n/a Heavy metals 10 6 months 6 months ICPOES 1 to 10 Anions - Cl, SO4, Kone/IC 10 Anions - NO3, NO Kone/IC 1 to 2 Total sulphate ICPOES 100 Easily liberated sulphide n/a ISE 10 Total and free cyanide n/a Skalar 1 Asbestos 100 n/a n/a Microscopy n/a VOCs 2 x GCMS 0.02 SVOCs 20 7 pre 40 post extraction 7 GCMS 0.2 TOC n/a Furnace 100 PAHs 20 7 pre 40 post extraction 4 GCMS 0.1 EPH and mineral oil GCFID 5 Total phenols 20 7 pre 40 post extraction 4 HPLC/GCMS 1 Chlorinated pesticides 20 7 pre 40 post extraction 28 days GCMS 0.1 Organo N and P pesticides 20 7 pre 40 post extraction 7 GCMS 0.1

22 Summary of Water Holding Times Parameter Sample Holding time Holding time Preservative Method LoD Size (ml) USEPA BS/ISO 5667 (mg/l) (days) (days) ph 50 Immediate 6 hours Cool Meter n/a Heavy metals months 28 HNO3 ICP Anions - Cl, SO4, PO Cool Kone/IC Anions - NO3, NO Cool Kone/IC BOD Cool O2 meter 3 Sulphide Zn Ac ISE 0.05 Total and free cyanide NaOH Skalar 0.02 VOCs 2 x Cool GCMS SVOCs pre 40 post extraction 7 Cool GCMS 0.02 TOC Cool TOC analyser 1 PAHs pre 40 post extraction 7 Cool GCMS 0.1 ug/l EPH and mineral oil pre 40 post extraction 28 Cool GCFID 0.01 Total phenols Cool HPLC/GCMS 0.01 Chlorinated pesticides pre 40 post extraction 1 pre 5 post ext. Cool GCMS 0.1 ug/l Organo N and P pesticides pre 40 post extraction 1 pre 5 post ext. Cool GCMS 0.1 ug/l

23 Deviating Samples holding times Confusion within the industry At least three different standards USEPA, ISO and ISO 5667 Not possible for labs to comply with some time critical parameters UKAS advised labs to undertake stability trials Different holding times from different labs Statement on report data may be compromised causing issues for end users of data

24 Deviating Samples holding times Industry initiatives UKAS issuing Technical Policy Statement imminent EIC written to EA and UKAS highlighting issues Labs want consistent holding times agreed Clients want consistent and reasonable holding times

25 Sampling QA/QC Replicate samples Dual laboratory analysis Trip blanks Field blanks Equipment/ rinsate blanks Matrix spikes

26 Chain of Custody Documentation Essential to defend sample integrity Show movements of samples, i.e. field staff - courier - laboratory Communicate information on analysis required, preservation undertaken, sample matrices and turnaround required Currently, only 30% of samples received can be scheduled immediately this impacts on turnaround and holding times

27 Chain of Custody how not to do it

28 Chain of Custody how not to do it (2)

29 Chain of Custody Chain of custody Integrity of samples Legally defensible Faster scheduling Hazardous samples warning

30 Thank you Any questions?