Interpreting Your Lab Report & Quality Control Results Your report contains all sample info from sampling thru data reporting It will contain up to 10 sections, if you have requested that the Quality Control Results be included in your report package. The 10 sections are as follows: Cover Letter (General Information) Report Contents (Content Index) Definitions (Abbreviations you may see in the report) Case Narrative (Important Information about the report ) Laboratory Results (Results for each sample in the Work Order) Sample Summary (Lab and Client IDs, Matrix, Collection Dates) Dates Report (Listing of important sample dates and times) Quality Control Results (Listing of associated Quality Control Indicators) Receiving Check List (Sample acceptance criteria and Special Notes) Chain of Custody (Chain of Custody that accompanied the samples) The first 3 Pages give some very useful info Definitions (Abbreviations you may see in the report) The 4th page the is a must read! Here important abnormalities & report revisions are Documented Case Narrative (Important Information about the report ) Locations and Accreditations (Our contact info ) (Our accreditation info ) The next pages contain the lab results for each sample tested. Reporting Limit Smallest Case NarrativeMeasurable Level (Important Information Method about the report ) Used Locations and Accreditations (Our contact info ) Analyte (Our accreditation info ) Measured Data flags for QC alerts Result Dilution Factor Reporting Limits (RL) The reporting limit (RL) is the smallest accurately measureable number for the sample as tested. If we have to use a smaller sample size or dilute the sample during the testing phase the RL will be adjusted. The RL is determined for each sample result by multiplying the Practical Quantitation Limit (PQL) by any Prep Factor (PF) or Dilution Factor (DF) used to produce that result. Following the Lab Results are a summaries of the samples and the processing dates Sample Summary (Lab and Client IDs, Matrix, Collection Dates) Dates Report (Listing of important sample dates and times) Next we have the Quality Control Report – Each test is listed with its QC Next – The Receiving Check List When the samples arrive at the lab, this is where any excursions from Teklab’s Sample Acceptance Policy are recorded. The Lab Report Ends with a Copy of your Chain of Custody The chain of custody is an important piece in making your report legally defensible. This copy also contains lab notes and documents some conversations between you and the lab. You will also see the lab numbers added next to each of your Sample ID’s Quality Control Results The following presentation will help you better understand the Quality Control Results portion of the report. The Laboratory Results portion of the report and the Quality Control Results work together to help assess the data. The column headings will be printed in light blue in the explanations. Quality Control Indicators will be printed in bold dark blue. There are 3 basic things to look for when reviewing the QC report. 1. Contamination 2. Accuracy 3. Precision Data Qualifier Codes are used in the Qual column as Alerts (commonly known as flagging the data) B – Contamination in associated method blank S – Recoveries that are not within QC limits R – RPD of duplicate analysis exceeds QC limit J – Result is above the method detection limit, but below the reporting limit E – Result is above the calibration range H – Sample analysis time exceeded holding time listed for test within its method Samples are Processed in a Batch Batch: Environmental samples that are prepared and/or analyzed together with the same process and personnel, using the same lot(s) of reagents.1 A preparation batch is composed of 1 to 20 environmental samples of the same quality systems matrix, meeting the above mentioned criteria and processed within 24 hr from the start of the 1st to the start of the last sample.1 An analytical batch is composed of prepared environmental samples which are analyzed together as a group. They can include prepared samples from various matrices and can exceed 20 samples.1 As you review your data in the Laboratory Results section of the report, notice the Batch number listed for each analyte in the far right column. Use this number to find the associated Quality Control Indicators in the Quality Control Results section of the report. Notice the Batch Number in the Example. The Batch Number is located right below the Test Method on the QC Report Some tests and/or matrices do not have a preparation step before analysis and do not require a preparation batch. These tests have a “R” at the beginning of their batch number. Method Blank – MBLK MBLK – A clean matrix processed and analyzed with the samples to check for batch contamination. TNI 2009 definition - “Method Blank: A sample of a matrix similar to the batch of associated samples (when available) that is free from the analytes of interest and is processed simultaneously with and under the same conditions as samples through all steps of the analytical procedure, and in which no target analytes or interference are present at concentrations that impact the analytical results for sample analysis.” (TNI 2009) SampType: MBLK A analyte with a MBLK Result below the reporting limit (RL) indicates a batch free from contamination. If the Result was above the RL, there would be a B in the Qual column here and on the in the Laboratory Results section of the report. If the MBLK is above the reporting limit, the samples results that are below the reporting limit (RL) are reportable. If the MBLK is above the reporting limit, the sample results that are over 10 times the reporting limit (RL) are reportable, with comment. Quality Control Indicators are Reported in the Quality Control Results Section of the Report for each Batch (any or all of the following may appear based on the method and the amount of sample supplied to the lab) Method Blank (MBLK) Laboratory Control Spike (LCS) Laboratory Control Spike (LCSDUP) Checks Batch for Contamination Checks Batch for Accuracy by Measuring Recovery Checks for Accuracy and Checks for Reproducibility in place of MSD or DUP Checks Accuracy by Measuring Recovery in the Sample Matrix Matrix Spike (MS) Matrix Spike Duplicate (MSD) Duplicate (DUP) Surrogate (SUR) Checks Accuracy & Reproducibility in Sample Matrix Checks for Sample Result Reproducibility Checks Accuracy by Measuring Recovery in Organic Methods. Percent Recovery (%REC ) Measures the accuracy of the recovery for the LCS, LCSDUP, MS, & SURR Accuracy – “The degree of agreement between an observed value and an accepted reference value”. (TNI 2009) This degree of agreement is measured in %REC. The lab calculates the %REC as follows: Percent Recovery for LCS %REC = (LCS / Spike) x 100 Percent Recovery for MS & MSD %REC = ((MS – Sample / Spike) ) x 100 Laboratory Control Sample – LCS LCS – A clean matrix spiked with the analyte(s) of interest and processed and analyzed with the samples to determine whether the measurement system is performing as expected. Determines whether the laboratory is capable of making accurate and unbiased measurements. TNI 2009 definition – Laboratory Control Sample (however named, such as laboratory fortified blank, spiked blank, or QC check sample): A sample matrix free from the analytes of interest, spiked with analytes and taken through all sample preparation and analytical steps of the procedure unless otherwise noted in a reference method. It is generally used to establish intralaboratory or analyst specific precision and bias or to assess the performance of all or a portion of the measurement system. (TNI 2009) SampType: LCS The LCS in the above example had a Spike of 0.050 mg/L and a Result of 0.047. The %REC of 94.7 is within the LowLimit 85% and HighLimit 115%. The data is within the control limits; therefore, the sample results that were associated with this batch are reportable. You can find the associated sample Result in the Laboratory Results section of the report by using the Batch number R164760. LCS not within the Control Limits? The test must be redone - all samples must be reanalyzed with a new MBLK and LCS. Exceptions: If the LCS recovered above the upper control limit, samples that were below the RL can be reported. If the LCS for the test has 11 or more analytes the Allowable Marginal Exceedance rule may apply. (more on this later) If there is insufficient sample for re-analysis, the data must be reported with comments or more sample must be collected upon client request. SampType: LCS The LCS in the above example had a Spike of 0.025 mg/L and a Result of <0.005. The %REC of 0 is not within the LowLimit 90% and HighLimit 110%. This QC failure is indicated with a Qual of S. No data should be reported in the Laboratory Results section of the report with a Batch number of 78992. In the above example we see the LCS from the reanalysis of the failed batch. The %REC of 104.0 is within the LowLimit 90% and HighLimit 110%. All of the data for this analyte reported in the Laboratory Results section should have a Batch number of 79059. Allowable Marginal Exceedances in the LCS? If a large number of analytes are in the LCS, it becomes statistically likely that a few will be outside of the control limits. (TNI 2009) The number of allowable marginal exceedances is as follows: Number of Analytes in LCS Number Allowed as Marginal Exceedances > 90 5 71 – 90 4 51 – 70 3 31 – 50 2 11 – 30 1 < 11 0 If the same analyte exceeds the LCS control limit consecutively, it is an indication of a systemic problem. The source of the error shall be located and corrective action taken. Allowable Marginal Exceedances will be flagged with an S in the Qual column and will have a comment in the Lab Results section of the report that looks like this: Allowable Marginal Exceedances in the LCS verified per 2009 TNI Standard (Volume 1, Module 4, section 188.8.131.52). Matrix Spike – MS MS – A sample spiked with the analyte(s) of interest and processed and analyzed with the samples to determine whether the measurement system is performing as expected in that particular sample matrix. TNI 2009 definition – A sample prepared, taken through all sample preparation and analytical steps of the procedure unless otherwise noted in a referenced method, by adding a known amount of target analyte to a specified amount of sample for which an independent test result of target analyte concentration is available. Matrix spikes are used, for example, to determine the effect of the matrix on a method’s recovery efficiency. (TNI 2009) When a MS or MSD does not recover within the Control Limits (and the LCS did) we know there is a matrix or composition problem. Matrix Spikes (MS & MSD) are intended to let the client know how well the test method is working in their particular matrix. SampType: MS The MS in the above example had a Spike of 0.025 mg/L and a Result of 0.022. The %REC of 88.0 is not within the LowLimit 90% and HighLimit 110%. Notice the Qual of S to alert us that there is a matrix interference that caused a the spike not to recover within the limits. By looking for the Batch number of 79059, we find the associated sample Result in the Laboratory Results section of the report . Notice the S to alert you about the recovery problem and the comment with the results to explain. Relative Percent Difference (RPD) Measures the Precision or Reproducibility between the MS & MSD, the Sample & DUP, or the LCS & LCSDUP Precision – “The degree to which a set of observations under similar conditions, conform to themselves”. (TNI 2009) This degree is express as RPD. The lab calculates the RPD as follows: RPD for LCS and LCSDUP or Sample and DUP RPD = | ((A – B) / ((A + B) / 2)) X 100 | Where: A = first result B = duplicate result Notice the absolute value signs in the equation. The RPD will always be a positive number. Matrix Spike Duplicate – MSD MSD – An additional matrix spiked sample used to determine both precision and accuracy of the test method in that particular matrix. TNI 2009 definition – A replicate matrix prepared in the laboratory and analyzed to obtain a measure of precision. (TNI 2009) SampType: MSD The MSD in the above example is the duplicate analysis of the MS that we just viewed. Notice the Result of the MS is listed under the RPD Ref Val. The MSD has a Spike of 0.025 mg/L and a Result of 0.024. The %REC of 97.0 is within the LowLimit 90% and HighLimit 110%; therefore, no S Qualifier. Notice the RPD Limit of 15 listed in the top line. The %RPD must be below 15 to pass the duplicate test. The %RPD of 10.32 falls below the limit; therefore, the duplicate analysis passes. If the %RPD had been above 15 there would be a R in the Qual column and a comment with the Laboratory Results. In this case we have the MS slightly below the control limit, the MSD within the limit and the %RPD passing. DUP & LCSDUP DUP – a duplicate preparation and analysis of the sample. Used to determine reproducibility of the test when the method does not require an matrix spiking. LCSDUP – a duplicate preparation and analysis of the LCS. Used to determine reproducibility of the test when there is insufficient sample provided to perform an MSD or DUP. Surrogates - Surr Surr - Used in organic analysis to evaluate the method in each sample matrix. Surrogates spiked into all of the QC and samples to monitor the efficiency of the test method. They mimic the analytes of interest and are compounds unlikely to be found in environmental samples. Notice that the Control Limits for the surrogate recovery are listed under the RL column heading. Surrogates that are not within the limits will have a S flag in the Qual column and a comment in with the lab results. 3 Basic Evaluations of the QC Report Contamination, Accuracy & Precision The batch number is your reference key to the associated QC in the QC Report. The MBLK checks for contamination ( B flags ) The LCS & LCSD check for Accuracy of the Test Method ( S flags) The MS & SURR check for Accuracy of the Test Method in the sample matrix ( S flags ) The MSD & DUP check for Precision or Reproducibility of the sample matrix ( R flags ) The LCSDUP checks for Precision of the Method ( R flags ) We work very hard to give you everything you need to understand your Lab Report – If you need further assistance, your project manager will be happy to assist you!