Reading your Report

by | Jul 23, 2020 | Resources

If you’re not familiar with the format and terminology, your sample’s analytical report may be confusing. Here are some explanations to get you started.

Cover Page

The first page will contain your company name and address, the project name, SVL work order number that we assigned to your project, receipt date of your samples. and a list of samples submitted and their condition upon receipt (we qualify any non-conformances).  The case narrative is also listed. 

Client Sample Results Pages

These pages identify client sample ID and SVL’s corresponding ID. The date sample was taken, when we received it and who it was sampled by. We identify the analytical method used, the analyte tested for, the result, units, reporting limit,  MDL, dilution factor, batch ID, analyst, date analyzed, and any qualifiers assigned.

The following break down the column headers:

Result—This is the number we analytically determined, you can compare it to your action level.

Units—Liquids will usually be in mg/L or µg/L. Soils will be in mg/kg or µg/kg.

RL—The reporting limit is the statistically determined level above which the presence of an analyte is within the lowest calibration standard. The lowest quantified level within an analytical method operational range.

MDL—The method detection limit  is lower than the RL (often much lower) and is a statistical calculation. Since the MDL is below the point of calibration, results reported down to the MDL must be qualified as estimated values

Dilution—Depending on the amount of analyte in the sample or matrix interferences on the analyte, a sample may be diluted to bring the analytical result back to within the calibration range. If a sample is diluted for any reason, the RL and MDL will be multiplied by that same factor (any value below these limits will be an estimation of what could be in the sample). 

Batch—SVL uses analytical batches which means that we can combine multiple work orders until we are at 20 samples per batch to maximize efficiency. Batch QC is applied to all samples within the batch.

Notes—Show the abbreviations that we use for our qualifiers. We assign qualifiers to provide you with information involved with the running of your sample.

Method, Analyte, Analyst, and Analyzed are all self explanatory.

Quality Control Page

This section breaks down potential errors that can be applied to your sample results. We run batch QC so this page is applied to every work order in the batch.

The BLANK and LABORATORY CONTROL SAMPLE (LCS) are used to show any possible contamination that could be introduced to your sample by undergoing the same preparation steps as your sample. The LCS recovery indicates if we recovered more or less of a known spiked amount of the tested analyte.

The MATRIX SPIKE (MS) and MATRIX SPIKE DUPLICATE (MSD) are more of an indication of a single sample’s interferences and should not be applied to the whole analytical batch. Spike recovery and reproducibility of sample analysis are indicated. The following breaks down what to look for in each QC sample:

Blank—Most of our blank criteria are either < RL or < ½ RL. When you see a number that is not immediately preceded by a < sign you know there is contamination in your sample. Your results should be qualified. If there is 10 times the blank result in your sample it will not have a qualifier because the EPA finds that level of contamination to be acceptable. MDL and RL listed are SVL’s default values.

LCS—The LCS (Laboratory Control Sample) is the most useful of all the batch QC, it shows you how well a lab can recovery a known amount of spike in a pristine medium (de-ionized water or an inert solid material). LCSs show how well the analyst prepared the analytical batch.  You can take the +/-  % Recovery based on the  LCS True column and apply it to your sample result. The adjusted value will give you a better idea if you are potentially above your action level. We say “potentially” because there is still a scientifically acceptable range around the reported result that the LCS recovery may not account for.

MS—The MS(Matrix Spike) is QC that really only applies to the source sample spiked. Poor recovery shows that there is an interferent that is not allowing the instrument to indicate the true value of the source sample. MSs are measured by an acceptance range around a true or known value. Labs use MS data to show if their prepatory methods work on real world samples.

MSD—MSDs (Matrix Spike Duplicate) are actually more useful than an MS because the results show that the lab has the skills necessary to repeat like measurements. You will have an acceptance range and an RPD column. The RPD shows reproducibility, any value under 20 is acceptable.

Notes and Definitions Page

Our qualifiers are explained on this page. The abbreviations from the Notes column are defined here.  Qualifiers explain when there is a deviation from normal procedures or testing ranges. Qualifiers are a way for the lab to explain what was going on with your sample at any time after we receive them. Sometimes an explanation is outside of the qualifiers available to us or may not be acceptable by your state, in this situation we will have to write a case narrative (which is on the first page of the report).

You are always welcome to contact your project manager to get answers to any questions you may have about your report. 

 

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Reading your Report

If you’re not familiar with the format and terminology, your sample’s analytical report may be confusing. Here are some explanations to get you started.

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