Frequent Questions

The client did not indicate which sample should be used for the matrix spike, or did not provide additional sample volume for spiking. What should we do?

The first answer is "call the client as soon as the samples are received and the problem is noted." In some cases, the problem is an oversight on the part of the samplers. It may also be due to difficulties in obtaining sufficient volume, such as from a poorly producing groundwater well. It may also be that the additional volume was shipped separately. Therefore, call the client and determine what they intended to do.
 
If the client does not specify a particular sample to be spiked, but all samples have enough volume, then choose a sample that is similar to many others in the group. Do NOT choose the cleanest looking sample, or a trip blank, or field blank, since such samples will not tell you much about the other field samples. 

In other instances, the client simply may assume that the laboratory will prepare the matrix spike/matrix spike duplicate (MS/MSD) from some other sample prepared at the same time. Unfortunately, this situation can lead to MS/MSD results for a matrix that is only marginally related to the samples in question. If this occurs, the utility of the MS/MSD results is severely limited and may simply increase the cost of the analyses without providing any real benefit to the client or the ultimate data user. 

Due to the importance of the relationship between the matrices of the MS/MSD and the field samples, the Office of Resource Conservation and Recovery (ORCR) stresses that an MS/MSD pair (or a spiked sample and a duplicate sample) should be prepared from additional volumes of the material collected from the site in question. Each MS/MSD will require that additional sample volume from the site be provided to the laboratory by the field sampling personnel. ORCR further recommends that data users should be routinely provided with the MS/MSD results from only those quality control (QC) samples associated with the field samples from the same site.
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