Failing M0011 spikes

From: "Jordan Laster" <jordan.laster@enthalpy.com> To: "Quentin Best" <QBest@kleinfelder.com> Date: 5/19/2010 2:45 PM Subject: Failing M0011 spikes

Quentin -

Per our conversation yesterday, I had our HPLC mana ger put together the following list of things we have attempted to deal with poor formaldehyde spike recoveries. Generally M0011 is a very versatile method and should be appropriate for most sources, but as we discussed we are seeing issues with many of the EGU ICR sampl es.

1) Spiking and extracting the archive portion: Samp les are homogenized when we receive them. A portion of the original sa mple is archived before we perform the extractions to serve as a bac k-up should issues arise during the preparation or analysis of the sam ples. We have in the past taken this archive portion of an unspiked run, spiked it with a known mass of formaldehyde, then extracted and anal yzed. Generally if there was an issue with the primary spike analysis, this does not correct the problem.

2) Extracting and analyzing an unspiked archive por tion: This uses the archived portion of the sample for the unspiked num ber that is used in the matrix spike calculation. For example - if Run 1 was used for the matrix spike, the sample is split in half. Half of the sample is extracted as the unspiked portion, the other half i s divided into thirds. These are the MS, MSD, and archive portion s. If the results of this matrix spike do not meet method criteria, we h ave attempted to use the archive portion to replace the unspiked fractio n. If the results are different, there was most likely a homogeneity issue with the sample - if the results are the same as the original analy sis, there is most likely an issue with the actual sample matrix.

3) Adjust the amount of time between spiking and ex traction: We have noticed that in some samples the amount of time bet ween spiking the sample and extracting it can affect the recoveries. We have tried minimizing the amount of time - literally injecting the spike with the sample in the separatory funnel and immediately beg inning the extraction, increasing the amount of time - letting the spike sit in the sample for an extended period of time (up to the am ount of time that the samples were held between collection and extraction ), and a range in between. While we have found that this can make a difference in some samples, generally the shortest hold time provides the best results.

These investigations all seem to point to the fact that there is something else in the sample matrix from these engi nes that is causing an incompatibility with the method. Some sample se ts are fine, but for the most part, poor recoveries have been more commo n with these than averagely expected from M0011 projects across the b oard.

We still occasionally perform one or more of these checks on samples with failing spikes, but for the most part we recog nize that the corrective actions do not improve the results, and do not pursue them on every project.

I hope this answers your questions - if not please feel free to contact me for any further discussion.

Best Regards,

-Jordan Page 1Failing M0011 spikes

Jordan Laster - Sales / Engineer Enthalpy Analytical Inc. 2202 Ellis Rd, Durham, NC jordan.laster@enthalpy.com V: 919-850-4392 x300 M: 919-699-9991 F: 919-850-9012

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