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 manager 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 samples. 

1) Spiking and extracting the archive portion: Samples are homogenized

when we receive them. A portion of the original sample is archived

before we perform the extractions to serve as a back-up should issues

arise during the preparation or analysis of the samples. We have in the

past taken this archive portion of an unspiked run, spiked it with a

known mass of formaldehyde, then extracted and analyzed. Generally if

there was an issue with the primary spike analysis, this does not

correct the problem. 

2) Extracting and analyzing an unspiked archive portion: This uses the

archived portion of the sample for the unspiked number 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 is divided into

thirds. These are the MS, MSD, and archive portions. If the results of

this matrix spike do not meet method criteria, we have attempted to use

the archive portion to replace the unspiked fraction. If the results

are different, there was most likely a homogeneity issue with the sample

- if the results are the same as the original analysis, there is most

likely an issue with the actual sample matrix.

3) Adjust the amount of time between spiking and extraction: We have

noticed that in some samples the amount of time between 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 beginning the

extraction, increasing the amount of time - letting the spike sit in the

sample for an extended period of time (up to the amount 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 engines that is causing

an incompatibility with the method. Some sample sets are fine, but for

the most part, poor recoveries have been more common with these than

averagely expected from M0011 projects across the board.

We still occasionally perform one or more of these checks on samples

with failing spikes, but for the most part we recognize 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

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Failing 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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