the minimum detection limit in Metrohm 883 Basic IC Plus

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Dear Sir or madam,

We have a new IC Machine Model 883, but i dont know the detection limit of the machine can go. I got asking for the representative sales person, they SAY the detection limit is 1ppb.

So how i can validate the machine in order to come out with a report to show our customer?

How to getting started with the machine validation?

Is it need to do Specificity, linearity and range, Limit of Detection and limit of quantification?

Appreaciate for you all kind advice.
Whoa! If you are using this machine for environmental analysis the MDL of 'the method' is given in APHA's (American Public Health Association) 'Standard Methods of Analysis of Water and Wastewater'. It is the method that is 'validated'. Even though you are not required, I would structure my method protocol on ICH's Q2(r1). The EPA may have something similar.

The instrument is 'commissioned and qualified' as per the ISPE (International Society of Pharmaceutical Engineers) baseline guide. Again, you are not required to use it if you are in the environmental arena. Again, the EPA may have something similar.

Get the specification sheet for this instrument from the manufacturer and use it for your 'installation, operational, and performance qualification' (IQ, OQ, PQ).
Most environmental work in the US is loosely based on the NELAC standards, which define your LOQ as the lowest calibration point in your calibration curve.

For EPA criteria work you should run the procedure set forth in 40 CFR 136 appendix B to determine your LOD. EPA will normally accept an LOQ defined as 3.3 times the LOD if you are not in a NELAC state.

AOAC defines LOQ as 3.3 times the LOD, and the LOD is determined by examination of the chromatogram. I much prefer the EPA definition of LOD, even if the statistics are a bit iffy.

Note that all of the agencies require you to determine the LOD/LOQ and working range PRIOR to analyzing samples.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
Dear psade149

Quote: I got asking for the representative sales person, they SAY the detection limit is 1ppb.

Under perfect conditions (stable lab temperature, no vent etc.) you might get single digit ppb dectection limits. I rather would expect that 10 ppb would be more the everyday LOD.

To do IQ/OQ please contact your Metrohm representative.
Dr. Markus Laeubli
Manager Marketing Support IC
(retired)
Metrohm AG
9101 Herisau
Switzerland
Many things affect detection limits, such as injection volume, column diameter and length, temperature stability of the cell. even how clean your DI water is that you use to make blanks and standards. As mentioned above you will need to do a study to show the limits of the instrument, if you can spread it over a few days that is even better to show variability from day to day.

Start with something like 1ppm, then dilute by ten and inject again, then by ten again until you are not seeing a peak, that will give you a rough idea of where to begin. 1ppm to be sure you are identifying the peak, maybe even 10ppm to be sure, then 100ppb, 10ppb and 1ppb. If you see 10ppb but not 1ppb, try 5ppb. You will want a peak that will give you at least a signal to noise of 5 to have a solid detection.

The %RSD of the areas at the detection limit can be high, since this is a limit of detection not limit of quantitation. Start about 5 times higher than the limit of detection as the lowest standard of your calibration curve and work up from there. Then see how accurately you can quantify the lowest standard, should give nice reproduceability and accuracy, if not you have to go higher, if it is very very good, you can go lower.

Detection limit and quantitation limit are something you have to work at when doing it initially. Once you find the limits of the instrument using clean standards, you will need to work with blank samples and spiked blank samples to find the true limits of the method you are using, so you take into account all of the preparation steps. It takes a while to do it right. Then you also need to be sure you meet any regulatory conditions that may govern the testing as mentioned above such at EPA, FDA, ISO, ect.
The past is there to guide us into the future, not to dwell in.
Also what is the ANALYTE you're looking for? The detection limit depends on the analyte as well. I would look at EPA 300.1, if you're looking for the standard anions, just starting out to get a general idea of what is usually required. If you're looking for some of the organic acids then you're MDL could be in the PPM's.
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