What an ICP-OES machine CANNOT test
As the company that developed the method for sea water analysis and making broadband testing available to aquarists, we at TRITON often get asked what an ICP-OES machine CAN test. These days it is getting more and more confusing with the proliferation of companies offering ICP lab testing services.
Maybe it is easier to explain what an ICP-OES machine CANNOT test and why.
Nitrate and/or Nitrite
An ICP-OES machine cannot test Nitrite (NO2) or Nitrate (NO3). You cannot test these molecules as an ICP-OES machine atomises the water sample into single atoms prior to testing.
This means that NO3 in the ICP-OES is as follows:
1 x N
1 x O
1 x O
1 x O
That being said the ICP-OES will measure every atom separately so it will first count the N’s and then count the O’s. You might think “What is the problem with that?” If you have 5 x N and 15 x O you effectively have 5 x NO3 but unfortunately it is not that simple. The problem is that there are many things, including the air that we breathe, that contain N and O. Therefore the measurement is unable to determine the variety of combinations of these specific elements in the water sample, only just the total number of each element.
Nitrate measurements are often used in marketing to add “perceived” value to an ICP-OES lab test even though the Nitrate measurement is coming from another testing method. The marketing trick is to make people believe that the measurement is coming from the ICP-OES machine with a similar level of precision and accuracy while this is obviously not the case.
Phosphate
Similar applies for Phosphate (PO4) as it also cannot be directly measured. Fortunately in the case of PO4 the ICP-OES machine can measure Phosphorous (P) without any interference and this value can be used to calculate the Total Phosphate (organic and reactive). Total PO4 is different to what is measured by a home test kit or even at your local LFS as these tests only measure the reactive PO4 that is in the water sample. In most cases the PO4 readings should be similar but in some instances, where organic PO4 is present, the ICP-OES machine phosphate reading will be higher. This being said there is a very good reason why you should test your PO4 with an ICP-OES machine as it is important to know if organic PO4 is present so that the source or export mechanisms can be addressed.
Alkalinity/Carbonate Hardness (kH)
The Alkalinity or Carbonate Hardness (kH) of your water cannot be measured using an ICP-OES machine for similar reasons as mentioned previously. In the case of Alkalinity it is actually worse as the kH of water is comprised of not one molecule but actually a chain of molecules present in the water sample. Alkalinity and kH are surrogate measurements for measuring the Total Inorganic Carbon (TIC) in seawater which is consumed by animals in the process of calcification. TIC can be measured directly by another type of lab device (not ICP-OES) and this is what we call the TRITON N-DOC lab test. kH measurements in a lab, using the same methodology as home and LFC tests (titration), are low in value because of the high error associated with this type of testing. Same as with Nitrate testing Alkalinity under the banner of ICP-OES lab testing is another common marketing trick.
Flouride
Flouride also cannot be tested with an ICP-OES machine. The main difficulty is exciting the fluoride atom as it is a halogen. All of this group are notoriously difficult to measure using ICP-OES with Flouride being the hardest of all. Don’t get us wrong, there are experimental ways of testing this element with an ICP-OES but it remains in the developmental stages and, to the best of our knowledge, not commercially available.
So now you know what an ICP-OES machine CANNOT test and are able to differentiate between tests that have been conducted using an ICP-OES as opposed to another type of lab device. It is widely accepted that parameters that are not ICP-OES tested are not on the same level due to a range of potential errors and actions based on these tests should always take this into consideration.
As the company that developed the method for sea water analysis and making broadband testing available to aquarists, we at TRITON often get asked what an ICP-OES machine CAN test. These days it is getting more and more confusing with the proliferation of companies offering ICP lab testing services.
Maybe it is easier to explain what an ICP-OES machine CANNOT test and why.
Nitrate and/or Nitrite
An ICP-OES machine cannot test Nitrite (NO2) or Nitrate (NO3). You cannot test these molecules as an ICP-OES machine atomises the water sample into single atoms prior to testing.
This means that NO3 in the ICP-OES is as follows:
1 x N
1 x O
1 x O
1 x O
That being said the ICP-OES will measure every atom separately so it will first count the N’s and then count the O’s. You might think “What is the problem with that?” If you have 5 x N and 15 x O you effectively have 5 x NO3 but unfortunately it is not that simple. The problem is that there are many things, including the air that we breathe, that contain N and O. Therefore the measurement is unable to determine the variety of combinations of these specific elements in the water sample, only just the total number of each element.
Nitrate measurements are often used in marketing to add “perceived” value to an ICP-OES lab test even though the Nitrate measurement is coming from another testing method. The marketing trick is to make people believe that the measurement is coming from the ICP-OES machine with a similar level of precision and accuracy while this is obviously not the case.
Phosphate
Similar applies for Phosphate (PO4) as it also cannot be directly measured. Fortunately in the case of PO4 the ICP-OES machine can measure Phosphorous (P) without any interference and this value can be used to calculate the Total Phosphate (organic and reactive). Total PO4 is different to what is measured by a home test kit or even at your local LFS as these tests only measure the reactive PO4 that is in the water sample. In most cases the PO4 readings should be similar but in some instances, where organic PO4 is present, the ICP-OES machine phosphate reading will be higher. This being said there is a very good reason why you should test your PO4 with an ICP-OES machine as it is important to know if organic PO4 is present so that the source or export mechanisms can be addressed.
Alkalinity/Carbonate Hardness (kH)
The Alkalinity or Carbonate Hardness (kH) of your water cannot be measured using an ICP-OES machine for similar reasons as mentioned previously. In the case of Alkalinity it is actually worse as the kH of water is comprised of not one molecule but actually a chain of molecules present in the water sample. Alkalinity and kH are surrogate measurements for measuring the Total Inorganic Carbon (TIC) in seawater which is consumed by animals in the process of calcification. TIC can be measured directly by another type of lab device (not ICP-OES) and this is what we call the TRITON N-DOC lab test. kH measurements in a lab, using the same methodology as home and LFC tests (titration), are low in value because of the high error associated with this type of testing. Same as with Nitrate testing Alkalinity under the banner of ICP-OES lab testing is another common marketing trick.
Flouride
Flouride also cannot be tested with an ICP-OES machine. The main difficulty is exciting the fluoride atom as it is a halogen. All of this group are notoriously difficult to measure using ICP-OES with Flouride being the hardest of all. Don’t get us wrong, there are experimental ways of testing this element with an ICP-OES but it remains in the developmental stages and, to the best of our knowledge, not commercially available.
So now you know what an ICP-OES machine CANNOT test and are able to differentiate between tests that have been conducted using an ICP-OES as opposed to another type of lab device. It is widely accepted that parameters that are not ICP-OES tested are not on the same level due to a range of potential errors and actions based on these tests should always take this into consideration.
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