Dilution should not be necessary. Concentrations are low.

There are a few questions:

1. Which metal ions you are looking at in the ICP?

2. Do you have a check on the literature about the probable metal ions concentration?

Better dilute the sample first and check the peaks, accordingly increase or decrease the dilution factor.

Hello,

Whether or not to dilute a river water sample before testing it using ICP-OES depends on the concentration of the target heavy metals in the sample. If the concentration of the metals is within the linear range of the instrument and the sample matrix does not cause any interference, then dilution may not be necessary. However, if the concentration of the metals is too high, it may be necessary to dilute the sample to bring the concentration within the linear range of the instrument. Additionally, if the sample matrix contains significant amounts of interfering substances, it may be necessary to dilute the sample to reduce the matrix effects.

It is always a good practice to perform a preliminary analysis to determine the concentration range of the metals in the sample and check for any interference effects from the matrix. Based on these results, you can decide whether or not to dilute the sample before analyzing it using ICP-OES.

First, you need to read the instruction of the instrument used to determine the metals in water samples. Second if the expected levels of metals in water are out of the recommended detective limits by the instrument, then you need to dilute the samples before going through the procedure of examination. Third, keep in mind that the dilution may result in losing some accuracy in the results, especially for high dilution ratios.

For river water, i believe, if there are no big pollution sources, the levels of heavy metal could be very tiny. By this, you probably will need to concentrate the samples not to dilute.

I hope that helps.

Riyadh Saleh Barath Kumar S Priyabrata Pal Arne Andersen

Thank you for answering my question. Much appreciate that.

I will check the literature first for the common concentration of the metals and decide accordingly referring to these suggestions.

Thank you so much.

For surface water analysis with ICP-OES applications, it is essential to minimize the number of organics and particles:

• It is recommended to use a 0.45 µm filter for filtering samples before running.

• Some types of organic content could stick to the nebulizer and harm the aerosol. A plasma that contains an organic solvent will appear green due to the emission of carbon and carbon species (C, C2, CN). The emissions from carbon-based molecules may interfere with signals emitted from other analytes, especially alkali elements that emit light in the visible region of the spectrum.
  • Bacteria in samples can behave similarly to particles.

I agree with all of above answers. However, you also need to consider the reason behind this activity, in relation to which form of metals you need, i.e. total metal concentrations, or soluble forms. This is strongly dependent on the subsequent interpretation requirements of your results. If this is relevant to a suspected contamination incident, then you may need to consider total metal determinations, otherwise water soluble forms will be adequate. Just bear in mind that, filtering will only be applicable to the soluble forms.

That depends upon:

-the pollution level in the river.

- the concentration of pollutants/metals

-check the equipment Range for metal detection..

these can be the the deciding factors whether to dilute or not !

-if concentration is very less then metals can’t be detected in the diluted sample..

hope you will consider these points before proceeding ahead with your water samples

For river water, except it contains organic particles, you don't need to dilute. Dilution will reduce the heavy metals concentration which are usually low except the water is heavily polluted which may result in the readings going out of the linear range.

Absolutely agree with the previous comments provided. Depending on the overall water quality you may need to; a) dilute, b) dilute and filter (using different pore sizes, c)digest, dilute and filter.

In many cases, if the water is not showing macro - level contamination (ie. sewage mixtures, industrial discharges etc.), a simple Total Dissolve Solids (YDS) removal is sufficient as a pre - step. You can try 0.45um filters, disposable, per sample usage (perfectly in agreement with Francesco Barbangelo).

Too concentrated sample (as others have also stated) can harm linearity and influence matrix interference.

Perhaps it is better to use pre-diluted samples (if the concentration is known)