Sample Preparation

I have some catalyst composed of PtPdRu/C. However, Pd and Ru are difficult to get dissolved even in aqua regia. Is there any solution to get their composition from ICP?

Sample Preparation

I am interested in measure the Pb to S ratio in PbS nanocrystals (NC) using an ICP-OES instrument. These NC are dispersed in an organic solvent and stabilized with long chain ligands like oleic acid. I can also deposit the NC as a film to remove the solvent.My concern is that when I digest the PbS NC film the acid will volatilize the sulfur thus skewing my results. Would the universal solvents you use for zeolite measurements work on such a system? Any other sample prep advice for this system is most appreciated. FYI: Everything entering our ICP-OES has to be in an aqueous solution, we do not have an organic solvent line.

We need to perform low-alloy steel analysis by ICP, and wanted to know what would be considered an adequate sample size in grams. Our sample digestion uses acids under pressure in a microwave oven.

I'm trying to dissolve Pt isotopic spikes. I've dissolved Pt metal before with no problem by first dissolving the metal in concentrated aqua regia in a teflon beaker, then evaporating the aqua regia by placing the beaker on a hotplate with the lid off, redissolving the residue in concentrated HCl, evaporating that, and ultimately dissolving this residue in 6M HCl. The Pt isotopic spikes are in the form of a very fine powder. In fact the powder was so fine that I could not remove all of it from the vials without washing them out with something. I chose to wash the vials out with methanol because I could evaporate it quickly afterwards both to begin the aqua regia dissolution and to reweigh the shipping vial after removal of the spike so that I knew how much spike I had dissolved. I also thought methanol would not react with the Pt at low temperatures. After washing the Pt+methanol into teflon beakers, I put the beakers (unlidded) on a hotplate set to 100 C to evaporate. After they were totally dry, I added the concentrated aqua regia and allowed the spikes to dissolve for two days. After two days, the spikes appeared to be dissolved, although it was hard to tell since the powder is so fine. I have dissolved a greater mass of Pt wire in the same amount of time, so I suspect the spikes were dissolved, or would have dissolved if they were still Pt metal. I evaporated the aqua regia and instead of the normal dark red residue (which dissolves in conc. HCl in seconds), I had a black residue. I added the concentrated HCl anyway, and a small amount of residue dissolved but most did not, even after sitting in lidded beakers on a hotplate for 24 hours. This has happened with two Pt metal spikes that were on a hotplate at 100 C with methanol and never with Pt metal that did not contact methanol, so it seems that Pt and methanol do react at temperatures as low as 100 C.I've tried re-doing the aqua regia step and have gotten to the point where I now have both an easily-dissolved reddish residue and an insoluble black residue in each beaker. I need to dissolve everything because I don't want to fractionate my isotopic spikes. But the problem is I have no idea what I made and so no clue how to ultimately get it to dissolve into 6M HCl. Do you have any suggestions?

A question has come up regarding the neutralization of HF using TEA (triethanolamine).The digested sample will have residual HF, and we are asking what concentration of TEA may need to be added to perhaps 1 to 2% residual HF. The elements of interest in the sample are Mg and Ti.

We've experienced some trouble while running nitrate (NO3) by automated colorimetry using EPA Method 353.2. There seemed to be an interference from the filter paper that results in a false positive. We've noticed that the false positive was not seen when analyzing for NO2. The filter paper used is Whatman filter paper 541 - Hardened Ashless. Is there a more appropriate filter paper?

I need to analyze the mineral composition of concrete, and wondered if you had any recommendations for what approaches I should follow?

We are using your Tungsten (W) standard and are having trouble keeping the tungsten in solution. We would prefer not to use HF due to safety concerns. We use a matrix of 2% HNO3 and dilute your standard to 0.1, 1, 5, and 10 ppm for standards. We calibrate W separately due to stability issues. Usually if we make the standards fresh daily, everything runs fine. We are having trouble with LCSs and matrix spikes that have gone through an EPA 3050 method digestion. We have tried with and without HCl in the final 3050 step. Adding HCl made the LCS lower than without using it. Can you give me any tips or tricks to stabilize W without using HF?

I have been doing some method development on Sn and Tl in soils, and noticed that the recovery on various CRMs is very low. We've performed both both nitric acid and aqua regia preps. Can you offer any suggestions as to why we have low recoveries?