Measurement and Results

We have recently purchased QCP-DMD have some questions regarding the certified values and the acceptance limits stated on the Certificate of Analysis. The certified value for the BOD is 154 ±3 and the acceptance limits are 109-199, Can you please explain why the acceptance limits so wide (30%)? We have checked the standard via the COD value and are getting figures at nearly the nominal value so the standard seems ok.. we would just would like to have an explanation of the acceptance limits.

Do you know why Hg results by ICP-OES are not reliable? The same sample will generate different concentration values on different days....?

I need to make a solution with following ion concentration without using hydroxides. Please advise about the suitable compounds and amounts: Na 150 mmol/L, K 5.0 mmol/L, Cl 115 mmol/L, Ca 0.9 mmol/L.

I've been using your AA standards for quite a while now, and have been very pleased with them. I'm interested in your Lanthanum releasing agent, but the COA doesn't tell me how much Ca or Mg is in it. I'm guessing you don't test it for it? Is this supposed to be the same solution using in SM 3111 B-2011 Section 3 Paragraph f (Page 318 of 22nd Edition of SM)? Thank you.

Knowing that the detection limit or LOD is the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value), how can you determine a Method Detection Limit when the blank value is contaminated with the analyte? The level of contamination of Mg on 10 different samples is 222 µg/L (mean) with a SD of 16.

Is there a known interference between Bismuth and HF? Meaning, if I run an internal standard with Bismuth and a sample matrix or standard with trace HF (2% which is then serially diluted in the standard or sample) and I see an effect on my Bi in the internal standard, why might this be happening? The element of interest is Tantalum.

I am hoping that you may be able to give me some advice on preparing a sample for ICP-MS analysis. We have capsules for analysis and due to their enteric coating the only way we have been able to produce a suitable sample solution is using HF and microwave digestion; due to health and safety concerns when using HF and the amount of analysis required we are trying to find an alternative prep method. After research on your website we would like to try ashing the sample and would you be able to advise on a procedure? The elements of interest are As, Cd, Pb, Hg, Co, V and Ni. We have Pt crucibles and a muffle furnace, can you please advise if the crucibles should be cleaned in any particular way before use and if there is anyway we can minimize contamination from the furnace?

Is CGOS1 really tracable to NIST? What is the NIST catalog number?If not traceable to NIST, what is the reference material and batch number?

I would like to know the starting material for your turbidity standard, QCP-TURB. Is it formazin based? We need a turbidity standard based upon formazin of about 500-1000 NTU. We work with Standard Methods 2130B using equipment calibrated with formazin compound as primary standard.