Dear Nikhil,

You have a technic for metal ion determination called, in pharmacology, atomic absorption spectrophotomettry.

Regards

Didier

Sir,

Thank you very much for your prompt reply as always. I also wanted to know if it will only detect metal ions or can it detect any type of metal that is in compound form or something similar. I have also heard of a method called Energy Dispersive X-Ray Spectroscopy which can detect even low levels (both qualitatively & quantitatively) but am not sure of the sample preparation procedure.

Regards,

Nikhil George

Hi, Nikhil,

In my personal opinion, maybe you should make sure the traces of crystalline powder are mixture or pure compound. You could solve the crystals in solvent and check them by HPLC and/or TLC etc. Only pure compound might be easier analyzed the chemical structure. NMR and/or IR or Energy Dispersive X-Ray Spectroscopy could later help you analyze the cubic or liner structure. Good Luck.

Regards,

Hsiu-Hui

Dear Nikhil,

Atomic Absorption Spaectrometry (AAS) , a technic I know and had used in the past, allows the detection of free atoms in general. So a lot of different ones possibly and in various compound as you burn/drye the sample till 2000 °C temmperature. Differents appications have been developped.

I join a description by authors from Perkin-Elmer by mail (attached document impossible here)

Regards

Didier

Nikhil:

We do Energy Dispersive (X-Ray) Spectroscopy (EDS) with a JEOL scanning electron microscope. One applies a little powder from the crystals onto a carbon pad on a metal sample holder to run the specimen.

I am curious about why you want to know the metal composition. What is the specific medium you use for these plates? What sort of organism are you trying to grow on them? Could the crystals be mainly or wholly organic instead of metal? Are you concerned that the trace metals are inhibiting growth?

Sir,

Actually we received a broth culture sample from another lab. They wanted to check if their sample was faulty or any problem in their protocols. So we tried growing the same culture at our facility. There was no growth that would indicate a product failure and we are suspecting that the trace metals are inhibiting growth. So we wanted to do a trace metal analysis for any thing that is inhibiting growth. In case the compound is not a metal could you suggest me any other methods we should use??

Regards,

Nikhil George

@Hsiu-Hui Chiu, we have also considered HPLC or other chromatography but want to know any extraction protocol from the broth of Nutrient agar.

Nikhil:

If the nutrient agar has any bile salts or crystal violet as contaminant, almost every Gram-positive species will be inhibited. Both form crystals. What are the color and physical characteristics of the crystals? What is the formula for the Nutrient agar?

For HPLC, I recommend extraction from the broth with organic solvent. If that does not work, I recommend trying to dissolve the crystals in deionized water and in organic solvent, then running some sort of chromatography (not necessarily HPLC) on the extract iin which the crystals dissolved.

Wales

Dear Nikhil,

You have received valuable feedback such as chemical analysis by either method. Additionally, I recommend that you check the quality of the water, that you are using to prepare culture media

Cheers,

Beatriz

I agree with Duester to use ICP-MS to analyze metal content. It is a sensitive measurement for trace metals (in ppb level). Just digest your samples with microwave digestion system and proceed to ICP-MS.

Hi, Nikhil

Initially you could solve the crystals in solvent (deionized water perfectly). Acidify the suspension to PH≤3, and then filter with paper filter (Watman 0.45 μm).Analysis the filtrate with Atomic Absorption Spectrometry (AAS) in unit mg/l or Graphite Atomic Absorption Spectrometry (GAAS) in unit μg/l.

Regards

Marzieh Vahid Dastjerdi

If you have a matrix material ,you could digest the suspension with nitric acid on a hat plate or sandy oven before filtration step(see STANDARD METHODS examination of water and wastewater ,sample prepration for metals section.

If want a non-destructive bulk-analysis method...XRF would be the best. You can go for the polarized EDXRF (Cartesian-geometry & selective excitation) for higher sensitivity if needed...You have almost all elemental signatures at once and being thin deposits (crystal-traces) could be quantified easily.

Nikhil: What were your results? — Wales