Can gas chromatography be used to analyze hydrocyanic acid produced by the methanol ammonia oxidation method?

Determination can be carried out using colorimetry, atomic absorption spectrophotometry, or cyanide-selective electrodes. However, for the determination of hydrocyanic acid by gas chromatography, CN- is converted to cyanogen chloride in an acidic solution using chloramine-3; the resulting cyanogen chloride is dissolved in n-hexane, and after chromatographic separation, detection is performed using an electron capture detector or a nitrogen-phosphorus detector

In the case of sampling for analysis, as mentioned above, hydrogen cyanide needs to be oxidized in order to reduce its toxicity, allowing analysts to handle it and conduct the analysis safely. Sampling may require specialized samplers and personnel who have received specialized training to operate them. For online analysis, an online chromatograph can be used, but there is also a safety issue, as hydrogen cyanide is a highly toxic gas. Perhaps many manufacturers are reluctant to take on such projects, mainly because during the calibration and commissioning of the chromatograph, someone needs to be on site to carry out the adjustments, and this safety issue is difficult to resolve. Direct chromatographic analysis is no problem; hydrogen cyanide at this concentration can be detected completely using a TCD detector. However, the analyzed samples cannot be released along with the carrier gas; they need to be rendered non-toxic by passing them through a sodium hypochlorite solution to oxidize cyanide into the non-toxic cyanate ion (CNO-). Previously, I discussed online analysis of hydrogen cyanide, acrylonitrile, high-concentration carbon monoxide, and high-concentration acetylene at my former company; the manufacturers can provide the configuration and hardware, but not on-site service. After all, the consequences of a toxic substance leak are beyond what the company can bear.

I’ve learned it... :lol, thanks for the advice!

It makes perfect sense, but I’ve never done it in practice. I learn from it. :victory:

Reply to 3# qugd: If using thermal conductivity, what are the values for thermal conductivity temperature and injection temperature? And what kind of columns are suitable?

This post was last edited by qugd on 2010-11-25 at 15:48. You need to choose the analysis conditions based on the settings of the chromatograph, and you also need to look up some information regarding the chromatography columns. I don’t have any available materials for reference. In my opinion, the injection temperature should be determined based on the conditions and state of the sample, and the water content in the sample may also need to be taken into consideration. When selecting a chromatography column, the specific composition of the sample also needs to be taken into account, and columns that are resistant to water should be chosen whenever possible. Columns may preferably be weakly polar to polar columns.

Thank you... :D It seems my task is tough!

Question: Which companies in China are currently producing hydrocyanic acid and sodium cyanide via the methanol-ammonia oxidation method?