Chromatography Forum

I posted this topic in early October, 2005, but haven't seen any response yet. Is there any GC Guru who could tell whether it's possible to develop a capillary GC method for a sub-ppm level of p-Nitrosophenol using an NCD or NPD detector ? Many recent attempts to identify and quantify this electron-withdrawing compound using the most advanced detectors, S/S inlets with direct injections, and polar or non-polar columns have been inconclusive.

Thank you.

AZK

hi,
i too not getting any reply for my qys.
some time before i anaysed 1-napthol and 2-napthol in wax column using fid. with high temp, flow.
i may need some more information like sample preparation, column used. if you have gc-ms try first ensure with std preparation.
let us dicuss.
vijay
india

I have no experience with this particular analyte, but I would say a column such as ZB-5 and a ECD or MSD detector should bring out results!

Thanks for your comments.

p-Nitrosophenol (PNP) is a highly polar and an acidic compound with a low vapor pressure (< 1 torr) and decomposes (at > 130 C) before boiling thereby making it difficult to be analyzed by a GC-TCD, FID or GC/MS. Because of the presence of the nitroso (-NO) group, a 6890 GC fitted with a dual plasma nitrogen-selective chemiluminiscence detector (NCD), a non-polar amine column (RTx5 5m x 0.32 mm, 1.5 u) and an S/S direct inlet was found to be suitable initially for low ppm levels. The conditons are: oven 60 C, hold 1 min, ramp 10 C/min, 200 C, hold 1 min; inlet 130 or 200 C; inj. vol. 1 ul splitless direct; helium linear velocity 42 cm/s; const. flow mode; plasma temp. 950 C, cell pressure 205 torr, data acquisition rate 10 Hz, analog signal interfaced with a RS-232 and an A/D converter.

The presence of the -OH group makes the major peak tailing, but derivatization with trimethyl silyl groups is ineffective. Depending on the nature of the stationary phase (polar or non-polar), PNP shows 2 or 3 peaks, which are unpredictable and sometimes unreproducible, and the linearity is poor. An NPD detector has been found to be less sensitive than the NCD. The problems may not be with the detectors, but with the poor partitioning coefficients or the inlet incompatibility or with some thermodynamic pitfalls. A cool on-column inlet is being tested. An ECD is not known to be selective towards nitroso compounds, but would be tested later.

Any suggestion would be appreciated.