Retention Indices by Wide-Bore Capillary Gas Chromatography with Nitrogen-Phosphorus Detection

Abstract

The use of wide-bore capillary columns in gas chromatography (GC) with nitrogen-phosphorus detectors (NPD) is gaining popularity in the toxicology laboratory. Though the preferred method to achieve reproducible results and to make interlaboratory comparisons of GC data is by retention index (RI), the selectivity of the NPD has relegated its users to calculations of relative retention time. The present study utilizes a set of drugs as reference standards under temperature programmed conditions and presents a unique method of RI calculation. RI calculations are highly reproducible with this technique (day-to-day variations range from 0.3 to 3.4 RI units) and are comparable to packed column, FID generated reference data. A program, written in Basic, calculates RI values based on daily injections of the reference standards and searches a library of over 100 basic and acidic drugs.

Spectrophotometric Determination of Chlorzoxazone in pure State and Formulations Through Oxidative Coupling of its Hydrolysis Product

“…The existing analytical procedures reported for its determination are based mainly on either HPLC 1 " 7 or UV spectrophotometry 7 ' 8 ' 15 , while other methods include GLC 16 ' 18 and titrimetry 19 ' 20 . The only reported visible spectrophotometric procedure 21 for its determination so far is based on a diazocoupling reaction of the hydrolysis product with BM reagent.…”

Water analysis

“…A review on the determination of drugs of abuse by GC utilizing polysiloxane liquid phases modified by attachment of barbiturate moieties has been published (250). Retention indices have been used in various ways for the gas chromatographic screening of drugs in forensic toxicology (251)(252)(253)(254)(255)(256). HPLC methods for the screening of drugs of abuse have been published with various procedures (257)(258)(259)(260)(261)(262)(263)(264)(265)(266)(267).…”

Reproducibility of Retention Indices Examining Column Type

“…As of this writing, these RI values were being added to the SWGDRUG MS library as of 2013. (Christ et al, 1988) and 1150 iu (Oyama et al, 1987). If a forensic laboratory determines an RI value of 1160 for a peak thought to be methamphetamine, this data would likely not be comparable to the NIST database, nor to the published values unless uncertainties are provided for all four measured RIs.…”