Application of On-Line Sorbentless Cryogenic Needle Trap Extraction Coupled with GC-FID for Analysis of Some Organic Volatile Impurities in Solid Pharmaceuticals.

An automated sorbentless cryogenic needle trap device (ASCNTD) was developed for the extraction of organic volatile impurities (OVIs) from solid pharmaceuticals prior to their determination by gas chromatography (GC). In this method, a new set up was designed and used to extraction of several OVIs from ceftazidime, ceftriaxone sodium and amoxicillin. For this purpose, a proper amount of the sample was transferred into the extraction vessel. The sample headspace components were started to circulate through a needle with a flow rate of 20 mL min-1. The OVIs were trapped on the inner surface of a needle placed on top of the sample by flowing liquid nitrogen. After a predetermined time, the coiled nichrome resistance wire placed into the hollow ceramic rod was heated and the trapped analytes were desorbed and swept into the GC capillary column using the carrier gas. The effective parameters such as volume of the sample vial, headspace flow rate, extraction temperature and time, and desorption conditions have been investigated. Qualification studies reveal that pyridine (as a degradation product of ceftazidime), methylene chloride, diethylamine, triethylamine, isopropyl alcohol and n-butyl acetate are the main impurities in the studied pharmaceuticals. Detected OVIs were quantitated using external standard method. The obtained relative standard deviation values were <8%, and the limits of detection (LOD) for the detected OVIs were in the range of 1-34 ng g-1.

On-Line Sorbentless Cryogenic Needle Trap and GC-FID Method for the Extraction and Analysis of Trace Volatile Organic Compounds from Soil Samples.

In this study, an automated sorbentless cryogenic needle trap device (ASCNTD) coupled with a gas chromatograph (GC) was developed with the aim of sampling, pre-concentration and determination of volatile organic compounds (VOCs) from soil sample. This paper describes optimization of relevant parameters, performance evaluation and an illustrative application of ASCNTD. The ASCNTD system consists of a 5 cm stainless steel needle passed through a hollow ceramic rod which is coiled with resistive nichrome wire. The set is placed in a PVC (Polyvinyl chloride) chamber through which liquid nitrogen can flow. The headspace components are circulated with a pump to pass through the needle, and this results in freeze-trapping of the VOCs on the inner surface of the needle. When extraction is completed, the analytes trapped in the inner wall of the needle were thermally desorbed and swept by the carrier gas into the GC capillary column. The parameters being effective on the extraction processes, namely headspace flow rate, the temperature and time of extraction and desorption were optimized and evaluated. The developed technique was compared to the headspace solid-phase microextraction method for the analysis of soil samples containing BTEX (Benzene, Toluene, Ethylbenzene and Xylene). The relative standard deviation values are below 8% and detection limits as low as 1.2 ng g-1 were obtained for BTEX by ASCNTD.

Determination of phthalate esters in cow milk samples using dispersive liquid-liquid microextraction coupled with gas chromatography followed by flame ionization and mass spectrometric detection.

A simple and economic method for the analysis of phthalate esters, dimethyl phthalate, diethyl phthalate, di-iso-butyl phthalate, di-n-butyl phthalate, and di-2-ethylhexyl phthalate in cow milk samples by means of gas chromatography-flame ionization detection and gas chromatography-mass spectrometry has been developed. In this work, NaCl and ACN were added to 5 mL of the milk sample as the salting out agent and extraction solvent, respectively. After manual shaking, the mixture was centrifuged. In the presence of NaCl, a two-phase system was formed: upper phase - acetonitrile containing phthalate esters -and lower phase - aqueous phase containing soluble compounds and the precipitated proteins. After the extraction of phthalate esters from milk, a portion of supernatant phase (acetonitrile) was removed, mixed with 1,2-dibromoethane at microliter level and injected by syringe into NaCl solution. After the extraction of the selected phthalate esters into 1,2-dibromoethane, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Under the optimum extraction conditions, low limits of detection and quantification between 1.5-3 and 2.5-11 ng/mL, respectively was observed. Enrichment factors were in the range of 397-499. The relative standard deviations for the extraction of 100 ng/mL of each phthalate ester were in the range of 3-4% (n = 6). Finally, some milk samples were successfully analyzed using the proposed method and two analytes, di-n-butyl phthalate and di-2-ethylhyxel phthalate, were determined in them in nanogram per milliliter level.

Ultrasonic assisted SPME coupled with GC and GC-MS using pencil lead as a fiber for monitoring the organic volatile impurities of ceftazidime.

A simple, rapid, non-destructive, and in-situ method for the isolation and sampling of organic volatile impurities in Ceftazidime is developed using solid-phase microextraction (SPME). For the monitoring of the extracted compounds, gas chromatography (GC) and GC-mass spectrometry analyses are used. The effective factors such as nature of the fiber, SPME mode, extraction temperature, and ultrasonic assistance have been investigated and detailed here. Qualification studies reveal the existence of pyridine (as a degradation product of ceftazidime) and the residual solvents; acetone, methylene-chloride, and diethylamine are the main impurities in the studied pharmaceutical. External standard method is used for quantitative analysis. The % relative standard deviation values are below 10%, and the limits of detection for the detected solvents are 1.06, 0.98, 0.83, and 0.51 ppm, respectively. The proposed method is both accurate and linear and could be used in quality control of ceftazidime and also its stability investigations.