Fast GC instrumentation and analysis for field applications

Abstract

Environmental contaminants are found in a wide variety of molecular shapes and sizes, with organic pollutants exhibiting vapor pressures in the 10 3 -10 ؊6 torr range. This translates into a need for chemical analyzers that are capable of analyzing both volatile compounds (i.e., those compounds that have high vapor pressures at ambient temperatures) as well as semivolatile substances (i.e., those compounds that must be heated before they exhibit substantial vapor pressures). Volatile environmental analytes are found in gaseous, liquid, or solid sample matrices, whereas semivolatile analytes exist as either liquids or solids, including aerosol dispersions. Unfortunately, conventional field-portable GC analyzers are only capable of analyzing for volatile analytes. A small, fast, dual-high-resolution-column GC instrument that is capable of analyzing both volatile and semivolatile analytes has been developed and patented. As typically configured, it uses two narrow-bore, 100-micron ID separation columns, is temperature programmable at rates of 5-20 ؇C per second, and uses less than 150 W of dc power. Typical separation times for compounds with Kovatt's retention indices of Ͻ1000 are 10-15 s, and compounds with retention indices of up to 2500 are separated in Ͻ1min. Because the instrument has dual columns and detectors, analytes are simultaneously analyzed on columns with different liquid phases, thus providing added confidence in the quality of the analytical data. Because this fieldable GC device uses a solid-sorbent trapping system with a conventional heated injector inlet system, it can analyze a wide variety of sample matrices, including gases, dilute gases, thermal extracts from VOS tubes, purge-and-trap water/soil extracts, headspace samples, membrane extracts, SPME, thermal and SCF extracts, liquid organic solvent extracts, and direct aqueous samples. This report describes this new instrument and presents typical data from analysis of volatile and semivolatile analytes in a variety of sample matrices.

Forensic Mass Spectrometry

“…Fast GC/MS (77)(78)(79) with microbore columns has been around for decades but has not been widely adopted by crime labs even though modern GC ovens can easily handle the elevated head pressures and fast temperature ramps required to accomplish fast GC. Fast high-performance liquid chromatography (HPLC)-MS or ultra-performance liquid chromatography (UPLC)-MS (80) is common in research and clinical laboratories, less common in toxicology laboratories, and almost never used in controlled Herbal marijuana: vague term implying physiological or psychological effects of administration should be similar to those of marijuana, even though cannabis is not contained in the botanic matter and the active chemicals are not natural cannabinoids (e.g., spices that contain synthetic cannabinoids spiked on unknown botanic matter)…”

Cromatografia gasosa ultrarrápida: uma visão geral sobre parâmetros, instrumentação e aplicações

“…19,28,40 A ideia do aquecimento resistivo direto da coluna surgiu na década de 60, mas teve sua eficácia experimental comprovada somente a partir dos anos 90, quando diferentes propostas deste sistema foram publicadas na literatura. [40][41][42][43][44][45][46][47][48][49][50] A partir do trabalho de Ehrmann et al 40 e das patentes de Mustacich et al [47][48][49] e Magni et al 50 foram concebidos os diferentes módulos de aquecimento ultrarrápidos comercializados atualmente, projetados para comportar colunas de vários comprimentos e que podem ser instalados tanto em cromatógrafos convencionais quanto em sistemas portáteis de análise cromatográfica. Esses módulos de aquecimento resistivo da coluna permitem atingir taxas de aquecimento de até 20 o C s -1 , sendo que o resfriamento da coluna é rápido, indo de 350 a 50 °C em cerca de 1 min.…”

“…Vários trabalhos têm sido publicados com a utilização da técnica, sendo que alguns destes serão apresentados com maiores detalhes a seguir. 2,[17][18][19]25,[27][28][29][30][31][32]38,39,43 Em 1982, Jonker et al conseguiram obter a separação de nalcanos (C1-C4) naquela que viria a ser a separação cromatográfica mais rápida da época utilizando colunas empacotadas, finalizada em menos de 0,15 s. As condições cromatográficas utilizadas foram: coluna empacotada: 32 x 1,19 mm d.i. ; 10 µm de tamanho de partícula, Lichrosorb Si-60; pressão de entrada 64 bar; gás de arraste hélio, 1,5 µL injetado no modo splitless.…”

Portable, Battery Operated Capillary Electrophoresis with Optical Isomer Resolution Integrated with Ionization Source for Mass Spectrometry

“…Correspondence to: Mehdi Moini; e-mail: moinim@gwu.edu techniques, such as fast GC and fast LC, as well as supercritical fluid chromatography MS and capillary electrophoresis MS (CE-MS), have been introduced [13][14][15][16][17]. Among these separation techniques, CE is the easiest one to miniaturize since it only requires high voltage power supplies for its operation.…”