Application Notes: GC

EPA Method 525.2 describes the procedure to determine low ppb levels of semi-volatile organic material in drinking water using solid phase extraction (SPE) or liquid-solid extraction (LSE) techniques. The City of Fort Worth, Water Department implemented an automated SPE process for the analysis of semi-volatiles by EPA Method 525.2, using the Atlantic "Certified for Automation" SPE Disk for EPA Method 525.2. Ethyl acetate, methanol, and water were used to condition the Atlantic disk prior to the extraction step. The extraction solvents used were a 1:1 mixture of methylene chloride and ethyle acetate. Extracts were then analyzed by GC–MS using a splitless injection technique.

The purge-and-trap (P&T) technique for analysis of volatile organic compounds (VOCs) was pioneered in the 1970s at the United States Environmental Protection Agency (USEPA) research laboratory in Cincinnati. Many of the operational parameters developed during this time period are still included in USEPA methods. While these parameters still produce good analytical results, they do not take advantage of advances in instrumentation that enable analysis of emerging contaminants such as fuel oxygenates, and increased sample throughput.

The Zebron ZB-Bioethanol GC column reduces fuel ethanol analysis time to less than 8 min, while providing complete resolution of methanol and ethanol from all denaturant components. This newly developed GC column is suitable for analysis following ASTM Method D 5501 and Europe prEN 15376.

A method for trace odor components, isopropyl-methoxypyrazine (IPMP), isobutyl-methoxypyrazine (IBMP), methylisoborneol (MIB), and geosmin in drinking water involving the use of solid phase microextraction (SPME) and the SLB-5ms capillary column using gas chromatography/mass spectrometry (GC–MS).

Gel permeation chromatography (GPC) has been used as an effective cleanup procedure for removing high molecular weight interfering molecules such as lipids, pigments, proteins, and polymers before GC or HPLC analysis. The GPC cleanup method has been extensively documented (1–3) and is also recommended in US EPA SW-846 Method 3640A. To demonstrate the efficacy of this method to extract polar and nonpolar substances by using the KNAUER Smartline GPC Cleanup Unit 6500, olive oil samples were investigated by spiking these with different types of organic pollutants, including PAHs, phthalates, phenols, and triazine.

Phthalates are added to plastics to increase flexibility. Recently, concerns have been raised over the effect of phthalate exposure from plastic materials on human health.

PLOT columns are often used in GC analyses when it is necessary or desirable to retain one class of solutes in favour of other solutes that have little or limited interactions with the surface of the stationary phase. With a PLOT column, chromatographers can even cause lower boiling point compounds to elute well after higher boiling point compounds, thus providing better qualitative and quantitative separations for the solutes of interest.

AC Analytical Controls developed a new chromatographic solution that complies with all ASTM & EN chromatographic test methods listed in biodiesel specifications: the AC all-in-one Biodiesel analyser. Analysis results demonstrate that the AC analyser complies with EN 14103, EN 14105, EN 14106, EN 14110 & ASTM D6584 methods.

The performance of lubricating oil is significantly degraded by the presence of fuel contaminants such as gasoline and diesel. Recycled oil is particularly susceptible to this form of contamination. Consequently, producers and distributors of lubricating oil must go to great lengths to ensure the levels of fuel contamination are kept to a safe limit (typically 4–5%) in these products.

The continual increase in sample numbers in busy labs means that it is often difficult for quality control or contract analysis labs to maintain short turnaround times, particularly when instruments are already running at full capacity. To address the need for faster analysis while retaining the quality of separation offered by dedicated amino acid analysers, an improved formulation of sodium citrate based buffers has been developed by Biochrom.

Bob Wiedemer, Grace Davison Discovery Sciences

Gas chromatography (GC) coupled to time-of-flight mass spectrometry (TOF-MS) offers unique solutions for various analytical applications including the analysis of food quality, authenticity and safety markers. This article provides a general overview of TOF-MS basic features, highlighting its advantages and limitations compared with GC using conventional mass analysers. Examples of recent results obtained for selected food contaminants and flavour components are described to illustrate the potential of this recently introduced technique.

The analysis of peptides and additives using a new HPLC innovative column technology, Pathfinder, was shown. For the analysis of flavours in lemon juice GC–MS with a new MS library, FFNSC, with linear retention indices was used.

Soft drink formulas often include preservatives, artificial sweeteners, flavours or caffeine in their list of ingredients. Using the Acclaim OA column, as many as eight common additives may be determined in a single run. Many of these additives are hydrophilic organic acids for which this column was designed. Notably, benzoate and sorbate, which do not resolve on C18 columns at low pH, are fully separated.

Column lifetime is a more and more important issue when developing an analytical method for HPLC. Besides sample treatment, column cleaning and storage, operational parameters of the analytical method will have an influence on column lifetime. This question may not always be addressed early enough in the methods development process.

Protease inhibitors are a class of anti-HIV drugs used in combination therapy to block replication of the HIV virus in a person's blood. It is important to monitor the levels of these drugs in the patient since resistance can develop at low levels and at high levels the drug can exhibit toxic effects.

Mini application notes summaries

Maltodextrin is an easily digested carbohydrate made from corn starch...

VENTURE A affinity columns utilize ICEtechTM surface passivation technology...