Determination of 2,5-hexanedione in urine and serum by gas chromatography after derivatization with O-(pentafluorobenzyl)hydroxylamine and solid-phase extraction

New automated and high-throughput quantitative analysis of urinary ketones by multifiber exchange-solid phase microextraction coupled to fast gas chromatography/negative chemical-electron ionization/mass spectrometry

The present research is focused on automation, miniaturization, and system interaction with high throughput for multiple and specific Direct Immersion-Solid Phase Microextraction/Fast Gas Chromatography analysis of the urinary ketones. The specific Mass Spectrometry instrumentation, capable of supporting such the automated changeover from Negative Chemical to Electron Ionization mode, as well as the automation of the preparation procedure by new device called MultiFiber Exchange, through change of the fibers, allowed a friendly use of mass spectrometry apparatus with a number of advantages including reduced analyst time and greater reproducibility (2.01-5.32%). The detection limits for the seven ketones were less than 0.004 mg/L. For an innovative powerful meaning in high-throughput routine, the generality of the structurally informative Mass Spectrometry fragmentation patterns together with the chromatographic separation and software automation are also investigated.

Solid-phase analytical derivatization: enhancement of sensitivity and selectivity of analysis

Analytical derivatizations enhance the sensitivity and selectivity of determinations for organic compounds. Classical techniques are often based on solution chemistry. Most modern sample preparation techniques, however, are based on solid-phase extractions. Solid-phase analytical derivatization bridges this gap and facilitates sample preparation by combining the isolation step with the derivatization. The solid-phase retains both reagents and derivatized analytes and often permits facile separation of excess reagent or selective elution of the desired products. The most recent solid-phase extraction techniques have been used in conjunction with analytical derivatization to automate the analysis. In this review, analytical derivatizations are presented as functional group analysis.

Analytical derivatizations of volatile and hydrophilic carbonyls from aqueous matrix onto a solid phase of a polystyrene-divinylbenzene macroreticular resin

Extraction and derivatization of carbonyls to benzyloximes, pentafluorobenzyloximes or 2,4-dinitrophenylhydrazones is simplified and reaction times are substantially reduced by simultaneous sorption and derivatization from aqueous solution onto a solid phase. In this reaction a macroreticular polystyrene-divinylbenzene resin acts as a sorbent and catalyst to allow simultaneous extraction and derivatization of hydrophilic and lipophilic aldehydes and ketones from simple as well as complex matrices including plasma. Conversion to the 2,4-dinitrophenylhydrazones or pentafluorobenzyloximation at ambient temperature requires 10 and 20 min, respectively. These reaction conditions correspond to at least a 6-fold reduction in reaction times for derivatization of the reactive aldelhydes and a 36-72-fold reduction for preparation of derivatives for the slower reacting ketones.

High-performance liquid chromatographic determination of urinary 2,5-hexanedione as mono-2,4-dinitrophenylhydrazone using ultraviolet detection

The good correlation between exposure to n-hexane and 2,5-hexanedione urinary excretion confers on this diketone an important toxicological meaning. this paper proposes a reversed-phase HPLC method which includes, after acid hydrolysis, a derivatization step of 2,5-hexanedione with 2,4-dinitrophenylhydrazine at 70 degrees C for 20 min. The reaction conditions, such as temperature, reagent concentration and time, are optimized so as to allow the condensation of a single carbonyl group. A linear response was obtained in the 0.19-20.0 mg/l range with a detection limit of 0.03 mg/l, corresponding to a signal-to-noise ratio of 3. A phosphate buffer (pH 3.3)-acetonitrile mixture (50:50) as the eluent and UV detection at 334 nm were used.

Determination of 2,5-hexanedione, a metabolite of n-hexane, in urine: evaluation and application of three analytical methods

Three methods for the determination of 2,5-hexanedione (2,5-HD) in urine were compared in order to assess their applicability for toxicokinetic studies and biological monitoring of occupational exposure to n-hexane. Two of them were based on derivatization, followed by gas chromatography and electron-capture detection. Of these two, one is a modification of the other, already published, method. The third one involves direct extraction of 2,5-HD followed by gas chromatography and flame-ionization detection. To determine 2,5-HD in urine of workers occupationally exposed to n-hexane, the most straightforward method, direct extraction of 2,5-HD from urine, has been proven to be the most suitable. However, in case of very low concentrations of 2,5-HD in urine, or analysis of small samples of blood, e.g. in kinetic studies, it is necessary to use a more sensitive procedure. The sensitivity of the methods based on the derivatization of 2,5-HD followed by electron-capture detection, was, as expected, much higher in terms of analytical reliability. By using these methods, however, precautions are necessary to avoid a matrix effect.

O-(2,3,4,5,6-pentafluorophenyl)methylhydroxylamine hydrochloride: a versatile reagent for the determination of carbonyl-containing compounds

A review on the use of O-(2,3,4,5,6-pentafluorophenyl)methylhydroxylamine hydrochloride (PFBHA) for the determination of carbonyl-containing compounds is presented. PFBHA has been used in the determination of such diverse compounds as thromboxane B2, prostaglandins, amygdalin and a variety of other aldehydes, ketones and acids. PFBHA has been used for the determination of these compounds found in water, blood, urine, air and even clothing. The review covers literature referenced in Chemical Abstracts from 1975, when PFBHA was first synthesized, through March 1992.