Sensitive Headspace Solid-phase Microextraction Research Articles

Optimum Method of Analyzing Hop Derived Aroma Compounds in Beer by Headspace Solid-Phase Microextraction (SPME) with GC/MS and Their Evolutions during Chinese Lager Brewing Process

A simple and sensitive headspace solid-phase microextraction (SPME) and gas chromatography with mass spectrometer detection (GC/MS) method was developed for simultaneous determination of 19 key hop derived aroma compounds at trace levels in beer. Nineteen hop derived aroma compounds were classified into four groups: esters, terpenes, terpenols, and ketones. A PDMS-coated fiber was found to be the most effective with optimum extraction temperature (50°C) and time (60 min). Degassed beer matrix was found to yield better recovery and possess greater reliability with calibration standards than a 5% ethanol/H2O solution. This method is advantageous over conventional extraction methods because it allows for lower detection limits, higher reproducibility and accuracy, and offers simple manipulation. The integration of effective enrichment, qualification, and accurate quantification of a wide variety of compounds in one injection is made possible. Thus, this method promises to be suitable for a routine beer hop-aroma analysis and applicable for quality control of aroma hop usage and hop aroma assessment during the brewing process and finished beer. The result of evolution of them during Chinese lager brewing process suggests that the esters and free terpenols derived from the yeast metabolism and biotransformation of glycosidically bound terpenols play more important roles.

Investigation of possible endogenous formation of furan in Fischer-344 rat

A sensitive headspace solid phase micro-extraction gas chromatography/mass spectrometry analytical procedure was used to determine the furan content in blood and liver tissue. The method was employed to investigate in vivo metabolism leading to possible furan formation by feeding both 13C labeled and unlabeled (native) ascorbic acid, linoleic acid ethyl ester, or glucose to Fischer-344 rats. Rats were fed via oral intubation 0.16–0.96 g of a test compound in two 3 h intervals, and sacrificed 6 h later. The liver and blood tissues were collected and analyzed for the presence of furan. No significant formation of 13C labeled or native furan was observed from the substrates tested. Only minute traces attributable to 13C labeled furan were detected in blood and liver of rats fed ascorbic acid or linoleic acid ethyl ester but not glucose. Native furan was found in tissues of all animals tested. However, animals administered orally d4-furan at doses similar to those expected from the contribution of native furan in rat feed, showed no detectable levels of d4-furan. Data indicate the possibility that there is an endogenous formation of furan from substrates other than those tested in this study.

Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r 2 ≥ 0.993) over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r 2 ≥ 0.991) and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350°C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples.

Rapid analysis of captopril in human plasma and pharmaceutical preparations by headspace solid phase microextraction based on polypyrrole film coupled to ion mobility spectrometry

A rapid, simple, and sensitive headspace solid phase microextraction coupled to ion mobility spectrometry (HS-SPME-IMS) method is presented for analysis of the highly specific angiotensin-converting enzyme (ACE) inhibitor, captopril (CAP). Positive ion mobility spectra of CAP were acquired with an ion mobility spectrometer equipped with a corona discharge ionization source. Mass-to-mobility correlation equation was used to identify product ions. A dodecylsulfate-doped polypyrrole (PPy-DS) coating was used as a fiber for SPME. The results showed that PPy-DS based SPME fiber was suitable for successfully extracting CAP from human blood plasma and pharmaceutical samples. The HS-SPME-IMS method provided good repeatability (R.S.D.s < 4%) for aqueous and spiked plasma samples. The calibration graphs were linear in the range of 10–300 ng mL −1 ( R 2 > 0.99) and detection limits were 7.5 ng mL −1 for aqueous and 6.3 ng mL −1 for plasma blank samples. Finally, a standard addition calibration method was applied to HS-SPME-IMS technique for the analysis of blood plasma samples and tablets. Purpose method seemed to be suitable for the analysis of CAP in plasma samples as it is not time consuming (state total time from sample preparation to analysis), it required only small quantities of the sample, and no derivatization was required.