HS-SPME

Figure 11.14 Analysis of amphetamines by GC-NPD following HS-SPME exti action from human hair (a) Normal hair (b) normal hair after addition of amphetamine (1.5 ng) and methamphetamine (16.1 ng) (c) hair of an amphetamine abuser. Peak identification is as follows 1, a-phenethylamine (internal standard) 2, amphetamine 3, methamphetamine 4, N-propyl-/3-phenethyamine (internal standard). Reprinted from Journal of Chronatography, B 707,1. Koide et ai, Determination of amphetamine and methamphetamine in human hair by headspace solid-phase microextraction and gas cliromatography with niti ogen-phosphoms detection, pp. 99 -104, copyright 1998, with permission from Elsevier Science.

In a recent report, HS-SPME was used for the extraction of amphetamines from human hair (142). Human hair analysis is gaining interest in the analysis of drugs of abuse, since it offers attractive features easy and unlimited sampling, and as the... 

Another recently developed technique is headspace sorptive extraction (HSSE) with PDMS stir bars [552]. HSSE-GC was compared with SHS and HS-SPME. SBSE and HSSE extract organic analytes from aqueous or vapour samples. In SBSE, the stir bar is inserted into the aqueous sample and extraction takes place during stirring whereas in HSSE the glass rod is suspended within the headspace volume and sampling takes place during headspace equilibration. New trends are the development of selective sorbents. 

Time-saving direct sampling from solutions/slurries (SPME) and solids (HS-SPME)... 

Organotin compounds (biocides and polymer stabilisers) in water were analysed by means of HS-SPME-GC and GC-MS (SIM) [296],... 

HS-SPME Headspace solid-phase INAA Instrumental neutron activation... 

Headspace solid phase microextraction (HS-SPME). With this extraction technique, it is possible to concentrate volatile compounds thus allowing their detection even at trace levels, as in the case of volatile and semi-volatile terpenes in archaeological findings [7,31]. Chapter 10 outlines how resinous materials are investigated using HS-SPME-GC/MS. 

D. Zabaras, S. G. Wyllie, Quantitative analysis of terpenoids in the gas phase using headspace solid phase microextraction (HS SPME), Flavour Fragr. J., 16, 411 416 (2001). 

Fig. 3.1.4. Temperature profiles for in-sample derivatisation HS-SPME of NPEOs-NPECs using the CW-DVB fibre. Conditions as in Fig. 3.1.3. Compound identification ( ) NP ( ) NPEOi (A) NPEiC (X) NPE02 and (O) NPE2C compounds the relative area response is magnified by a factor of three (Figure taken from Ref. [80]).

Fig. 3.1.5. HS-SPME-GC-MS single-ion chromatograms of derivatised compounds from river water entering Sant Joan Despi...

The use of headspace solid-phase microextraction (HS-SPME) combined with GC was effective for isolation and determination of alkylpyrazines in cocoa liquor <2004JBS267, 2004MI291>, and similarly methoxypyrazine in wine was analyzed by HS-SPME/2-D GC <2005MI1075>. 

Sorbent/ solid phase Solid phase extraction (SPE) Solid phase microextraction (SPME) Stir bar sorptive extraction (SBSE) INCAT/OTT/in-tube-SPME SPDE Headspace-solid phase microextraction (HS-SPME) Headspace stir-bar sorptive extraction (HS-SBSE) Purge-and-sorbent trapping Spray-and-sorbent trapping... 

NT OTME Needle trap Open-tubular microextraction Device with a hypodermic needle, whose tip is filled with a solid adsorbent onto which the sample is adsorbed. For desorption, which takes place inside the GC injection port, the carrier gas flow is forced through the needle, entering it through a hole at its side As in-tube (micro)extraction Similar application profile as HS-SPME however, the NT device is more robust and also has a higher capacity, potentially allowing exhaustive extraction. Also useful in P T analysis... 

An SPME fiber can be exposed in two modes—by immersing it directly in the liquid sample to be analyzed (direct immersion SPME—DI-SPME), or by exposing it to the headspace (HS-SPME). In the latter case, the fiber is inserted into the headspace, above a liquid or solid sample. 

Sampling volatile analytes from samples having complex matrices usually takes place in the HS-SPME mode. This variant yields decidedly better results in the determination of aroma compounds59 and other volatile components.60 Moreover, HS-SPME prolongs the life of the fiber because it is not in direct contact with the sample. On the other hand, the direct extraction of less volatile compounds from solution is possible using DI-SPME. But in this case, the fiber deteriorates more quickly, increasing the cost of analysis. Headspace sampling is therefore employed whenever possible. 

Michulec, M. and W. Wardencki. 2005. Selected aspects of chromatographic solvents residues determination using HS, SPME an SDE techniques for isolation and preconcentration of analytes. Book of abstracts of 11th International Symposium on Separation Sciences, September 12-14, 2005, Pardubice, Czech Republic. 

Sampling of the head space (Head Space- Solid Phase Microextraction- HS - SPME) ... 

TABLE 7.2 Madeira wine volatiles isolated by HS-SPME using a DVB/CAR/PDMS fiber and identified by gas chromatography-mass spectrometry, their principal m/z signals,0 and the corresponding odor descriptors and odor thresholds... 

Most of the static headspace methods determine the partition coefficient by quantifying volatile concentration above a sample by gas-chromatography. The vapour phase calibration method (VPC) uses an external vapour standard for calibration. One must assure that the pure component is completely vaporized before injection. A widely employed alternative is the Liquid calibration static headspace (LC-SH) method (YoiWey et al. 1991 Nedjma 1997). A third approach uses HS-SPME. SPME may be used to determine partition coefficients if short sampling times are applied the process must only sample the headspace and not disrupt the equilibrium (Jung and Ebeler 2003). This method has become very popular to study the effect of wine macromolecules on the liquid-vapor equilibrium, (Whiton and Zoecklein 2000 Escalona et al. 2002 Hartmann et al. 2002 Aronson and Ebeler 2004). 

Headspace solid-phase microextraction (HS-SPME) is a rapid and solvent-free modification of the SPME technique in which a fine fused silica fiber with a polymeric coating is inserted into a headspace gas to extract organic compounds and directly transfer them into the injector of a gas chromatograph for thermal desorption and analysis. In this technique, the quantity of compounds extracted onto the fiber depends on the polarity and thickness of the stationary phase as well as on extraction time and concentration of volatiles in the sample. 

The headspace (HS) SPME analysis can be performed by means of a 100 pan PDMS fiber (Carlin, 1998). Sodium chloride (0.9 g) and 8 pT 2-octanol solution as internal standard (230 ppm) are added to 4mL of wine in a 10 mL vial this is stirred (1500 rpm) for 10 min in a water-bath at 30 °C to stabilize the conditions of the solution then the fiber is placed in the sample headspace. After stirring for 40 min, the fiber is taken out and inserted into the injection port of the GC to perform gas chromatographic analysis. 

For the precision of the HS-SPME method we can refer to the work of Vas et al. (1998) with a peaks evaluation based on percentage, and to the data of Carlin (1998) obtained more properly referring to internal standard method. Ulrich et al. (1997) also achieved precise results by using SPME analysis on fruit juices. Table 5.1, referring to the working conditions of one of the chromatograms in Figure 5.2, reports a study of repeatability for some wine compounds adsorbed in a HS-SPME 1 cm PDMS fiber and analysed by GC-MS. 

GC-MS chromatograms of a Miiller-Thurgau wine sample extracted with both polystyrenic resin (XAD-2) and a 100 xm PDMS HS-SPME fiber, are shown in Figure 5.2. 

Differences in retention times in the chromatograms are due to the different oven temperature program used. Some remarkable differences in the profiles evidence the different enrichment obtained by the two methods. Data reported in Table 5.2 and Figure 5.3 show evidence of generally good linear correlations between XAD-2 extraction and HS-SPME enrichment methods. In the conditions used for SPME/GC-FID analysis, some compounds such as octanoic and decanoic acids partially overlap ethyl myristate and ethyl palmitate, respectively. 

By HS-SPME using a PDMS coated fiber, a rather low adsorption for 2-phenylethanol and also, perhaps tenfold more, for 1-hexanol, is... 

Table 5.1 Repeatability (mean Ax/Ai.s. value of 5 data) for some compounds in a young Gewiirztraminer wine adsorbed by HS-SPME in a 1 cm PDMS fiber and analysed by GC-MS using a PEG capillary column. Values referred to Ax/Ai.s. ( m/z 45) with 2-octanol as internal standard. S.D. standard deviation.

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