Organic liquid samples

Initial screening of organic liquid samples focuses on the presence of volatile CWC-related chemicals. Organic liquid samples can be screened directly using techniques such as ... 

Organic liquid samples are also screened for the presence of polar nonvolatile CWC-related chemicals. The presence of such compounds cannot simply be discarded, because organic liquids may contain traces of water. GC analysis of polar nonvolatile chemicals is possible after derivati-zation (e.g. silylation with A,0-bis(trimethylsilyl) trifluoro-acetamide (12) and/or methylation with diazomethane). 

One of the samples in the eighth proficiency test was an organic liquid sample with dichloromethane (CH2C12) as solvent. The sample was spiked with ... 

Figure 4. Sample preparation flowchart of an organic liquid sample in the eighth proficiency test...

The efficiency of a cleanup method depends on the type of background chemicals to be removed and the type of target chemicals to be recovered. This particular cleanup method proved to be effective for the organic liquid sample composition in the eighth proficiency test. 

As described in the introduction of this article, sample preparation procedures for off-site laboratories for the CWC have been developed and tested in international interlaboratory comparison (round-robin) tests (1 5), in two trial proficiency tests, and in over (14> official proficiency tests (see Chapter 6). Tables 2 and 3 list the types of samples in these tests. The first three tests were arranged mainly for purposes of method development, the fourth and fifth also for testing and validating of methods. The reports describing these tests (the round-robin books) contain a thorough description of how each of the participating laboratories prepared their samples (1 5). Most often, water samples (16 times), organic liquid samples (14 times), or soil samples (12 times) were used as... 

The Second Trial Proficiency Test (1995) Organic liquid samples Water samples Soil samples... 

The Ninth Official Proficiency Test (2001) Organic liquid samples Decontamination solutions Emulsion samples... 

The Fourteenth Official Proficiency Test (2003) Organic liquid samples Water samples Decontamination solutions... 

Twenty-five laboratories participated in the sixth official proficiency test where lewisite 1 (CAS 541-25-3) was used as spiking chemical in the organic liquid sample. Five of the seven laboratories that performed sample preparations to derivatize the... 

In the twelfth official proficiency test, evaporation was considered to be a reason for one laboratory not finding 0,0 -diisopropyl A,A-dimethylphosporami-date (CAS 2404-04-8) in the organic liquid sample. The laboratory evaporated the sample to dryness and silylated the residue. 

In the twelfth official proficiency test, one laboratory failed to identify BHESO in the organic liquid sample because of unconventional sample preparation. The concentrated extract was silylated with BSTFA at room temperature rather than at the recommended 60 °C. 

Supercritical fluid extraction (SFE) and Solid Phase Extraction (SPE) are excellent alternatives to traditional extraction methods, with both being used independently for clean-up and/or analyte concentration prior to chromatographic analysis. While SFE has been demonstrated to be an excellent method for extracting organic compounds from solid matrices such as soil and food (36, 37), SPE has been mainly used for diluted liquid samples such as water, biological fluids and samples obtained after-liquid-liquid extraction on solid matrices (38, 39). The coupling of these two techniques (SPE-SFE) turns out to be an interesting method for the quantitative transfer... 

Distillation is a suitable technique for the isolation of volatile organic compounds from liquid samples or the soluble portion of solid samples [24,27-30]. The physical basis of separation depends on the distribution of constituents between the liquid mixture and the vapor in equilibrium with that mixture. The more volatile constituents are concentrated in the vapor phase, which is collected after condensation. The effectiveness of the separation is dependent on the physical properties of the... 

Analysis can be improved if clean-up and/or preconcentration of sample components is achieved. Traditionally, analytes are preconcentrated from liquid samples using LLE. This technique is characterised by a low number of theoretical plates, is laborious, uses vast amounts of expensive and toxic organic... 

TXRF is most applicable to liquid samples, but success has also been achieved with direct analysis of some solids, e.g. very thin sections of organic tissue and polymer film. Alternatively, small amounts of solid material can be analysed by TXRF after acid digestion. 

---