Columns direct injection into

Table V shows the concentrations of polymer (usually in THF/polymer/monomer mixtures), the GPC that they were directly injected into, and the Column Code involved (Ref. Table 1). No effect of different concentration was observed in the chromatograms from GPC 2 when concentrations of samples A to E inclusive were changed by 33%. GPC 1 chromatograms were too disturbed by sampling to be useful except as a rough guide to sampling position.

Other techniques to improve throughput are instrumentation based and may involve multiple HPLC systems. The simplest method involves the automated use of solid phase extraction cartridges for sample cleanup followed by direct injection into the mass spectrometer [114], Coupling of multiple HPLC systems to one mass spectrometer allows one column to equilibrate and separate while another column to flow into the mass spectrometer. Multiple HPLC systems may be configured such that the mass spectrometer is only exposed to each serial HPLC eluent as the analyte of interest is eluted [115,116]. Although multiple H P LC-based methods may increase throughput, they also typically decrease sensitivity and may confound data workup and interpretation. 

Analytical Procedures. Incubation mixtures were extracted with diethyl ether except in the case of toxaphene where a mixture of chloroform-methanol (5 1, v/v) was used instead. Ether extracts of DDT, dieldrin, and lindane were dried over anhydrous sodium sulfate, evaporated using a gentle stream of nitrogen, and the residues were redissolved in n-hexane. Aliquots of the hexane solutions were directly injected into a gas liquid chromatograph (GLC, Varian, model 240 ) equipped with an electron capture (EC) detector (Aerograph Sc H detector) and a 1.5% 0V-101 on chrom GHP 100/120, 5 x 1/8" stainless steel column. The detector temperature was 245°C, injection port 235°C, and the oven temperature was 125°C for lindane, 180°C for DDT and 200°C for dieldrin. Carrier gas was nitrogen at the flow rate of 40 ml/min. 

Hydrazine may be derivatized with salicylaldehyde to a hydrazone derivative, separated on a suitable HPLC column and determined by a UV detector. Aqueous samples may be directly injected into a polar GC column interfaced to an FID. Anhydrous hydrazine may be appropriately diluted in alcohol or ether and determined by GC/MS. The molecular ion for GC/MS determination by electron-impact ionization is 32. 

Solid waste matrices Purge (inert gas) trap (Tenax or Chromosorb W) or thermally desorb or headspace sampling or direct injection into capillary GC column GC/PID 0.005 pg/L Enviromnental Protection Agency (1996a) [Method 8021B]... 

If the sample is free of particulate, it may be directly injected into the HPLC column for analysis. 

The sample preparation techniques described in the Basic and Alternate Protocols require 1 to 3 hr prior to sample injection into the HPLC. No additional time for sample cleanup is necessary if the sample is directly injected into the HPLC column without solid-phase extraction. 

Aqueous samples, especially those that are clean, may be directly injected into the reverse phase HPLC column. No extraction is required for this. A 200-to 400-pL aliquot of the sample may be injected. Wastewaters, aqueous indus-... 

Aqueous samples may be directly injected into a GC column for FID determination separation from other triazines, however, may be difficult. 

Serum (Al-organic acid species) Addition of sodium bicarbonate direct injection into chromatography column HPLC/ICP-AES No data No data Maitani et al. 1994... 

The assay was conducted by adding 10 / L of serum or plasma to 100 tiL containing 500 fiM substrate in 100 mM Mops-NaOH (pH 7.0), 1 mM phenylmethylsulfonyl fluoride, and 3 mM o-phenanthroline. The reaction mixture was incubated at 37°C for an hour, and then 60 fih was directly injected into the column. 

NP-HPLC Normal-phase liquid chromatographic methods applying Diol-columns or common silica columns are well suited for the analysis of the total steryl ferulate content. They require very little sample preparation, as total lipid extracts can frequently be directly injected into the column without purification or fractionation. Run times for SFs are also relatively short, and a good separation from other lipid components can be obtained in less than 10 min in traditional HPLC systems. Depending on the column type and the sample, SFs elute as one or two peaks. Two peaks are obtained from the separation of SFs, which have ferulic acid both in cis- and trans- configuration (Nystrom et ah, 2008). The relative retention time (obtained with a silica column and hexane/ethyl acetate 97 3 as eluent) of the cis- form is about 0.5 smaller than that of steryl irans -ferulates (Akihisa et al., 2000). 

To perform analysis of young wines, where anthocyanins are mainly present as monomers, a satisfying HPLC separation can be achieved by direct injection into the column of the sample previously acidified. In... 

For analysis of OTA in wine, the sample is directly injected into the column without performing sample concentration or purification steps. 

In this method the wine sample is filtered through a 0.45 am PTFE cartridge and analysis is performed by direct injection into the HPLC column using a system equipped with a fluorimetric detector operating at excitation and emission wavelengths 225 and 320 nm, respectively... 

Sample injected onto LC column, or directly injected into source, is totally consumed. 

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