A bout separation tecnique in analytical chemistry.

1. In the name of GOD

8. Side hole design needle trap device; SB: sorbent; SP: spiral plug; SH: side hole; NH: needle head; PS: PTFE sealer.

9. Purge and trap apparatus for extracting volatile substances from a liquid or solid by flowing gas.

10. Comparison

15. Diagram of INCAT devices with A; 2.5 cm length of GC column, and B; carbon.

16. Active Sampling

17. Chromatograms from a thermally deposited carbon coated INCAT device exposed to ambient air. Sampling locations were: A; the laboratory and B; solvent storage cabinet. Conditions: passive sampling for 24 and 2 h, respectively. Comparison between A; colloidal graphite coated INCAT device, B: blank needle and, C; 1.0 gl direct injection of BTEX compounds. Conditions for A and B: active sampling, 5 ml headspace withdrawn through the needle over 60 s; saturated solution of BTEX compounds in water; equivalent GC parameters.

18. Schematic representation of an inside needle capillary adsorption trap (INCAT) device.

19. The amounts of benzene, toluene, ethyl benzene and xylenes (BTEX) compounds determined by active sampling with a 26 gauge inside needle capillary adsorption trap (INCAT) device.

21. The amount of benzene determined by active sampling with a 26 gauge inside needle capillary adsorption trap (INCAT) device in the absence of all other benzene, toluene, ethyl benzene and xylenes (BTEX) compounds. The amount of benzene and toluene determined by active sampling with a 26 gauge inside needle capillary adsorption trap (INCAT) device in the absence of heavier benzene, toluene, ethyl benzene and xylenes (BTEX) compounds.

23. Scheme of INCAT system. (N) stainless steel needle; (O) stainless steel O-ring; (F) stainless steel frits; (P) adsorbent Porapak Q; (A) adsorbentalumina; (V) shut-off micro valve with stainless steel body; and (T) viton tubing.

24. Scheme of sorption and desorption process of INCAT device. (A) Sampling of aqueous samples; (B) removing of residual water; (C) desorption; (D) cleaning.

25. The dependence of peak area of o -xylene on the temperature of injection port. The number of measurements for each temperature were three.

26. The dependence of relative standard deviation of o -xylene peak area on the temperature of injection port. The number of measurements for each temperature were three.

28. Schematic of the NT-1 packed with PDMS, DVB and CARBOXEN particles (a) and the NT-2 filled with Carboxen 1000 (b).

29. Diagram of the coupling of the NT with the narrow-neck glass liner. The carrier gas enters the needle through the side hole, flows through the sorbent and facilitates the introduction of the desorbed analytes into the GC column.

30. The scheme of closed stripping system. H, holder; C, stainless steel capillary tubing; N, needle trap device; V, vial; S, sample; T, viton tubings.

31. Comparison of continuous purge and trap sampling (CPNT), sequential purge and trap sampling (SPNT), and headspace sampling for extraction of BTEX from headspace of a 10 ng/mL solution. Sampling volume: 10mL and sampling flow rate: 1.9mL/min.

33. Desorption temperature and desorption time Desorption time profiles for BTEX using a DVB (10mm) packed NTD. Transferred amounts only by the first injection are plotted at different desorption times.

34. The effect of sampling/purging flow rate Effect of purging flow rate on extraction efficiency of BTEX from headspace of 10 ng/mL solutions. Sorbent: 1cm DVB, sampling rate: 1.9 mL/min, sampling volume: 10 mL.

35. Concentration range Calibration graphs for BTEX sampled using the sequential purge and trap (SPNT) sampling technique from the headspace of 5mL water samples (sampling volume: 10 mL). The 10mm DVB-packed needle trap was used and the temperature was fixed at 30 ◦C.

36. The effect of sampling volume Effect ofsampling volume on the extraction coefficient ofBTEXfrom10 ng/mL headspace solutions. Sorbent: 1cm DVB, sampling rate: 1.9 mL/min, purging rate: 40 mL/min.

37. The effect of temperature Effect of temperature on extraction efficiency of BTEX from 10 ng/mL headspace solutions. Sorbent: 1cm DVB, sampling rate: 1.9 mL/min, purging rate: 40 mL/min, sampling volume: 5mL.

38. Comparison with SPME Comparison of SPME and SPNT methods in extraction of BTEX from the headspace of 5mL of 10 ng/mL. SPNT conditions: sampling volume = 30mL, sampling flow rate = 1.9 mL/min, purging flow rate = 40mL/min, temperature = 30 ◦C. SPME conditions: fiber: 65-m DVB/PDMS, extraction time=5min, stirring speed = 600 rpm, temperature = 30 ◦C.

39. Storage time for NTDs with loaded BTEX mixture The devices were then stored in a glass container at room temperature (∼22 ◦C). Oneweek later, the BTEX mixture was injected and analyzed by a GC and then the response (peak area) of the BTEX was compared with the response obtained by injections done immediately after sampling.

40. Injection port for split injection into an open tubular column. The glass liner is slowly contaminated by nonvolatile and decomposed samples and must be replaced periodically. For splitless injection, the glass liner is a atraight tube with no mixing chamber. For dirty samples, split injection is used and a packing material can be replaced inside the liner to adsorb undesirable components of the sample.

41. Representative injection conditions for split, splitless, and on-column injection into an open tubular column.

42. Advantage of splitless 1) High sensitivity ( 95 % of sample on column ) 2) Solvent effect produces narrow sample bands 3) Same hardware as split injection Disadvantage of splitless 1) Slow sample transfer to column 2) Must dilute sample with volatile solvent 3) Time consuming : must cool column

44. Thank You for Attention