Continuous flow thin layer headspace (TLHS) analysis

Kozlowski, E.; Sieńkowska-Zyskowska, E.; Górecki, Tadeusz

doi:10.1007/bf00321683

Cited by 6 publications

(5 citation statements)

References 21 publications

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“…(87) that (Aci max ) re i = (Ar t max ) re i, and that for b > 0, (Ar, max ) re i < 0, hence this error always has a negative sign, and its absolute value |(Ar t max ) re i increases monotonically to 1 (100%) for b approaching infinity. [15] Assuming that v g can oscillate around v g opt in the Av g p interval, determined by the intersection points of a secant parallel to the X-axis x = v g = a and crossing the inflexion point of the r, =f(v g ) or r, = g(a) curve, the relative error of precision [(6c\ j n f) re i] of determination of the VA concentration at the inflexion point of the recovery curve (i.e. for r t = r t inf ) with respect to the maximum VA concentration ci max = c°Fr tm ax, can be determined from Eq.…”

Section: Downloaded By [Temple University Libraries] At 16:19 16 Novementioning

confidence: 97%

“…[14,15] The allowable ratio of bromide-to-chloride ion concentration (VOBr< 0.1VOC1) limits the applicability of the direct potentiometric method. Moreover, should volatile organoiodine compounds be present in the sample, organic iodine (VOI) cannot be co-determined, since elemental iodine (I 2 ) will be the mineralization product rather than hydrogen iodide.…”

Section: Rtmentioning

confidence: 99%

“…(88) that (6c\ j nf ) rel = (6r t i n f) r eh and that the (6r t in f) rei = f{b) dependence is more confounded than (Ar tmax ) rel =g(è). After substituting a inf =Z) 1/3 +è~1 /3 and appropriate rearrangements (dividing the numerator and denominator by 6^0 and multiplying by Critical Value of the Synthetic Parameter b [15] Equations (87) and (88) indicate that both the systematic error and the error of precision are functions of the synthetic parameter b. Assuming that the parameter b reaches its critical value (è cr> inf ) when both kinds of errors are equal to one another, the following equality occurs according to (87) and (88):…”

Section: Error Of Precision Of Determination Of the Va Concentration mentioning

confidence: 99%

“…Even though only a rough approximation of v gopt is obtained, it is useful for method optimization. [15] The When Vg = v gopt , i.e. for a = 1, the relative systematic error [(Ac t max )rei] of the maximum VA concentration in the liquid sorbent (i.e.…”

Section: Conclusion For Optimization Of the Operating Conditionsmentioning

confidence: 99%

“…Volatile Analyte[15] For given v s and vj values, it is possible to calculate v g opt from Eq. (23) using the values of k s and k\ determined, and then, using Eq.…”

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confidence: 99%

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Theoretical principles of thin layer headspace analysis

Polkowska

Kozlowski

Górecki

et al. 1999

Toxicological & Environmental Chemistry

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Theoretical principles of thin layer headspace (TLHS) analysis are reviewed. TLHS utilizes a special heated column in which a continuously flowing thin film of a liquid sample is contacted with a continuously flowing pure gas. Volatile analytes contained in the liquid sample pass to the gas phase and are carried away from the column. For the determination of volatile organic halogen (VOX), the analytes in the gas are mineralized at 900°C, and the mineralization products (hydrogen halides) are absorbed in an appropriate solvent in a second TLHS column kept at ambient or sub-ambient temperature. The mineralization products can be quantified in the liquid sorbent using conductometric, spectrophotometric, as well as direct and indirect potentiometric methods. The unique feature of this method is the dynamic preconcentration of the analyte in the liquid sorbent. When analyte speciation is required, the liquid sorbent can be generated in TLHS column II by condensation of the water vapour carried by the gas from TLHS column I, and the condensed phase can be analyzed by direct liquid injection gas chromatography. General equations describing the recovery of the analyte or its conversion products in TLHS column II are given, followed by general and partial solutions yielding insight into the nature of the processes and being useful for optimization of the operating parameters of the method. Conditions under which TLHS analysis can be used to separate two compounds are discussed.

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Section: Downloaded By [Temple University Libraries] At 16:19 16 Novementioning

confidence: 97%

Section: Rtmentioning

confidence: 99%

Section: Error Of Precision Of Determination Of the Va Concentration mentioning

confidence: 99%

Section: Conclusion For Optimization Of the Operating Conditionsmentioning

confidence: 99%

“…Volatile Analyte[15] For given v s and vj values, it is possible to calculate v g opt from Eq. (23) using the values of k s and k\ determined, and then, using Eq.…”

mentioning

confidence: 99%

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