PMID- 18405905
OWN - NLM
STAT- MEDLINE
DCOM- 20081001
LR  - 20090115
IS  - 0021-9673 (Print)
IS  - 0021-9673 (Linking)
VI  - 1201
IP  - 2
DP  - 2008 Aug 8
TI  - Construction of an automated gas chromatography/mass spectrometry system for the 
      analysis of ambient volatile organic compounds with on-line internal standard 
      calibration.
PG  - 134-40
LID - 10.1016/j.chroma.2008.03.071 [doi]
AB  - An automated sampling and enrichment apparatus coupled with a gas 
      chromatography/mass spectrometry (GC/MS) technique was constructed for the 
      analysis of ambient volatile organic compounds (VOCs). A sorbent trap was built 
      within the system to perform on-line enrichment and thermal desorption of VOCs 
      onto GC/MS. In order to improve analytical precision, calibration accuracy, and 
      to safe-guard the long-term stability of this system, a mechanism to allow 
      on-line internal standard (I.S.) addition to the air sample stream was configured 
      within the sampling and enrichment apparatus. A sub-ppm (v/v) level standard gas 
      mixture containing 1,4-fluorobenzene, chloropentafluorobenzene, 
      1-bromo-4-fluorobenzene was prepared from their pure forms. A minute amount of 
      this I.S. gas was volumetrically mixed into the sample stream at the time of 
      on-line enrichment of the air sample to compensate for measurement uncertainties. 
      To assess the performance of this VOC GC/MS system, a gas mixture containing 
      numerous VOCs at sub-ppb (v/v) level served as the ambient air sample. Various 
      internal standard methods based on total ion count (TIC) and selective ion 
      monitoring (SIM) modes were attempted to assess the improvement in analytical 
      precision and accuracy. Precision was improved from 7-8% RSD without I.S. to 2-3% 
      with I.S. for the 14 target VOCs. Uncertainties in the calibration curves were 
      also improved with the adoption of I.S. by reducing the relative standard 
      deviation of the slope (Sm%) by an average a factor of 4, and intercept (Sb%) by 
      a factor of 2 for the 14 target VOCs.
FAU - Su, Yuan-Chang
AU  - Su YC
AD  - Department of Chemistry, National Central University, Chungli 320, Taiwan.
FAU - Chang, Chih-Chung
AU  - Chang CC
FAU - Wang, Jia-Lin
AU  - Wang JL
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20080329
PL  - Netherlands
TA  - J Chromatogr A
JT  - Journal of chromatography. A
JID - 9318488
RN  - 0 (Organic Chemicals)
SB  - IM
MH  - Calibration
MH  - Gas Chromatography-Mass Spectrometry/*methods
MH  - Organic Chemicals/*analysis/isolation & purification
EDAT- 2008/04/15 09:00
MHDA- 2008/10/02 09:00
CRDT- 2008/04/15 09:00
PHST- 2008/01/27 00:00 [received]
PHST- 2008/03/13 00:00 [revised]
PHST- 2008/03/14 00:00 [accepted]
PHST- 2008/04/15 09:00 [pubmed]
PHST- 2008/10/02 09:00 [medline]
PHST- 2008/04/15 09:00 [entrez]
AID - S0021-9673(08)00515-3 [pii]
AID - 10.1016/j.chroma.2008.03.071 [doi]
PST - ppublish
SO  - J Chromatogr A. 2008 Aug 8;1201(2):134-40. doi: 10.1016/j.chroma.2008.03.071. 
      Epub 2008 Mar 29.