Knowing the inter-unit variability, especially the technological error, is important when using many physiological measurement systems, yet no such inter-unit analysis has been undertaken on duplicate automated gas analysis systems.
Plasma glucose concentration was determined from whole blood samples immediately after each blood sample was taken using a Yellow Springs Instrument (Lynchford House, Farnborough, Hants, U.K ., and [6,6-H2]glucose and [1,2,3,4,5,6,6-H2]glucose isotopic enrichment was measured in duplicate by gas chromatography mass spectrometry using an Agilent 5973N (Agilent Technologies, Workingham, U.K).
Composition and content of neutral carbohydrates in homogenized compost samples (see above) was determined in technical duplicates using gas chromatography with inositol as an internal standard (Englyst et al. 1982).
All non-duplicate pharyngeal GAS clinical isolates included in the study were identified by colony morphology, β-hemolysis on blood agar, latex agglutination test (Streptococcal Grouping Kit, Oxoid, Basingstoke, UK), and susceptibility to bacitracin disks (10 U, Oxoid, Basingstoke, UK).
The true density measurement of the PCZ and polymers was determined in duplicate using a gas displacement pycnometer (Accupyc 1330; Micromeritics, Norcross, Georgia).
Following cycle 5, one duplicate reactor (lower gas production rate) was set at a more negative potential of −650 mV, and the other one was set to a more positive potential of −550 mV (cycle 6).
pH was determined in duplicate immediately by blood gas analysis (Corning 865; Chiron Diagnostics) and plasma [H+] calculated.
We analyzed 13 field duplicate samples for particle and gas bound PAH's.
Atmospheric pressure electrospray ionization mass spectra in both positive (PIM) and negative (NIM) ion modes (PIM = 150 1400 amu; NIM = 150 2000 amu) were recorded on duplicate injections of the same sample (drying gas flow 10 L/min; nebulizer pressure 30 psig; dry gas temperature 350°C; PIM capillary voltage 3000; NIM capillary voltage 3500).
