Just a note to pass on the results of bird feather autoclaving experiment I promised to update the list serve about some weeks ago (no need to read further if this isn't your sort of thing).
The question: Does autoclaving (120degrees C; 21minute cycle) change the stable C and N isotopic composition of bird feathers? [this question was motivated by biosecurity requirements to autoclave imported feathers
prior to releasing samples from quarantine areas]
The answer: No.
Summary details: Two different bags of commercially available guinea fowl feathers were homogenised. Both homogenates were split into autoclaved and non-autoclaved sample sets and analysed several times for both
d15N and d13C.
d15N of autoclaved feather homogenates were 3.12 (1sigma=0.11; n=8; Bag#1) and 3.75 (1sigma=0.09; n=8; Bag#2).
d15N of the non-autoclaved feather homogenates were 3.16 (1sigma=0.11; n=11; Bag#1) and
3.71 (1sigma=0.06; n=8; Bag#2).
d13C of autoclaved feather homogenates were -16.17 (1sigma=0.06; n=8; Bag#1)
and -17.02 (1sigma=0.07; n=8; Bag#2).
d13C of the non-autoclaved feather homogenates were -16.27 (1sigma=0.10; n=11; Bag#1) and -17.00
(1sigma=0.04; n=8; Bag#2).
The Bag#1 non-autoclaved homogenates were analysed 11 times (instead of 8) as I wanted to run a few extras across a wider range in sample mass.
Not the biggest experiment, but these results suggest that autoclaving at 120degC for ~20minutes does not effect either the C nor N stable isotope compositions of keratin feathers.
All the best and especially to you Zach! You've always been a bass playing rockstar in my (more virtual) book.
University of Canterbury
P.S. Random other point: ideal sample mass was in the 0.5mg (~5V on mass28; ~1V on mass44) to 1.2mg (~13V on mass28; ~2.5V on mass 44) range.This was with a DeltaVplus; ConFloII; CosTechECS410; ~100ml/min UHP-He set-up. The middle
of this ideal mass range equates to ~2-3mm of an unhomogenised penguin feather rachis of 1-2mm diameter (I did this experimental stuff in the lead up to some Adelie and Emperor penguin feather analyses; I gather the sample collection which I was not a part
of will appear on a NatGeo show sometime soon...).
P.P.S. Homogenising samples lost an unexpectedly large amount of sample mass (SpexMill). Just a word of caution to any one out there wanting to homogenise small bird feathers: think about potential recovery issues during homogenisation.