Standard, control and specimens were deproteinised with sulfosalicylic acid 10% and
norleucine was added as internal standard.
A reversed-phase HPLC in a Pico-Tag amino acid analysis system (Waters Corporation) was used with
norleucine as the internal standard.
Norleucine (Nor) was used as an internal standard (I.S.2).
Amino acid analyses were performed by HPLC in a Waters Reversed-Phase Amino Acid Analysis System equipped with a PicoTag column (3.9 x 300 mm), using
norleucine as an internal standard.
Less critical were truncated variants,
norleucine and deamidation, all of which were assessed using some form of chromatography.
Sample preparation and description for amino acid analysis: Each lyophilized homogenized muscle sample was treated with
norleucine as an internal standard and dried in a pyrolysed tube by placing it in a centrifugal evaporator.
Amino acid content was determined, following acid hydrolysis (6 N HCl), on a Biochrom 20 amino acid analyzer, using the synthetic amino acid
Norleucine as an internal standard.
The 30 mg ground sample was weighed into glass ampoules and 5 mL of 6 M HCl and 5 mmol
norleucine were added.
Biochrom recommends that the extracts are deproteinised with sulphosalicylic acid solution containing
Norleucine as the internal standard.
Oxalic acid, citric acid, tartaric acid, lithium hydroxide, potassium perchlorate, guanidine thiocyanate, D-tert-leucine,
norleucine, [gamma]-aminobutyric acid (GABA), taurine, citrulline, glutamine, asparagine, and amino acid standard mixture (AA-S-18) were from Sigma.
6.7 (Scientific Software Inc.) using
norleucine (Sigma) as internal standard.
The peptide, A[beta](M[right arrow]norL), which differs from A[beta](1-40) in only one respect, the replacement of the S of Met35 by a [CH.sub.2] group (i.e.,
norleucine), is not neurotoxic.