Regulatory Approach to Determination of Lysine in Feedstuffs by Liquid Chromatography with Fluorescence Detection via Precolumn Dansylation

Abstract

A method for compliance analysis for total lysine in animal feed is described. One g portions of finely ground feed sample are spiked with a calculated amount of diaminobutyric acid internal standard and hydrolyzed by heating with 100 mL 6N aqueous HC1 at 120°C in a closed bottle. A very small aliquot (25 /*L) of hexane-washed hydrolysate is evaporated under vacuum to dryness and derivatized with dansyl chloride. Lysine is separated from other amino acids by isocratic reverse-phase (LC-18) liquid chromatography; the mobile phase is acetonitrile-O.OlM sodium phosphate (pH 7.0) buffer (100 + 210, v/v). The internal standard method along with a fluorescence detector (310-410 nm excitation and 435-650 nm emission), is used for quantitation. Thirty-five feed samples of various types (lysine 0.2- 8.2%) were analyzed with no interference from the matrix. The results were compared with those furnished by an independent laboratory using an amino acid analyzer; no statistical difference was found at the 95% confidence level. Six replicate analyses of a feed sample showed a coefficient of variation of 2.8%; no significant differences were found when between-day results of 9 samples (lysine 0.90- 4.30%) were compared. This procedure has been tested for ruggedness and can be applied for compliance determination of total lysine in feedstuffs by laboratories with limited resources

Graphene/Poly(vinylferrocene) Composite Based Amperometric Biosensor for L‐lysine Determination

“…Therefore, L‐lysine content is an important marker for the nutritional value of food . Various analytical techniques have been reported for L‐lysine determination, e. g. liquid chromatography , reverse phase liquid chromatography , high performance thin layer chromatography and densitometry . These methods are generally time‐consuming and require expensive instrumentation/reagents and qualified personnel which result in high cost per analysis.…”

Gavaserin and saltavalin, new peptide antibiotics produced by Bacillus polymyxa

“…Purified HPLC fractions were hydrolysed with 6.25 M HCI at 1 10°C for 24 h and reacted with o-phtaldialdehyde (OPA) or dansyl chloride (DnsCl) as described by Lindroth and Mopper [7], and Thio and Tompkins [8]. Derivatives were analysed by HPLC, and detected by fluorescence (Fluorichrom detector, Varian).…”