AOAC 2019 First Action Methods

(j) AQC derivatizing reagent: Into a 2 mL HPLC vial, weigh out 4.0 ± 0.2 mg of 6-aminoquinolyl-N- hydroxysuccinimidyl carbamate. Add 1.0 mL of acetonitrile, cap the vial tightly. Vortex mix for approximately 10 seconds. Keep the vial in a heating block with shaking at 55 ± 2 0 C, 1000 rpm for 10 minutes until AQC is completely dissolved. Do not heat the reagent for longer than 10 minutes. Reconstituted AQC is approximately 10mM. Prepare fresh reagent at the time of use.

Note : Do not use discoloured reagent, especially, if it is yellow or green.

(k) Mobile phase A: Measure separately 984 mL water, 10 mL acetonitrile, 6 mL formic acid and mix well. Filter and degas. (l) Mobile Phase B: 100% Acetonitrile. D. Apparatus (a) Autopipets

(b)

Vortex mixer

(c)

Volumetric flasks.—100 and 10 mL

(d)

Analytical balance.—2 and 4 decimal places

(e)

Thermoshaker set at 55 ± 2 ° C, speed 1000 rpm (Grant USA Inc.) or equivalent

(f)

Oven set at 110 ± 2°C

(g)

Solvent filtration unit with 0.45 µm hydrophilic membrane filters

(h)

Syringe filter, 0.45 µm (CS 045 AN Advantec) or equivalent

(i)

Disposable syringes, 3 mL

(j) Digestion tubes.--Glass ampoule, 20 mL or culture tubes 16 mL 16 x 125 mm with PTFE caps (Kimax, KIML45066A-16125) or equivalent.

(k)

Safe-lock tubes, 2 mL (0030120094 Eppendorf) or equivalent

(l)

UHPLC vials, 2 mL

(m)

Glass vial inserts, 250 µL flat bottom

(n)

Glass screw neck total recovery vial.--12 x 32 mm

(o)

Sonicator bath

(p)

Plastic container, 120 mL