Cleaning Procedure for MALDI sample targets

1.1

　Ultrasonic bath for target cleaning

1.2

　Cleaning solution concentrate: Micro 90 (available from Sigma Aldrich)

1.3

　Hotplate or oven capable of heating a 5 % Micro 90 solution to approx. 60 °C

1.4

　HPLC grade methanol and acetone
　Note: when handling solvents, wear suitable PPE (e.g. safety glasses, lab coat and gloves).
　Refer to manufacturers MSDS for instructions on safe handling and disposal.

1.5

　Deionised or HPLC grade water

1.6

　Small oven for drying targets (up to 50 °C)

2.1

　Prepare 100 mL of a 5 % (v/v) solution of Micro 90 in deionised or HPLC grade water
　[5 % (v/v) = 5 mL of Micro 90 concentrate + 95 mL water]

2.2

　Heat the 5 % Micro 90 solution to approx. 60 °C

2.3

　Using a tissue and a suitable solvent (e.g. methanol), remove any visible signs of samples from the surface of the
　target

2.4

　Place the target face up into a small container and immerse (cover) with acetone

2.5

　Cover the container and place into an ultrasonic bath.

2.6

　Sonicate the target in acetone for 15 min. Sonication is performed at room temperature.

2.7

　Discard the used acetone. Rinse the target (x2) with 100 mL deionised or HPLC grade water.
　Discard rinsing solutions.

2.8

　Place the target face up into a small container and immerse (cover) with the heated 5 % (v/v) Micro 90 solution

2.9

　Cover the container and place into an ultrasonic bath.

2.10

　Sonicate the target in the 5 % Micro 90 cleaning solution for 15 min. Sonication is performed at room
　temperature.

2.11

　Discard the used 5 % Micro 90 solution. Rinse the target (x2) with 100 mL deionised or HPLC grade water.
　Discard rinsing solutions.

2.12

　Cover the target with approx. 100 mL of deionised or HPLC grade water.
　Sonicate target for 5 min. at room　temperature.

2.13

　Cover the target with approx. 100 mL of methanol. Sonicate target for 15 min. at room temperature.
　Discard the rinsing solution

2.14

　Cover the target with approx. 100 mL of deionised or HPLC grade water.
　Sonicate target for 15 min. at room temperature. Discard the rinsing solution

2.15

　Shake the target to remove excess water from the rinsing step.
　Flood the target with methanol and allow excess to evaporate.

2.16

　Place the target in an oven at 50 °C for at least 6 hours (e.g. overnight).
　This oven drying step is necessary to minimise unwanted sample spreading during use.