Protocol for saltwater stable isotope analysis on Picarro

Liquid run setup salt water

1. Prepare standards

- Use BERM for drift

- Use DI2 and EVAP2 for sample calibration

- Prepare once for a whole set of runs, using inset vials (300 uL)

2. Run setup

- Sequence from DI2 to BERM to EVAP2

- Define blocks of 8 samples

- Insert BERM as drift standard after 8 samples

- Repeat 3x for total 24 samples, with 2 drift samples in between, takes up 29 spots

- Rinse syringe with extra sample in position #43, after 10 samples

3. Select method

- Single wet peak, requires 2 extra injections, peak goes to waste (salt)

- FARLAB_Rinse_2, strokes, small injection

4. Number of Injections

- Standards: 14 injections (12 in data file)

- Samples: 8 injections (6 in data file)

5. Rinsing method

- 5 injections, results in one small injection of rinse sample due to single wet peak routine

6. Equipment cleaning

- Salt mesh exchanged after 24 samples, clean in ultrasonic bath, dry in glass oven, keep with septa

- Septum washed after each run, exchanged if needed after inspection

- Syringe washing in DI before and after run, repeated strokes until flow is smooth, moving plunger up and down over whole volume