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