Protocol for Analysis of DIC samples

Introduction

The following protocol describes the analysis of water samples for δ13C of dissolved inorganic carbon at a
Thermo Scientific Gas Bench II and Delta V+ Isotope ratio gas spectrometer or a Delta Ray isotope spectrometer.

Safety info

Wear lab coat, Nitrile gloves (TouchNTuff 92-600 or equivalent), protection glasses and closed shoes when handling
HgCl2 solutions. Work on a designated area, with water absorbing bench paper with plastic coating towards the bench.

In the event of spillage of HgCl2 containing samples on a person

Remove items that you have spilt on immediately and rinse area that has been in contact with HgCl2 with water and soap
for approximately 5 minutes. Watch to see in area becomes inflamed or irritated. If in doubt call giftkontrollen (22 59 13 00)
or contact Legevakt (phone 116 117 or 113 for emergencies).

If HgCl2 containing solutions are ingested or someone get it in the eyes, call 113, wash the eyes with appropriate equipment
immediately.

Samples will contain approximately 0.2 mg HgCl2 per ml or less.

Spillage and waste handling

If Hg containing liquids are spilled on benches or the floor etc., wipe with paper towels, and wash properly. Paper towels etc.
are put in zip bags and in yellow special waste boxes.

All waste and consumables that have been in contact with HgCl2 should be packed in plastic bags and yellow special waste boxes.

Vials with Hg containing sample should be closed and packed so they will not break and be put in red hazardous waste boxes
(https://www.uib.no/hms-portalen/74275/farlig-avfall) after analyses or sent back to sample owner. Remember to fill in and attach
the declaration form.

Samples that are in reusable containers should be poured into a larger (e.g. 10L bucket) with approximately 100 ml (sorbent) and
stirred over night. The water is then decanted out, and the sorbent is put in a closed container (e.g. plastic bottle) and put in red
hazardous waste containers including a declaration form.

Sample identification

A sample list should first be made for each batch of samples, including standards, with autosampler position, Sample ID (from user)
and Lab ID (including project nr). The analyses project should be registered in the project database http://delta.geo.uib.no:8085

Weighing in standards

Equipment: Spatula, tweezers, tray, brush, container and 12 ml exetainers with new caps and septa, Nitrile gloves
(TouchNTuff 92-600 or equivalent when handling acid).

Weigh in between 200 – 500 μg of the carbonate standard needed for the run using a spatula and small container.
Put required amount into exetainer and seal well (with a slight bend in the septum).
Make sure to clean all apparatus thoroughly when changing to a new standard to avoid contamination of standard.
Repeat procedure for all the standards on the sample list.

Adding acid

Apparatus: Needle (0.9mm in diameter), Syringe 1ml Safety wear: Nitrile gloves, protective eyewear, lab coat and closed shoes.

Cover bench surface with protective sheet and have a paper towel at hand.
Add 5 drops of 99-100% phosphoric acid to each standard.
Wipe acid off the septum of exetainer.
Place in oven 3-12 hours at 40 degC.

Preparation and Analyses of Samples

Preparation of vials for DIC samples

Apparatus: Needle (0.9mm diameter), Syringe 1ml (insulin), 12ml exetainers, trays for exetainers. Safety wear: Nitrile gloves, protective eyewear, lab coat, closed shoes and apron.

Put a protective sheet over work bench
Set out empty, clean exetainers with no caps.
Add 5 drops of 99-100% phosphoric acid to each exetainer, using a 1 ml single use syringe. Close

vials after filling 10-15 vials (one syringe full). Avoid acid on the rim, neck or threading.

The acid container is kept closed, dry and heated (70 degC) until use and between syringe fillings.

The acid is very viscous and difficult to handle; dripping and minor spilling is difficult to avoid. Keep paper towels handy.

Put lid on exetainer soon after addition of acid
Keep paper cloth on the table when working. Wash bench and reusable equipment (e.g. trays) with hot water after use.
Wipe septum of exetainers thoroughly with cloth.
Vials are flushed on the Delta Ray or Gas Bench respectively. See ‘flushing standards on delta ray and gas bench’.

Flushing vials on Gas Bench

Pack exetainers into tray from left to right, back to front
Make sure the correct needle is in place in the needle socket (open circuit needle for flushing).
Look at tip of needle with hand-lens and if needed, clean with another needle to avoid blockage.
Fasten needle into place.
Close the lid of the tray.
Turn He nozzle on the back of the autosampler up to 1bar.
In Isodat Acquisition window: File –> browser – > sequences –> Flushfill Sequence –> Select number of standards to run – > Run
Check the flow of gas (90-100 ml/min) at the open end of the needle tubing using the flow meter. Adjust He pressure if necessary.

If the flow changes significantly, the needle may be clogged.

Flushing vials on Delta Ray

Pack exetainers into rack from right to left.
Take needle out/apart and clean with water if necessary.
I Qutegra software: Home –> lab books –> Select appropriate location for lab book -> create new lab book from existing file –> use an existing lab book (look for recently used lab book) –> Rename file and correct date -> alter to suite run -> Start run (Green arrow)

Preparation of samples with HgCl2

Apparatus: Single use needle (0.6-0.8mm in diameter), Single use syringe 1ml, 1 bucket for mercury waste, one for needles and one for other waste. Safety wear: Nitrile gloves (as above), protective eyewear, lab coat, closed shoes and apron. Should work with samples in fume hood.

Put protective sheet over work bench.
The samples are labelled with lab ID and put in a rack according to the sequence they are to be run in. 3 replicates for each sample.
Open sample bottle using the decrimping tool, take care to open correctly to avoid spillage. Press down on lid keeping crimp horizontal, squeeze and tilt. In the event of struggling to get a lid off, obtain help or use pliers to pull of the aluminum crimp.
Put the aluminum lid in the normal waste and septum in mercury waste if the samples are not to be recapped.
Add 1ml of sample to each exetainer with as little atmosphere contamination as possible. Replicates are taken out at the same time.
Throw needle and syringe in mercury waste and use a new needle and syringe for the next sample.
Clean any excess sample of the septum of exetainer.
Close lid of sample bottle using closing device.
Exetainers should be refrigerated until analysis.

Running samples on Gas Bench

Pack exetainers into rack from left to right, back to front.
Make sure the correct needle is in place in the needle socket (closed circuit needle).
Look at tip of needle with hand-lens and clean with another needle to avoid blockage if needed.
Fasten needle into place (left needle slot).
Close the lid of the bench.
File –> browser – > sequences –> DIC PTM
Gas bench -> Put on reference gas 1 -> MS – 45 ->peak center -> x-focus -> autofocus -> select samples and run

Running samples on Delta Ray

Pack standards into rack from right to left. Put an empty vial in last slot.
Take needle out/apart and clean with water.
Home –> lab books –> choose one with the same number of samples, that has recently been edited – > Rename file and correct date –> change location to same folder –> create labbook -> Edit if not correct no. of samples -> check if samples are in the right place –> run (green arrow)
Change empty exetainer to sample after initial autosampler cleaning has taking place.

Written by Allegra Liltved and Pål Tore Mørkved 20.03.2019 Updated 13/08 -19 by Pål Tore Mørkved