About

Located at the University of Hong Kong’s Kadoorie Biological Science Building, the Stable Isotope Mass Spectrometry Laboratory (SIRMS Lab) is a part of the Faculty of Sciences’ Central Facilities dedicated to stable isotope analysis (SIA) for paleoclimatological and ecological research via isotope ratio mass spectrometry (IRMS).

The HKU SIRMS lab provides services for the analysis of carbon, nitrogen, sulfur, hydrogen, and oxygen (CNSHO) stable isotope ratios in a variety of sample types and has processed 10,000+ samples on a yearly basis since the establishment of SIRMS lab at the James Hsioung Lee Building in 2011.

Thanks to the support of the Faculty of Science, the lab was later moved in 2018 to our current location at KBSB and has expanded to include four new instruments to better serve the research needs of the scientific community.

The SIRMS Lab offers a wide range of professional services regarding SIA available to researchers at HKU and other institutes.

Kadoorie Biological Sciences Building

Services

Services & Instrumentation

The SIRMS lab currently houses five different continuous flow IRMS and a cavity ring down spectrometer (CRDS) for the isotope ratio analysis of CNSHO in various samples. We currently offer routine services for:

C, N, S isotope ratios and percentages in solid organic matter, natural or enriched, via EA-IRMS combustion
H, O isotope ratios and percentages in solid organic matter, natural abundance via EA-IRMS pyrolysis
H, O isotope ratios in water samples via CRDS
C, O isotope ratios in carbonates, solids or dissolved, via headspace IRMS
N, O isotope ratios of dissolved nitrates/nitrites via bacterial denitrification and headspace IRMS
Compound Specific Isotope Analysis (CSIA) of C, N of ratios in amino acids of derivatized organic extracts via GC-IRMS

A Nu Instruments Perspective IRMS with a Eurovector EA3028 Elemental Analyzer is used for the routine analysis of CN isotopic ratios (δ13C / δ15N) and their percentages of solid organic material such as animal tissue, plant matter and sediment.

Samples encapsuled in tin undergo combustion at 1020 degrees in the reaction tube packed with chromium oxide and silvered cobalteous/ic oxide. Carrier He gas transports the evolved CO2 and NOx gas to the reduction tube, where NOx is reduced to N2 by granulated copper at 600 degrees. The two gases are then separated by a packed GC column at 115 degrees before entering the IRMS for analysis.

This Thermo IRMS system consists of a Thermo Delta V Advantage IRMS connected to one of two different sample introduction units at a given time:

Thermo Isolink elemental analyzer
Thermo GasBench II headspace analyzer

Connection with the Isolink EA enables the determination of C, N, S ratios and percentages of organic samples via combustion.

The GasBench II system allows the measurement of N, O of dissolved nitrates/nitrites in water samples prepared via bacterial denitrification. Headspace gas is sampled and passes through a CO2 scrubber (Ascarite), where the N2O is trapped and concentrated in liquid nitrogen cryo-traps. It is carried by helium to the IRMS via a gas chromatography column which separates N2O from the interfering gases and is analyzed.

This Thermo Delta V Advantage IRMS is equipped with a GC IsoLink II system to facilitate CSIA of C, N of various amino acids from organic extracts of sample matter.

Constituent free amino acids are first released from sample proteins via acid hydrolysis during sample preparation; subsequent derivatization with acetyl chloride and trifluoroacetic anhydride renders the amino acids volatile for GC analysis.

Derivatized amino acids are then analyzed via GC, where they are separated, combusted and reduced as CO2 and N2 gas.

Elementar IRMS

Pyrocube

GHG

Elementar IRMS

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The Elementar isoprime precisION IRMS can be connected to one of three different sample introduction modules:

Pyrocube elemental analyzer
Iso FLOW headspace analyzer
Iso FLOW GHG greenhouse gas analyzer

When linked to the Pyrocube EA, either C,N,S or H,O ratios and their percentages of organic solids can be measured when configured for combustion or pyrolysis respectively. Larger samples such as sediments and filters are analyzed using this instrument due to its sample size capacity.

In addition, the isoFLOW headspace analyzer is used to analyze C,O ratios of inorganic carbonates in solids or liquids via the addition of phosphoric acid, whilst the GHG module enables C, O measurements of greenhouse gases.

Other Equipment

The SIRMS lab also provides access to other small equipment for sample preparation:

Mettler Toledo Microbalance x 2
Buehler Isomet 1000 precision saw
Geomill326 high precision micromill
N-EVAP 112 nitrogen evaporator & fumehood

Please contact our lab staff if there are any inquiries regarding the availability and use of these equipment.

Microbalance

Geomill

Nitrogen Evaporator

Microbalance

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Pricing

The general prices for the SIA services listed below are per unit sample and in Hong Kong Dollars (HKD). Please contact SIRMS lab staff for any inquiries regarding service and before submitting samples to determine requirements and other services needed.

Ms. Kit-Sum Leung

E-mail: kitsuml@hku.hk

Office Tel: 852 3917 3651

Price (HKD)

Services - Sample Analysis only	HKU Faculty of Science	Other HKU Users	External Users
13C and/ or 15N of solid organic matter by EA-IRMS (natural abundance)	50	60	70
13C and/ or 15N of solid organic matter by EA-IRMS (natural abundance, difficult samples- filters, soil, sediments, salts)	60	70	85
13C and/ or 15N of solid organic matter by EA-IRMS (15N and/ or 13C enriched)	60	70	85
13C and/ or 15N of solid organic matter by EA-IRMS (15N and/ or 13C enriched, difficult samples- filters, soil, sediments, salts)	70	80	100
34S only / CNS combined analysis of solid organic samples by EA-IRMS (natural abundance)	80	95	120
*CNS combined analysis of solid organic samples by EA-IRMS (natural abundance, difficult samples- soil, sediment)	120	140	170
2H and/ or 18O of solid organic matter by EA-IRMS (natural abundance)	100	120	150
2H and/ or 18O of water samples by water analyzer	80	95	120
13C and/or 18O of carbonate by Gas Bench-IRMS	80	95	120
15N and/or 18O of nitrate in water by bacteria denitrification	220	250	320
13C/ 15N (single isotope only) compound specific analysis of Amino Acids by GC-IRMS	450	550	700
Dual 13C & 15N compound specific analysis of Amino Acids by GC-IRMS	900	1100	1300