Analytics

Isodetect analyzes the isotope ratios of in a wide variety of compounds (e.g. in water, gases, CHC, BTEX, PAH, MHC).

Carbon (13C/12C and 14C)
Hydrogen (2H/1H and 3H)
Nitrogen (15N/14N)
Chlorine (37Cl/35Cl)
Sulphur (34S/32S)
Oxygen (18O/16O)

Isodetect’s analytical methods are based on internationally established standard procedures recommended by environmental authorities (IAEA, US EPA, LABO, Drinking Water Ordinance). We strictly adhere to the rules of good analytical practice and document all analysis steps.

Isodetect masters a large number of methods for determining isotopes, concentrations and molecular genetic parameters. These methods can be flexibly adapted to the specific needs of each investigation, for example through special temperature programs or GC columns. We prefer these optimizing options to the use of rigid, possibly certified protocols. In addition, we directly take over the innovative analytical know-how of the research laboratories in Munich and Leipzig that we cooperate with, which we also continuously develop in our own R&D projects.

Limits of determination and measurement accuracies

The analytical behaviour of environmental samples is fundamentally more difficult to predict than that of pure substances. Undefined substance mixtures sometimes show artifacts (peak overlapping, memory effects, foam formation) that require additional analysis procedures. Due to flexible laboratory protocols, we can react quickly to analytical challenges.

In practice, the limits of determination and measurement inaccuracies of the most important test parameters in groundwater and soil are as follows (example Rondenbarg landfill):

1 2 3 4 5 6 7 8

Needle valve

Device check P&T-GCC-IRMS

Isotope laboratory in Munich

Installation of a GC column

Gas chromatograph configuration

Ion source

Weighing of samples for the Elemental Analyzer

Manual sample injection on the GCC-IRMS

Processing times

You should plan generally 1 – 2 months after sampling as processing time for contaminated site investigations as well as for drinking water investigations. If special time-consuming analysis methods are used, up to 2 additional months may be required for the completion of the project. Particularly, ¹⁴C and ⁸⁵Kr analysis for drinking water investigations take longer.

The specific time frame depends heavily on the workload and the capacity utilization of our analytical devices. We would be happy to draw up a schedule for the expected course of the project. Express orders with a surcharge can be processed with priority.

Scheme of sample processing in a GCC-IRMS measurement (see photos below).

P&T-GCC-IRMS: Gas chromatographic isotope analysis with Purge & Trap

Sensitive component-specific isotope analysis of pollutants requires highly specialized analytical devices that are connected online. Due to the interlocking, the measurements can in principle be carried out consecutively. In practice, however, complex device checks, permanent reference measurements and possibly complicated changes to the device configuration are required. Each sample is measured several times, the measured values obtained are checked individually. For these reasons, isotope analyzes are much more complex than simple concentration determinations.

Our devices for isotope analysis in BioCity Leipzig

P&T Autosampler: Concept, PAS Technology
P&T Purge & Trap unit: Stratum, Teledyne Tekmar
GC Gas Chromatograph: Agilent 7890A
C combustion unit: GC-Isolink, Thermo Fisher Scientific
IRMS isotope mass spectrometer: MAT 253, Thermo Fisher Scientific
EA/Pyr Elemental Analysis: Flash 2000 HAT, Thermo Fisher Scientific

Thanks to special preparation methods, detection limits in the range of 1 µg/L have now been reached for many components in the isotope analysis of carbon or chlorine. For hydrogen isotopes the limit is about 2 orders of magnitude higher.

Device units and sample processing on Isodetect’s GC-IRMS device in BioCity Leipzig. 1) injection, 2) separation in GC column, 3) combustion to form CO2 molecules or H2 molecules, 4) separation of water, 5) occasional addition of the gaseous reference standard, 6) continuation to IRMS.

7) injection into IRMS through a needle valve, 8) ionization of CO2 molecules or 2H molecules, 9) separation of heavy (e.g. 13C-Co2+) and light (e.g. 12C-CO2+) ions in a high-vacuum magnetic field, 10) Measurement slots for quantification of targeted isotopes.

For elemental analysis, the target isotopes (e.g. of nitrate, sulfate) are often preparatively converted, separated by precipitation, dried and then weighed into metal capsules.

EA/Pyrolysis-IRMS: Isotope analysis of elements by oxidation or pyrolysis

The areas of application for elemental analysis of certain isotopes are extremely diverse and range from archaeological and geobiological investigations to forensic analyzes and product authentication. Elemental analysis usually requires prior preparation of the material. Before ionization in the IRMS, the sample is either oxidized (to determine C, N, S isotopes) or pyrolyzed (to determine H, O isotopes) online.

Frequent materials in elementary isotope analysis

13C/12C & 15N/13N: oil, bones, hair, teeth, food, pharmazeutics, ….
18O/16O & 2H/1H: any kind of waters, ….
34S/32S & 18O/16O: sulfate, sulfide, sulphur, ….
15N/13N & 18O/16O: nitrate, nitrite, ammonium, ….

Recently, Isodetect analyzed primate hair (gorillas, chimpanzees) as part of the PanAf project at the Max Planck Institute for Anthropology in Leipzig. We look forward to similar challenges.

Detail of the ion source of an IRMS, which uses electron bombardment to ionize simple molecular building blocks (e.g. CO2, H, O) of the analytes.

Isotopic analysis of groundwater tracers

Isodetect offers the analysis of all tracers for groundwater dating. We carry out the measurements in the BioCity Leipzig, in the environmental laboratories of our Helmholtz partners UFZ or HMGU or with cooperating partner laboratories that are specialized in certain tracers.

Recently, some tracers (14C, 18O, 2H, 85Kr) can be analyzed using new, fluorescence-based methods that require significantly smaller amounts of sample. This makes sampling easier, but can lead to significantly longer processing times.

Brief protocols for sampling and analysis of the main groundwater tracers

Tritium

Sampling and storage until analysis is done in 1 L glass or plastic containers. To measure tritium in H2O, the samples are electrolytically enriched and, after adding a scintillation cocktail, analyzed spectrometrically (liquid scintillation counting, LSC). Each sample is measured up to ten times for at least 100 minutes each and then the mean value is determined. Additional standards and blank samples are used to evaluate the data. The inaccuracy of the entire measurement method is ± 0.35 TU (standard deviation) for low tritium levels (<7 TU) and approx. 10% for higher tritium levels >7 TU. At 1 TU, a sample has an activity of 0.119 Bq/L.

oxygen-18 and deuterium

Samples were taken and stored until analysis in 20 ml glass or plastic containers. The determination of oxygen (18O) or deuterium (2H) in groundwater is carried out on a laser absorption device (e.g. PICARRO L2130-iδD/δ18O Ultra High-Precision). Here, an energy loss of a laser beam caused by the respective isotopes is determined. The measured values of the samples (10 individual measurements) are calibrated with international standards (SLAP, SMOW, GISP) and any drift or memory effects are corrected. The general measurement error is ±0.1‰ for 18O/16O or ± 0.5‰ (standard deviation) based on the VSMOV standard.

The method is limited to samples with no oil contamination and normal or low salinity (no seawater). For such samples we use a different measurement method (EA/Pyr-IRMS).

Carbon-14

Carbon-14 and carbon-13 are determined using accelerator mass spectrometry (AMS; Scharf et al. 2007). The mean measurement inaccuracies are 0.26 ‰ for pm 14C (percent modern) and 0.65 ‰ for δ13C.

This determination takes about 3 months.

Helium-3, Helium-4 and Neon

To determine helium isotopes and neon, approx. 40 mL groundwater is filled into a copper tube which is sealed with screw clamps. The dissolved gases are extracted from the water samples and transferred to a glass ampoule. After separation of helium and neon in a multi-stage cryogenic system, 4He, 20Ne and 22Ne are determined in a quadrupole mass spectrometer and 3He and 4He in a sector field mass spectrometer (Syltenfuss et al. 2009, The Bremen Mass Spectrometric Facility for the measurement of helium isotopes , neon, and tritium in water, Isotopes in Environmental and Health Studies 45(2), 1-13). Defined amounts of air are used for calibration.

CFCs and sulfur hexafluoride

To determine CFC and SF6, 1 L of groundwater is filled into ground glass bottles with the exclusion of air and free of gas bubbles. The bottles are transported in groundwater-filled metal containers. SF6 and CFC are determined using gas chromatography (ECD) according to Oster, Sonntag, Münnich (1996).

Krypton-85

To determine krypton-85, several cubic meters of water are degassed on site with a special device and collected in a gas tank. After drying the gas sample with a molecular sieve, the sample is concentrated and enriched to 85Kr by cryogenic distillation (passing through an activated carbon trap cooled with liquid nitrogen) and subsequent gas-chromatic purification. Subsequently, the 85Kr isotopes of approx. 10 µL krypton are recorded by means of laser excitation in a magneto-optical trap (so-called ATTA analysis; atom trap trace analysis). The detailed analysis protocol is discussed by Tu et al. (2014).

These determinations may take up to 6 months.

Manual sample injection on the GCC-IRMS.

GC-MS: fingerprint and concentration analysis with gas chromatographic mass spectrometry

Our GC-MS analyzers are specifically designed to identify and quantify metabolites, biomarkers (amino acids, fatty acids) and oil components (fingerprints).

Devices for the preparation, identification and quantification of metabolites and oil components

CTC Autosampler: PAL RTC, CTC Analytics
GC: Agilent 7890B (GC)
MS: 5977A MSD (MS)