Analytical Services Unit

Analytical Services Unit
Analytical Services Unit

Hydride Generation Spectroscopy

Hydride Generation - Atomic Absorption Spectroscopy

Hydride generation is a technique in which a reduction step is employed to convert certain elements to volatile metal hydrides. The atomization efficiency is thus greatly increased with a corresponding decrease in detection limits.

The technique has been in use for several decades and interferences are few and well known. Elements such as arsenic are routinely analyzed.

The ASU has a Vapor Generation Accessory (VGA77) from Agilent Technologies (formerly Varian) with electrothermal controller unit (ETC60) and furnace.

VGA Accessory

Hydride generation setup using a VGA77 unit and an ETC60 (not shown) with a furnace unit.


HG-AAS Laboratory Considerations

General

"The vapor generation technique demands a particularly high standard of care in all of the activities which affect the accuracy and precision of the analytical result. Scrupulous cleanliness is essential in all laboratory procedures. Standards and samples must be meticulously prepared and carefully handled. Strict precautions must be taken to avoid contamination of apparatus and even though laboratory ware is stored under ideal conditions, it should be carefully re-washed before use.

Strict care should also be taken to avoid contamination of all reagents and distilled water. Ideally, reagents should be entirely free of the elements of interest, but this is obviously impossible for all the analytes of interest in all reagents. Consequently, you must always establish the level of the analytical signal from the blank solution before calibrating the instrument and carrying out the analytical program".

See: Agilent Vapor Generation Accessory VGA77 Users Guide, P60.

Applications:

The following papers from Agilent Technologies illustrate some of the uses of HG-AAS.


Flameless Hydride Generation

Benefits of using the ETC60:

  • Flameless atomization for vapor generation AA
  • Reduced running costs because no acetylene gas required
  • Determines Hg and the 6 hydride-forming elements
  • Unattended operation for maximum productivity
  • Eliminates flame flicker noise
  • Improves sensitivity 20-30%
  • SpectrAA software controls the ETC 60 temperature directly (with Version 5 or later)
  • The ETC 60 is compatible with any instrument that can use the VGA77

ETC 60 and VGA 77 details from Agilent's website

The VGA77

Vapor Generation Accessory

See: Agilent Vapor Generation Accessory VGA77 Users Guide, P19.

  • Exceptional precision -1-2% RSD at ppb levels
  • High sample throughput - up to 70 samples/hour
  • Simple operation - the integral pump automatically adds reagents
  • Low sample consumption - < 8 mL per element during analysis

HG-AAS in a Mobile Laboratory

CAPE DYER - DYE-M

HG Instrument in DYE-M

A Varian FS240 with an ETC60 controller, VGA77 unit and furnace was setup in 2005 and 2006 to support the cleanup project located in Cape Dyer, (DYE-M), Nunavut, Canada. The unit was setup to analyze for arsenic in soil samples. The mobile laboratory was operated north of the arctic circle.