Batch Hydride Generation AAS

What is the Batch Hydride Generation AAS?

A batch hydride generation AAS reacts each sample in a closed vessel and transfers the hydride to the atomizer. It is a low-cost manual option for small laboratories and occasional arsenic or selenium tests.

Overview

In batch operation a measured volume of sample is placed in a reaction vessel, acid and reductant are added, and the vessel is quickly sealed. The generated hydride accumulates in the headspace and is swept by carrier gas into the heated quartz tube, producing a transient peak. Because each sample is treated separately, the operator controls timing manually and throughput is lower than with flow systems. The approach uses simple, inexpensive glassware and is easy to understand, which suits teaching and occasional testing. Peak reproducibility depends on fast, consistent mixing and transfer, and the reaction vessel must be purged between samples to avoid carry-over. Detection limits are similar to continuous flow when the timing is well controlled, but precision is usually worse and operator skill matters more. It is best for low sample numbers and moderate sensitivity requirements.

How does it work?

The sample is mixed with acid and sodium borohydride, which reduces the analyte to a volatile covalent hydride such as arsine or selenide. A carrier gas sweeps the hydride into a heated quartz tube or a small flame, where it decomposes into free atoms. The atoms absorb light from an element-specific hollow-cathode lamp, and absorbance follows the Beer-Lambert law. Because the hydride is separated from the liquid matrix before atomization, most interferents remain behind, which gives high sensitivity and low background. Mercury can be determined by cold vapor generation without heating because it is already volatile. Reaction conditions such as acid type and concentration, borohydride concentration, flow rates and reaction temperature must be tightly controlled, and interfering ions such as copper and nickel are masked or removed. Calibration uses aqueous standards treated in the same way as samples.

What are the key features?

• Closed reaction vessel with manual reagent addition
• Headspace accumulation and carrier gas transfer
• Simple low-cost glassware and fittings
• Heated quartz tube atomizer
• Manual timing and purge between samples
• Suitable for teaching and occasional testing

What are the technical specifications?

A typical batch hydride generation aas configuration offers elements of As, Se, Sb, Bi, Sn, Hg, detection limit of 0.1–1 µg/L, reaction vessel volume of 25–100 mL, carrier gas of argon or nitrogen, 200–600 mL/min, quartz cell temperature of 800–900 °C and reductant of 1–3% sodium borohydride. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Batch Hydride Generation AAS is used in occasional arsenic testing in small laboratories, teaching and method demonstration, on-site or remote testing without automation and sample screening before confirmatory analysis. Across the wider Hydride Generation AAS class, laboratories also deploy it for arsenic and selenium in drinking water, arsenic and mercury in rice, fish and seafood and antimony and tin in packaging material migration.

Which standards and certifications apply?

Relevant standards and methods include Ph. Eur. 2.2.22 Atomic absorption spectrometry, USP <852> Atomic Absorption Spectroscopy, ISO 11969 Water quality — Determination of arsenic by AAS, US EPA Method 7062 Arsenic by hydride generation, US EPA Method 7473 Mercury in solids and solutions and IEC 61010-1. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety compliance; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Hydride generation uses sodium borohydride solutions that must be prepared fresh or kept cooled, and reactions can release hydrogen gas, so ventilation is required. Acid and reductant concentrations, tubing lengths and gas flows affect the yield and must be fixed in the method. Interfering elements are controlled with masking agents such as thiourea or by separation. Quartz cells cloud with use and need periodic cleaning or replacement, and their temperature affects atomization efficiency. Because the technique measures a transient or steady signal from a gas, blank contamination from reagents is a common problem; ultrapure reagents and method blanks are essential. Install the system on the flame or furnace instrument with the correct gas supply and waste handling.

How do I select the right Batch Hydride Generation AAS?

Select the batch variant only when sample numbers are low, budget is limited and manual operation is acceptable. Confirm that the operator can reproduce mixing and timing, and that ventilation handles the hydrogen released during the reaction. For routine or regulated work, a continuous-flow system gives better precision and traceability.

How does it compare with other Hydride Generation AAS variants?

Choose a hydride generation system when the target elements are arsenic, selenium, antimony, bismuth, tin, tellurium or mercury and detection limits around 0.01 to 0.5 micrograms per litre are required at moderate cost. Continuous-flow designs offer stable signals and good throughput, flow-injection designs use less reagent and allow fast transient measurements, and batch systems are cheapest but slowest. If mercury is also required, add a cold vapor module or select an instrument with both modes. Multi-element configurations reduce time when several hydride-forming elements are measured together. For very low detection limits on arsenic and selenium, compare with ICP-MS, which may offer lower limits at higher cost.