A Salmonella Antigen Test Kit is a rapid diagnostic device used to detect the presence of Salmonella bacteria antigens in human stool, food, or environmental samples. It is designed for quick and accurate screening to help in the diagnosis of Salmonella infection (salmonellosis) — a common cause of foodborne illness.

1. Ion-Selective Electrode (ISE) Method

Most modern chemistry analyzers use ISE for sodium.

Reagents include:

• Reference solution / Internal standard

• Electrolyte solution for electrode stability

• Conditioning solution

• Cleaning solution

• Calibration solutions (Low & High Na⁺ standards)

Principle:

The sodium ISE membrane selectively binds Na⁺ ions, generating an electrical potential proportional to sodium concentration. Calibration solutions are crucial for accuracy.

2. Flame Photometry Method

Older or standalone electrolyte analyzers may use flame photometry.

Reagents include:

• Diluent

• Standard sodium solution

• Internal lithium standard (in some systems)

• Cleaning solutions

Principle:

Sodium emits light at a characteristic wavelength (589 nm) when introduced into a flame. The emitted intensity is proportional to concentration.

3. Colorimetric (Photometric) Method

Used in some semi-automatic chemistry analyzers when ISE is not available.

Reagents include:

• Ionophore-based chromogenic reagents

• Buffer solution

• Color-forming indicator dye

• Stabilizers and preservatives

Principle:

Sodium ions react with a specific ionophore dye to produce a measurable color change.

Reagent Format

Sodium reagent kits may include:

• Single bottle (for colorimetric systems)

• Multi-solution packs (ISE systems)

• Standards in sealed ampoules or bottles

• Ready-to-use liquid formulations

Sample Types

• Serum

• Plasma

• Urine (diluted appropriately)

• Whole blood (in ISE blood gas analyzers)