🔬 1. Direct Bilirubin (Conjugated) — Diazo Method

Principle

Direct (conjugated) bilirubin reacts directly with diazotized sulfanilic acid to form azobilirubin, a reddish-purple complex.

• Absorbance: ~540–560 nm

• Method: Endpoint or timed endpoint

• No accelerator needed (only conjugated bilirubin reacts)

Reagent Components

• Sulfanilic acid

• Sodium nitrite

• Hydrochloric acid (for diazo formation)

• Buffer (acetate)

• Preservatives

Some manufacturers supply:

• R1: Buffer

• R2: Diazo reagent

🧪 2. Total Bilirubin — Diazo Method (Accelerated)

Principle

Unconjugated bilirubin requires an accelerator to react with the diazo reagent.

Common accelerators:

• Caffeine–benzoate

• Surfactants

• Methanol or DMSO (older methods)

Total bilirubin reacts with diazo reagent to form azobilirubin.

• Absorbance: ~540–560 nm

• Method: Endpoint or timed endpoint

Reagent Components

• Caffeine-benzoate accelerator

• Sulfanilic acid

• Sodium nitrite

• Acid buffer

• Stabilizers and preservatives

Formats:

• 1-reagent systems (common today)

• 2-reagent systems (R1 accelerator + R2 diazo reagent)

1. Diagnostic Purpose

Biochemistry reagents are designed to quantitatively measure analytes such as:

• Liver function markers (ALT, AST, ALP, GGT, Bilirubin, Total Protein)

• Renal function markers (Urea, Creatinine, Uric Acid)

• Electrolytes (Sodium, Potassium, Chloride—depending on analyzer type)

• Lipid profile (Cholesterol, Triglycerides, HDL, LDL)

• Glucose metabolism (Glucose, HbA1c kits depending on system)

• Enzymes and substrates (LDH, CK, Amylase, Lipase)

2. Types of Formulations

Biochemistry reagents may come in:

• Single-reagent systems
  (One ready-to-use bottle)

• Two-reagent systems
  (R1 buffer + R2 starter/working reagent)

• Lyophilized reagents
  (Require reconstitution)

• Liquid-stable reagents
  (Long shelf-life, preferred for automated analyzers)

3. Compatibility

Designed for:

• Fully automated clinical chemistry analyzers

• Semi-automated bench-top analyzers

• Point-of-care analyzers (specific formats)

• Portable and Lightweight: Weighs only about 3.65 kg (8.05 lb), with a built-in rechargeable battery allowing for up to 50 continuous tests, making it highly mobile for bedside use.
• Easy to Use: Features an intuitive 7-inch color LCD touch screen and a simple, three-step operation procedure (sample collection, mixing, and introduction).
• Maintenance-Free: The use of disposable test cartridges and calibrant fluid packs eliminates the need for routine maintenance, gas cylinders, and minimizes biohazard risks.
• Fast Results: Provides results in as little as 35 seconds to one minute after sample aspiration, enabling quick clinical decisions.
• Data Management: Capable of storing up to 10,000 patient data points and supports seamless integration with Laboratory Information Systems (LIS) or Hospital Information Systems (HIS) via wired (USB, RS232) or wireless (WLAN) networking.
• Built-in Quality Control: Ensures accuracy and reliability through internal quality control mechanisms, an electronic simulator, and liquid quality control solutions. 

Key Features Highlighted:

• Built-in printer – allows on-the-spot result printing.

• Built-in multi-timers – supports simultaneous testing of multiple assays.

• On-board QC & system check – automatically verifies calibration and system performance.

• Battery and AC operated – supports both portable and stationary use.

Design Overview:

• It has a touchscreen interface displaying various test parameters and results.

• The sample cartridge slot is located at the front, below the touchscreen.

• The overall appearance is sleek, compact, and white, with a professional, lab-grade finish.