Protein Reagents | Total Protein Clinical Chemistry Kit

(Biuret Method – Liquid Stable)

Vanguard Diagnostics’ Protein Reagents kit enables precise, quantitative determination of total protein in human serum or plasma by the classic Biuret colour-reaction. The liquid-stable formulation delivers reliable results across routine and high-throughput laboratories, helping clinicians monitor nutritional status, liver function, and kidney disease with confidence.

Key features (per IFU)

• Method: Biuret end-point, absorbance 546 nm
• Linearity: up to 12 g/dL (120 g/L); dilute high samples 1 + 1 with saline and multiply result by 2
• Reaction time: 10 minutes at 37 °C / 20 minutes at room temperature
• Pack size: 2 × 50 mL ready-to-use reagent + calibrator
• Stability: unopened kit stable for 18 months at 2 – 8 °C; working reagent stable 30 days at 2 – 8 °C
• Interference (per IFU):
  

• Haemoglobin ≤ 500 mg/dL – no significant effect

• Bilirubin ≤ 20 mg/dL – no significant effect

• Lipaemia (Intralipid 1 000 mg/dL) – no significant effect

• Instrument compatibility: validated on semi-automated photometers and fully-automated chemistry analysers

Why choose Vanguard’s Protein Reagents

The Biuret method is the international reference technique for total protein measurement. Our liquid-stable formulation eliminates daily reagent reconstitution, reducing handling errors and saving technician time. Consistent linearity up to 12 g/dL ensures accurate results even in hyper-proteinaemia, while the long on-board stability suits busy, multi-shift laboratories.

For a comprehensive liver and renal panel, pair this kit with our Bilirubin Reagents and Urea UV Reagents – all calibrated to work seamlessly on the same analyser platform.

Clinical relevance

Total serum protein reflects the combined concentration of albumin and globulins. Low values may indicate malnutrition, nephrotic syndrome, or liver failure, whereas elevated results often accompany dehydration or chronic inflammation. The Biuret assay’s proven robustness makes it ideal for routine screening and for monitoring patients alongside albumin (see our Albumin Reagents) and globulin fraction calculations.

For reliable adult reference values, the NHS Total Protein test page cites typical serum protein ranges of 60–80 g/L, which can assist clinicians in evaluating laboratory results.

Frequently asked questions

What principle does the Protein Reagents kit use?

It follows the Biuret method: peptide bonds complex with copper(II) ions in alkaline solution to form a violet colour proportional to protein concentration.

What is the assay’s linearity range?

Accurate up to 12 g/dL (120 g/L). Dilute and re-run samples above this range.

Which sample types are acceptable?

Fresh serum or heparinised plasma. Avoid haemolysis and icterus above IFU limits.

How should I store the kit?

Keep unopened vials at 2 – 8 °C. After opening, the combined working reagent remains stable for 30 days at 2 – 8 °C when capped.

Is the kit compatible with automated analysers?

Yes. The ready-to-use liquid reagent is validated on leading semi- and fully-automated chemistry systems; follow your analyser’s programme for the Biuret total protein assay.