MEDIVEERSETHE PRACTICAL HUB
Comparator body: located on the reference instrument. Compare its shape and position with the apparatus used in your practical.
Zoom in, then drag to inspect. Keyboard: + / − to zoom, arrows to pan, 0 to reset. Tap the numbered markers to explore parts.
Sahli haemoglobinometer — reference view
Image: Ajay Kumar Chaurasiya · Source / original · CC BY-SA 4.0Resized and converted to WebP; original colours retained.
Sahli haemoglobinometer
Sahli’s apparatus · acid haematin method
What is its use?
Estimates haemoglobin by visual matching of acid haematin colour in a teaching laboratory.
Tap a number to locate its part. Zoom, drag or use full screen to inspect the reference. Models and graduations can differ; check the actual apparatus used in your laboratory.
How to recognise it.
- Comparator with coloured reference standards
- Graduated haemoglobin tube sits in the comparator
- A matching blood pipette belongs to the set
A haemocytometer counts cells; Sahli’s apparatus estimates haemoglobin concentration. Modern validated laboratory analysers use different measurement methods.
Point them out.
Choose a part to bring its numbered marker into view.
The science behind the reading.
Haemoglobin is converted to brown acid haematin; colour intensity is compared with the instrument standards. Visual matching introduces observer error.
Think first. Then reveal.
Explain your answer aloud before opening it.
01What is the principle?+
Visual colour comparison after formation of acid haematin.
02What units are commonly read?+
g/dL on the appropriate graduated scale; verify the scale on the actual tube.
03Why is the method relatively imprecise?+
Subjective colour matching, ageing standards and incomplete conversion of some haemoglobin derivatives can affect results.
04Is it a cell-counting device?+
No. Haemoglobin concentration and red-cell count are different measurements.
Read the references.
Teaching and clinical references are listed here. Image attribution and licence appear below the viewer.