DrBaboon
10-23-05, 22:55
From this other thread: http://medtech.syrene.net/forum/showthread.php?t=2063&page=4
FWIW - the Compur line of products has been made and marketed under a variety of names in the last 20 years or so.
I have a Compur M1000 hand-held, AA battery (5 cells) operated spectrophotometer from the 1980's. It's no longer marketed in the US, but I believe is available in Europe, or at least Germany.
It's set up for hemoglobin (using Drabkin's method) and RBC estimation by turbidity. It operates at a fixed 540nm on the spectrophotometer.
Unfortunately, it uses proprietary plastic cuvettes (color coded - red for hemoglobin, green for RBC's) that come prefilled with reagent. A 5microliter capillary filled with blood is dropped into the cuvette and mixed with reagent, and then run in the spectrophotometer.
The scale reads in hemoglobin and RBC numbers.
Ames distributed it in the US. I found some links indicating some retailers carrying stuff for it in Germany recently.
It's been years since I used mine. I have a few expired cuvettes left. I suppose they could be recharged with reagent if push came to shove. I haven't looked to see if a modern reuseable cuvette for *normal* laboratory spectrophotometers is a close enough fit to work. It's easy enough to buy some Drabkin's reagent - perhaps even make some, although it contains potassium cyanide and potassium ferrocyanide. It's also possible to micropipette the correct amount of blood into a cuvette filled with reagent.
I wouldn't bother with the RBC method by turbidity. It's "iffy." It also depends on having RBC cell sizes (see earlier discussion of MCV) that is very much in the normal range. Low MCV cell populations will give lower RBC readings than actually what the RBC count is, and HIGH MCV cell populations will give higher RBC counts than what is actually the RBC count. I'd consider this to be primarily a Hemoglobin machine.
Which would I prefer if I could choose micro-capillary "spun" hematocrits or hemoglobin? I don't think it matters. I have a decades old microhematocrit centrifuge, which is pretty bulletproof. It'll last a few more decades. I'd probably choose it. The trade-offs are that it's a *lot* heavier than the Compur M1000 hemoglobin machine, but all you need are capillary tubes and the means to get blood into them, and a few cards/tubs of clay (or a reasonable facsimile) to plug the end of the capillary after filling it. Oh yeah - you also need some sort of hematocrit measurer - there is of course, an example of one in the book.
The Compur M1000 is light (maybe a pound or 2 with the case, batteries, some supplies) and maybe 8" or so square and maybe 2" thick in the case. It has its advantages.
Oh - FWIW - while I mentioned in my introduction I'm in internal medicine/geriatrics, and I think I mentioned I used to do more labwork in my office, my undergrad degree is chemistry. If I had not gone to med school, I was set to do graduate work in analytical chemistry - more along the lines of automated instrumentation development - as it relates to clinical chemistry. I'm 20+ years out of step with that industry, but at one point did have an interest and at least some of the skill and experience to work on some of these things.
I'm thinking outloud when I add this... But I've started to consider which other clinical chemistry tests would be most useful, or even possible as wet lab work goes, and whether it could be worked out that would produce an absorption peak at or near 540nm. If so, something might be possible by calibrating to the hemoglobin/RBC scale on the Compur. No idea at this time if anything is possible. I'm simply tossing out the idea.
I guess it's actually *not* still available in Europe, but has aftermarket prefilled cuvettes available from a third party in Germany.
http://www.diaglobal.de/de/produkte/reagenzien-kontrollen/eckkuevetten.html
I actually settled down and looked at some of the leftover cuvettes.
They are 12.5mm x 12.5mm - which turns out to be a standard size, with a 10mm light path. There are disposable plastic cuvettes at decent prices.
http://www.scicominc.com/cuvettes.htm
http://novabiotech.com/cells.htm
There are, of course, also the nice, expensive, reuseable cuvettes in that size. I suppose that in the long run, they would be nice to have, and maybe not so expensive in a long-term situation.
All you need is to dispense the correct volume of Drabkin's solution, and the corresponding volume of whole blood.
I think I'm going to try to rehabilitate my Compur 1000 for hemoglobin determinations, but not RBC estimations (for reasons already given - namely, concern that RBC by this method is not as reliable - due to varying MCV).
FWIW - the Compur line of products has been made and marketed under a variety of names in the last 20 years or so.
I have a Compur M1000 hand-held, AA battery (5 cells) operated spectrophotometer from the 1980's. It's no longer marketed in the US, but I believe is available in Europe, or at least Germany.
It's set up for hemoglobin (using Drabkin's method) and RBC estimation by turbidity. It operates at a fixed 540nm on the spectrophotometer.
Unfortunately, it uses proprietary plastic cuvettes (color coded - red for hemoglobin, green for RBC's) that come prefilled with reagent. A 5microliter capillary filled with blood is dropped into the cuvette and mixed with reagent, and then run in the spectrophotometer.
The scale reads in hemoglobin and RBC numbers.
Ames distributed it in the US. I found some links indicating some retailers carrying stuff for it in Germany recently.
It's been years since I used mine. I have a few expired cuvettes left. I suppose they could be recharged with reagent if push came to shove. I haven't looked to see if a modern reuseable cuvette for *normal* laboratory spectrophotometers is a close enough fit to work. It's easy enough to buy some Drabkin's reagent - perhaps even make some, although it contains potassium cyanide and potassium ferrocyanide. It's also possible to micropipette the correct amount of blood into a cuvette filled with reagent.
I wouldn't bother with the RBC method by turbidity. It's "iffy." It also depends on having RBC cell sizes (see earlier discussion of MCV) that is very much in the normal range. Low MCV cell populations will give lower RBC readings than actually what the RBC count is, and HIGH MCV cell populations will give higher RBC counts than what is actually the RBC count. I'd consider this to be primarily a Hemoglobin machine.
Which would I prefer if I could choose micro-capillary "spun" hematocrits or hemoglobin? I don't think it matters. I have a decades old microhematocrit centrifuge, which is pretty bulletproof. It'll last a few more decades. I'd probably choose it. The trade-offs are that it's a *lot* heavier than the Compur M1000 hemoglobin machine, but all you need are capillary tubes and the means to get blood into them, and a few cards/tubs of clay (or a reasonable facsimile) to plug the end of the capillary after filling it. Oh yeah - you also need some sort of hematocrit measurer - there is of course, an example of one in the book.
The Compur M1000 is light (maybe a pound or 2 with the case, batteries, some supplies) and maybe 8" or so square and maybe 2" thick in the case. It has its advantages.
Oh - FWIW - while I mentioned in my introduction I'm in internal medicine/geriatrics, and I think I mentioned I used to do more labwork in my office, my undergrad degree is chemistry. If I had not gone to med school, I was set to do graduate work in analytical chemistry - more along the lines of automated instrumentation development - as it relates to clinical chemistry. I'm 20+ years out of step with that industry, but at one point did have an interest and at least some of the skill and experience to work on some of these things.
I'm thinking outloud when I add this... But I've started to consider which other clinical chemistry tests would be most useful, or even possible as wet lab work goes, and whether it could be worked out that would produce an absorption peak at or near 540nm. If so, something might be possible by calibrating to the hemoglobin/RBC scale on the Compur. No idea at this time if anything is possible. I'm simply tossing out the idea.
I guess it's actually *not* still available in Europe, but has aftermarket prefilled cuvettes available from a third party in Germany.
http://www.diaglobal.de/de/produkte/reagenzien-kontrollen/eckkuevetten.html
I actually settled down and looked at some of the leftover cuvettes.
They are 12.5mm x 12.5mm - which turns out to be a standard size, with a 10mm light path. There are disposable plastic cuvettes at decent prices.
http://www.scicominc.com/cuvettes.htm
http://novabiotech.com/cells.htm
There are, of course, also the nice, expensive, reuseable cuvettes in that size. I suppose that in the long run, they would be nice to have, and maybe not so expensive in a long-term situation.
All you need is to dispense the correct volume of Drabkin's solution, and the corresponding volume of whole blood.
I think I'm going to try to rehabilitate my Compur 1000 for hemoglobin determinations, but not RBC estimations (for reasons already given - namely, concern that RBC by this method is not as reliable - due to varying MCV).