[Histonet] GLASSWARE CALIBRATION

[Smith, Allen]

Glass glassware, including glass pipets, has always been accurate enough for my needs in making up histological stains.  This is not (repeat NOT) true of pipettors with disposable tips: Some of my pipettors deliver exactly what they say they do, some deliver 50% more, and some deliver 3 times as much as their factory calibration claims.  I calibrate my pipettors by weighing the average volume of water delivered in 5 trials and write the "true" volume on a tape label on the barrel of the pipettor.  Antibody dilutions using 2 pipettors thus require a bit of calculation.
Allen A. Smith
Barry University School of Podiatric Medicine

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Rene J Buesa
Sent: Wednesday, March 28, 2012 8:39 AM
To: histonet; histonet; shehnaz khan
Subject: Re: [Histonet] GLASSWARE CALIBRATION

Calibrating glassware is a most in analytical chemistry but is of lesser importance while preparing staining solutions that, at the end, are going to used to determine if a tissue component has been stained or not, and seldom subjected to a quantitative intensity determination.
A (+) PAS-Schiff reaction is what is needed and the intensity can depend on the temperature of the reaction, the condition of the solution or the amounts of the (+) components in the tissue. With so many sources for intensity it is of little importance if your cylinder is reading exactly 100mL when you are preparing the solution or if that amount is ± 0.5mL, especially when human error has to be considered also at the moment of the preparation.
You have to trust the manufacturer of your glass equipment and accept the calibration provided with each glassware as true. Mind that, in addition, those calibrations are usually made at 20ºC and I do not think that 20ºC is the room temperature in most laboratories.
But, IF you want to calibrate some glassware, you will need an analytical balance (not a common piece of equipment), a good thermometer to determine the distilled water temperature, a table with the density of water at different temperatures and you have to fill your cylinder, pipette, or whatever glassware you want to calibrate to a certain mark and them weigh the water. Divide the result (in grams) between the density of the water at the temperature you made the measurement and you will get the value of the volume. 
Too much trouble, just trust the manufacturer of your glassware!
René J. 

--- On Wed, 3/28/12, shehnaz khan <shehnazster <@t> gmail.com> wrote:


From: shehnaz khan <shehnazster <@t> gmail.com>
Subject: [Histonet] GLASSWARE CALIBRATION
To: "histonet" <histonet <@t> pathology.swmed.edu>, "histonet" <histonet <@t> lists.utsouthwestern.edu>
Date: Wednesday, March 28, 2012, 4:51 AM


Hi netters,

Could someone please shed some light:

1. How is calibration for glassware performed on non-Class A glassware?

2.  If Class A glassware is used but no certificate is located - does
it still require calibration?

Thanx again.

S Kahn

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