All Questions
Tagged with equipment analytical-chemistry
14
questions
7
votes
1
answer
2k
views
Why are amber bottles used to store Water for HPLC?
Image Source: https://www.calpaclab.com/water-hplc-spectro-grade-4-liter-bottles-case-4/ted-ws2211-001
When ordering HPLC/Spectro grade Water for HPLC from certain vendors(not all), it comes in an ...
- 1,528
1
vote
0
answers
49
views
What is the sample density used for a buoyancy mass correction?
For a lab exercise to calibrate volumetric glassware I was given the follow equation to correct weighings for the density of air:
$$m_\mathrm{c} = m_\mathrm{s}\,\frac{1 - \rho_\mathrm{a}/\rho_\mathrm{...
- 29
6
votes
2
answers
844
views
Is there a simple way to distinguish grades of purity for copper metal?
Is there a simple way to distinguish different grades of fine copper purity (on a trace metal basis) that can be carried out in a small lab?
Specifically, I would like to be able to differentiate 4N, ...
- 1,097
10
votes
3
answers
5k
views
Is it better to use a smaller, more accurate measuring cylinder several times or a larger, less accurate one for the same volume?
I need to measure out 70 ml of liquid.
I have a 10 ml measuring cylinder with a maximum uncertainty of 0.1 ml and a 100 ml measuring cylinder with a maximum uncertainty of 1 ml.
I've calculated that ...
- 111
7
votes
2
answers
10k
views
How to identify a blow-out pipette?
Is my pipette a blow-out pipette?
I suspect that it is a blow-out pipette, though the double lines aren't rings. My guess is it is a TC blow-out pipette. It's a big 50 mL pipette, longer than my arm.
...
- 197
0
votes
0
answers
86
views
BOD5 respirometric method
I operate in a wastewater treatment plant laboratory and I use respirometric method for BOD5 measurement (hach direct plus). Recently I am obtaining high value for BOD (biological oxygen demand) for ...
- 13
1
vote
0
answers
391
views
How does the "sample type" selection on the MassHunter software for Agilent 7900 ICP-MS affect the quantitative results?
I'm new to using the instrument, and recently I have tried to measure Cr in both the eluent(1% nitric acid) and a method blank (also 1% nitric acid, but after it has gone through the entire analytical ...
- 136
22
votes
2
answers
5k
views
pH probe bulb - what is happening within the glass?
I am trying to understand how the glass bulb of a pH electrode of a pH meter works - the glass bulb itself. Not the reference electrode or the rest of the electrode (HCl, Ag/AgCl wire, etc...), the ...
- 5,900
1
vote
0
answers
471
views
Possible Method for Testing Ammonia (and Nitrite/Nitrate) Concentration in Water
I am designing an automated system testing device for my high school's aquaponics club. We need to test for a number of ion concentrations, including ammonia and nitrite/nitrate. In my research, the ...
- 11
0
votes
3
answers
15k
views
How to judge accuracy and precision of measurement devices?
I am unsure about the accuracy and/or precision of measuring instruments.
For example, if we have a graduated cylinder, a pipette and a beaker, how and why can we assert them that they can be used ...
- 11
7
votes
3
answers
39k
views
What's the difference between pipettes calibrated "TD", "TC", "Blow-out" and related terms?
I've never blown-out the last drop of any glass pipette I've ever used during my undergraduate studies. Recently I re-read some notes I had lying around in order to prepare a class I had to give to a ...
- 966
10
votes
2
answers
8k
views
0
votes
1
answer
1k
views
Estimating magnitude of percentage and absolute error
Can someone at least give me a hint to push me in the right direction of how to estimate the magnitude of the absolute and percentage errors when using a smaller amount in mL of a substance for a lab ...
- 749
2
votes
0
answers
476
views
Glassware Test Instruments CAD blocks library
I am designing a fairly simple distillation for dichloromethane.
Being an engineer I feel more comfortable working with precise dimensions of both the separate glass vessels (condensers, evaporators, ...
- 211