Questions tagged [lab-reagents]

Chemicals used in the lab for experiments.

Filter by
Sorted by
Tagged with
0
votes
0answers
36 views

Is an uninoculated control (slant) catalase positive or negative?

The catalase test is a laboratory test utilized in identifying organisms which produce the enzyme catalase. Is an uninoculated control (slant test only) catalase positive or negative? I am assuming ...
1
vote
0answers
13 views

Does the preservation fluid (ethanol or formaldehyde) leach heavy metals from mollusc tissue?

In a thread on researchgate, the concern was raised that long term exposure to unbuffered preservation fluids such as ethanol or formaldehyde may leach heavy metals from biological samples due to a ...
0
votes
0answers
62 views

What is the difference between saturated phenol and equilibriated phenol?

I was confused about phenol while searching it in the context of PCI solution (phenol:chloroform:isoamylalcohol 25:24:1) recipe. -First, what is the difference between saturated phenol and ...
5
votes
1answer
91 views

Is there a reliable source for storage and stability of reducing agents like DTT?

Reading the literature on DTT, one is confronted with a confusing mass of papers; some claim that a 1M solution in water is stable, other papers say it is not. I use the reaction with DTNB to show ...
11
votes
2answers
33k views

Agarose vs agar? Why do DNA gels use agarose only and how do you obtain agarose from agar?

Agar is a relatively cheap substance from red algae. And it contains a saccharide agarose as well as a small amount of pectin. Agar is used for culture plates as is, but for DNA gels a grade of ...
0
votes
1answer
171 views

Use lab agar for cooking [closed]

Our lab manager suspect that something wrong with our lab Bacto agar (Difco). So she decide to throw it to the garbage. I think that it's just a waste to throw that thing. Can someone think of reason ...
4
votes
1answer
128 views

DNA quantification in a high school bio lab

I'm working on a project in a high school bio lab (so limited resources), and I need a way to quantify the concentration of DNA in a PCR product. I can't use spectrophotometry (cheap ...
1
vote
1answer
244 views

What is the difference between the usages of bis-tris methane and bis-tris propane?

I came across "bis-tris" buffer in Rodney Boyer's Biochemistry Laboratory book and tried looking it up. Then I found that there's bis-tris methane and bis-tris propane that are both buffers. What ...
3
votes
2answers
829 views

Agarose gel Ladder smear

We are having trouble with agarose gel electrophoresis. It used to work a couple of months ago but now the ladder always look smeared. We switched the components (1x TBE, 100bp ladder, different type ...
1
vote
0answers
31 views

What is the best solvent for Mutagen X?

Many solvents can be used for mutagen X (3-chloro-4-(dichloromethyl)-5-hydroxy-5H-furan-2-one), however, long-term stability is not specified. Which would be the best solvent for long-term storage? ...
2
votes
0answers
119 views

Can NADP be converted to NADPH using d glucose?

For one of our reaction, we require NADPH enzyme. We have NADP in our stock. Is it possible to convert NADP to NADPH using D-glucose anhydrous and if so please provide me how to go about it?
3
votes
1answer
156 views

FPLC based separation of serum proteins

I am working on a project which involves bio-marker discovery in neuro-developmental disorders. I have an akta-prime FPLC instrument in my lab but I do not know how to use it. According to theory, ...
2
votes
1answer
121 views

where can I find estimated costs of laboratory equipment? [closed]

Often when I am curious about purchasing new laboratory equipment I cannot find a ballpark figure for the price. Companies that sell expensive lab equipment prefer if you contact their customer ...
3
votes
1answer
2k views

“X” in stock solutions

We prepare buffer solutions with concentration in terms of x, for example 50x TAE buffer. How do we come up with ...
1
vote
0answers
107 views

Effective Mycoplasma Elimination from Primary Human Cultures

Obviously the best way to avoid mycoplasma contamination is to avoid it in the first place. In our case, however, it is not possible to avoid. We are culturing viruses and tissues out of human nasal ...
3
votes
1answer
886 views

Why is it advised to avoid bubble formation during mixing?

I have been told not to vortex solution containing protein. The reason I was given is bubble formation. Here I am interested in the effect of bubble formation in general.
3
votes
1answer
518 views

Reason for the source of fetal bovine serum

What is the reason that perhaps the most commonly used serum in labs is fetal bovine derived? Is there something about fetal serum that is particularly useful over say serum just harvested ...
4
votes
1answer
3k views

Is there a difference between Luria Broth and Lysogeny Broth?

Is there a difference between Luria Bertani and Luria Broth? Or are they both the same thing? Is it necessary to autoclave LB medium after it has been made?
0
votes
0answers
12 views

Must one autoclave LB medium after it has been made? [closed]

Is it necessary to autoclave LB medium after it has been made?
5
votes
3answers
792 views

Is NADPH salt still usable after an hour at room temperature?

I accidentally left a delivery of NADPH Tetrasodium Salt (Santa Cruz Biotechnology) at room temperature for a little over half an hour. In addition, when I opened up the package, I briefly held the ...
2
votes
2answers
519 views

Why do many DNA solutions contain additional compounds?

DNA solubility data in only water is scarce. A previous question asked for a quantification of DNA solubility in water. It seemed like it would be easily answerable, however isn't quite that simple ...
1
vote
3answers
2k views

Trypsin and cell culture

I am doing an experiment where I have treat the cells with a drug and calculate their counts. I would like to know if is bad to trypsinize the cells in consecutive days i.e. twice within 48 hours. How ...
5
votes
1answer
862 views

Is there a protocol for freezing and thawing Bacillus subtilis cells?

There is a book that says to store Bacillus spores in 50% glycerol at -70 degrees Celsius (doesn't mention if the 50% is final concentration or not). But from what I know, the cells themselves can be ...
1
vote
2answers
953 views

How to safely sterilize urea-containing growth medium?

I'm using urea-containing growth medium for experiments with bacteria (1-2 l/day). After the experiment, the growth medium has to be sterilized and disposed. I did this so far by autoclaving, but our ...
1
vote
1answer
837 views

What is Trypsin? [closed]

I am currently helping a PhD student in his research lab. We have been using Trypsin for the past couple of weeks but I am unsure of its purpose. I was wondering how Trypsin functioned and what it was ...
3
votes
3answers
4k views

Long term storage of agarose-ethidium bromide gels that have already been cast

I have come up with what I thought was a clever idea: Store the agarose gels I pour, and only cut as many lanes as I need to run later, minimizing wasted agarose (and wasted effort/time) when I need ...
5
votes
2answers
4k views

Is wiping with RNAse Zap enough to destroy RNAse activity?

From the RNAseZap MSDS, it is an SDS at some unknown concentration, maybe with some NaOH? Some other links suggest there is some NaOH as well. The Ambion site states that RNAseZap destroys RNAse ...
5
votes
1answer
809 views

What is the extent of the effect of Tris on E. coli?

I was a fool and dissolved my antibiotic (Kanamycin) into Tris Buffer rather than H₂O. The Kanamycin still seems to be active but a fellow labmate mentioned that Tris messes around with the membrane ...
4
votes
1answer
942 views

Can I heat Trizol?

I wonder if I can heat Trizol reagent for 30 min 65C. The goal is to disrupt protein-RNA complex while inhibiting nucleases. (I can't use RNasin cause it's inactivated in 65C, and can't use RVC cause ...
3
votes
1answer
529 views

PCR master mix contents

I am running PCR reactions with different sets of degenerate primers and I want to know what should go into the master mix My usual master mix: DEPC water PCR buffer (-Mg) 25mM MgCl2 10mM dNTPmix ...
2
votes
1answer
357 views

Substitute 25mM dNTPs mix with 10mM dNTPs

I need to make a solution of multiple compounds, one of them is dNTPs. The recipe calls for 20 μl 25 mM dNTPs in a 1250 μL master mix. Unfortunately I do not have it available at that concentration, ...
3
votes
1answer
522 views

What is the best way to clean plastic flasks that have been used for cell cultures - is virkon a good idea?

When you use cultures e.g. insect cells, which are infected with virus one way to clean the (plastics) shake flasks is with virkon. Which is the most effective way to clean your flasks in order to ...
3
votes
2answers
3k views

Just how light-sensitive is ethidium bromide?

One lab I was in was paranoid about keeping it in a foil-wrapped conical tube; my current lab leaves it out on the bench (and it works fine for staining gels). It's the same company/concentration in ...
3
votes
1answer
288 views

How do different tissue culture matrices affect background in fluorescent microscopy?

In response to my previous question, I've been reading up a little bit on poly-D-lysine, Collagen I, Collagen IV, laminin, and other tissue culture coatings that promote cell adhesion. I've always ...
4
votes
1answer
340 views

Is DNA green viewer carcinogenic?

I use DNA green viewer in Lab to see DNA and RNA bands. Some peers told me it is carcinogenic and is not safe. Is this correct? If yes, are there better choices to use in working with gel?
6
votes
1answer
2k views

What are good practices with reusing desalting columns

At least according to a few sources Prozyme and Protocols-Online, it is possible to reuse desalting columns and since I'm cheap I would like to also. Key things seem to be washing with several column ...
8
votes
2answers
397 views

What are key factors when evaluating and comparing miniprep columns?

I'm looking to comparing different protocols for minipreps for plasmid DNA purification. What factors should I be looking at? A few things come to mind: Cost Yield Time per step Replacement with ...