21

According to technical information for volumetric measurement provided by Brand, it is acceptable to use an ultrasonic bath. Both glass and plastic labware may be cleaned in an ultrasonic bath. However, direct contact with the sonic membranes must be avoided. Nevertheless, For gentle treatment of labware, clean immediately after use – at low ...


18

The analytical technique is called inductively coupled plasma optical emission spectroscopy. It was invented by a chemist V. A. Fassel, although it is pure physics. The specimen is digested in an acid, and a fine spray is created. That "spray" is heated to a temperature, which is higher than the surface of the Sun. Most of the elements of the periodic table ...


11

Inductively Coupled Plasma (ICP) based techniques are very common for elemental analysis. The goal of such analyses is to quantify the elements present in a sample. The neat thing about this, in my opinion, is that the integrity of the molecular compounds does not need to be maintained throughout the analysis, since we only care about the elements that ...


6

Neutron activation analysis is a technique that can be used for trace mineral quantification in a sample. You start by irradiating your sample in a small experimental nuclear reactor. These were more common in the 1960's and '70's than they are today. Slow neutrons are absorbed by many different isotopes, converting them to radioactive species. The sample ...


6

If your supervisor is unconvinced by Brand's guidance on this (as supplied by Loong in his answer), you could always test the effect of ultrasonic cleaning directly: Take, say, six volumetric flasks, and weigh the amount of water each holds when filled to the line. Then subject three to several cycles of ultrasonic cleaning (the other three can be left to ...


3

I see two possible answers. Not (A) and (B) but rather (A) and (D). Chakravarthy Kalyan is responsible for reminding us that (D) can be an answer too (refer to comments). For option (D): $\ce{HC ≡ CH + 2AgNO3 + 2NH4OH→ AgC ≡ CAg↓ + 2NH4NO3 + 2H2O}$ The greyish precipitate of silver acetylide will readily form when ethyne is passed through freshly ...


3

Easy marks for phenolphthalein usability are: $99.9\%$ of acetic acid is titrated at about $$\mathrm{pH} = \mathrm{p}K_\mathrm{a} + \log{1000} = 7.75$$ $100\%$ of acetic acid is titrated at $$\mathrm{pH} = 7 + \frac12 \cdot (\mathrm{p}K_\mathrm{a} + \log c) = 9.385 + \frac12 \log c$$ Phenolphthalein color transition is $8.2-10.0.$


2

I found one study that examined cerium(III) polyoxometalate salts and concluded that at least under the conditions of their study, $\ce{Ce(III)}$ did not oxidize under electrospray conditions. The study is Bray et al. 2011 in the International Journal of Mass Spectrometry. They say: The presence of the redox active $\ce{Ce}$ metal ion introduces ...


2

No, isotopes are always an issue, even just for hydrocarbons. $\ce{^13C}$ may only be 1.1% of most natural pools of carbon atoms, but as molecules get larger and larger, i.e. as they consist of more and more carbon atoms, the probability that at least one of the carbon atoms in a large molecule is carbon 13 becomes much larger. Molecules with more than ~...


1

The key point is estimation of standard deviation of estimation of measurement standard deviation on Stats SE. The exact formula is complicated with extensive Gamma function involvement. The essential info is the relative uncertainty of $s$ decreases very slowly with number of measurements. It can be approximated by involving Stirling approximation for ...


1

These parameters arise from non-dimensionalization of the Mathieu equations for ion motion in exogenous, periodically varying electric fields (i.e. oscillating potentials). You can't calculate $m/z$ directly from $a$ and $q$. For a fixed $U$ and $V$, you can regard $a$ and $q$ as non-dimensional parameters that correspond to $m/z$. (Conversely, at fixed $...


Only top voted, non community-wiki answers of a minimum length are eligible