NANJING LAB

Do you have any questions: Why are there double charge indicators on the performance report and calibration report? That's because double charge is also a common type of mass spectrometry interference that needs to be controlled. This kind of interference is very unfamiliar to ordinary users, and the flow rate KED method generally recommended by manufacturers cannot solve it or even has the opposite effect. Below, I use a little experience and a lot of speculation to sort out the way a single quadruple rod copes with double charges. The conclusion is not important and it is purely a sharing of ICP-MS technology. If it can arouse everyone's thinking, it will be very valuable. I hope it can serve as a starting point. For the convenience of discussion, this article only takes As and Se as examples to describe.

Wafer foundries (Fabs), especially those with advanced processes, are extremely stringent about particle control. In the 7nm and 5nm processes, any tiny particles may cause serious defects, and humans, as the primary source of particles, naturally become the subject of strict control. Wearing ultra-clean clothes is particularly important, and there are strict wearing procedures. Today I will teach you how to standardize wearing ultra-clean clothes.

During the etching process, dopants increase the conductivity of silicon, making it more susceptible to electrochemical etching. Different doping concentrations will result in different etching rates, with highly doped silicon generally etching faster. In the diffusion process, the doping concentration of the silicon wafer also affects the diffusion rate of dopants in silicon. Highly doped silicon causes the dopants to diffuse deeper.

As detection technology continues to advance and people pay more and more attention to food safety, the detection limits for the analysis of certain harmful heavy metal elements in food are getting lower and lower. For the detection of elements with a content of 10-6 mg/kg (ppm, trace level), flame atomic absorption spectrometer and inductively coupled plasma emission spectrometer can meet the requirements; but For element detection at the 10-9 mg/kg (ppb, trace level) level, We need to use an atomic fluorescence photometer, a graphite furnace atomic absorption spectrometer, and an inductively coupled plasma mass spectrometer (ICP-MS) to meet the requirements. Ⅰ. Atomic Fluorescence Photometry The atomic fluorescence photometer uses potassium borohydride or sodium borohydride as the reducing agent to reduce the element to be measured in the sample solution into volatile covalent gaseous hydride (or atomic vapor)

The purpose of sample pretreatment is to remove interfering substances, increase detector sensitivity (enrichment), protect the chromatographic column, etc., and also to prevent instrument failure. Among them, sample extraction is a key step in success or failure. It is extremely difficult to extract trace components from a large number of interferences. Sample pretreatment should include all operations before injection. In addition to steps such as weighing, dissolving, and diluting, these steps are also required: ① Filtration; ② Extraction; ③ Derivatization (pre-column derivatization); ④ Liquid chromatography (low-pressure column chromatography). You can do it manually or automate it. Do you know how to preprocess samples? Some samples cannot be injected and analyzed after pretreatment and need to be derivatized.

Referring to the work of Dr. Paul R. Gaines, this article further describes the nine elements that are prone to problems. These elements include: Hg, Au, Si, Os, Na, Ag, As, Ba and Pb. In fact, enough has been written about the issue of Hg: Does the stubborn memory effect of Hg trouble you? Specific experimental results are listed below. Hg stability experimental results. ① Mercury is stable in glass (only borosilicate glasses studied) in 5% nitric acid at room temperature for 4 years at all concentrations studied (0.05 to 1000 µg/mL).

Referring to the work of Dr. Paul R. Gaines, this article further describes the nine elements that are prone to problems. These elements include: Hg, Au, Si, Os, Na, Ag, As, Ba and Pb. In fact, enough has been written about the issue of Hg: Does the stubborn memory effect of Hg trouble you? Specific experimental results are listed below. Hg stability experimental results. ① Mercury is stable in glass (only borosilicate glasses studied) in 5% nitric acid at room temperature for 4 years at all concentrations studied (0.05 to 1000 µg/mL).

① Because the element Ag is too special, I want to talk about it again. Ag is very stable in pure nitric acid, but it cannot contain trace amounts of Cl, otherwise elemental Ag will eventually be formed and will not be stable in the solution. 35% hydrochloric acid can keep 100ppm of Ag element in complex form and exist stably. For 10% hydrochloric acid (here refers to pure hydrochloric acid diluted approximately 4 times), 10ppm Ag can be stabilized. Further: ppb level Ag can actually be obtained with a lower concentration of hydrochloric acid. ②Hg can form a complex with four Cl, so it can stabilize Hg. But the concentration cannot be too high. If the Hg concentration is too high, Cl will not be enough, so the Hg standard solution is a nitric acid matrix. Because even if 1000ppm of Hg is adsorbed on the container to dozens of ppb, the impact is so small that it can be ignored.

First of all, red means good solubility. It can be seen that most elements are easily soluble in dilute nitric acid aqueous solution. I lack experience with the insoluble Mo element here and have not found any instability. I temporarily think it may be unstable in a nitric acid system. Elements that are not easily soluble are divided into several categories: The first category, F, represents elements that are complexed with F and can be soluble in nitric acid, which means that only a small amount is needed (I think less than 0.1%). These elements include Ti, Zr, Hf, Nb, Si, Ge, Sn, Sb (T stands for tartaric acid which can also stabilize Sb). The second category, elements that require a large amount (percentage content) of hydrofluoric acid to stabilize: Ta, W. Category III: Ru, Rh, Ir, Pt, and Au require a percentage of HCl to be dissolved in nitric acid.

hydrofluoric acid matrix The HF matrix must be a hydrofluoric acid-resistant system. There is really insufficient funds, and the Nebulizers must be PFA. Hydrofluoric acid-resistant systems tend to have more severe memory effects and are more expensive. However, as long as the sample contains Si-related substances, HF is necessary, and some elements can only be stabilized by the HF system. Of course, more elements cannot be stabilized in the HF matrix with a percentage content at ppb level concentration.