Analytical chemistry is the science of obtaining, processing, and communicating information about the composition and structure of matter. In other words, it is the art and science of determining what matter is and how much of it exists. In 2012 (salary survey data), analytical chemistry was the most popular field of work for ACS chemists.
Analytical chemists use their knowledge of chemistry, instrumentation, computers, and statistics to solve problems in almost all areas of chemistry and for all kinds of industries. For example, their measurements are used to assure the safety and quality of food, pharmaceuticals, and water; to assure compliance with environmental and other regulations; to support the legal process; to help physicians diagnose diseases; and to provide measurements and documentation essential to trade and commerce. Analytical chemists often work in service-related jobs and are employed in industry, academia, and government. They conduct basic laboratory research; perform process and product development; design instruments used in analytical analysis; teach; and work in marketing and law. Analytical chemistry can be a challenging profession that makes significant contributions to many fields of science.
Stand-off remote Raman. In standoff Raman, the sample is measured at a distance from the Raman spectrometer, usually by using a telescope for light collection. Remote Raman spectroscopy was proposed in the 1960s and initially developed for the measurement of atmospheric gases. The technique was extended In 1992 by Angel et al. for standoff Raman detection of hazardous inorganic and organic compounds. Standoff Raman detection offers a fast-Raman mode of analyzing large areas such as a football field in minutes. A pulsed laser source and gated detector allow Raman spectra measurements in the daylight and reduces the long-lived fluorescent background generated by transition ions and rare earth ions. Another way to avoid fluorescence, first demonstrated by Sandy Asher in 1984, is to use a UV laser probe beam. At wavelengths of 260 nm, there is effectively no fluorescence interference and the UV signal is inherently strong. A 10X beam expander mounted in front of the laser allows focusing of the beam and a telescope is directly coupled through the camera lens for signal collection. With the system's time-gating capability it is possible to measure remote Raman of your distant target and the atmosphere between the laser and target.
Vibrational spectroscopy is concerned with the transitions due to absorption or emission of electromagnetic radiation. These transitions appear in the range of 102 to 104 cm−1 and originate from the vibration of nuclei constituting the molecules. A chemical bond in a molecule can vibrate in many ways, and each vibration is called vibrational mode. There are two types of molecular vibrations, stretching and bending. A stretching vibration is characterized by movement along the bond axis with increasing or decreasing of the interatomic distances, whereas a bending vibration consists of a change in bond angles with respect to the remainder of the molecule. The two widely used spectroscopic techniques based on vibrational energy are the Raman spectroscopy and the infrared spectroscopy. Both methods give complementary information and are based on the fact that within any molecules the atoms vibrate with a few definite sharply defined frequency characteristics of that molecule. When a sample is eradiated to a beam of incident radiation, it absorbs energy at frequencies characteristic to that of the frequency of the vibration of chemical bonds present in the molecules. This absorption of energy by vibrating chemical bond results in an Infrared spectrum. Raman spectroscopy is a scattering phenomenon, and arises due to the difference between the incident and scattered radiation frequencies. It utilizes scattered light to gain knowledge about molecular vibration, which can provide information regarding the structure, symmetry, electronic environment, and bonding of the molecule.
The increasing demand for product quality improvement and production rationalization in the chemical, petrochemical, polymer, pharmaceutical, cosmetic, food, and agricultural industries has induced a significant renaissance of the vibrational spectroscopic techniques of Raman, infrared (IR), and near-infrared (NIR) spectroscopy. This trend has partly led to the gradual substitution of time consuming conservative analytical techniques (gas chromatography (GC), high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and mass spectroscopy (MS)) and nonspecific control procedures (temperature, pressure, pH, and dosing weight) by the more specific and environmentally compatible analytical tools of vibrational spectroscopy. Thus, infrared (IR), NIR, and Raman spectroscopy have emerged over the last decade – in combination with imaging accessories, light-fiber optics, new in-line and on-line probes, and chemometric evaluation procedures – as extremely powerful methods for industrial research, quality control, and process monitoring. Specifically, the NIR wavelength gap between the visible and the IR region, which has over a long period been lying idle, has eventually also been filled with life and is now used according to its real potential.
1960年にドイツでGünther Laukienによって設立された。1965年に独立した3チャンネルを備える全半導体式の最初の高分解能核磁気共鳴分光計であるHFX 90を発売した。この製品は欧州とアメリカでの市場で普及して会社の発展の原動力になった。 マサチューセッツ州ビレリカに本社があり、6000人以上の従業員を擁する。核磁気共鳴分光計の代表的な企業で日本国内の大学、研究機関にも多数の納入実績がある。1976年にはMRIを開発した。現在ではM&Aによって分析機器メーカーを傘下に収め、蛍光X線分析装置や赤外・近赤外・ラマンスペクトロスコピー、質量分析計や画像診断装置等を手がける。
株式会社堀場製作所（ほりばせいさくしょ 英名：HORIBA, Ltd.）は、京都府京都市南区に本社を置く独立系の分析・計測機器大手。設立以来、分析・計測機器の総合メーカーとして、多彩な製品を世界各国に送りだしてきた。その分野は、自動車や半導体産業をはじめ新素材、エネルギー、鉄鋼、食品、バイオ、化学等々多岐にわたる。最近では、地球温暖化ガス分析装置や酸性雨測定装置など、環境保全に貢献する製品も、多数活躍している。 M&Aを積極的に行い企業価値向上に努めている。社是は「おもしろおかしく」。エンジン排ガス測定・分析装置分野で80%の世界トップシェアを握る。
1945年（昭和20年）10月 - 堀場雅夫が京都市下京区で「堀場無線研究所」を創業。
2015年（平成27年）9月 - フォルクスワーゲンの排出ガス規制不正問題を発見した研究所が使用したポータブル測定機が堀場製作所が製造した製品である事が報道されて一時的に株価が上昇した
株式会社島津製作所（しまづせいさくしょ、英: Shimadzu Corporation）は、京都府京都市中京区に本社を置く、精密機器、計測器、医療機器、航空機器を製造する企業である。
Mass spectrometer analysis is used in detection and identification of chemical structure of given unknown mixture. It provides precise quantitative analysis and technique to detect the ultra-trace levels.
The spectrometer works in following steps
Mass spectra contains several sets of peaks which corresponds to the molecular ion, isotope peak, fragmentation peaks and metastable peaks. Out of these peaks the molecular ion peak is mostly visible and can be weak or missing. The molecular ion is a cation (M+) formed by removing one electron from the molecule.
The relative intensity of the molecular ion peak decreases with branching and with molecular mass in a homologous series. For example in mass spectra of toluene the molecular ion peak is located at 92 m/z same as the molecular mass of toluene and preceded by a M-1 or M-2 peak.
The peak with the highest intensity is called the base peak which is not necessarily the molecular ion. Other peaks are larger than the molecular ion peak because of isotope distributions and known as isotope peaks.
10e-18 of a mole
The mass-to-charge ratio (m/Q) is a physical quantity that is most widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics. It appears in the scientific fields of electron microscopy, cathode ray tubes, accelerator physics, nuclear physics, Auger electron spectroscopy, cosmology and mass spectrometry. The importance of the mass-to-charge ratio, according to classical electrodynamics, is that two particles with the same mass-to-charge ratio move in the same path in a vacuum when subjected to the same electric and magnetic fields. Its SI units are kg/C. In rare occasions the thomson has been used as its unit in the field of mass spectrometry.
A positively charged ion. Opposed to anion.
Psi = Pound per square inch
1 Psi = 0.0689475729 Bar = 6 894.75729 pascals
1 Bar = 100 kilopascals.
It is very close to the atmospheric pressure (atm) which is the pressure at the sea level (1 atm equals to 101.325 kilopascals).
1 Torr = 1/760 of a standard atmosphere = 133.3 Pa
Pascal is a SI derived unit of pressure.
1 Pa = 1 newton per square metre
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound. In preparative chromatography, GC can be used to prepare pure compounds from a mixture.
In gas chromatography, the mobile phase (or "moving phase") is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen. Helium remains the most commonly used carrier gas in about 90% of instruments although hydrogen is preferred for improved separations. The stationary phase is a microscopic layer of liquid or polymer on an inert solid support, inside a piece of glass or metal tubing called a column (an homage to the fractionating column used in distillation). The instrument used to perform gas chromatography is called a gas chromatograph (or "aerograph", "gas separator").
The gaseous compounds being analyzed interact with the walls of the column, which is coated with a stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound. The comparison of retention times is what gives GC its analytical usefulness.
Programmable Temperature Vaporizer (PTV), Flame Ionization Detector (FID), Electron Capture Detector (ECD)
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules (biopolymers such as DNA, proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft (low fragmentation) ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multiply charged ions.
MALDI methodology is a three-step process. First, the sample is mixed with a suitable matrix material and applied to a metal plate. Second, a pulsed laser irradiates the sample, triggering ablation and desorption of the sample and matrix material. Finally, the analyte molecules are ionized by being protonated or deprotonated in the hot plume of ablated gases, and can then be accelerated into whichever mass spectrometer is used to analyse them.
Matrix assisted laser desorption/ionization (MALDI)
By incorporating the (bio)molecules in a large excess of
matrix molecules, strong intermolecular forces are
reduced. The matrix molecules absorb the energy from the
laser light and transfer it into excitation energy of the solid
system. The effect is an instantaneous phase transition of
small molecular layers of the sample into a gaseous state.
Thus solid (and liquid) material can be easily analyzed by
MALDI uses a nitrogen UV laser (337 nm) to generate ions from high mass, non-volatile samples such as peptides and proteins. The key to this technique, which was discovered several years ago, is that in the presence of an energy absorbing matrix like α-cyano-4- hydroxy cinnamic acid (CHCA), large molecules like peptides ionize instead of decomposing.
In this technique, purified or partially purified proteins are mixed with a crystal-forming matrix, placed on an inert metal target, and subjected to a pulsed laser beam to produce gas phase ions that traverse a field-free flight tube and then are separated according to their mass/charge ratio (m/z).
MALDI-MS for herbs
The type of a mass spectrometer most widely used with MALDI is the TOF (time-of-flight mass spectrometer), mainly due to its large mass range. The TOF measurement procedure is also ideally suited to the MALDI ionization process since the pulsed laser takes individual 'shots' rather than working in continuous operation. MALDI-TOF instrument or reflectron is equipped with an "ion mirror" that reflects ions using an electric field, thereby doubling the ion flight path and increasing the resolution.
In the MALDI-TOF process, the sample to be analyzed is mixed with another compound, called a matrix. The mixture is applied to a target slide, placed inside the instrument, and irradiated with a laser. The matrix absorbs the laser light and vaporizes, along with the sample, in the process gaining an electrical charge (ionization).
Electric fields then guide the ions into the flight tube, which separates them according to ‘weight’ (mass) and displays the results as a series of lines (spectrum) which correspond to different fragments that have broken away from the original molecule. By analyzing the pattern of fragments it is possible to deduce the structure of the molecule.
Finally, compare the sample spectrum to an extensive database of spectra from bacterial species to allow the system to accurately identify the microorganism in question.
High performance liquid chromatography is basically a highly improved form of column chromatography. Instead of a solvent being allowed to drip through a column under gravity, it is forced through under high pressures of up to 400 atmospheres. That makes it much faster.
The time taken for a particular compound to travel through the column to the detector is known as its retention time. This time is measured from the time at which the sample is injected to the point at which the display shows a maximum peak height for that compound.
Different compounds have different retention times. For a particular compound, the retention time will vary depending on:
(3)示差折光检测器(RID) RID也称光折射检测器，是一种通用型检测器。基于连续测定色谱柱流出物光折射率的变化而用于测定溶质浓度。溶液的光折射率是溶剂(流动相)和溶质各自的折射率乘以其物质的浓度之和，溶有样品的流动相和流动相本身之间光折射率之差即表示样品在流动相中的浓度。原则上凡是与流动相光折射率有差别的样品都可用它来测定。其检测限可达10-6 - 10-7g/mL，一般不能用于梯度分析。
(6)电导检测器(CD) CD是离子色谱中使用最广泛的检测器，其原理是用两个对电极测量水溶液中离子型溶质的电导，由电导的变化测定淋洗液中溶质浓度。这种检测器的死体积小，如采用抑制电导法，其灵敏度可达10-8 g/mL，线性动态范围为103。
其它HPLC检测器还有： (9)化学反应检测器 也就是将被检物质进行某种化学反应(衍生反应，酶反应等)后再用高灵敏度的某种检测器检测。如氨基酸分析仪，固相化学反应检测器(固定化酶反应器)等。
The total ion current (TIC) chromatogram represents the summed intensity across the entire range of masses being detected at every point in the analysis. The range is typically several hundred mass-to-charge units or more. In complex samples, the TIC chromatogram often provides limited information as multiple analytes elute simultaneously, obscuring individual species.
(In chromatography) The amount of time elapsed from the injection of a sample into the chromatographic system to the recording of the peak (band) maximum of the component in the chromatogram.
“Deconvolution” is a term often applied to the process of decomposing peaks that overlap with each other, thus extracting information about the “hidden peak”.
Gas chromatography–mass spectrometry (GC-MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of unknown samples, including that of material samples obtained from planet Mars during probe missions as early as the 1970s. GC-MS can also be used in airport security to detect substances in luggage or on human beings. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification. Like liquid chromatography–mass spectrometry, it allows analysis and detection even of tiny amounts of a substance.
GC-MS has been regarded as a "gold standard" for forensic substance identification because it is used to perform a 100% specific test, which positively identifies the presence of a particular substance. A nonspecific test merely indicates that any of several in a category of substances is present. Although a nonspecific test could statistically suggest the identity of the substance, this could lead to false positive identification.
The Pegasus HT system combines gas chromatography and mass
spectrometry, two very powerful analytical techniques.
Gas chromatography (GC) is an analytical technique for the separation of volatile and semi-volatile components in chemical mixtures. Mass spectrometry (MS) is a universal, specific, and very sensitive detection technique for measuring the mass and quantity of ions. Mass spectrometry can provide unambiguous information about the identity and quantity of individual components in a mixture. Common to all mass spectrometers are four main operational steps: sample introduction, ionization in ion source, mass analysis, and ion detection.
There are several types of mass spectrometers available for
conventional GC/MS analysis including quadrupole, ion trap, and
magnetic sector, however, the Pegasus uses a very non-traditional
type of mass spectrometer: a TOF (time-of-flight) mass spectrometer.
A TOF mass spectrometer (TOFMS) offers tremendous benefits for analysis, most notable are a dramatically reduced analysis time and an improved quality of the analytical results. This is because the TOFMS acquires sample information very fast and orders magnitude faster than other types of mass spectrometers. Combining GC/MS with TOFMS (GC-TOFMS), the Pegasus can analyze the chemical composition of volatile and semi-volatile mixtures, providing quantitative and qualitative information on the individual components of the mixture.
Raman spectroscopy is a spectroscopic technique based on inelastic scattering of monochromatic light, usually from a laser source. Inelastic scattering means that the frequency of photons in monochromatic light changes upon interaction with a sample. Photons of the laser light are absorbed by the sample and then reemitted. Frequency of the reemitted photons is shifted up or down in comparison with original monochromatic frequency, which is called the Raman effect. This shift provides information about vibrational, rotational and other low frequency transitions in molecules. Raman spectroscopy can be used to study solid, liquid and gaseous samples.
Although not yet used as commonly as in other scientific fields, Raman spectroscopy is gaining popularity as an analysis technique in food and beverage applications.
Typically, analytical techniques for food and beverage characterization involve determination of the composition via quantitative methods, quality control (including adulteration, bacterial contamination), and identification of impurities or undesired material. Usually, chromatography (GC, GC-MS, HPLC), is employed for such characterization but might be time-consuming, use solvents and require sample preparation. Additionally, contrary to infrared techniques, Raman spectroscopy is not sensitive to high water content, and is thus well adapted to analyze aqueous solutions.
Reference: Introduction to Raman Spectroscopy
In practice - What is the difference between dispersive Raman and FT-Raman?
1. 只能使用1064 nm 近红外激光，带来的缺点是：低灵敏度、不适合测量水溶液、 不适合测量深色样品.
绿光最适宜无机物和共振拉曼（如碳纳米管和其它碳材料）和表面增强拉曼测量。 红色或近红外激光(780-830 nm) 最适宜抑制荧光的产生，通常不差于使用1064 nm近红外激光的傅立叶变换拉曼。 红色或绿色激光适宜水溶液测量。 紫外激光适宜于诸如蛋白质之类生物分子的共振拉曼。
2. 拉曼显微镜 - 真共焦拉曼显微镜 (傅立叶变换拉曼的光学设计不支持使用这种功能) 能够提供大约1微米左右的空间分辨率。使用技术上成熟稳定的真共焦针孔能够提供灵敏的样品拉曼图象， 从而显示样品的化学组成、分布、形态以及很多其他的样品特征。
|Wavenumber (cm-1)||Raman Shift Interpretation|
One of the greatest benefits is the use of a true CONFOCAL Raman microscope (共聚焦拉曼成像) design. This enables a very small sample area or volume to be analysed – down to the micron scale. Combine this micro Raman analysis with automated focusing, XYZ movement (3D 拉曼成像和深度剖析), and it becomes possible to produce ‘chemical’ images of a sample.
共聚焦拉曼显微方法是高分辨率拉曼成像技术，可广泛用于材料化学成分的表征与分析。固体和液体成分的化学信息可实现衍射受限的空间分辨，即分辨率为激发波长的一半，低至 200 nm。无需任何标记或特殊样品制备技术。拉曼图像可以获得样品内所含的化学化合物及其空间分布信息。
Formation of gas-phase ions without extensive fragmentation.
This method uses protein chip arrays with different selective surfaces such as cation or anion exchange surfaces, hydrophobic surfaces and metal binding surfaces. Biofluids such as cell lysate, plasma or urine are applied onto the selective surface and, after washing, a subset of proteins is specifically bound. The chip is then analyzed in a (MALDI) TOF-MS which generates a protein spectrum of the different molecular masses present on the protein chip. This technology is therefore highly suited for research into molecular mechanisms of disease and biomarker identification
When irradiating X-rays onto a material, fluorescent X-ray (characteristic X-ray), which has energy (wavelength) unique to the element that composes the material will be generated. When we measure the fluorescent X-ray energy, the contained element is identified (qualitative analysis), and we can calculate the concentration (quantitative analysis) from the intensity of the fluorescent X-ray of each element. Thus, the qualitative or quantitative analyses of a material by irradiating X-rays onto an unknown material and analyzing the fluorescent X-ray that is generated, is called fluorescent X-ray spectrometry.
There are two types of fluorescent X-ray spectrometry; the wavelength dispersive type (WDXRF) using analyzing crystals, and the energy dispersive type (EDXRF) using semiconductor detectors (EDS).
The characteristics of a wavelength dispersive type spectrometer (WDXRF) are high sensitivity, high accuracy, high resolution, and high reproducibility. We can expect sensitivity and accuracy at levels one order of magnitude higher than those of the energy dispersive type spectrometer (EDXRF). These characteristics are provided by a high-power X-ray tube (3 to 4 kW) and its cooling device, a goniometer which makes complicated movements and an exchange mechanism for the analyzing crystal and detector and so on. Naturally, the instruments are larger, with a complicated structure and high price. The specimen surface is required to be flat and the available analysis area is from several mm to 30mm or so. This type of device is suitable for process management where specimens with the same form are analyzed one after another.
The characteristics of the energy dispersive type spectrometer (EDXRF) are simple structure and low price, its adaptability to a variety of specimens, and its user-friendliness. The X-ray bulb is compact (several tens W) and air-cooled, and since the EDS (semiconductor detector) itself performs the analysis, a complicated spectroscopy section is not necessary.
Electronic nose is an analytical tool composed of an array of sensors (e.g. metal oxide, polymer) responding to volatile compounds with changes in their electrical properties. The combined pattern of these changes from all the sensors forms a fingerprint for the sample.
image source: 10.3390/s16040520
双抗体夹心法是检测抗原最常用的方法，操作步骤如下： 一、将特异性抗体与固相载体连接，形成固相抗体：洗涤除去未结合的抗体及杂质。 二、加受检标本：使之与固相抗体接触反应一段时间，让标本中的抗原与固相载体上的抗体结合，形成固相抗原复合物。洗涤除去其他未结合的物质。 三、加酶标抗体：使固相免疫复合物上的抗原与酶标抗体结合。彻底洗涤未结合的酶标抗体。此时固相载体上带有的酶量与标本中受检物质的量正相关。 四、加底物：夹心式复合物中的酶催化底物成为有色产物。根据颜色反应的程度进行该抗原的定性或定量。 根据同样原理，将大分子抗原分别制备固相抗原和酶标抗原结合物，即可用双抗原夹心法测定标本中的抗体。
Ion-mobility spectrometry (IMS) is an analytical technique used to separate and identify ionized molecules in the gas phase based on their mobility in a carrier buffer gas. Though heavily employed for military or security purposes, such as detecting drugs and explosives, the technique also has many laboratory analytical applications, including the analysis of both small and large biomolecules. IMS instruments are extremely sensitive stand-alone devices, but are often coupled with mass spectrometry, gas chromatography or high-performance liquid chromatography in order to achieve a multi-dimensional separation.
IMS系统的核心部分是迁移管，迁移管分为电离区和迁移区两部分，中间以离子门分隔开。被测样品被加热气化后，由载气带入电离区，载气分子和样品分子在离子源放射性Ni的作用下发生一系列的电离反应和离子－分子反应，形成各种产物离子。在电场的作用下，这些产物离子通过周期性开启的离子门进入迁移区。一方面从电场获得能量作定向漂移, 另一方面与逆向流动的中性迁移气体分子不断碰撞而损失能量，由于这些产物离子的质量, 所带电荷, 碰撞截面和空间构型各不相同, 故在电场中各自迁移速率不同,使得不同的离子到达探测器上的时间不同而得到分离。
A CCD (Charge Coupled Device) is a silicon based multichannel array detector of UV, visible and near-infra light. They are used for Raman spectroscopy because they are extremely sensitive to light (and thus suitable for analysis of the inherently weak Raman signal), and allow multichannel operation (which means that the entire Raman spectrum can be detected in a single acquisition). CCDs are widely used, not least as the sensors in digital cameras, but versions for scientific spectroscopy are of a considerably higher grade to give the best possible sensitivity, uniformity and noise characteristics.
CCD detectors are typically one dimensional (linear) or two dimensional (area) arrays of thousands or millions of individual detector elements (also known as pixels). Each element interacts with light to build up a charge – the brighter the light, and/or the longer the interaction, the more charge is registered. At the end of the measurement read out electronics pull the charge from the elements, at which point each individual charge reading is measured.
In a typical Raman spectrometer, the Raman scattered light is dispersed using the diffraction grating, and this dispersed light is then projected onto the long axis of the CCD array. The first element will detect light from the low cm-1 edge of the spectrum, the second element will detect light from the next spectral position, and so on...the last element will detect light from the high cm-1 edge of the spectrum.
CCDs require some degree of cooling to make them suitable for high grade spectroscopy. Typically this is done using either peltier cooling (suitable for temperatures down to -90oC), and liquid nitrogen cryogenic cooling. Most Raman systems use peltier cooled detectors, but for certain specialised applications liquid nitrogen cooled detectors still have advantages.