This is a working overview of size-exclusion chromatography, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-08-19. Anything still debated is marked as such rather than presented as settled.
定量分析的主流方法是反相高效液相色谱联用紫外或质谱检测，利用肽在疏水固定相上的保留行为确定纯度与含量。对于生物基质中的浓度测定，常采用液相色谱串联质谱，并配合固相萃取或蛋白沉淀进行样品前处理。免疫分析法也可使用，但可能受到结构相关肽的交叉反应干扰。
纯度评估通常综合反相色谱、体积排阻色谱与质谱三方面信息：前者反映疏水性杂质，后者反映聚集体，质谱则确认分子量与主要降解产物。有关降解途径的完整图谱——例如脱酰胺、氧化与水解各占多大比例——在不同储存条件下仍有差异，属于需要逐案验证的问题。
质量控制环节关注外观、含量、纯度、有关物质、水分与微生物限度等项目。检测结果需要有对照品和系统适用性数据支持，单次测定不足以判定批次的稳定性。实验室之间方法转移时，色谱柱品牌与梯度差异常导致保留时间漂移，因此方法验证十分必要。
Long-term storage of the solid generally relies on temperatures at or below minus twenty degrees Celsius, while short-term working stocks may be held refrigerated. Light exposure is limited because photodegradation can alter side chains over extended periods. Solutions prepared for analysis are less stable than the dry powder and are typically used within the same working day. Buffer choice matters, since some aqueous conditions favor deamidation or oxidation at specific residues. Stability data are usually generated under defined accelerated conditions and then extrapolated with stated assumptions.
Identity and purity are established with reversed-phase high-performance liquid chromatography, often paired with mass spectrometry for confirmation of the expected mass. Peptide mapping after enzymatic digestion verifies the primary sequence and detects substitutions. Size-exclusion chromatography quantifies aggregates and fragments, which are the impurities most often tracked for peptides of this size. Residual solvents, counterions, and water content fall under separate tests described in pharmacopeial chapters. Circular dichroism or nuclear magnetic resonance may be used in research settings to probe secondary structure, though such methods are less common in routine release testing.
| Property | Value | Notes |
|---|---|---|
| 储存温度 | 2 至 8 摄氏度 | 固体粉末，避光密封 |
| 外观 | 白色至类白色冻干粉 | 溶解后为澄清至微乳光 |
| 溶解性 | 易溶于水性缓冲液 | 避免剧烈振荡 |
| 常规纯度方法 | 反相高效液相色谱 | 紫外或质谱检测 |
| 定量方法 | 液相色谱串联质谱 | 配合固相萃取前处理 |
Identity and purity are assessed by reversed-phase high-performance liquid chromatography, with mass confirmation by electrospray ionisation mass spectrometry. Peptide mapping after enzymatic digestion verifies the primary sequence. Size-exclusion chromatography quantifies aggregates, while circular dichroism provides a secondary-structure fingerprint. Bioanalytical quantification in plasma uses immunoassay or LC-MS/MS. Reported purity for research-grade lots is commonly 95 percent or higher, and residual water content is checked by Karl Fischer titration.
As a peptide, tirzepatide is handled as a lyophilised solid in research settings and as a preserved solution in finished products. Aqueous solubility is pH dependent and reaches a minimum near the isoelectric point, which lies close to pH 5.4. Stock solutions are typically prepared in neutral or slightly basic buffer to limit precipitation. The solid is hygroscopic and should be equilibrated to room temperature before opening so that condensation does not form on the powder surface.
Long-term storage of lyophilised peptide powder is generally at minus twenty degrees Celsius or colder, with desiccant and protection from light. Short-term storage at two to eight degrees Celsius is common during active use. In solution, stability depends strongly on pH, concentration, and the presence of preservatives, and hydrolysis or aggregation can develop over weeks. Published stability data specific to this molecule are limited, so recommended conditions for research material are usually extrapolated from general peptide handling practice rather than from a dedicated study.
Bulk peptide material is normally characterised by reversed-phase high-performance liquid chromatography, which separates the target sequence from truncation products and other closely related impurities. Ultraviolet detection near 214 nanometres is common because the peptide backbone absorbs in that region. Mass spectrometry, usually electrospray ionisation coupled to a mass analyser, is used to confirm the molecular mass. Because the molecule carries a lipophilic side chain, gradient methods often need a relatively high organic modifier fraction to elute it within a practical retention window.
== Medical uses == Loperamide is effective for the treatment of a number of types of diarrhea. Loperamide is often compared to diphenoxylate. Studies suggest that loperamide is more effective and has lower neural side effects.
=== Historical assessments === Journalist Amy Walter, editor of the nonpartisan The Cook Political Report, argued that the public deemed Biden's presidency a failure particularly due to frustration over inflation. Economists debate the extent to which Biden's policies were responsible for inflation, but according to Gallup, public perception of the economy in 2024 was worse only in 2008 and 1992, helping Trump win the 2024 presidential election. The Siena College Research Institute's 2022 survey ranked Biden 19th out of 45 presidents. The 2024 Presidential Greatness Project Expert survey ranked Biden 14th. A February 2024 American Political Science Association poll of historians and scholars also ranked Biden the 14th-greatest president, diverging from public assessments. The pollsters noted that Biden's ranking was unusually high for a presidency without military victories or institutional expansion. In 2026, historian Julian E. Zelizer described Biden's presidency as similar to those of George H. W. Bush and Jimmy Carter, who were elected to office on a platform of change but served only one term.
The left paratracheal stripe is more variable and only seen in 25% of normal patients on posteroanterior views. Localization of lesions or inflammatory and infectious processes can be difficult to discern on chest radiograph, but can be inferred by silhouetting and the hilum overlay sign with adjacent structures. If either hemidiaphragm is blurred, for example, this suggests the lesion to be from the corresponding lower lobe. If the right heart border is blurred, than the pathology is likely in the right middle lobe, though a cavum deformity can also blur the right heard border due to indentation of the adjacent sternum. If the left heart border is blurred, this implies a process at the lingula.
^ 1 On early U.S. and Canadian pressings, "Down in a Hole" appeared as track 12 placed between "Angry Chair" and "Would?". Current U.S. and Canadian editions of the CD and the Vinyl have "Down in a Hole" as the fourth track, located between "Rain When I Die" and "Sickman", which was the track listing that the band originally intended before the record company changed the order. ^ 2 Track 9 or 10, "Iron Gland", appears without a title on the album. The title appeared on the compilations Nothing Safe and Music Bank. The iTunes Store lists it incorrectly as "Iron Man". Before the name "Iron Gland" was revealed, it was labeled in some online databases as "Intro (Dream Sequence)". On editions in which "Down in a Hole" is track 4, "Iron Gland" is track 10. The track is unlisted on some versions of the album, and some editions remove the track completely or merge it with "Hate to Feel". On the back cover of the edition in which "Iron Gland" is track 9, "Hate to Feel", "Angry Chair", "Down in a Hole" and "Would?" are listed from 9–12. However, when the CD is played, the songs are on tracks 10–13.
Sources: en.wikipedia.org
===== Other types of infection ===== Other types of infection consist of mixed, iatrogenic, nosocomial, and community-acquired infection. A mixed infection is an infection that is caused by two or more pathogens. An example of this is appendicitis, which is caused by Bacteroides fragilis and Escherichia coli. The second is an iatrogenic infection. This type of infection is one that is transmitted from a health care worker to a patient. A nosocomial infection is also one that occurs in a health care setting. Nosocomial infections are those that are acquired during a hospital stay. Lastly, a community-acquired infection is one in which the infection is acquired from a whole community.
== Polymerization chemistry == Production of polymers requires the repeated joining of two groups to form an amide linkage. In this case this specifically involves amide bonds, and the two groups involved are an amine group, and a terminal carbonyl component of a functional group. These react to produce a carbon-nitrogen bond, creating a singular amide linkage. This process involves the elimination of other atoms previously part of the functional groups. The carbonyl-component may be part of either a carboxylic acid group or the more reactive acyl halide derivative. The amine group and the carboxylic acid group can be on the same monomer, or the polymer can be constituted of two different bifunctional monomers, one with two amine groups, the other with two carboxylic acid or acid chloride groups. The condensation reaction is used to synthetically produce nylon polymers in industry. Nylons must specifically include a straight chain (aliphatic) monomer. The amide link is produced from an amine group (alternatively known as an amino group), and a carboxylic acid group. The hydroxyl from the carboxylic acid combines with a hydrogen from the amine, and gives rise to water, the elimination byproduct that is the namesake of the reaction. As an example of condensation reactions, consider that in living organisms, amino acids are condensed with one another by an enzyme to form amide linkages (known as peptides). The resulting polyamides are known as proteins or polypeptides.
=== Against warts === Repeated daily application of silver nitrate can induce adequate destruction of cutaneous warts, but occasionally pigmented scars may develop. In a placebo-controlled study of 70 patients, silver nitrate given over nine days resulted in clearance of all warts in 43% and improvement in warts in 26% one month after treatment compared to 11% and 14%, respectively, in the placebo group.
=== Bacteriophage Morphology === In 1956, Kaesberg and his colleagues studied staphylococcus bacteriophages via electron microscopy and found that freeze-dried particles and air-dried particles had significant morphological differences, specifically in size and shape. They were then able to classify the phages into two serological categories: large with flattened heads and long tails and smaller with long tails and circular heads. They noted that phages within the same class had structural similarities, and phages from different classes differed in structure.
=== Sublima === In 2019, Cave founded Sublima Pharmaceuticals in an effort to develop the first non-hormonal birth control in the United States. She made this decision after having some side effects from her previous birth control pill. After three to four doctors and a span of six months, they figured out that the hormonal birth control was the problem. Sublima is still in early stages. Cave is expecting the fundraise after the drug gets approved by the FDA. The drug is currently in Phase Three of clinical trials.
Sources: en.wikipedia.org
== SL == sl – (s) Slovene language (ISO 639-1 code) SL (s) Sierra Leone (ISO 3166 and FIPS 10-4 country code digram) (i) Start Line SLA (i) Service Level Agreement Symbionese Liberation Army SLAA – (i) Sex and Love Addicts Anonymous SLAC – (a) Stanford Linear Accelerator Center SLAN – (i) sine loco, anno, nomine (Latin, "without place, year, or name") SLAP – (a) Saboted light armor penetrator (type of firearms ammunition) SLAPP – (a) Strategic lawsuit against public participation SLB – (s) Solomon Islands (ISO 3166 trigram) SLBM – (i) Sea/Submarine-Launched Ballistic Missile SLC – (i) Scan Line Corrector SLE – (s) Sierra Leone (ISO 3166 trigram) SLI/SLi (i/s) Scan-Line Interleave Scalable Link Interface SLIT – (p) SubLingual ImmunoTherapy slk – (s) Slovak language (ISO 639-2 code) SLL – (s) Sierra Leone leone (ISO 4217 currency code) SLO – (s) Slovenia (IOC trigram, but not FIFA or ISO 3166) SLOC (a) Sea Lines Of Communication Source Lines Of Code SLORC – (a) State Law and Order Restoration Council (of Burma) SLP (i) Sea Level Pressure (i) Super Long Play slph – (s) Standard litre per hour (air flow) slpm – (s) Standard litre per minute (air flow) slps – (s) Standard litre per second (air flow) SLR – (i) Single-Lens Reflex (camera) SLT (i) Single Lens Translucent (i) Speech and language therapist (i) Solid Logic Technology (electronics) Swing Landing Trainer (paratroops) (i) Secondary lymphoid tissue slv – (s) Slovenian language (ISO 639-2 code) SLV – (s) El Salvador (ISO 3166 trigram)
Frederic Durán-Jordà established one of the earliest blood banks during the Spanish Civil War in 1936. Duran joined the Transfusion Service at the Barcelona Hospital at the start of the conflict, but the hospital was soon overwhelmed by the demand for blood and the paucity of available donors. With support from the Department of Health of the Spanish Republican Army, Duran established a blood bank for the use of wounded soldiers and civilians. The 300–400 mL of extracted blood was mixed with 10% citrate solution in a modified Duran Erlenmeyer flask. The blood was stored in a sterile glass enclosed under pressure at 2 °C. During 30 months of work, the Transfusion Service of Barcelona registered almost 30,000 donors, and processed 9,000 liters of blood. In 1937 Bernard Fantus, director of therapeutics at the Cook County Hospital in Chicago, established the first hospital blood-bank in the United States. In setting up a hospital laboratory that preserved, refrigerated and stored donor blood, Fantus originated the term "blood bank". Within a few years, hospital and community blood-banks were established across the United States. Until the middle of World War II, the newly established US blood banks rejected African-American donors. During the war, Black people were allowed to donate blood, but the donated blood was labeled as being suitable only for transfusion into another person from the same race.
classical genetics The branch of genetics based solely on observation of the visible results of reproductive acts, as opposed to that made possible by the modern techniques and methodologies of molecular biology. Contrast molecular genetics.
=== Postgraduate students === During the course of his career Sanger supervised more than ten PhD students, two of whom went on to also win Nobel Prizes. His first graduate student was Rodney Porter who joined the research group in 1947. Porter later shared the 1972 Nobel Prize in Physiology or Medicine with Gerald Edelman for his work on the chemical structure of antibodies. Elizabeth Blackburn studied for a PhD in Sanger's laboratory between 1971 and 1974. She shared the 2009 Nobel Prize in Physiology or Medicine with Carol W. Greider and Jack W. Szostak for her work on telomeres and the action of telomerase.
The conflict is commonly referred to simply as "the Boer War" because the First Boer War (1880–81) was much smaller. Boer (meaning "farmer") is the common name for Afrikaans-speaking white South Africans descended from the Dutch East India Company's settlers at the Cape of Good Hope. Among some South Africans, it is known as the (Second) Anglo–Boer War. In Afrikaans, it is called the 'Tweede Vryheidsoorlog ("Second Freedom War"), 'Tweede Boereoorlog ("Second Boer War"), Anglo–Boereoorlog ("Anglo–Boer War") or Engelse oorlog ("English War"). In South Africa, it is officially called the South African War. According to a 2011 BBC report, "most scholars prefer to call the war of 1899–1902 the South African War, thereby acknowledging that all South Africans, white and black, were affected by the war and that many were participants".
Sources: en.wikipedia.org
建议在低温、避光、干燥环境中密封保存，常见条件为 2 至 8 摄氏度，长期存放可置于更低温度。应避免反复冻融，并尽量减少容器开启次数。
溶解后的稳定时间通常短于固体形态，受浓度、缓冲液和容器材质影响。冷藏条件下一般只能维持较短时间，具体期限应通过实际稳定性实验确认。
反相高效液相色谱用于纯度与含量测定，液相色谱串联质谱用于生物基质中的定量，体积排阻色谱用于检测聚集体。多种方法结合才能较完整地表征样品。
Water promotes hydrolysis and deamidation, so removing it slows degradation during transport and storage. The dry solid is also less prone to microbial growth than a solution. Reconstitution is therefore performed close to the point of use.