If you have been reading about Stationary phase and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-03-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Routine quality control uses system suitability, blank injections, check standards, and control samples to detect drift or contamination. System suitability criteria may specify minimum resolution, maximum tailing factor, and a permitted range for repeated injections. Blank injections reveal carryover or solvent contamination, while check standards confirm calibration accuracy over a batch. Control samples with known analyte levels can show whether results remain within statistical limits. When a control result falls outside limits, the analyst investigates the cause and may invalidate affected results before repeating the batch.
Documentation and traceability are central to regulated HPLC testing. Records typically include instrument logs, column history, mobile-phase preparation, sample preparation, injection sequences, raw chromatograms, and audit trails. Electronic systems may require user access controls, time-stamped changes, and backup procedures. Training records show that analysts are qualified for assigned methods. Audits and inspections check whether written procedures match actual practice and whether deviations are documented. These controls support reproducibility and allow results to be reconstructed if questions arise later.
Method validation establishes that an HPLC procedure is suitable for its intended purpose. Typical parameters include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, robustness, and solution stability. Accuracy reflects closeness to a reference value, while precision reflects agreement among repeated measurements. Specificity shows whether the method can measure the analyte without interference from matrix components. Validation is documented through protocols and reports, and the required extent depends on the method's use and regulatory context.
In quality control laboratories, HPLC testing supports batch release, raw material checks, stability studies, and impurity profiling. A validated method defines sample preparation, instrument settings, calibration, and acceptance criteria. Analysts compare results with specifications and investigate out-of-specification outcomes before a batch is approved. Documentation includes chromatograms, integration records, audit trails, and reagent details. Because results influence product decisions, laboratories follow formal quality systems and data integrity rules. The exact tests and limits depend on the material, its intended use, and the applicable regulatory framework.
Method validation examines whether an HPLC procedure is suitable for its intended purpose. Common parameters include accuracy, precision, specificity, linearity, range, detection limit, quantification limit, and robustness. Accuracy describes closeness to a true or accepted value, while precision describes agreement among repeated measurements. Specificity shows whether the method can measure the analyte without interference from related substances. Robustness tests small deliberate changes in flow, temperature, or solvent composition. Validation is not a one-time event; methods may need partial revalidation after changes to instruments, columns, sample handling, or specification limits. Regulatory guidance provides frameworks, but some details remain method-specific.
Regulatory and pharmacopeial texts shape how HPLC testing is performed and documented. The International Council for Harmonisation provides validation guidance, while pharmacopeias publish general chromatography chapters and monographs for specific materials. Accreditation standards such as ISO/IEC 17025 address laboratory competence and traceability. Inspectors may review instrument qualification, analyst training, reference material control, and electronic records. Open questions include how best to validate methods for new complex products and how to handle automated data processing. Laboratories generally resolve these issues through risk assessment, method lifecycle management, and documented scientific justification.
| Property | Value | Notes |
|---|---|---|
| Accuracy | Recovery near 100% | Depends on acceptance criteria and matrix |
| Precision | Relative standard deviation | Often at or below 2% for replicate injections |
| Limit of detection | Signal-to-noise ratio 3:1 | Approximate and method-specific |
| Limit of quantitation | Signal-to-noise ratio 10:1 | Confirmed by precision and accuracy |
| Resolution | 1.5 or greater | Typical system suitability target |
High-performance liquid chromatography is an analytical technique that separates components in a liquid sample by passing them through a packed column under pressure. A pump delivers a mobile phase at a controlled flow rate, and an injector introduces the sample into the stream. Differences in how analytes partition between the mobile phase and the stationary phase cause them to exit the column at different times. Detection then records a signal proportional to the amount of each separated substance. The resulting chromatogram provides retention times and peak areas for identification and quantification.
Instrumentation includes a solvent delivery system, an autosampler, a column oven, and one or more detectors. Reversed-phase columns with chemically modified silica are widely used, but normal-phase, ion-exchange, size-exclusion, and affinity modes exist for specific separations. Detectors may rely on ultraviolet absorbance, fluorescence, refractive index, or mass spectrometry. Column temperature, mobile phase composition, and flow rate are adjusted to improve resolution. System pressure is monitored because rising pressure can indicate column blockage or deteriorating packing.
Separation performance depends on particle size, pore size, column length, and the chemistry of the stationary phase. Smaller particles generally improve efficiency but require higher pressure and suitable instrumentation. The mobile phase often contains buffers and organic solvents that influence retention and selectivity. Testing labs select conditions based on the analytes, sample matrix, and required sensitivity. Method development frequently involves screening several columns and solvent mixtures before a final set of conditions is chosen.
== Phone intercepts == In September 2008, Georgia presented to the public recordings of intercepted phone calls made on 7 August by Ossetian border guards on a Georgian cellular network, which were then independently translated from the original Ossetian language by The New York Times. The recordings, allegedly proving that entry of Georgian troops into Tskhinvali was preceded by movement of part of a Russian armoured regiment into South Ossetia nearly a day earlier, were reviewed and assessed as valid by senior American government and military officials. According to a call recorded at 3:52 am on 7 August, a South Ossetian servicemen at the tunnel with the surname Gassiev was asked by a supervisor at the headquarters if the armor had arrived, to which he replied: "The armor and people." The guard also said that the people had gone through, while "they had already arrived" 20 minutes earlier. Gassiev told the supervisor in the first call at 3:41 am that an inspection of military vehicles inside the tunnel had been requested by the Russian colonel, but Gassiev did not know the exact identity of the colonel. Gassiev reported the exit of armored vehicles from the tunnel to the supervisor at 3:52 am. Authenticity of the calls was not questioned by Russia. Colonel Andrei Kazachenko who was mentioned in the recording, belonged to the 135th Motorized Rifle Regiment, according to Russian media reports after the war.
=== Early History (1819-1823) === Physician Daniel Drake founded the Medical College of Ohio, the precursor to the University of Cincinnati College of Medicine, in 1819. It was the first medical school west of the Allegheny Mountains. Originally located in a room above a drugstore, the college graduated its first class of 24 students in 1821.
== Veterinary use == Sufentanil is used both as an analgesic and as part of an anaesthetic protocol. In cats the half-life of sufentanil is longer than that of fentanyl and alfentanil. In dogs sufentanil produces a better anaesthetic recovery with similar analgesic and respiratory depression than fentanyl. One report suggest that for post-operative pain bupivacaine and sufentanil provides greater analgesia than fentanyl and bupivacaine in dogs. There is little information on the use of sufentanil in large animals. Due to the greater risk of cardiovascular and respiratory depression sufentanil is rarely used in practice.
Sources: en.wikipedia.org
=== Diagnosis === In 2010, a team from New York described detection of PrPSc in sheep's blood, even when initially present at only one part in one hundred billion (10−11) in sheep's brain tissue. The method combines amplification with a novel technology called surround optical fiber immunoassay (SOFIA) and some specific antibodies against PrPSc. The technique allowed improved detection and testing time for PrPSc. In 2014, a human study showed a nasal brushing method that can accurately detect PrP in the olfactory epithelial cells of people with CJD.
=== Early 2007: Deaths in younger populations === The first middle-school "cheese" death in published accounts was that of Oscar Gutierrez, a 15-year-old eighth grader in northwest Dallas, who died February 18, 2007; his brother stated that the boy had previously survived an overdose of the same drug. Community rallies followed Gutierrez' death as parents and others urged the police and school district to become more active in fighting what was viewed as a growing problem. The death of Fernando Cortez Jr., a high school student, on March 31, 2007, led to further community activism. Initially this death was linked to cheese heroin based on the father's comments in press reports; the father said his son was at a Corvallis party when he was offered "cheese" and that the boy had not tried drugs before that he was aware of. Cortez's father went on to become a speaker at community meetings within the school system, urging that parents keep closer watch over their children. On April 24, the same day toxicology results were announced confirming the link to cheese, police announced a family friend would be charged with murder for having mixed the drugs for Cortez.
== Commonly monitored vaccines == The vaccine vial monitor is intended for use on vaccines which may travel outside of the cold chain, but its use on certain vaccines has had an especially notable impact.
Sources: en.wikipedia.org
=== Targeting the tricarboxylic acid cycle and glutaminolysis === The tricarboxylic acid cycle (TCA) and glutaminolysis can also be targeted for cancer treatment, since they are essential for the survival and proliferation of cancer cells. Ivosidenib and enasidenib, two FDA-approved cancer treatments, can arrest the TCA cycle of cancer cells by inhibiting isocitrate dehydrogenase-1 (IDH1) and isocitrate dehydrogenase-2 (IDH2), respectively. Ivosidenib is specific to acute myeloid leukemia (AML) and cholangiocarcinoma, whereas enasidenib is specific to just acute myeloid leukemia (AML). In a clinical trial consisting of 185 adult patients with cholangiocarcinoma and an IDH-1 mutation, there was a statistically significant improvement (p<0.0001; HR: 0.37) in patients randomized to ivosidenib. Still, some of the adverse side effects in these patients included fatigue, nausea, diarrhea, decreased appetite, ascites, and anemia. In a clinical trial consisting of 199 adult patients with AML and an IDH2 mutation, 23% of patients experienced complete response (CR) or complete response with partial hematologic recovery (CRh) lasting a median of 8.2 months while on enasidenib. Of the 157 patients who required transfusion at the beginning of the trial, 34% no longer required transfusions during the 56-day time period on enasidenib. Of the 42% of patients who did not require transfusions at the beginning of the trial, 76% still did not require a transfusion by the end of the trial.
Cellular angiofibroma is usually a small, slow-growing tumor arising in the vulva-vaginal areas of adult woman and the inguinal-scrotal areas of adult men although some of these tumors, especially in men, can grow up to 25 cm. Affected men are usually older (7th decade) than women (5th decade). Less commonly. cellular angiofibromas have occurred in various other superficial soft tissue areas throughout the body. These tumors are edematous (i.e. abnormally swollen with fluid), highly vascular, spindle-shaped cell lesions with a variable amount of fibrous stroma. In 2020, the World Health Organization classified cellular angiofibroma tumors in the category of benign fibroblastic/myofibroblastic tumors. The tumor cells in these lesions contain chromosome and gene abnormalities including a loss of one of the two RB1 genes. It has been suggested that the loss of this gene contributes to the development of cellular angiofibroma tumors.
Today, it is considered that GBS pigment (granadaene) and hemolysin are identical or closely related molecules. Sialic acid is a notable virulence factor in S. agalactiae despite being found normally in humans and many other animals. By expressing an unusually high amount of sialic acid on the bacterial cell surface, S. agalactiae can subvert the innate immune system, convincing leukocytes that the bacteria are human cells.
After the Dekarangers delete his fellow Gas Drinkers and being defeated by Deka Red, Volger flees to Planet Leslie to use an army of tank-like Kaijuki called Killer Tanks (キラータンク, Kirā Tanku) in an attempt to destroy Earth, only to be deleted by Dekaranger Robo Full Blast Custom. Volger is voiced by Kenichi Endō (遠藤 憲一, Endō Ken'ichi), who also portrays his human form. Ginjifuan Kazak (ギンジフ星人カザック, Ginjifu Seijin Kazakku): A cobra-themed criminal from Planet Ginjifu and a leading member of the Cosmic Violent Group Birono Family (広域宇宙暴力団ビローノファミリー, Kōiki Uchū Bōryokudan Birōno Famirī) who can disguise himself as any object or person and appears exclusively in the crossover film Tokusou Sentai Dekaranger vs. Abaranger. He attempts to resurrect the Abarangers' enemy Dezumozorlya and use its power to rule the world, only to inadvertently resurrect Abare Killer. After being defeated by the Dekarangers and Abarangers, Kazak retaliates by piloting a Kaijuki called Pallette View (パレットビュー, Paretto Byū), only to be deleted by Super Dekaranger Robo and Killer AbarenOh. Kazak is voiced by Ryūzaburō Ōtomo (大友 龍三郎, Ōtomo Ryūzaburō). Chigukadean Builjeek (チグカデ星人ビルヂーク, Chigukade Seijin Birujīku): A giant piranha-themed Mechanoid from Planet Chigukade who appears exclusively in the crossover film Mahō Sentai Magiranger vs. Dekaranger. He attacks a restaurant that the Magirangers and Umeko were eating in until he is captured by the Dekarangers and killed by his partner Babon.
Sources: en.wikipedia.org
Validation establishes suitability for a new method, while verification confirms that a method works in a specific laboratory. Verification is often used when a validated method is adopted with existing equipment and staff. Both rely on documented acceptance criteria.
Quantification usually compares detector response to a standard curve made from reference standards. The curve may be external, internal, or based on standard addition depending on matrix effects. Results are reported with units and, when required, uncertainty.
Carryover occurs when analyte from a previous injection remains in the system and appears in a later chromatogram. It can come from the injector, column, or tubing. Blank injections and needle washes help detect and reduce it.
System suitability is a set of checks performed before and during an HPLC run to confirm that the instrument and method are working as expected. It may include retention time repeatability, resolution between peaks, peak symmetry, and signal intensity. Failing suitability criteria usually invalidates the run.