accuracy is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-30. Numbers and descriptions here follow the published literature rather than marketing material.
Routine HPLC testing depends on controlled reagents, calibrated instruments, and documented procedures. Columns degrade over time, so retention times and peak shapes are monitored for drift. Mobile phases are filtered and degassed to prevent pump damage and detector noise. Reference standards must be traceable and stored under suitable conditions. Data handling systems record injections, calculations, and audit trails. Quality control samples interspersed with unknowns help detect errors during a run.
Developing an HPLC method begins with defining the purpose, such as quantifying a main component, measuring impurities, or confirming identity. Analysts select separation mode, column, mobile phase, detection, and sample preparation based on analyte properties and matrix. Experiments vary solvent strength, pH, buffer type, and temperature to achieve resolution between critical peaks. The goal is a robust method that produces reliable results across instruments and operators. Method development often involves trial runs and statistical optimization.
Several separation modes exist, including reversed-phase, normal-phase, ion-exchange, size-exclusion, and hydrophilic interaction liquid chromatography. Reversed-phase uses a nonpolar stationary phase with a polar mobile phase and is widely applied to small organic molecules. Gradient elution changes mobile phase composition during the run, while isocratic elution keeps it constant. Column chemistry, particle size, temperature, flow rate, and mobile phase pH all influence retention and resolution. Method development selects conditions that separate analytes from matrix components and from each other.
Detection commonly uses ultraviolet-visible absorbance, fluorescence, refractive index, or mass spectrometry. Ultraviolet detection depends on molecular chromophores that absorb light at specific wavelengths. Mass spectrometry provides mass information and sensitive quantification, often after electrospray ionization. Before sample batches, performance checks examine resolution, elution time repeatability, peak symmetry, and plate count. Matrix effects and co-elution remain recognized uncertainties; formal validation studies and orthogonal detection help address them. Detector choice depends on analyte properties and required sensitivity.
High-performance liquid chromatography, or HPLC, separates dissolved compounds by passing a liquid mobile phase through a packed column. Components distribute differently between the stationary phase and the moving liquid, so they travel at different speeds and exit at different times. A detector records these eluting bands as peaks, and peak area or height relates to amount. The technique supports testing in pharmaceuticals, foods, environmental samples, and industrial chemicals. Quantification usually depends on calibration with known standards.
| Property | Value | Notes |
|---|---|---|
| Validation parameter | Accuracy | Closeness of measured value to accepted reference value |
| Validation parameter | Precision | Agreement among repeated measurements under specified conditions |
| System suitability check | Resolution ≥ 1.5 | Baseline separation between critical peak pair |
| System suitability check | Tailing factor ≤ 2.0 | Common target for peak symmetry |
| Documentation | Validation report | Summarizes experiments, acceptance criteria, and conclusions |
Detection in HPLC testing commonly relies on ultraviolet-visible absorbance, fluorescence, refractive index, or mass spectrometry. A diode array detector records full spectra across a wavelength range, which helps identify co-eluting peaks. Mass spectrometry provides mass-to-charge ratios and can confirm molecular identity at low concentrations. The choice of detector depends on analyte structure, required sensitivity, and whether quantitation or identification is the goal. No single detector works for every compound, and method development often compares responses before selecting one.
High-performance liquid chromatography is an analytical technique that separates components of a liquid sample by passing it 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 interaction with the stationary phase cause analytes to migrate at different rates. Detectors record elution as peaks, and a data system converts signals into a chromatogram. The method is suited to compounds that dissolve in a liquid and are not volatile enough for gas chromatography.
== Nutrition == Boletus edulis mushrooms are 9% carbohydrates, 3% fat, and 7% protein (table). Fresh mushrooms consist of over 80% moisture, although reported values tend to differ somewhat as moisture content can be affected by environmental temperature and relative humidity during growth and storage. The carbohydrate component contains the monosaccharides glucose, mannitol and α,α-trehalose, the polysaccharide glycogen, and the water-insoluble structural polysaccharide chitin, which accounts for up to 80–90% of dry matter in mushroom cell walls. Chitin, hemicellulose, and pectin-like carbohydrates—all indigestible by humans—contribute to the high proportion of insoluble fibre in B. edulis. The total lipid, or crude fat, content makes up 3% of the dry matter of the mushroom. The proportion of fatty acids (expressed as a % of total fatty acids) are: linoleic acid 42%, oleic acid 36%, palmitic acid 10%, and stearic acid 3%. A comparative study of the amino acid composition of eleven Portuguese wild edible mushroom species showed Boletus edulis to have the highest total amino acid content. B. edulis mushrooms are rich in the dietary minerals, sodium, iron, calcium, and magnesium, with amounts varying according to the mushroom component and to soil composition in the geographic region of China where they were sampled. They also have high content of B vitamins and tocopherols. B. edulis contains appreciable amounts of selenium, a trace mineral, although the bioavailability of mushroom-derived selenium is low.
2.A.1 Major Facilitator superfamily (MFS), see also Lactose permease, Phosphate permease and Glucose transporter 2.A.2 The Glycoside-Pentoside-Hexuronide (GPH):Cation Symporter Family 2.A.3 The Amino Acid-Polyamine-Organocation (APC) Family 2.A.4 Cation diffusion facilitator (CDF) Family 2.A.5 Zinc (Zn2+)-Iron (Fe2+) Permease Family 2.A.6 Resistance-Nodulation-Cell Division Superfamily, see also SecDF protein-export membrane protein 2.A.7 The Drug/Metabolite Transporter (DMT) Superfamily 2.A.8 The Gluconate:H+ Symporter (GntP) Family 2.A.9 The Membrane Protein Insertase (YidC/Alb3/Oxa1) Family 2.A.10 The 2-Keto-3-Deoxygluconate Transporter (KdgT) Family 2.A.11 The Citrate-Mg2+:H+ (CitM) Citrate-Ca2+:H+ (CitH) Symporter (CitMHS) Family 2.A.12 ATP:ADP Antiporter Family 2.A.13 The C4-Dicarboxylate Uptake (Dcu) Family 2.A.14 Lactate Permease Family 2.A.15 The Betaine/Carnitine/Choline Transporter (BCCT) Family 2.A.16 Tellurite-resistance/Dicarboxylate Transporter Family 2.A.17 Proton-dependent Oligopeptide Transporter Family 2.A.18 The Amino Acid/Auxin Permease (AAAP) Family 2.A.19 The Ca2+:Cation Antiporter (CaCA) Family 2.A.20 The Inorganic Phosphate Transporter (PiT) Family 2.A.21 Solute:Sodium Symporter Family 2.A.22 The Neurotransmitter:Sodium Symporter Family 2.A.23 The Dicarboxylate/Amino Acid:Cation (Na+ or H+) Symporter (DAACS) Family 2.A.24 The 2-Hydroxycarboxylate Transporter (2-HCT) Family 2.A.25 Alanine or Glycine:Cation Symporter (AGCS) Family 2.A.26 The Branched Chain Amino Acid:Cation Symporter (LIVCS) Family 2.A.27 The Glutamate:Na+ Symporter (ESS) Family 2.A.28 Bile Acid:Na+ Symporter Family 2.A.29 Mitochondrial carrier Family 2.A.30 Cation-Chloride Cotransporter (CCC) Family 2.A.31 Anion Exchanger Family 2.A.32 The Silicon Transporter (Sit) Family 2.A.33 NhaA Na+:H+ Antiporter (NhaA) Family 2.A.34 The NhaB Na+:H+ Antiporter (NhaB) Family 2.A.35 The NhaC Na+:H+ Antiporter (NhaC) Family 2.A.36 Monovalent Cation:Proton Antiporter-1 (CPA1) Family 2.A.37 Monovalent Cation:Proton Antiporter-2 (CPA2) Family 2.A.38 K+ Transporter (Trk) Family 2.A.39 Nucleobase:Cation Symporter-1 (NCS1) Family 2.A.40 Nucleobase:Cation Symporter-2 (NCS2) Family 2.A.41 The Concentrative Nucleoside Transporter (CNT) Family 2.A.42 The Hydroxy/Aromatic Amino Acid Permease (HAAAP) Family 2.A.43 The Lysosomal Cystine Transporter (LCT) Family 2.A.45 Arsenite-Antimonite Efflux Family 2.A.46 The Benzoate:H+ Symporter (BenE) Family 2.A.47 Divalent Anion:Na+ Symporter (DASS) Family 2.A.48 The Reduced Folate Carrier (RFC) Family 2.A.49 Chloride Carrier/Channel (ClC) Family 2.A.50 The Glycerol Uptake (GUP) Family 2.A.51 The Chromate Ion Transporter (CHR) Family 2.A.52 The Ni2+-Co2+ Transporter (NiCoT) Family 2.A.53 Sulfate permease (SulP) Family 2.A.54 The Mitochondrial Tricarboxylate Carrier (MTC) Family 2.A.55 The Metal Ion (Mn2+-iron) Transporter (Nramp) Family 2.A.56 The Tripartite ATP-independent Periplasmic Transporter (TRAP-T) Family 2.A.57 The Equilibrative Nucleoside Transporter (ENT) Family 2.A.58 The Phosphate:Na+ Symporter (PNaS) Family 2.A.59 The Arsenical Resistance-3 (ACR3) Family 2.A.60 Organo Anion Transporter (OAT) Family 2.A.61 The C4-dicarboxylate Uptake C (DcuC) Family 2.A.62 The NhaD Na+:H+ Antiporter (NhaD) Family 2.A.63 The Monovalent Cation (K+ or Na+):Proton Antiporter-3 (CPA3) Family 2.A.64 Twin Arginine Targeting (Tat) Family 2.A.65 The Bilirubin Transporter (BRT) Family 2.A.66 The Multidrug/Oligosaccharidyl-lipid/Polysaccharide (MOP) Flippase Superfamily 2.A.67 The Oligopeptide Transporter (OPT) Family 2.A.68 The p-Aminobenzoyl-glutamate Transporter (AbgT) Family 2.A.69 The Auxin Efflux Carrier (AEC) Family 2.A.70 The Malonate:Na+ Symporter (MSS) Family 2.A.71 The Folate-Biopterin Transporter (FBT) Family 2.A.72 The K+ Uptake Permease (KUP) Family 2.A.73 The Short Chain Fatty Acid Uptake (AtoE) Family 2.A.74 The 4 TMS Multidrug Endosomal Transporter (MET) Family 2.A.75 The L-Lysine Exporter (LysE) Family 2.A.76 The Resistance to Homoserine/Threonine (RhtB) Family 2.A.77 The Cadmium Resistance (CadD) Family 2.A.78 The Branched Chain Amino Acid Exporter (LIV-E) Family 2.A.79 The Threonine/Serine Exporter (ThrE) Family 2.A.80 The Tricarboxylate Transporter (TTT) Family 2.A.81 The Aspartate:Alanine Exchanger (AAEx) Family 2.A.82 The Organic Solute Transporter (OST) Family 2.A.83 The Na+-dependent Bicarbonate Transporter (SBT) Family 2.A.84 The Chloroplast Maltose Exporter (MEX) Family 2.A.85 The Aromatic Acid Exporter (ArAE) Family 2.A.86 The Autoinducer-2 Exporter (AI-2E) Family (Formerly the PerM Family, TC #9.B.22) 2.A.87 The Prokaryotic Riboflavin Transporter (P-RFT) Family 2.A.88 Vitamin Uptake Transporter (VUT or ECF) Family 2.A.89 The Vacuolar Iron Transporter (VIT) Family 2.A.90 Vitamin A Receptor/Transporter (STRA6) Family 2.A.91 Mitochondrial tRNA Import Complex (M-RIC) (Formerly 9.C.8) 2.A.92 The Choline Transporter-like (CTL) Family 2.A.94 The Phosphate Permease (Pho1) Family 2.A.95 The 6TMS Neutral Amino Acid Transporter (NAAT) Family 2.A.96 The Acetate Uptake Transporter (AceTr) Family 2.A.97 The Mitochondrial Inner Membrane K+/H+ and Ca2+/H+ Exchanger (LetM1) Family 2.A.98 The Putative Sulfate Exporter (PSE) Family 2.A.99 The 6TMS Ni2+ uptake transporter (HupE-UreJ) Family 2.A.100 The Ferroportin (Fpn) Family 2.A.101 The Malonate Uptake (MatC) Family (Formerly UIT1) 2.A.102 The 4-Toluene Sulfonate Uptake Permease (TSUP) Family 2.A.103 The Bacterial Murein Precursor Exporter (MPE) Family 2.A.104 The L-Alanine Exporter (AlaE) Family 2.A.105 The Mitochondrial Pyruvate Carrier (MPC) Family 2.A.106 The Ca2+:H+ Antiporter-2 (CaCA2) Family 2.A.107 The MntP Mn2+ Exporter (MntP) Family 2.A.108 The Iron/Lead Transporter (ILT) Family 2.A.109 The Tellurium Ion Resistance (TerC) Family 2.A.110 The Heme Transporter, heme-responsive gene protein (HRG) Family 2.A.111 The Na+/H+ Antiporter-E (NhaE) Family 2.A.112 The KX Blood-group Antigen (KXA) Family 2.A.113 The Nickel/cobalt Transporter (NicO) Family 2.A.114 The Putative Peptide Transporter Carbon Starvation CstA (CstA) Family 2.A.115 The Novobiocin Exporter (NbcE) Family 2.A.116 The Peptidoglycolipid Addressing Protein (GAP) Family 2.A.117 The Chlorhexadine Exporter (CHX) family 2.A.118 The Basic Amino Acid Antiporter (ArcD) Family 2.A.119 The Organo-Arsenical Exporter (ArsP) Family 2.A.120 The Putative Amino Acid Permease (PAAP) Family 2.A.121 The Sulfate Transporter (CysZ) Family 2.A.122 The LrgB/CidB holin-like auxiliary protein (LrgB/CidB) Family 2.A.123 The Sweet; PQ-loop; Saliva; MtN3 (Sweet) Family 2.A.124 The Lysine Exporter (LysO) Family 2.A.125 The Eukaryotic Riboflavin Transporter (E-RFT) Family 2.A.126 The Fatty Acid Exporter (FAX) Family 2.A.127 Enterobacterial Cardiolipin Transporter (CLT) Family
The main foreign policy goal of Franz Joseph had been the unification of Germany under the House of Habsburg. This was justified on grounds of precedence; from 1452 to the end of the Holy Roman Empire in 1806, with only one brief period of interruption under the House of Wittelsbach, the Habsburgs had generally held the German crown. However, Franz Joseph's desire to retain the non-German territories of the Habsburg Austrian Empire in the event of German unification proved problematic. Two factions quickly developed: a party of German intellectuals favouring a Greater Germany (Großdeutschland) under the House of Habsburg; the other favouring a Lesser Germany (Kleindeutschland). The Greater Germans favoured the inclusion of Austria in a new all-German state on the grounds that Austria had always been a part of Germanic empires, that it was the leading power of the German Confederation, and that it would be absurd to exclude eight million Austrian Germans from an all-German nation state. The champions of a lesser Germany argued against the inclusion of Austria on the grounds that it was a multi-nation state, not a German one, and that its inclusion would bring millions of non-Germans into the German nation state. If Greater Germany were to prevail, the crown would necessarily have to go to Franz Joseph, who had no desire to cede it in the first place to anyone else.
Although a further tiny energy gain could be extracted by synthesizing 62Ni, which has a marginally higher binding energy than 56Fe, conditions in stars are unsuitable for this process. Element production in supernovas greatly favor iron over nickel, and in any case, 56Fe still has a lower mass per nucleon than 62Ni due to its higher fraction of lighter protons. Hence, elements heavier than iron require a supernova for their formation, involving rapid neutron capture by starting 56Fe nuclei. In the far future of the universe, assuming that proton decay does not occur, cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into 56Fe nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting all stellar-mass objects to cold spheres of pure iron.
Sources: en.wikipedia.org
The converse happens when the plasma pH rises above normal: bicarbonate ions are excreted into the urine, and hydrogen ions released into the plasma. When hydrogen ions are excreted into the urine, and bicarbonate into the blood, the latter combines with the excess hydrogen ions in the plasma that stimulated the kidneys to perform this operation. The resulting reaction in the plasma is the formation of carbonic acid which is in equilibrium with the plasma partial pressure of carbon dioxide. This is tightly regulated to ensure that there is no excessive build-up of carbonic acid or bicarbonate. The overall effect is therefore that hydrogen ions are lost in the urine when the pH of the plasma falls. The concomitant rise in the plasma bicarbonate mops up the increased hydrogen ions (caused by the fall in plasma pH) and the resulting excess carbonic acid is disposed of in the lungs as carbon dioxide. This restores the normal ratio between bicarbonate and the partial pressure of carbon dioxide and therefore the plasma pH. The converse happens when a high plasma pH stimulates the kidneys to secrete hydrogen ions into the blood and to excrete bicarbonate into the urine. The hydrogen ions combine with the excess bicarbonate ions in the plasma, once again forming an excess of carbonic acid which can be exhaled, as carbon dioxide, in the lungs, keeping the plasma bicarbonate ion concentration, the partial pressure of carbon dioxide and, therefore, the plasma pH, constant.
=== Barrel-aged coffee === In March 2017, Starbucks announced the launch of two new limited-edition specialty drinks made from beans aged in whiskey barrels at its Seattle roastery. Starbucks's barrel-aged coffee were sold with a small batch of unroasted Starbucks Reserve Sulawesi beans, which were then hand-scooped into whiskey barrels from Washington state.
== Applications == For the past 30 years, isothermal titration calorimetry has been used in a wide array of fields, ranging from metal binding studies to drug discovery, and nanomaterials research. In the old days, this technique was used to determine fundamental thermodynamic values for basic small molecular interactions. In recent years, ITC has been used in more industrially applicable areas, such as drug discovery and testing synthetic materials. Although it is still heavily used in fundamental chemistry, the trend has shifted over to the biological side, where label-free and buffer independent values are relatively harder to achieve.
=== Anti-sp100 === Anti-sp100 antibodies are found in approximately 20–30% of primary biliary cirrhosis (PBC). They are found in few individuals without PBC, and therefore are a very specific marker of the disease. The sp100 antigen is found within nuclear bodies; large protein complexes in the nucleus that may have a role in cell growth and differentiation.
For instance, in Riverwood International Australia Pty Ltd v McCormick an employee claimed after working 36 years and being made redundant that the company policy manual's redundancy policy was incorporated. His contract said 'You agree to abide by all company policies... and any new ones', and the company redundancy policy said it 'shall apply' to redundancies at work, providing at least 3 weeks' pay for each year of service. The Court held by a majority that the agreement was an express term of the contract by incorporation, because the fact that the employee had to 'abide by' the policy meant the employer must as well. However, in Commonwealth Bank of Australia v Barker the High Court accepted that when a manual said 'This Manual is not in any way incorporated as... any industrial award... nor does it form any part of an employee's contract' this was effective to prevent incorporation. Moreover, in Byrne v Australian Airlines the High Court held that part of an award on a 'Termination, Change and Redundancy' procedure, which had been imposed on the employer, was not a term because it was a statutory instrument with its own sanctions for breach, and so it was not 'necessary' to incorporate or imply a contract term to match this.
Sources: en.wikipedia.org
It is a set of checks performed before or during an HPLC run to confirm the system works as expected. Parameters may include resolution, tailing factor, theoretical plates, and retention time precision. Failure can trigger maintenance, method adjustment, or repeat analysis.
Validation follows a planned protocol that tests accuracy, precision, specificity, linearity, range, detection limits, quantitation limits, and robustness. Results are compared against predefined acceptance criteria. The validation report supports regulatory filing or routine use.
Revalidation may be needed after changes to column chemistry, mobile phase, detection, sample preparation, or instrument type. It can also follow a pattern of out-of-specification results. The scope depends on whether the change affects method performance.
HPLC separates and quantifies compounds in a liquid sample. Detectors produce a response proportional to the amount of a compound passing through the flow cell. Identification by retention time requires comparison with a known standard.