HT Laboratories is an analytical service company with expertise in mass spectrometry, HPLC separation, structure elucidation, and pre-clinic PK Studies. Our facility is currently equipped with numerous LC/MS systems, robotic systems, stand alone HPLC systems, and a MALDI-TOF system, and so on. We are a small company with a wide range of analytical expertise, and unparalleled flexibility in meeting our customers' needs. For companies large and small, we offer comprehensive service unmatched by similar analytical departments, all at an affordable cost. And for the larger companies, we are able to act as a backup analytical facility, covering for any additional work load or instrument interruption in your analytical department. All in all, we are basically a group of highly experienced experts offering you reliable help in various uncommon analytical tasks.
High Throughput Laboratories, Inc. was founded in 2000 based on the mass analysis business acquired from Mass Consortium, Inc. Over the past ten years, HT Labs has successfully provided mass analysis services with high quality and fast turn-around of results. Furthermore, we expanded the operation to encompass a wide variety of high throughput analytical techniques, such as auto FIA-MS, mass driven prep HPLC, and HT PK studies. Our auto FIA-MS can run as fast as 10 second per sample and is perfectly suited for library QC. Moreover, we employ proprietary microsampling procedures to provide DMPK service with the highest data convergence, fastest turn-around time, and lowest cost. The high throughput PK study program ensures a turnaround time of less than a week for even extensive preclinical PK studies. Our analytical lab routinely analyzes polymers and biomolecules by MALDI-TOF and smaller peptides or chemicals by LC/MS, MSn. We are also equipped for GC/MS, CE/MS, high accuracy mass analysis, and elemental analysis.
Our mass analysis lab has been serving the scientific research community since 1994. Over the years, we have followed closely with the ever-changing needs of our customers and developed new services to meet the emerging challenges. But of course, our fast, high-quality service, and reasonable prices have never changed.
HT Laboratories is equipped with a Voyager DE MALDI-TOF system made by Applied Biosystems. We are routinely using this instrument in analyzing polymers, oligonucleotides, peptides, proteins, and many other macro-molecules that would be difficult or not possible to be detected with API sources or any other mass spec techniques. Masses of peptides (low molecular weight, 750-4,500) can be determined on low picomol quantities with an average mass accuracy about 0.2%. Under optimum conditions, the limit of sensitivity of tryptic peptides (below 4,000) is in the lower femtomol range. Masses can potentially be obtained on numerous biopolymers including oligosaccharides, nucleotides and proteins that range from ~600 to 750,000 Daltons.
During sample analysis on MALDI-TOF, the sample is dissolved in a volatile solvent, and then spotted onto a sample plate with a total volume up to 2 µl. Depending on the type of the sample, a matrix may be spotted before, after, or mixed with the sample on to the same spot where the sample is. Spectral data acquisition takes place after the sample is completely dry and placed inside the high vacuum chamber of the instrument. Salts in the sample can seriously affect the data quality, many times totally suppress the ionization of the sample. Therefore, it is critical to reduce the concentration of any light metal salts in the sample before performing MALDI-TOF analysis with it.
So far the mechanism of MALDI ionization is not entirely clear yet. However, its configuration is fairly simple. It strikes a UV laser (337 nm) on to a dry sample deposit together with a matrix on a metal surface to generate ions from high mass, non-volatile samples such as peptides and proteins. The key to this technique is that in the presence of an aromatic matrix large molecules like peptides ionize instead of decomposing. The process may involve absorption of UV light by the matrix followed by transfer of this energy to the peptide - which then ionizes into the gas phase as a result of the relatively large amount of energy absorbed. To accelerate the resulting ions into a flight-tube in the mass spectrometer they are subjected to a high electrical field.
Three different models have been proposed to explain desorption of the matrix-sample material from the crystal surface: (1) quasithermal evaporation as a result of increased molecular motion, (2) expulsion of upper lattice layers, and (3) an increase in the hydrodynamic pressure due to the rapidly expanding molecules in the crystal lattice. However, there is no consensus yet as to how the sample molecules are ionized. The widely accepted view is that, following there desorption as neutrals, the sample molecules are ionized by acid-base proton transfer reactions with the protonated matrix ions in a dense phase just above the surface of the matrix. The protonated matrix molecules are generated by a series of photochemical reactions.
The matrix performs two important functions: (1) it absorbs photon energy from the laser beam and transfers it into excitation energy of the solid system, and (2) it serves as a solvent for the analyte, so that the intermolecular forces are reduced and aggregation of the analyte molecules is held to a minimum. Some desirable characteristics of a typical MALDI matrix are:
Several matrix-laser combinations have been tested successfully. For peptides and small molecular mass proteins (<10,000 Da), good results are obtained with a-cyano-4-hydroxycinnamic acid (CHCA), whereas high-mass proteins are analyzed with sinapinic acid. The use of 3-amino-4-hydroxybenzoic acid and 2,5-dihydroxybenzoic acid (DHB) has been recommended for the analysis of oligosaccharides.
Our MALDI instrument is a linear model with one meter flight tube length. The ions travel down a linear flight path and their mass/charge (m/z) ratio (see below for an explanation of the difference between mass and mass/charge ratio) is determined by the time it takes for them to reach the detector. Hence, this instrument is called a time of flight (TOF) instrument. The relationship that allows the m/z ratio to be determined is E = ½ (m/z)v2. In this equation, E is the energy imparted on the charged ions as a result of the voltage that is applied by the instrument and v is the velocity of the ions down the flight path. Because all of the ions are exposed to the same electric field, all similarly charged ions will have similar energies. Therefore, based on the above equation, ions that have larger mass must have lower velocities and hence will require longer times to reach the detector, thus forming the basis for m/z determination by a mass spectrometer equipped with a time of flight detector.
During high voltage extraction of the peptide ions produced by exposure to UV light, there are slight differences in the amount of energy that is actually acquired by similarly charged ions. In a linear instrument these differences result in slight differences in times of flight which results in broader peaks and lower mass accuracy. In terms of resolving fragment ions, a reflector also compensates for similarly charged ions having slightly different overall energies (the more energetic ions that have slightly faster velocities will penetrate further into the ion mirror and hence be slightly delayed relative to less energetic ions - thus both will tend to reach the detector at the same time). As a result, the reflector improves both resolution and mass accuracy. Although there is always the possibility of observing fragmentation ions when using the reflector (and mistaking these for contaminating peptide ions), by adjusting the settings on the instrument it is possible to minimize the possibility of seeing peptide fragmentation in the reflector mode.
LC/MS refers to liquid chromatography(LC) coupled directly with Mass Spectrometry (MS) via an atmosphere pressure ionization source (API). There are commonly two major types of API sources: the electro-spray ionization (ESI) source and the atmosphere pressure chemical ionization (APCI) source. Although the mass spectrometer in a LC/MS system is essentially a chromatography detector, LC/MS technology literally revolutionized the way we carry out chemical analysis today.
Currently, HT Labs is equipped with almost all types of LC/MS systems: Single-quo, Triple-quo, Ion-trap, Q-TOF, and so on. In addition to ESI and APCI sources, every LC/MS system has a nanospray and a photon-ionization sources for detecting molecules that are normally not detectable with other API sources. All of our LC/MS systems are also connected to photodiode array (PDA) detector and/or evaporative light scattering detector (ELSD). Therefore, they are actually LC/MS/PDA and LC/MS/PDA/ELSD systems. The combination of our LC/MS capacity enables our lab to meet wide variety of analytical needs ranging from compound characterization, quality control, and accurate mass measurement to quantitative analysis, structure elucidation, impurity profiling, and metabolite identification and so on.
Samples that require characterization or quality control (QC) are normally run on our single-quo or ion-trap systems. The analysis is usually carried out in full scan mode, meaning the mass spectrometer is set to scan over a mass range covering at least 200 Dalton above the sample mass. The lower mass limit in a full can is usually set at 100 or 150 Dalton. The sensitivity of full scan mode is around the low-micromole level, or ~1 µg/ml.
Our generic LC/MS method is a 10-minute gradient run on a 2.1x50 mm 3u C18 column with binary mobile phases: A) Water + 25mM NH4Ac, and B) Pure ACN. Depending on the polarity of the sample, we usually need to make several runs and adjust the gradient profile to optimize the separation and then only report the best result from the multiple trials. The report always contains a UV trace at custom designated wavelength or a total summation of 190-400 nm, and a TIC (total ion current) trace. Also included in the report are the spectra of the major chromatographic peaks, except the void volume peak. Since the 10-minute run include equilibrium time, our report may or may not include the equilibrium port of the chromatogram depending on whether there is any meaningful peak showing up during that time.
We routinely accept customer designated method to run on our systems. Usually, the customer has to provide the specific column if the method requires a column other than what we have. In some cases, the customer also needs to provide the solvent(s), such as for normal phase and ion-pair runs.
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