===== Annotated Recurrent Unidentified Spectra – ARUS (Experimental Version) =====

We have provided 8 library files of recurring spectra found in NIST reference materials that have not been identified by NIST libraries, many of which are partly identified using our Hybrid Search methods. Those that have not been identified are simply labeled ‘Cluster nnn” – nnn is a sequence number. These are intended to assist NIST 17 users with making identifications of compounds in the our libraries.

We include libraries for Plasma/Serum and Urine that were created using NIST Standard Reference Materials (see below), and include positive and negative polarities. Separate libraries are given for fragmentation by collision cell (HCD) and ion trap, all at high mass accuracy. The name of the library gives the material and fragmentation conditions.

These libraries can be searched using the NISTMS.EXE program (the NIST 17 version is preferred and is available for download from this website, though most earlier versions should work). 

For spectra with a sufficiently high Hybrid Search scores, the name of the matching compound in a preliminary version of the NIST 17 Tandem Library (labeled Sara_2016) is given in the ‘Name” field. Also in this field is ‘DeltaMass’, which is the difference in mass of the recurrent library spectrum and the matching NIST 17 compound. The Hybrid match score is also shown. Nreps in the comment field gives the number of original spectra used to make the consensus spectrum / total spectra found along with collision energy.

Searching any of these spectra against the NIST 17 Tandem Library should find the matching NIST 17 compounds – though scores may differ slightly. Furthermore, it will show which product ions were ‘shifted’ by DeltaMass, which assists in making more details identifications.

Note that this is not the final version and is intended for research purposes only.

NIST SRMs Used:

**Plasma/Serum (pooled)**  
|1950 |     Metabolites in Frozen Human Plasma|  
|909c |     Frozen Human Serum| 
|967a |     Creatinine in Frozen Human Serum|
|968e |     Fat-Soluble Vitamins, Carotenoids, and Cholesterol in Human Serum| 
|971  |     Hormones in Frozen Human Serum | 
|972a |     Vitamin D Metabolites in Frozen Human Serum| 
|1951c|     Lipids in Frozen Human Serum| 
|3950 |     Vitamin B6 in Frozen Human Serum| 
|956d |     Electrolytes in Frozen Human Serum| 

**Urine (pooled)**  
|3667 |      Creatinine in Frozen Human Urine| 
|3671 |      Nicotine Metabolites in Human Urine (Frozen, 3 levels)| 
|3672 |      Organic Contaminants in Smokers' Urine (Frozen)|
|3673 |      Organic Contaminants in Non-Smokers| 
|3674 |      Organic Contaminants in Fortified Smokers| 


^ Library ^  Instrument ^ Charge  ^  Download Link ^
| <color white/red> Plasma/Serum </color> |  HCD |  neg | {{:chemdata:nist17:plasma_hcd_neg_rec.zip|plasma_hcd_neg_rec.zip}}|
| ::: |  HCD |  pos | {{:chemdata:nist17:plasma_hcd_pos_rec.zip|plasma_hcd_pos_rec.zip}}|
| ::: |  Ion Trap |  neg| {{:chemdata:nist17:plasma_it_neg_rec.zip|plasma_it_neg_rec.zip}}|
| ::: |  Ion Trap |  pos | {{:chemdata:nist17:plasma_it_pos_rec.zip|plasma_it_pos_rec.zip}}|
| <color black/yellow> Urine </color> |  HCD |  neg | {{:chemdata:nist17:urine_hcd_neg_rec.zip|urine_hcd_neg_rec.zip}}|
| ::: |  HCD |  pos | {{:chemdata:nist17:urine_hcd_pos_rec.zip|urine_hcd_pos_rec.zip}}|
| ::: |  Ion Trap |  neg| {{:chemdata:nist17:urine_HR_it_neg_rec.zip|urine_HR_it_neg_rec.zip}}|
| ::: |  Ion Trap |  pos | {{:chemdata:nist17:urine_HR_it_pos_rec.zip|urine_HR_it_pos_rec.zip}}|